Moon of Alabama Brecht quote
July 09, 2021

The Space Race: Technical Facts vs Popular Narrative - by Gordog

by Gordog

lifted from a comment

A little while ago, commenter Karlof1 asked me about the space race, the Apollo Program, and the role of Nazi scientists recruited under Operation Paperclip.

This is a fascinating subject that has also been severely distorted by the American narrative.

What prompted Karlof's query was my earlier, and somewhat lengthy technical discussion of today's state of space technology, where the media narrative is that the US is greatly advanced, due mostly the 'exploits' of Space X---when in fact the situation is quite the opposite.

The US is far behind important core technologies like advanced rocket engines and space station tech, both of which it acquired from Russia. China has similarly acquired nearly all of its core space technology from Russia, but has built impressively on that technology transfer---including developing its very own space station tech, and its own advanced rocket engines.

During the 1990s, many important Russian industries were on the verge of collapse due to the disintegration of the USSR. Hence there was something of a firesale of Russian space tech, something that would have been considered unthinkable previously. The Chinese acquired their entire manned program, Shenzhou, lock, stock and barrel through direct technology transfer from Russia, resulting in the first Chinese man in space in 2003.

The US similarly bought its way into the Mir2 space station that was already built, but not yet launched, abandoning its own effort to build an indigenous station to rival Mir---the Freedom space station that was killed on the drawing board. Those Mir2 modules, now known as the Russian Orbital Segment, would become the functional core of the ISS.

The US also acquired advanced Russian engines and key engine technologies, mostly the RD180, which is in fact the undisputed workhorse for both high profile Nasa missions [such as the current mars rover mission], and the US Space Force, which launches nearly all of its mission-critical payloads on the Russian engines.

Other Russian engines, including the RD190 and even the 1960s era mothballed NK33s were also bought up and pressed into service by the US. That the Russians possessed this advanced engine technology was completely unknown in the west until the 1990s, which had regarded the 'closed-cycle' technology as technically 'impossible.'

So let's take a look back to the 1950s, when spaceflight was first achieved. This was an exciting era, and there is much to discuss here, so I will leave the Apollo story for another time.

By the latter stages of Word War 2, the Germans were the undisputed leaders in rocket technology. The V2 rocket, which was used to bombard London, was a hugely impressive piece of engineering for the time.

Russia, whose rocket technology in the 1930s was considered comparable to the Germans, had fallen behind. But the country did develop smaller, albeit usable rocket engines, for instance the experimental Bereznyak-Isayev BI1 interceptor aircraft. The US really had no rocket engine technology to speak of during this era.

But the US would import most of the German rocket engineers, as well as some working copies of the V2 itself. This would provide a strong base to build on, not just for the space race a decade later, but also the far more important race for strategic weapons, namely the intercontinental ballistic missile.

A quick tale of the tape on the V2: It had a mass of 12.5 metric tons, and a thrust of about 25 tons, from a single engine burning alcohol and liquid oxygen. It could reach a speed of 3,500 mph, and a flight range of about 300 km. Incredibly, over 3,000 of these were built during the war!

Von Braun and over 100 key V-2 personnel surrendered to the Americans, and many of the original V-2 team ended up working at the Redstone Arsenal. The US also captured enough V-2 hardware to build approximately 80 of the missiles.

The Soviets captured the V2 manufacturing facilities in Eastern Germany and used some of the remaining German engineers and technicians to build 30 V2s of their own by 1946.

The following year, a group of these engineers were transferred to Russia to work under the direction of Sergei Korolev, on the R1 missile, a copy of the V2, but built using Russian industrial plants.

This was quickly followed by the substantially improved R2, which first flew in 1949, and featured a number of key design improvements. R2 achieved double the V2's range, and a much higher speed of nearly 5,000 mph.

By 1953, the Russians started on what would become the world's first ICBM and also the world's first space launch vehicle---the R7 'Semyorka' rocket.

This was a huge leap forward in rocket technology. The R7 first flew in 1957 and launched Sputnik, the first satellite in earth orbit, later that year. It was also the launch vehicle for the first TWO humans in space, Yuri Gagarin in April, 1961 and Gherman Titov in August of the same year.

In the meantime, the US launched its first 'astronaut,' Alan Shepard on a suborbital 'spaceflight' atop a Mercury-Redstone rocket that was basically a slightly improved V2, comparable to the Russian R2 of a decade earlier.

In this photo from 1961, we see the Mercury-Redstone rocket that carried Shepard on America's first 'spaceflight' [more on that in a moment]. Joachim Kuettner, the Mercury project manager, and former V2 engineer is seen at left. 'Astronaut' Gus Grissom is sixth from left.

The size difference between the Mercury Rocket and the Russian Semyorka is obvious. With a mass of 30 tons, it was barely one tenth the mass of the R7. The latter's thrust of over one million pounds was more than TWELVE times the power of the single engine Mercury rocket with its 78,000 pounds of thrust!

Crucially, the single-stage Mercury could only reach a speed of about 5,000 mph, less than one third of orbital velocity of 18,000 mph [8 km/s].

A little basic physics to explain what 'space flight' really means. In short, it means achieving orbit, which is a function of SPEED, not altitude.

To understand this, a spacecraft must generate enough centrifugal force to overcome the earth's gravitational pull. When the spacecraft's centrifugal force is exactly equal to the earth's gravity, the spacecraft will continue orbiting the earth indefinitely, just as the space station stays aloft [provided it is high enough above the atmosphere that collisions with few and far between air molecules don't slow down its speed, which will cause it to descend, and require an engine burn to speed back up].

A good way to visualize this equilibrium of forces is with the Olympic hammer throw. As seen here, the athlete swings a metal ball attached to a length of cable he is holding. As he swings it around, the centrifugal force builds up and wants to hurl that ball off into space. But the cable is like the force of gravity keeping it from spinning off. The two forces are in exact equilibrium, until he lets go.

The only difference with an orbiting spacecraft is that the earth's gravity never lets go! Once equilibrium is reached the two opposing forces are equal and opposite, as per Netwon's Third Law. And since centrifugal force is a function of speed, it is necessary to reach a speed of about 8 km/s [18,000 mph] to counter the earth's gravitational acceleration of 9.8 meters per second squared.

[Here is the math: centrifugal force = mass x velocity squared, divided by radius of the circular motion. Since the radius of the earth is about 6,400 km, and we assume a unit mass of 1 kg, then it is a simple matter of algebra to solve for speed: square root of (earth's radius in meters x acceleration of gravity), which gives...square root of (6,400,000 m x 9.8 m/s^2) = 7,900 m/s, or ~8 km/s]

I am dwelling on this because it is important to understand what actual spaceflight means. Simply flying to any given height above the atmosphere is not spaceflight---anymore than a ski jump is 'flying.'

Similarly, feeling weightlessness also does not require actual spaceflight. Astronauts regularly train on large commercial jets that have had their interiors removed and the pilots fly the airplane in a ballistic arc that provides up to several minutes of zero g flight inside the cabin training space. In fact, you can have several seconds of zero g flight in a little Cessna student training aircraft!

So let's continue with the relevant stats for the first American 'spaceflight' of Alan Shepard. His 1961 flight aboard that Mercury rocket [a souped up V2] covered a total distance of 263 miles over the ground! While staying aloft for a grand total of 15 minutes!

Now compare that to Gagarin and Titov's real spaceflights, Gagarin making a complete orbit of the earth in about 90 minutes, which is 25,000 miles, almost one hundred times greater than Shepard's distance flown. Titov Orbited the earth 17 times in 25 hours aloft just a few months after Gagarin---covering a distance of 425,000 miles!

Obviously the US has been willfully deceiving folks about what spaceflight means for all of these decades.

And they have been doing it because they desperately wanted to show they could 'match' the Russians by sending a man into 'space.'

And the reason they could get away with this is because they knew that the majority of folks simply don't have any knowledge of physics.

It is a cynical charade that plays upon the public's lack of understanding!

It was only John Glenn's 1962 flight aboard a much more capable rocket, the Atlas, which put the first American in space. He flew three orbits, covering a distance of 75,000 miles in about four hours aloft.

This was in fact an incredibly daring feat, considering the shortcomings of the early Atlas rockets. This was also the first US ICBM. It was far less capable in both mass and thrust than the Soviet R7, and could only carry a fraction of the latter's payload. More importantly, it was prone to spectacular explosions.

After watching an Atlas ICBM explode shortly after launch, Mercury astronaut Gus Grissom remarked "Are we really going to get on top of one of those things?"

The numerous failures led to Atlas being dubbed an "Inter County Ballistic Missile" by missile technicians...

An 'inter-county' ballistic missile? Why not?...considering the first American 'astronaut' Shepard made an inter-county 'spaceflight.'

But hats off to John Glenn, who showed remarkable grit to fly one of these things at this stage in the game, where the Americans were clearly desperate to keep up. Glenn flew into orbit again at age 77, aboard the Shuttle STS95 mission.

What is clear to this point in time is that both the Russians and US piggybacked off the German V2 technology. The big difference in results was due to the Russians having their own, indigenous rocket capabilities that were not that far behind Germany.

The impressive Soviet buildup of higher education was perhaps the key, which built greatly on top of already world-leading institutions like the Bauman Moscow State Technical University, which pioneered the use of deep practical education in concert with industry, alongside the classroom theory. This influence was in fact adopted back in the latter 19'th century by MIT and other American technical universities.

During the Stalin era, 'Baumanka' founded more than 70 technical universities in the USSR. Among them some of the more storied names in specialist fields like rocketry, aviation [TSAGI] and many more.

I will leave the story at this point, but perhaps some interesting and hitherto unfamiliar aspects of the early space race have been presented.

There is still much more ground to cover before we get to the moon race, but it is worth noting that the R7 Semyorka evolved into the Soyuz launch vehicles, which have made nearly 2,000 spaceflights to date and are still carrying cosmonauts and astronauts to the space station.

There are many interesting technical details here, as the engines on the Semyorka-Soyuz are remarkably similar to the original V2. The Russians simply refined this basic engine technology and literally perfected it. However, the advanced closed-cycle engines would come along later, for larger and more demanding launches.

By comparison, the US space program was far more discontinuous. Neither the V2 nor the early Atlas technology was ever refined or taken to its logial evolutionary limit. The same was true for the Saturn V of the Apollo program, which was abandoned after just 13 flights. And so on down the line.

There is still lots of very interesting technical discussion engines to explore. And engines are of course the heart of any spacecraft---in the same way a turbojet engine is the beating heart of an aircraft.

Posted by b on July 9, 2021 at 16:17 UTC | Permalink

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Norwegian wrote:

you need to bring the extra fuel with you accelerate from 0 to 18000 mph with essentially 2xmass (twice the fuel). This requires much more thust, which burns up all the extra fuel on the way up.
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Lets say for argument's sake, the vehicle weight is 1/5 the weight and fuel is 4/5 the weight and lets say you consume all the fuel to get to orbit.

Now suppose you reduce the payload so that it is 1/20 the weight of the vehicle
and fuel is 19/20 of the mass. The vehicle starts at the same weight as before and uses the same amount of fuel to get to orbit, but now in orbit, the vehicle weight is 1/4 the weight and fuel is 3/4. It took 80% of the weight to get into orbit and if it takes 80% to get back safely there is not enough fuel to make it back safely with all the original vehicle weight. But if the vehicle drops off some of the payload in space (a small satellite for instance) then there should be barely enough fuel to make it back.
So braking by consuming fuel might be possible but only with a huge reduction in payload carrying capacity. The greater the ratio of fuel to vehicle weight just to get to orbit (and to get back) the greater the loss in carrying capacity will be.

Posted by: jinn | Jul 11 2021 13:45 utc | 201

jinn @Jul11 13:45 #201

That's a good point!

Gruff is completely right that it take less fuel to get back to earth if you have to use fuel to lift the fuel that you need to de-orbit and land.

!!

Posted by: Jackrabbit | Jul 11 2021 13:55 utc | 202

@Idiocrates | Jul 11 2021 11:32 utc | 187

Out of curiousity: have you done the experiment of confirming the device's existence?

As mentioned, this kind of experiment is outside of normal amateur capability, because of the cost and size of the equipment required. But, it does not mean I have not done any experiments... consider the lunar crater Plato on the north side of Mare Imbrium. https://en.wikipedia.org/wiki/Plato_(crater) . The crater is about 101 km in diameter. On the smooth crater floor there are some much smaller "craterlets" https://www.cloudynights.com/topic/34841-guide-to-plato-craterlets/ .

The largest Plato cratelets are
A = 1.7 miles (2.7 km) B = 1.5 miles (2.4 km) C = 1.5 miles (2.4 km) D = 1.3 miles (2.1 km)
https://www.cloudynights.com/uploads/monthly_07_2005/post-3169-14070940656612.jpg

Back in 2003, I decided to see how many of these cratelets I could capture using my own amateur equipment. The equipment was a Celestron C8 Shmidt-Cassegrain telescope fitted with a 3x barlow lens (i.e. total focal length=6 meter) and commercial Philips ToUcam 740k webcam. Here is what I got https://postimg.cc/640cDLvV

You can just about see the D crater, so the smallest feature detected (not resolved) is ~2.1km in this amateur image, which was stacked and processed from 40 video frames.

The main problem of resolution when observing from the ground is atmospheric turbulence, there is no chance of detecting features as small as the Apollo Lunar lander for example. Even outside the atmosphere, using a state of the art space telescope in orbit around the Earth such as the Hubble Space telescope, you cannot resolve the Apollo lander, because of limits imposed by optical diffraction. You can do it from lunar orbit, but then someone would say it was done in Hollywood...


Posted by: Norwegian | Jul 11 2021 13:56 utc | 203

Following up on my previous post:
Lets suppose that the ratio of total vehicle weight to fuel is 1:10 and that is what is needed to get the vehicle into orbit with all the fuel consumed. In other words, 90% of the weight is consumed to get to orbit and by extension it will need 90% of the weight to be fuel to get back.

Now if the vehicle empty weight is 1% of the total full weight at launch, then when in orbit the ratio of total mass to fuel will be about 10:1 which is what you need to get back. So now the question becomes can you build a vehicle where the ratio of full to empty weight is 100:1.

Posted by: jinn | Jul 11 2021 14:12 utc | 204

Jackrabbit wrote

Gruff is completely right that it take less fuel to get back to earth if you have to use fuel to lift the fuel that you need to de-orbit and land.
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Well of course it takes less fuel to brake coming back because at that point there is less mass. The question is how much more fuel do you need to start with so that you have that extra fuel to come back. It might be a lot more than you might guess.

You can't just keep adding more fuel to the same size vehicle. You need to change the ratio of fuel to vehicle weight so that you have the extra fuel to get back.

The ratio of fuel to empty weight to get back is likely to be much greater than for going up if we are only talking about the last stage going up and there is only that one stage going all the way down.

Posted by: jinn | Jul 11 2021 14:33 utc | 205

Now our liar/idiot Gordog is moving the goalposts. Let us revisit what our liar/idiot said:

"You would need the SAME amount of fuel coming down, as going up!"

Our liar/idiot did not claim that you would need more fuel going up. Our liar/idiot claimed that it would take the same amount going both ways, which if true in the real world would certainly doom SpaceX plans.

Now, however, our liar/idiot is saying that it will take more propellant to go up, and agreeing that it will take much less to go down, to which I will respond "So what?"

Sure, making your propellant to decelerate part of the payload that needs to be boosted to orbit reduces your payload. So? If you want more payload per launch then you just need a bigger rocket with more propellant capacity.

Note that SpaceX Starship and its first stage Super Heavy are bigger by a wide margin than any launcher ever made, yet the planned payload to orbit is little more than 100 tons. That is less than what the Saturn V could put in orbit. Is that a problem? No, because the Saturn V was thrown away after each use while Starship is intended to be reusable.

Now which does the reader think will cost more: A couple thousand tons of methane and LOX or an entire brand new Saturn V launcher?

In fact the cost for fuel for rocket launches is negligible. Maybe this idea is sacrilege to a commercial pilot, but that is only because they are not accustomed to throwing their aircraft away after every flight. If you couldn't ever refuel an airliner and had to throw it away when it ran out of fuel then nobody would care about the cost of jet fuel.

Goalpost-moving is the sign of being caught in a deliberate lie. I wonder what kind of axe the poster has to grind that the poster would be deliberately spreading FUD?

Posted by: William Gruff | Jul 11 2021 14:34 utc | 206

First oligarch (Richard Branson) in "space":
WATCH LIVE: Virgin Galactic Unity 22 Spaceflight Livestream

Posted by: Norwegian | Jul 11 2021 14:40 utc | 207

jinn @201: "So braking by consuming fuel might be possible but only with a huge reduction in payload carrying capacity."

Precisely. To which I respond "So?"

If you need more payload per launch then build a bigger rocket.

This is the performance cost to make a launcher reusable. SpaceX seems to believe the trade-off is worth it. I happen to agree.

Posted by: William Gruff | Jul 11 2021 14:46 utc | 208

Norwegian @207

It would be nice if he would stay there. Alas he's not going to orbit, just a ballistic flight.

Posted by: William Gruff | Jul 11 2021 14:47 utc | 209

I really enjoyed reading this series, which made me ponder the moonlandings. Never came around to go down this particular rabbithole.

http://centerforaninformedamerica.com/moondoggie/

Posted by: jv1 | Jul 11 2021 15:10 utc | 210

ATTN William Gruff (and some others others)

If you need 90% of your mass to be fuel going up OR 90% of your mass to be fuel going down, fine

It is like walking into a bank that needs 10% in reserves (I know that is high, esp when the Fed's legal requirement is zero) with a Benjamin for a deposit to checking and by the time the Benjamin is in a vault there are $900 in demand deposits and $900 in loans. As you might imagine my degree was Baccalaureate of Business Administration / Baccalaureate of Business (called the former at the time).

Try putting the relevant equations together (those here proficient enough to try) and my bets are the mathematics blows up like a 500 yottaton antimatter bomb.

You probably need chemical reactants having such a high potential energy to mass ratio (energy density) that it probably violates known chemistry and physics.

Now if you can make a vacuum energy power plant (or something equally exotic) that has a good enough power output to mass ratio, then you are in business. However, then you just solved peak oil and climate change (and drastically increased Earth's cultural carrying capacity) without going nuclear or green.

My bets are what we hear from the likes of Musk / SpaceX, etc is marketing hype to get seed money from speculators. If anything real is going on behind the scenes and whether it pans out, who knows. Given the control of the two factions of the Zionist, Neoconservative, Neoliberal, Corporatist Demopublican Party of the Delusional States of Amnesia and what they have done for the past 50 years since the end of Bretton Woods, only a delusional unipolar maniac would be optimistic.


Posted by: William Haught | Jul 11 2021 15:25 utc | 211

206 William Gruff
I can say that I deeply regret the flamefest and mudslinging this debate deteriorated into. I shall not judge or distribute guilt, but certainly each of you should moderate your tone and get back to factual arguments. As to Gordog, he joined the mudfest too, sadly, but also brought factual arguments I found convincing. The core argument is that every kg of fuel for re-entry is like payload and substract from any payload brought into orbit. He presented the equations where I find no fault in.

But apart from that, let us take the space shuttle: It had a mass of 70 tons, some of it fuel for manoeuvring, insulation, heat shield, life support, hull, EVA exits etc., remaining payload 30 tons. The start mass to bring those 70 tons into orbit was 2055 tons iirc.

Now, first, every kg fuel brought into orbit is a damn waste as it reduces sensible payload to be brought up. Further on, it needs an engine, not just fuel, and not just some steering muzzles like the shuttle or other spacecraft. Such an engine, its housing and tanks, eat up more mass. So, please elaborate how much payload would be left, and how much fuel would be needed. Granted, it is certainly less than the original 1000 to 2000 tons for takeoff. But how much less?

Posted by: aquadraht | Jul 11 2021 15:27 utc | 212

aquadraht @212

The engineers at SpaceX are familiar with the Tsiolkovsky rocket equation (or does one imagine they didn't read the Wikipedia page on it before cutting metal?). Their estimate is that they will have a revenue payload of 100 to 150 tons with Starship/Super Heavy.

"Now, first, every kg fuel brought into orbit is a damn waste as it reduces sensible payload to be brought up."

Precisely true... for an expendable launch vehicle.

But isn't your spacecraft itself and the ability to use it again "sensible"? Is it really so sensible to throw away a half billion to whole billion dollar vehicle for every launch?

It is possible that SpaceX will offer an expendable version of Starship/Super Heavy for a dozen or two times the cost of a reusable launch that can place 300 or 400 tons into orbit. Would that be more "sensible"? Unless you are launching something that absolutely has to be that big and cannot be broken into smaller components (launching something like the entire ISS all at once?) then I don't think it would be sensible at all.

Posted by: William Gruff | Jul 11 2021 15:53 utc | 213

When I look at the Musk enterprises I see promises and very few fulfillment. Btw. 100 tons payload brought to orbit is in no way impressive, MIR did more, so does Tianhe. And shooting up fuel is just crazy. Reusable, my ass. And no, I think Gordog explained quite well, and so did the guy with the videos. Reusable is not so much the greatest invention since sliced bread, and does not cut costs impressively.

When I hear Musk, I feel an urge to have a shit. I am not a rocket engineer, but worked with cars quite a lot. And the Tesla I saw so far are clunkers on wheels. Admittedly, most cars are more carelessly built than they were a few decades ago, but the Tesla is worse. In China, there are regular shitstorms about.

And that technical masterpiece (cough) so far has bled money everywhere than on the casino.

Posted by: aquadraht | Jul 11 2021 16:15 utc | 214

To add to Musk being a fraud and a gangster: In my area, he managed to get (dont ask how) the (preliminary) approval to build a battery factory - in a water protection area. The first buildings not completed yet they tapped into the water sources without permission and beyond recovery potential. Now they were caught with illicit buildings. That gangster has no respect for law, people, the environment. Just a madman.

Posted by: aquadraht | Jul 11 2021 16:22 utc | 215

The comments here tell all the story.

I'll repeat my argument in my last comment or so in this thread: the problem is not that SpaceX exist, but that the USG put all its eggs in its basket.

NASA was almost completely defunded to bail out SpaceX, and, as a result, was converted in what essentially is a department of SpaceX.

Now the American people is in a situation where it must defend SpaceX at all costs, as if it was NASA, the American space program itself. The Americans were forced by their own government to believe SpaceX will be successful. It will be because it has to be: its failure would mean the extinction of the American space program. In my opinion, this was completely unnecessary on the part of the USG: they did a needless bet based on the faith on the mythical genius entrepreneur, the personification of the God Free Market. This is cult of personality, liberal style. Neil Gaiman was wrong: Elon Musk et al are the true American Gods.

That's why many American commenters here are humiliating themselves, in public, defending Elon Musk and SpaceX. They have to make their sacrifice to their new gods.

Posted by: vk | Jul 11 2021 17:04 utc | 216

Posted by: William Haught | Jul 11 2021 15:25 utc | 211

If you need 90% of your mass to be fuel going up OR 90% of your mass to be fuel going down, fine
________________________________________________
What that suggests is that the payload will be 1/10 of what it might otherwise have been.
Or another way to look at it is you will need 10 trips to get the same job done

Posted by: jinn | Jul 11 2021 17:04 utc | 217

jinn @217: "What that suggests is that the payload will be 1/10 of what it might otherwise have been. Or another way to look at it is you will need 10 trips to get the same job done"

Ignoring for a moment that these are not even back-of-the-envelope figures, yeah, that basic idea is completely accurate. What's the problem if those ten flights are cheaper than one big expendable flight?

Posted by: William Gruff | Jul 11 2021 17:39 utc | 218

The problem is that it is not cheaper, especially when one in ten of the launches get lost in malfunction. Even without, the "refurbishing" is not free. All these "savings" are as real as the assertions that Tesla battery factory would comply with water protection laws. Only physics do not go away with a bribe.

Posted by: aquadraht | Jul 11 2021 18:02 utc | 219

In response to William Gruff@213,

But isn't your spacecraft itself and the ability to use it again "sensible"? Is it really so sensible to throw away a half billion to whole billion dollar vehicle for every launch?

It's sensible if the material cost of a new vehicle significantly exceeds the refurbishment cost of a reusable vehicle. If some mass-produced disposable launch vehicle offers more for the same cost in man-hours and resources then clearly that would be the more sensible option.

More to the point, no country disposes of its astronauts either, instead putting a critical priority on bringing them home safe -- that's sensible. The same is true for scientific equipment, when appropriate. Apart from designing a reentry vehicle that can take advantage of drag to slow itself down in the atmosphere, some of the potential payload weight is spent on parachutes and safety features to ensure a successful landing. This is the same general trade-off as the one being discussed, with the main difference being that retro-burning is inefficient and thus eats up a lot of weight that would otherwise be available to useful cargo. A vertical landing on Earth from orbit using this technique roughly means hauling enough fuel for a round-trip to the orbits of Mars or Venus, perhaps including a stop-over landing on one of the smaller moons. Not sure how sensible it is to burn this valuable fuel just to recover some engine parts -- would it make sense to do several trips hauling fuel for an interplanetary mission while burning the total amount of fuel required on every re-entry? Why not work on a recovery mechanism that takes advantage of our atmosphere instead?

Posted by: Skiffer | Jul 11 2021 18:02 utc | 220

re aquadraht | Jul 11 2021 16:22 utc | 215:

To add to Musk being a fraud and a gangster: In my area, he managed to get (dont ask how) the (preliminary) approval to build a battery factory - in a water protection area. The first buildings not completed yet they tapped into the water sources without permission and beyond recovery potential. Now they were caught with illicit buildings. That gangster has no respect for law, people, the environment. Just a madman

. . . as any Bolivian can tell you.

Posted by: corvo | Jul 11 2021 18:09 utc | 221

aquadraht @214

OK, you hate Musk. I get that, I really do. I hate oligarchs in general and Musk falls into that category so our feelings towards him are not too dissimilar.

aquadraht @214: "100 tons payload brought to orbit is in no way impressive, MIR did more, so does Tianhe"

I am afraid that you are confused here. Both Mir and Tianhe are/were space stations. They don't launch things. Furthermore, none of the modules used to assemble Mir were more than 20 tons. They launched on Proton-K launchers which have a maximum launch capacity of about 20 tons. The Tianhe core module is a little more than that at 22 tons. It was carried into orbit by a Long March 5 launcher, which has a max capacity to low Earth orbit (LEO) of about 25 tons. The SpaceX Falcon Heavy can, for comparison, launch over 60 tons to LEO while the Falcon 9 can launch 22 tons to LEO. The Long March 5 thus has a little more payload capacity than does the Falcon 9, but at more than three times the cost.

You can find some really useful facts and figures here (pdf on J-STAGE), which is a nice side-by-side comparison of launch capabilities and costs of all relatively current launch vehicles. One thing that you will notice perusing the data presented in this paper is that no other launcher in the "Heavy" category even remotely approaches Falcon 9 for $/ton to orbit. You can scoff at the idea of reusability, but somehow SpaceX undersells every other launch services provider in the world by more than half, and that includes the Chinese were presumably their rockets are made by Uighur slave labor, at least according to brainwashed Americans.

I also hate to break it to you, but nobody in the world has ever launched 100+ tons to orbit in a single launch before or after the Apollo program. The Saturn V is, so far, the only launcher in history to have ever accomplished that. Of course, at $1.5 billion per launch it is easy to see why it got cancelled. Still, putting a hundred tons into orbit at a whack is a big deal. If SpaceX Starship launches cost even a hundred times what they are targeting, it will still be a market-shattering bargain.

Posted by: William Gruff | Jul 11 2021 18:31 utc | 222

@ Posted by: William Gruff | Jul 11 2021 18:31 utc | 222

It doesn't matter. What matters is that none of what Elon Musk is proposing is revolutionary technology (if we're to trust the Russian and Chinese versions of the story).

Even if SpaceX manages to build a viable infrastructure of cheap payload, Roscosmos and China will be able to do the same. Elon Musk is not giving the USA any strategic advantage over Russia and China.

Posted by: vk | Jul 11 2021 18:46 utc | 223

Skiffer @220

Read this (same study linked above) and don't weep. Instead get excited thinking about how awesome it will be when the Chinese embrace and extend the ideas about reusability that SpaceX is pioneering.

As for refurbishment of the Falcon 9, I have asked people involved and these days it amounts to pressure washing and then a visual inspection with no disassembly unless unusual vibrations were detected in the previous launch, and then it is only the suspect engine that gets closer attention. The biggest part of prepping for another launch happens to relate to the landing legs, which use crushable aluminum honeycomb cartridges for shock absorbers because they are cheaper and lighter than hydraulic shock absorbers. The legs are removed to replace these cartridges. That takes a couple dozen man-hours for all the legs.

Posted by: William Gruff | Jul 11 2021 18:51 utc | 224

vk @223: "Even if SpaceX manages to build a viable infrastructure of cheap payload, Roscosmos and China will be able to do the same."

Bingo! We have a winner!

I cannot wait to see China do reusable launchers on a Three Gorges Dam kind of scale. SpaceX is talking $2 million for 100 tons to LEO. While that might be more than a little over-optimistic for SpaceX, I think China would be able to deliver. That would be a game changer for humanity in so many ways.

Posted by: William Gruff | Jul 11 2021 18:58 utc | 225

Breakdown of payload to Low Earth Orbit (LEO) versus cost per launch for the big heavies in use today:

Ariane       121000kg $175 million
Atlas 5 (Russian engines) 20520kg $152 million
Delta IV (US engines) 22560kg $215 million
Falcon 9      22800kg $56 million
H2-B (Japan)    16500kg $142 million
Long March 5    23000kg $150 million
Proton K      21000 $141 million
Soyuz 2      8200kg $54 million
Space Shuttle (ret)  28803kg $408 million

Posted by: William Gruff | Jul 11 2021 19:34 utc | 226

Oops! I got an extra one in the payload capacity for the Ariane 5 up there. It should be 21000kg to LEO.

Posted by: William Gruff | Jul 11 2021 19:37 utc | 227

Well, it has been suggested here that Gordog has 'sadly' joined the mudslinging.

I'm not going to dwell on this, because the point of my writing comments on this website is certainly NOT to engage in stupid games. But I will just point out that I have for the last several hours been going through my home copy of Orbital Mechanics for Engineering Students.


I am doing this so, I guess, for the reward of getting suckerpunched by some blowhard who has zero impulse control. Yeah, maybe I should just turn the other cheek, and continue spending my Sunday poring over physics texts---in the hope that I may be rewarded with yet one more volley of name-calling.

But I know there are lots of good folks reading this who want some REAL INSIGHT into what is going on with this SpaceX nonsense.

Now obviously I am not going to write the book-length monograph that is required to fully silence any and all psycho blowhards [if that is even possible, lol---especially when dealing with Musk-addiction!]

But I will bring the subject to a close that is perfectly adequate and acceptable to the reasonable folks here, who are in the vast majority---and many of them obviously knowledegable and many more also good logicians, as is plain from reading the comments.

Now the impulse-lacking blowhard, in all of his name-calling has raised a question that should be addressed. I pointed out just a very basic sketch of what happens when you try to send up enough propellant with your payload, so you can retroburn your way back in.

Now the objection raised was literally this: 'so what!'

The implication, of course being, that we have simply DOUBLED our payload, as in that silly example, and we are still sending 100 tons of payload up there, along with 100 tons of fuel to get us back down!

And here is the physical reality: The amount of fuel required to get ANY given amount of payload back down to earth by retroburning is going to be WELL over 90 percent. The commenter Jinn noted this already, but here is the math.

I have highlighted the relevant equation, which lets us 'compute the amount of propellant required,' in the words of the text.. But we are coming back down, so what this exact equation will compute will be the mass fraction---that is the total mass of the spacecraft other than propellant.

So let's work this out real quick: I will use 7,900 m/s as the orbital velocity, since that is what Curtis prefers in his text---and this is due to the additional energy, namely potential energy, that is required to also reach orbital height.

This is of course a small fraction of the KINETIC energy required to reach orbital speed, but I left that out for simplicity in my initial discussion.

Gravity is still 9.8 m/s^2, and specific impulse is 300 s, and 'e' is the exponent function of the right hand term.

So propellant fraction = 1 - e[-delta v / (ISP x g)] = 0.068

That's right, everything except 0.068 [also known as seven percent] will be propellant.

And propellant will be 93.2 percent!

It should be noted that no spacecraft has ever been made that could be this light, and still survive the forces that spacecraft have to endure!

And let's see just how much propellant we are going to have to carry up there for our 100 ton 'starship'

This is the easy peasy math part, lol! The inverse of 0.060 = 14.7

So we need 14.7 kg of 'retroburn' propellant for each kilogram of total spaceship we have sent up there---that includes the spacecraft structure, astronauts, supplies, everything!

Yes, I do agree with impulse-control blowhard that 100 tons should be perfectly adequate.

This will require only ~1,500 TONS of total payload sent up to a speed of 18,000 mph.

Piece of cake! That will only take about what 800 thousand 'raptor' engines?

Yeah, let's take Mr Polite's word for it. It's going to happen this year, just you all wait and see!

But I will stop here for now. I will only add this: note that at the top of that textbook page linked to above, the author notes that the simplifed expression for the rocket equation is 'at best' a rough approximation.

This is because it neglects important parameters like air drag, and also the tilt of the spacecraft from the vertical, which means only a part of its thrust is actually countering gravity.

What that means, is that this simplification WORKS AGAINST the performance numbers we compute here in our simplified way. Whatever we compute for SpaceX [I will get to that, for the decent folks here], is going to be way optimistic for reality. That includes the IMPOSSIBLE mass fraction we just computed above.

Here is the full rocket equation with the drag and flight path angle terms included, which I have highlighted.

Note that those drag and flight path angle values are shown in integral form---and also note that these CANNOT be computed by closed-form mathematical analysis. It is just too complicated. It requires 'numerical' methods, which are estimates performed by things like finite element software.

I apologize in advance to any impulse-control blowhards for simplifying to 'wikipedia' level. I know I should try harder, turning other cheeks and all---and heck even going to my colleagues who are proficient at running high end physics sim software.

Anyway, it's just Gordog's 'spare' time, right? No worries! Glad to have provided a face for a mudpie---and look forward to a few more.

I know, a little sarcastic.

But I will put in the time to bring a thorough understanding forward here, which will include doing up an actual math analysis of a Falcon 9, since its characteristics are known [well, sort of---but that's a whole 'nother story, lol!].

Because I know that decent people appreciate it. And that's the folks I am writing for.


Posted by: Gordog | Jul 11 2021 19:46 utc | 228

Hey @Gordog,

I, for one, REALLY appreciate your posts. They are very informative, and well written. As mentioned by others, it is extremely difficult to simplify complex technical issues to where a lay-man can understand them, and you have a real talent. It must be very frustrating to have to defend your simplifications as not being deceptive omissions, and to have to defend against accusations of impure intent. I too am really looking forward to your next installment - but take your time and don't let this blog be an all consuming past-time. We need you.

Posted by: retiredmecheng | Jul 11 2021 20:18 utc | 229

thank you, gordog. your work, research & insights are deeply appreciated. i have to believe you have published many articles & have dealt with many review boards are a more familiar with such responses. i for one am relieved you can hold the interest of the majority & as karlof has suggested forego the trolls. you, & the knowledge you bring, are vital for us in going forward in these challenging times. thank you.

Posted by: emersonreturn | Jul 11 2021 20:19 utc | 230

Wow, thanks guys! Emersonreturn and RetiredMechEng...how did I know you guys were out there?

Just a feeling I guess! ✊

Posted by: Gordog | Jul 11 2021 20:27 utc | 231

In response to William Gruff@224,

I would weep, but I'm not sure what I'm looking at. An attempt at deriving a system for the arrangement of sat-launch statistics by cost and success rate? What conclusion am I supposed to draw from it? And what's my stake in Chinese satellite launches?

As to refurbishment, that does sound very impressive. It's difficult to imagine a near-space launch platform operating without regular maintenance.

Posted by: Skiffer | Jul 11 2021 20:59 utc | 232

Here is the current Starship/Super Heavy engineering discussion thread over at Nasaspaceflight.com. There are real rocket scientists in those threads discussing the details of how Starship/Super Heavy is progressing. Interestingly none of those real rocket scientists are saying "It's impossible!" these days. I guess the high brainpower doubters getting burned back in 2009 (check out the SpaceX archives there. They are educational) still smarts all these years later and nobody wants to be on record again making flat assertions that end up being very conspicuously wrong.

Some good discussions going on there about how heat shield tiles are to be affixed, tank bulkhead thicknesses, controlling tank pressures (Starship/Super Heavy tanks/hull are pressure stabilized, like Boeing's ACES upper stage... basically stainless steel balloons!), actuators for the control surfaces (apparently they are using Tesla "Plaid" motors to drive the actuators!), stuff like that.

Yep, Starship is going to fly, regardless of people saying it is impossible. Will SpaceX get the cost per launch down to $2 million? Heheh! I doubt it, but if they get it to a hundred times that it will sure be something!

Posted by: William Gruff | Jul 11 2021 21:05 utc | 233

In looking at the so called space race, I wonder what is the total US government input into these 'private' enterprises (apart from published government funding). This looks to be a last ditch effort by the Americans to prove capitalism is better.

Musk's reusable rockets - Carry just over half the payload, thruster to slow from orbital velocity, free fall to a certain point then use thrusters for the landing.

What is the actual cost of refurbishment of a recovered stage? If a stage is designed to run multiple flights, thrust to weight ratio will be reduced....

Gruff, your payload weight for falcon 9 is the theoretical payload if no stages are recovered, yet you use that for your argument on the price savings of reusable rockets?


Posted by: Peter AU1 | Jul 11 2021 21:18 utc | 234

Most informative post and discussion, thanks a lot Gordog! And b for highlighting this!

As for the accusations that had been written, seems quite weird to antagonize someone who's laying numbers and scientific references with words alone. There's a moment where it becomes blatantly obvious "ok, pal, where are the links and formulas to support your claims?"

Posted by: Lost in La Mancha | Jul 11 2021 21:21 utc | 235

It really depends on how one arrives at the figure of cost p. launch. Is it a price agreed to by contract, or a price set by objective factors relating to the costs going into the launch? You could, and they presumably do, pay people to go into space -- that doesn't mean their presence aboard the launch vehicle adds thrust equivalent to their salaries. So, if we're talking about the former, SpaceX could get the cost per launch down to 500$ a pop by tomorrow, provided USG was willing to subsidize it. Even then, Chinese and Russian launch vehicles might retain their edge domestically, by virtue of not being priced in dollars at all.

Posted by: Skiffer | Jul 11 2021 21:21 utc | 236

Skiffer @232: "What conclusion am I supposed to draw from it?"

The costs (I included an excerpt from the table above) are very telling. How can SpaceX be selling launch services for half to a third what the competition is and still be turning a profit if the turnaround costs for their launchers are anywhere near the cost of manufacturing the launcher new?

"It's difficult to imagine a near-space launch platform operating without regular maintenance."

Not enough flights. Falcon 9 doesn't need any maintenance for the first ten or so flights (well, except replacing the shock absorbers) and they are making enough revenue to just replace them at that point. NASA wants "fresher" launchers and they are paying for them, so SpaceX is building more than they need to cover their flight manifest. SpaceX could probably drop their price further if they develop confidence that the launcher can be used reliably beyond that point, but of course then maintenance costs will start to become an issue. In other words, Falcon 9 is still partially expendable, just after ten launches.

Posted by: William Gruff | Jul 11 2021 21:22 utc | 237

Peter AU1 @234: "Gruff, your payload weight for falcon 9 is the theoretical payload if no stages are recovered, yet you use that for your argument on the price savings of reusable rockets?"

Those costs/capabilities are what is printed in the glossy brochure, and also what that study I linked to above quotes. Perhaps the authors of that study who hail from Beijing and Manchester UK are shilling for SpaceX and picked the high end performance and lowest cost for the Falcon 9 but the low end performance and top prices for all of the other launchers? Maybe...

From what I understand if the customer wants a new launcher and wants to push its envelope then the prices goes up to almost $80 million, but then they can get almost the same price performance from a Falcon Heavy that is fully recoverable, so why would anyone do that?

Posted by: William Gruff | Jul 11 2021 21:37 utc | 238

Skiffer @236

The price for a Falcon 9 launch varies depending upon new/used and recovery/no recovery, so it seems like some objective factors relating to the costs going into the launch are considered.

Posted by: William Gruff | Jul 11 2021 21:40 utc | 239

@gordog 136 I would describe the history of the american point of view with a narrative and a counternarrative: the dominant version is that the US is constantly threatened and needs to invest more in defense to 'catch up'. The counternarrative is that there is a culture which craves foreign threats to grow and increase funding and power. The latter always exaggerates the power and aggressive intent of the adversaries. The claim of 4 russian ICBMS comes from Ellsberg where he describes what the american estimates were at the time
I readily accept that in 1962 ICBM's were not that important compared to long distance bombers an that the Atlas was liable to blow up before hitting its target. I have no idea on the other hand what exactly the cloud of disinfo is you're claiming to detect in my text. If you want to claim that the soviets were ahead all the time in effective installed ICBMs please explain it so we can resolve the conflicts between the different versions.

Posted by: Tuyzentfloot | Jul 11 2021 21:44 utc | 240

William Gruff 238

At the moment, and most likely for a long time into the future, the cargo fairings and first stage is all that they can recover and that at a payload cost of 22000 kg to 12000 kg.

Musk is wrapped in the star wars stuff, A dreamer with money? His tweet on couping the president of Bolivia for the lithium gives an idea of the type of person he is. Space-x have recovered some parts of their launch vehicles - genuine tech or high priced scam to draw in investors? I think how long he lasts for is dependent on US government subsidies and how many investors he can draw in.

I guess it would be good to see how Musk's starwars enterprise is going twenty years from now and compare that to whatever level Russia and China are at that point in time.

Posted by: Peter AU1 | Jul 11 2021 22:04 utc | 241

In response to William Gruff@237,

The costs (I included an excerpt from the table above) are very telling. How can SpaceX be selling launch services for half to a third what the competition is and still be turning a profit if the turnaround costs for their launchers are anywhere near the cost of manufacturing the launcher new?

In a hypothetical scenario where this is the case, their funding would obviously have to come from somewhere else. Selling at a loss isn't unthinkable or even irrational, provided there's a clear objective behind it. Now, I'm not claiming that this is the case with SpaceX, only that B does not have to follow A -- in particular, there's no reason that I can see where the pricing of their launch services is pegged strictly to turnaround costs.

Secondly, unless I'm missing something, there's no surface level correlation between asking price and cost or asking price and utility. If I'm selling a house for 100.000$, that does not imply there's 100.000$ of value in the construction cost of that house, or that it'll provide the new owner with 100.000$ worth of utility. If my priority is to increase my market share and less so to profit from each individual sale, I'll certainly have a reason to consider selling at a net loss.

Third, although they may be competitors in the international market, domestically developed launch platforms have a multitude of advantages on their respective domestic market. The insinuation was, appropriately, that China would seek to imitate SpaceX methods rather than employ their services directly. But it makes sense to ask, why waste resources on building your own rather than employing SpaceX directly, if it provides the same service at a third of the expense? Or in other words, turning the argument on its head, how can SpaceX competitors turn a profit with disposable platforms at three times the cost p. launch?

Among other things, it also makes sense to question what the dollar denominated launch costs presented in the study actually represent -- is it a representation of the material cost of launches, i.e a money equivalent expenditure of effort on the part of the bureau? Is it simply the rate which they feel comfortable in charging for their services? I was not able to clarify this from perusing the Launch Cost Analysis paper, only the statement that the costs presented were averages of the entire launch history of the specific platform and excluded supplementary costs such as insurance.

Additionally, are the bureaus desperate for outside funding or comfortably subsisting on government contracts? Such questions, I think, have a more immediate impact on any price disparity than the presumed value of reusable platforms.

William Gruff@239,

The price for a Falcon 9 launch varies depending upon new/used and recovery/no recovery, so it seems like some objective factors relating to the costs going into the launch are considered.

Well, it wouldn't be definitive, but it would certainly support your argument if a new Falcon 9 launch without recovery was priced in the same range as other launch vehicles in the same weight category.

Posted by: Skiffer | Jul 11 2021 22:37 utc | 242

This supposedly is a graph showing velocity at the time the stages separate, height apparently 70km.
https://i.stack.imgur.com/xFYIh.png

If the graph is right, the first stage separates at around 1700 m/s. Musk seems to have now ruled out recovering the second stage .. I guess at some point, real world physics as Gordog put up earlier broke through his science fiction fantasies.

Posted by: Peter AU1 | Jul 12 2021 1:13 utc | 243

Fuel energy density is currently the biggest killer when it comes to space stuff. The massive weight of fuel required - Apollo 11 was close to 3000 tons. Energy density will be a big part of Russian hypersonic technology. As far as space exploration goes, we are still in the age of very basic sailing ships.
I guess if US in it decline and death throes doesn't lash out with nukes, at some point in time, a much better - ie higher energy density source will be found and used. Perhaps nuclear, perhaps an unknown as yet energy source.
Musk is trying to fulfill childhood science fiction fantasies with the current fuel technology.

Posted by: Peter AU1 | Jul 12 2021 2:17 utc | 244

Regarding moon landing claims by US in the 60s: watch the video of the "astronaut's" craft taking off from the moon to somehow connect with the lunar orbiter craft= terrible B level lifting of the craft with pullies or whatever and Nixon's zero lag phone call to the "astronauts"=case closed.

Posted by: jsanprox | Jul 12 2021 2:31 utc | 245

jsanprox

US has been able to starve China of high end chips. US tech. China will now concentrate on that area and most likely dominate the high end chip supplies. US though does develop tech, perhaps less so now. I guess tin foil hats can protect against reality as well as protecting the wearer from from whatever they think is being projected into their brain.

Posted by: Peter AU1 | Jul 12 2021 2:43 utc | 246

Peter, yes...recovering second stage is a pipe dream, just like this starship / flying dustbin, lol!

Btw, about my #228, where I mentioned that full payload for a 100 ton spacecraft would be 1,500 tons, with over 90 percent of that being propellant required...

Well, I'm just going to mention total rocket mass at launch for a science fiction rocket that is going to hurl 1,500 tons to 18,000 mph orbital velocity.

The best we can do is about four percent payload. Musk's Falcon 9 has never carried that big of a payload fraction! He hasn't even done THREE PERCENT.

[I'm still planning to do an analysis on Falcon 9, where we at least have some sketchy and half-believable data, lol; Did I mention secrecy and 'fudging' and 'alternative facts' is a very large part of the Musk MO?]

So getting back to launching a 'starship' that's going to 'retroburn' from orbit. With four percent payload, it means our total mass to payload mass ratio is 25!

Multiply 25 by 1,500 tons to get the launchpad mass of the rocket. That's 37,000 TONS, about 12 Saturn V's.

Yeah, that's what retroburning back a 100 ton spacecraft comes out to. Maybe Musk can invent a new kind of launchpad while he's at it? Not to mention the 100 MILLION pounds of engine thrust at liftoff? [That would require 200 'raptor' engines, if we are to believe the claims that each one makes 500,000 pounds.]

But look, even if we scale that returnable, retroburning spacecraft down by a factor of 10, so ten tons. It still means 150 tons payload, which has never been done. And a rocket mass of 3.75 million tons, bigger than Saturn V.

And that 10 tons of actual spacecraft would be just a bit bigger than the size of a 7.2 ton Soyuz that carries three people to the space station. Yeah, that's a real 'gamechanger' right there, lol! Use a Saturn V to launch a Soyuz. Brilliant!

And about landing that second stage of a Falcon 9 back. Some people will tell you that they are supposedly 'testing' that now, lol!

Those only weigh four tons empty. Although they would need to weigh 60 tons with enough propellant to do that...which means the Falcon 9 would need to be about five times bigger etc etc.

Thanks for that graph---1,700 m/s is about 3,800 mph. But here is the key to the whole thing. It comes to a complete STOP, zero UPWARD velocity, before gravity pulls it back down and it speeds back up. That is why it is possible to do this landing.

This graph is obviously Total velocity, because remember the rocket is tilted in the ascent, progressively more as it climbs, because it needs to get into a circular orbit in order to generate the centrifugal force needed for orbit.

So we see that this graph actually never goes down to zero speed, which is obviously impossible if we are talking about VERTICAL speed only. So 1,700 m/s is a combine vertical and horizontal vector speed.

After its apogee, it frefalls and reaches a maximum speed in freefall of about 1,300 m/s by the looks of it, before turning on the retroburners and running those for about a minute and a half or so.

So the deceleration from retroburn starts at only 1,300 m/s [2,900 mph]. This is a fraction of orbital velocity of ~8000 m/s

And we note that kinetic energy goes up by the SQUARE of speed [KE = m x v^2 / 2]. It means that reentering from orbit at nearly 8 km/s you will have nearly 40 times the kinetic energy. [(8 km/s / 1.3 km/s)^2 = 6.2^2 = 39]

That's the whole key right there. Nearly 40 times more ENERGY to dissipate.

This is nearly two orders of magnitude difference. Yet, the Musktards think it's all just the same deal, lol!

Also I see some are repeating the urban legend that all the 'scientists' were saying the landing back of that first stage supposedly couldn't be done.

Well, actually that's not true. The tail-landing of rockets idea has been around since the beginning of rockets. No serious rocket engineer would say it couldn't be done.

They might have said, 'what's the point'---and they would probably still be right, if we had a clear picture of how much corporate welfare Musk is getting.

Btw, here's another excellent video by this Thunderfoot fellow, from just two weeks ago: the Vaporware King, lol!

Posted by: Gordog | Jul 12 2021 3:00 utc | 247

Gordog

Vaporware looks a good word not just for Musk but the entire US political class. Musk comes on the scene when US has to rely on Russian space tech to get their astronauts to the space station.

I hope you keep posting the numbers on US space propaganda.

Posted by: Peter AU1 | Jul 12 2021 4:31 utc | 248

Here Gordog share his expertise that clearly comes from knowledge, while his detractors and SpaceX worshiper objects to simple of physics using hopes and dreams peddled by Elon Musk! It's alluring to buy into "out-of-the-box approach" narrative in fields as complicated as rocketry but really do you really expect that none of the Soviet-then-Russian and Chinese rocket scientist ever think of the SpaceX approach? It's shame to see otherwise respecter commenter of MoA turned into Musk zealot in the face of hard science and fact.

Posted by: Hangar | Jul 12 2021 4:33 utc | 249

I haven't much to add at this stage, but some might consider a "powered descent" and give Gordog some well deserved appreciation for his explanations of physics. In this case it is indeed rocket science :-)

Thanks, I am looking forward to whatever follow up there is in store.

Posted by: Norwegian | Jul 12 2021 7:18 utc | 250

Excuse my layman's interjection, but isn't space travel in real, practical, and meaningful terms, contingent on the discovery of new physical principles(i.e. anti-gravity) from which to engineer the devices needed to do it?

Just asking.

Posted by: john | Jul 12 2021 9:23 utc | 251

250
Can't agree more. Thanks to Gordog again, I learnt a lot. Only I hope there won't be lasting "factional" splits in the commenters' community.

Posted by: aquadraht | Jul 12 2021 9:25 utc | 252

There's so much evidence to force us to question if the US ever sent a man to the moon at all. The Americans didn't do it in the following 50 years. One of the technical questions that I've never had answered is how did they overcome the problem of cosmic rays coming through the thin skin of the Lunar Module and the thin skins of their space suits? All spacewalks since then have been done in earth orbit within the Van Allen belts.

Posted by: Bhupinder Singh | Jul 12 2021 9:55 utc | 253

@john | Jul 12 2021 9:23 utc | 251

Excuse my layman's interjection, but isn't space travel in real, practical, and meaningful terms, contingent on the discovery of new physical principles(i.e. anti-gravity) from which to engineer the devices needed to do it?

Not at all. To go to the Moon, all you need is Newtonian physics. This is just one approximation of reality, but it does the job just fine.

In order to discover "anti-gravity" we must first discover gravity, we really don't know what it is. Newton says it is a force (some kind of magic perhaps), Einstein says it is curvature in space-time (more complicated magic perhaps). I am sure there are others.

Why do you think space travel is outside the bounds of known physics when it has been practiced with Newtonian physics for 60+ years?

Posted by: Norwegian | Jul 12 2021 11:13 utc | 254

I disagree. Gravity is well understood and elaborated in general relativity theory, and the observations and predictions in astronomy and cosmology using the equations fit quite well. Anti-Gravity is science fiction babble, sorry.

There are problems harmonizing GRT with quantum mechanics, leading to a couple of theories such as string theory. But there is nothing directly contradicting GRT, much less pointing to ways to "anti gravity" or "warp drive" :) .

Posted by: aquadraht | Jul 12 2021 11:46 utc | 255

254 Norwegian
My disagreement only is about the gravity bit and GRT, I fully agree to the rest. Just to clarify.

Posted by: aquadraht | Jul 12 2021 12:01 utc | 256

"Excuse my layman's interjection, but isn't space travel in real, practical, and meaningful terms, contingent on the discovery of new physical principles(i.e. anti-gravity) from which to engineer the devices needed to do it?

Just asking."

Posted by: john | Jul 12 2021 9:23 utc | 251

The way I understand it, what you need is plenty of time. Many lifetimes. Maybe one lifetime to nearest stars. The local system is more less available in human time, but it still won't be fast. Arthur C. Clarke explored that sort of idea in his "Rama" series. "They oome in threes!"

So to travel, you need a travelling habitat to live in on the journey. And a stable society to live in it, which we don't have worked out yet either.


Posted by: Bemildred | Jul 12 2021 12:43 utc | 257

Fascinating. More Gordog, please!

Posted by: dadooronron | Jul 12 2021 12:50 utc | 258

Norwegian @ 254

Why do you think space travel is outside the bounds of known physics when it has been practiced with Newtonian physics for 60+ years

Well, I didn't say it was outside the bounds of known physics(at least not here in our own 'backyard' where it obviously isn't), just that in its present state it's kind of impractical(fuel loads vs payloads vs expense, etc). Sure, we'll probably master the arts of robotics and suspended animation, but deep space travel would certainly require lightspeed(at a minimum), and we don't even know if that's possible.

Posted by: john | Jul 12 2021 13:17 utc | 259

Guys, thanks for all the positive feedback. Really appreciate it! ✊

I'm just going to close out here on the retroburning from orbit discussion.

First the obvious physics. It takes the same amount of energy, for any given mass, to go from 18,000 mph to zero, as it does to go from zero to 18,000.

That is just simple physical fact. The only difference is that at launch, you are carrying all of that extra propellant you will need to get back down, so your launch mass is a lot bigger than your descent mass.

As any mountain climber knows, the descent is often as challenging as the way up [or a tree-climbing house cat for that matter, lol!]

So this implies an additional challenge for reentering by engine power:

It is equivalent to a single stage to orbit launch. Which has never been done of course!

Would doing it with two rocket stages make it more feasible? Of course. But here you would need to dump the bigger stage, and then descend on that smaller second stage. The opposite of what Falcon is doing.

Still, you could reduce the total payload mass to realistic numbers. Having 93 percent propellant and 7 percent spaceship is not doable! Simple as that.

Today's rockets are about 10 percent structure and another three or four percent payload, so that is propellant mass of about 86 to 87 percent. That may sound like a small difference, but it's enough to make all the difference. Spacecraft operate on the thin edge of physics!

Also I should note that there are a few typos in my #228. The numbers are absolutely correct, but just not always where they are supposed to be. For instance this equation should read:

propellant fraction = 1 - e[-delta v / (ISP x g)] = 0.93

That's the 93 percent propellant. What's left over is the 0.68 spaceship mass.

Also another typo: the payload to total mass ratio is the inverse of 0.068 = 14.7

I had typed '0.060' by mistake. But the 14.7 is the correct number.

I will plead that this is not uncommon even in top-notch engineering texts. some of which are riddled with dozens such innocuous typos. You can see this on Amazon book reviews where this is a constant theme. Subsequent editions often iron out most of them, but, some often remain, lol!

Thanks again, to our host for putting up my comment for discussion, and thanks to ALL the participants, even the negative ones. It is in fact useful and necessary to be challenged. That's how science works.

Only we don't resort to name-calling in professional circles---well, most of the time, lol!

Also I should make clear I am not a rocket engineer. I do have the academic background for it, but I chose a career in aviation---but have also worked aeronautical engineering gigs for many years, mostly in jet engine design. So it's not as if I'm coming from left field.

The heart of a rocket engine is basically a jet engine, the turbopump!

In the US many aerospace engineering hires will be mechanical or electrical background. In Russia they are more specialized. They have some really vertically integrated academic infrastructure just for real specialist fields like rocket engines, aircraft engines etc---so they turn out people who have become incredibly specialized. That doesn't exist in the US.

Of course the US powers that be have much different prioritie$. And that's what it's all about.

In any case, the interest level seems to be high for this kind of real technical discussion. I will at some point put up another comment on an open thread, but for now I am going to take a breather! 😺

Posted by: Gordog | Jul 12 2021 13:30 utc | 260

Guys, thanks for all the positive feedback. Really appreciate it! ✊

I'm just going to close out here on the retroburning from orbit discussion.

First the obvious physics. It takes the same amount of energy, for any given mass, to go from 18,000 mph to zero, as it does to go from zero to 18,000.

That is just simple physical fact. The only difference is that at launch, you are carrying all of that extra propellant you will need to get back down, so your launch mass is a lot bigger than your descent mass.

As any mountain climber knows, the descent is often as challenging as the way up [or a tree-climbing house cat for that matter, lol!]

So this implies an additional challenge for reentering by engine power:

It is equivalent to a single stage to orbit launch. Which has never been done of course!

Would doing it with two rocket stages make it more feasible? Of course. But here you would need to dump the bigger stage, and then descend on that smaller second stage. The opposite of what Falcon is doing.

Still, you could reduce the total payload mass to realistic numbers. Having 93 percent propellant and 7 percent spaceship is not doable! Simple as that.

Today's rockets are about 10 percent structure and another three or four percent payload, so that is propellant mass of about 86 to 87 percent. That may sound like a small difference, but it's enough to make all the difference. Spacecraft operate on the thin edge of physics!

Also I should note that there are a few typos in my #228. The numbers are absolutely correct, but just not always where they are supposed to be. For instance this equation should read:

propellant fraction = 1 - e[-delta v / (ISP x g)] = 0.93

That's the 93 percent propellant. What's left over is the 0.68 spaceship mass.

Also another typo: the payload to total mass ratio is the inverse of 0.068 = 14.7

I had typed '0.060' by mistake. But the 14.7 is the correct number.

I will plead that this is not uncommon even in top-notch engineering texts. some of which are riddled with dozens such innocuous typos. You can see this on Amazon book reviews where this is a constant theme. Subsequent editions often iron out most of them, but, some often remain, lol!

Thanks again, to our host for putting up my comment for discussion, and thanks to ALL the participants, even the negative ones. It is in fact useful and necessary to be challenged. That's how science works.

Only we don't resort to name-calling in professional circles---well, most of the time, lol!

Also I should make clear I am not a rocket engineer. I do have the academic background for it, but I chose a career in aviation---but have also worked aeronautical engineering gigs for many years, mostly in jet engine design. So it's not as if I'm coming from left field.

The heart of a rocket engine is basically a jet engine, the turbopump!

In the US many aerospace engineering hires will be mechanical or electrical background. In Russia they are more specialized. They have some really vertically integrated academic infrastructure just for real specialist fields like rocket engines, aircraft engines etc---so they turn out people who have become incredibly specialized. That doesn't exist in the US.

Of course the US powers that be have much different prioritie$. And that's what it's all about.

In any case, the interest level seems to be high for this kind of real technical discussion. I will at some point put up another comment on an open thread, but for now I am going to take a breather! 😺

Posted by: Gordog | Jul 12 2021 13:30 utc | 261

I believe john was talking about "practical space travel" as a mundane mode of transportation, something available to the average pleb like a bus ticket and about as exciting or adventurous. At our current level of technology, space travel is still a costly ordeal with substantial risks that can only be offset by rigorous preparation and at a monumental expense.

A good comparison would be early ocean exploration and transport, the viability of which relied on crucial technological advances over the period of thousands of years and which still hasn't peaked, arguably, in terms of practicality. If compared to technological advances in land and air travel, I believe it's more attainable today, for an individual with a basic understanding of the mechanics at play, to fashion a vehicle for himself for non-experimental utility in the field of land and air travel, while making a vessel truly sea-worthy is in a different category both in understanding and material investment. This wasn't the case for the majority of our history, however, and would only be true today due to fairly recent and critically important pieces of technology.

Maybe that's a personal bias on my part but, in my understanding, the sea is vast and unpredictable, with no technological advancement so far being able to trivialize it, the way, say, engines or aerofoil have done with the more accessible land and air. Space, being even more vast and foreboding, likewise awaits its "anti-gravity" moment to become truly accessible, although I'd rather suggest "teleportation" myself. Unfortunately, there's only "science-fiction babble" to describe as yet unknown advances that may in the future revolutionize our understanding and relation to travel and distances, and I believe john used the term purely for illustration and not in advocating the viability of some specific technology.

Posted by: Skiffer | Jul 12 2021 13:35 utc | 262

Thanks Gordog!

Really looking forward to your next instalment!

Posted by: A.L. | Jul 12 2021 13:51 utc | 263

Skiffer @ 261

Yeah, thanks for that. No doubt space-based research has improved our lot here on planet earth in a number of ways, but space travel for the average dude just isn't palpably relevant, and won't be any time soon, if ever.

At this point all an average dude billionaire like Richard Branson can organize is a one hour flight in some new fangled spacecraft not very far above the clouds...and that just for fun!

Posted by: john | Jul 12 2021 14:36 utc | 264

@vk #148
I agree with what you write - except that you try to excuse the propaganda exercise as somehow vital to national security.
Perhaps it was - or perhaps it was only in the minds of a few people.
Would the USSR failing to be first to put a rocket into space - have led to an invasion of that nation?
I highly doubt it.
Let's not forget - there are many channels to communicate military capability including the time-tested "defector" or the known spy fed data you want the other side to know.

Posted by: c1ue | Jul 12 2021 14:55 utc | 265

An update from the Russian side:

Space exploration cannot develop without state’s leading role, says Kremlin

"Of course, space exploration is actually impossible without the state’s leading role. The process is too costly, too enormous and capital-intensive," Peskov said, replying to a question about whether private space initiatives could emerge in Russia without the state’s participation similar to the suborbital flight performed by British billionaire Richard Branson on July 11.

Space projects based on private money only "are also a very rare example," the Kremlin spokesman stressed.

"Normally, private cosmonautics is linked to the state’s quasi-support in one way or another. This relates to various forms of subsidies, loans, government contracts and so on," he explained.

On a side note: Peskov doesn't know, but he's actually talking about an absolute limit of capitalist mode of production: profitability. Capitalism only invests in sector which are profitable, i.e. there's a physical ratio of massification and cost of production where capitalist exploitation is viable. Above or below that ratio, it escapes the imagination of the capitalist.

What's an innocent, isolated case today tends to become the norm tomorrow, as capitalism continues to develop is productive forces.

Posted by: vk | Jul 12 2021 14:59 utc | 266

@S #151
SpaceX etc is nothing more than Uber for space rockets.
It combines offshoring (from the USG) with USG shiploads of money and is a logical outgrowth of the model Amazon pioneered: use the state sales tax loophole to grow an enormous business, up until the point where you've captured the entire market.

Posted by: c1ue | Jul 12 2021 14:59 utc | 267

The moon landing was the first time the USA claimed a "First" in the space race. The USSR beat the USA in every space category all the way from sending up the first satellite to the Mars 2 probe in 1972.

The USA's accomplishment is equivalent to completing a polynomial equation prior to learning addition...

Posted by: Ladmo | Jul 12 2021 15:00 utc | 268

@ Posted by: c1ue | Jul 12 2021 14:55 utc | 264

The problem with your argument lies in a simple fact: the USSR never denied the USA was the first to send a man to the Moon.

If propaganda was so essential as you postulate, then the logical first step of the USSR would be to go all-in with the conspiracy theory the USA faked everything, and continued to try to send their man to the Moon only to then claim they were the first. That obviously didn't happen, and the USSR immediately recognized the American feat.

Posted by: vk | Jul 12 2021 15:01 utc | 269

@Tom Pfotzer #170
You are exactly wrong concerning resources.
The biggest single resource issue with space flight is fuel.
Oil in the 1960s/1970s was cheap and plentiful - and so fuel was not an issue.
Today? Fuel is a huge issue.
Controls? We aren't talking AI/magical tech crap.
The navigation of a spacecraft is almost doable with Keplerian astrography.
My father worked in Houston - after the Moon era but with the same equipment. There's nothing wrong or impossible about 1960s/1970s era analog computing gear being able to handle astrographic calculations to the moon.
The last issue is cost. The Apollo program cost $280B in inflation adjusted dollars - according to the official BLM-CPI.
To put this in perspective - $280B is 40% of the official US Department of Defense budget today.
To put in another, more correct, perspective: The Apollo program cost about $28B in dollars as spent. The entire US government budget in the mid-1960s was about $90B.
Even if we divide the $28B by 10 years, the Apollo program was around 3% of all federal spending for a decade!

This is an unimaginable spend in today's terms.

Even the Afghanistan war: $2.26 trillion over 20 years is only 2.3% of the entire US federal budget over that span.

Only the Vietnam war beats Apollo for one-off, utterly un-needed spend @ $168B in then dollars.

Posted by: c1ue | Jul 12 2021 15:13 utc | 270

@Gordog #200
Thank you for your posts.
It is pointless to argue, though, with people who have not even tried a little bit to understand the basic physics involved or the way Tesla et al use propaganda to further their profit motives (and founder egos).
Ironically much of this can be ascribed to Amazon. In its fight to stave off the repeal of the online sales tax exemption, Amazon pioneered the tech industry's use of regulatory capture.
Facebook, Uber, etc etc all profited from this to the point where Uber hired pretty much the entire leadership of Obama's election campaign to run point for its regulatory evasion existence.

Posted by: c1ue | Jul 12 2021 15:17 utc | 271

@Peter AU1 #244
Lone Skum is precisely doing the wheelbarrow scam - the wheelbarrow in this case being the government funding.

Posted by: c1ue | Jul 12 2021 15:23 utc | 272

@vk #268
Very sad and wrong argument.
What credible world newspaper would print the Soviet Premier (or Soviet spokesmodel) saying the US moon landing was fake?

Posted by: c1ue | Jul 12 2021 15:25 utc | 273

A footnote to #269
I should have also noted that $1 in the 1960s is not the same as a $1 today: $35 in 1960s = 1 ounce of gold redeemable by a national government to the US Treasury.
$1 today is redeemable for $1 at the US Treasury.
Thus the $28B = 24,880 metric tons of gold (28B/35/32150)
If world gold supply is ~180K metric tons - you can see the problem.
And you can see why Vietnam plus Great Society required Nixon to exit the gold window.

Posted by: c1ue | Jul 12 2021 15:32 utc | 274

@ Posted by: c1ue | Jul 12 2021 15:25 utc | 272

It would obviously be Soviet newspapers directed to the Soviet public. Evidently, in the height of the Cold War, no capitalist newspaper would claim or publish claims the Moon landing was fake.

If propaganda is so decisive as you claim, we would have Soviet newspapers and other propaganda pieces of the time (1969) claiming it was fake. We don't.

Posted by: vk | Jul 12 2021 15:36 utc | 275

@vk #274
I never said propaganda was so effective - what I said was that the primary purpose for the stunt orbits, etc was propaganda.
Nor would Soviet newspapers have any credibility internationally - which Sputnik did.
It is folly to say that the USSR did not engage in propaganda - whether defensive or offensive will be argued.

Your "defense" that it could not be propaganda because X was not done, is simply not credible.

I didn't kill him, your honor, because I don't have and didn't use a gun (victim was stabbed).

Fail.

Posted by: c1ue | Jul 12 2021 15:41 utc | 276

@ Posted by: c1ue | Jul 12 2021 15:41 utc | 275

You claimed the propaganda value alone would be worth it for the Soviets to land a man on the Moon, thus countering my initial argument the Soviets didn't seriously tried after they discovered there was no significant amounts of water and other resources there.

Then I counter-claimed your claim by stating that, if propaganda value is so valuable to the point it is worth to spend fortunes (and possibly human lives), then it would certainly be very profitable for the Soviets to spend some paper, ink and journalists working hours to simply deny the Americans landed a man on the Moon. But that didn't happen.

Therefore, your argument that landing a man on the Moon has only propaganda value is not likely to be true.

Posted by: vk | Jul 12 2021 15:51 utc | 277

This has been an interesting discussion on the art of simply getting a rocket, and payload, up to orbital speed around the earth, and then returning the rocket to the earth, for a 'rinse and repeat' recycling operation!

Now we need Gordog to evaluate the task of flying to the moon's orbit, landing on the moon, taking off again, and then returning to the earth.

I look forward to the calculations!

Posted by: Ric G | Jul 12 2021 21:03 utc | 278

Maybe I missed it, but Andreas Märki has written a great book in German: 50 Jahre Apollo 11 Mond-(F) Lüge.
An ETH engineer, he spent his career in the space industry. He spent some 10 years with a thorough analysis of Apollo. It is impossible to believe a man was on the moon in 1969.

Posted by: Stefan | Jul 13 2021 7:38 utc | 279

@Jul 12 2021 21:03 utc | 278

Now we need Gordog to evaluate the task of flying to the moon's orbit, landing on the moon, taking off again, and then returning to the earth.

As you wait for that, consider reading a couple of chapters on that topic in the excellent book by David Woods: How Apollo Flew to the Moon .

Chapter 6: Navigating to the Moon
It talks about how they determined position and velocity as they transitioned from the Earth to the Moon, including which instruments they had on board, including among other things the equivalent of a sextant! It was used to measure angles between the horizons of either the Earth or the Moon, with selected stars.

Chapter 7: Coasting to the Moon
Apollo 11 followed the "free return trajectory". Without breaking on the far side of the Moon, the trajectory would throw them back to Earth. https://i.stack.imgur.com/bvXYV.gif

Chapter 8: Entering lunar orbit: the LOI manoeuvre
Fascinating chapter on LOI (Lunar Orbit Insertion), or "How not to crash into the Moon"

There is a wealth of details in that book. Highly recommended for anyone with interest in how it was done.

Posted by: Norwegian | Jul 13 2021 9:23 utc | 280

In the age of the slide rule, not the computer, I cannot imagine sitting in the lander, on the moon, waiting for a radio signal from the earth to fire the rocket engine and try and dock with the orbiter, somewhere unseen above! A miss by metres would send one on a journey into the void, let alone a miss by kilometres!

Also, the diameter of the earth is roughly four times the diameter of the moon, so the earth should be huge when seen from the moon, roughly four times the size of the full moon, when seen from the earth. Where are the spectacular earth pictures, shot from the moon?

Posted by: Ric G | Jul 13 2021 11:13 utc | 281

@ricg


Where are the spectacular earth pictures, shot from the moon?

I see there is a gap between what you understand and what really happened and you distrust NASA. Sometimes such a gap is caused by lack of understanding and sometimes it is caused by the deliberate lack of transparency about what is happening. Not easy to know which.
It's up to you if you're going to bridge the gap with cheap and easy grand theories, by adopting someone elses cheap theories or by slowing building up an understanding. It's easy and wrong to demand other people convince you you're wrong. Especially when you can't even spell out what you are thinking. Do you think earth pictures are going to be a smoking gun showing up everything was a hoax? Why? Too blurry? Have you tried to find out how blurry it should have been? It's hard work. Ever taken a picture of the moon?

Posted by: Tuyzentfloot | Jul 13 2021 12:36 utc | 282

@Gordog #165:

As for retro-burning to slow down. This can only work AFTER the craft has slowed down to a quite LOW SPEED first.

Can you please explain why?

You would need the SAME amount of fuel coming down, as going up! […] Now it is obvious that if you are going to burn fuel to slow yourself right back down from 18,000 mph to zero mph, you will burn EXACTLY THE SAME AMOUNT OF ENERGY.

Wait, but doesn’t the rocket have less mass after spending the fuel to accelerate, meaning it now needs less fuel to decelerate?

Tsiolkovsky's rocket equation is the basic physics of all spaceflight, that governs this.

Yes, and when we apply the Tsiolkovskiy rocket equation to this situation (ignoring the atmosphere), we get

      Δv = vₑ ⋅ ln(m₀ / m₁) = vₑ ⋅ ln(m₁ / m₂) ,    i.e.,    m₀ / m₁ = m₁ / m₂ ,

where m₀ is the starting mass, m₁ is the mass after the rocket has accelerated to orbital speed, and m₂ is the mass after it has decelerated back to 0 (dry mass). It then follows that (m₀ − m₁), i.e., the amount of fuel spent speeding up, is (m₁ / m₂) times greater than (m₁ − m₂), i.e., the amount of fuel spent slowing down:

      m₀ − m₁ = m₁^2 / m₂ − m₁ = (m₁ / m₂) ⋅ (m₁ − m₂) .

So, no, according to the Tsiolkovskiy rocket equation, you would need less fuel coming down, not “the SAME amount of fuel” (again, ignoring the atmosphere). If you now account for the atmosphere, you need even less fuel.

I know, even experts make rookie mistakes, but since you have taken it upon yourself to educate the bar on aerospace matters, you have to be more careful with your statements, especially when using all caps.

Now, what you were probably trying to say is that the rocket equation precludes the creation of a “single-stage-to-Earth-LEO-and-back” chemical rocket based on known chemistry (ignoring the atmosphere). Assuming Δv = 9 km/s (no atmospheric drag) and vₑ = 3.05 km/s (best-in-class rocket engine RD-180, at surface level), we get:

      m₀ / m₁ = m₁ / m₂ = e^(Δv / vₑ) ≈ 19.1 ,

giving us the dry mass—the mass of engines, tanks, landing legs, etc.—of just 0.27% of the launch mass, which is impossible.

But, of course, Starship is not a single-stage rocket: it is the second stage launched on top of the first stage, Super Heavy. And our planet has an atmosphere, allowing the use of aero-braking. So the limitations placed by the simplest form of the rocket equation do not apply.

What you are suggesting has zero connection to the reality flight physics.

I haven’t suggested anything. I merely noted that there are two stages, not one, that the second stage, Starship, has two pairs of wings, and that it will have a thermal protection system installed for the atmospheric reentry test flight. These are not suggestions, these are facts. I then asked you a question: are you sure there’s no way this configuration could work? Which is a reasonable question to ask, because it’s very similar to the configuration of the Space Shuttle, which, as we all know, worked.

So yes, starship reentering the atmosphere at 18,000 mph is most definitely a physical impossibility, in every sense of the word!

You probably meant to say that it is physically impossible for it to survive such reentry. You strike a very authoritative tone, but your statements are not very precise.

Again, if you know even the basics of aerodynamics you know that a cylinder has only HALF the drag coefficient of a flat surface. It has no chance to do anything but to burn up.

No chance to do anything? Another incorrect statement. Doing half of something is not the same as doing nothing. The cylinder will aero-brake, just less than a flat surface would. Also, if a cylinder is thick enough, it won’t burn up.

Those 'wings' don't have nearly enough surface area to accomplish the amount of braking that is required from 18,000 mph. Look at the surface area of the Shuttle underside, like in this cfd image.

Okay, so your educated guess, as an expert, is that these two pairs of wings, or canards, or whatever you want to call them, are not enough to slow down Starship sufficiently. Of course, you haven’t actually run the numeric simulations. I’m pretty sure SpaceX’s engineers did. But if live tests show that they’re wrong and you’re right, what’s to prevent SpaceX from simply increasing their size, or replacing them with a delta-wing attached to the side?

The heat shielding on the bottom of that craft was an ENORMOUS scientific and engineering undertaking that took many years. This flying dustbin has ZERO heat shielding of any kind, lol!

Yes. And NASA will share the results of this enormous undertaking with SpaceX, just like they shared their know-how to help it build Crew Dragon. And SpaceX won’t have to pay for it, because a decision has been made to subsidize SpaceX. The Starship prototypes built so far didn’t have the heat shielding installed because they were built for low-altitude flight tests.

Look, you can drink the Musk koolaid if you prefer…

I don’t drink anyone’s Kool-Aid—neither Musk’s nor yours. Our discussion is about the technical aspects of the Super Heavy/Starship launch system. Musk has nothing to do with it.

…but his supposed 'orbital flight' is either going to be suborbital, or the whole thing is just going to burn up.

I actually agree with you on this. I too think that the first atmospheric reentry test flight will result in Starship burning up. I don’t think the termal protection system will work on the first try. However, they will collect detailed test flight data, the system will be improved, and eventually they will get it working. Because if it worked on the Space Shuttle, why can’t it work on Starship?

What little they have said is that it is only going to go as far as Hawaii and splash down in the ocean, lol. So that's no 'orbital' flight.

Yes, that’s an orbital flight. They’re launching from Texas eastwards towards Hawaii. You can see the trajectory in their filing with the FCC.

Like the guy in the video says. Musk can go ahead and 'evolve' that flying dustbin into a proper Shuttle-like reentry vehicle, which will take many many years and billions of dollars.

That is exactly what SpaceX will do. They will keep iterating until it survives reentry and lands. I thought you were saying the concept of Starship was “physically impossible”? Now you’re saying it will take time and money? That’s a completely different position.

And then he might as well put wheels on it, so it can glide in without any fuel, and without eating into the already precious payload to begin with.

Won’t work on Moon and Mars, which they eventually want to go to.

Posted by: S | Jul 13 2021 12:38 utc | 283

@Ric G | Jul 13 2021 11:13 utc | 281

Also, the diameter of the earth is roughly four times the diameter of the moon, so the earth should be huge when seen from the moon, roughly four times the size of the full moon, when seen from the earth. Where are the spectacular earth pictures, shot from the moon?

1968: When Apollo 8 First Orbited The Moon And Saw The Earth Rise In Space

Why didn't you look it up yourself?

Posted by: Norwegian | Jul 13 2021 13:29 utc | 284

Good point Norwegian. That photo, of course, is the iconic one of the earth from the moon.

I can imagine that the earth, from the moon, would be a stunning sight, breathtaking!

And yet..

“I put up my thumb and shut one eye, and my thumb blotted out the planet Earth. I didn’t feel like a giant. I felt very, very small.” -Neil Armstrong

A little more detail..

Overall, the Moon reflects only 11% of the sunlight striking it, but the Earth reflects approximately 37% of the sunlight incident upon it. Put this all together, and a “full Earth” as seen from the Moon is about 43 times brighter than the full Moon is as seen from Earth. When the icecaps are larger and the cloud cover is greater — and also when the deserts are visible in the Sun — the Earth appears at its brightest, up to approximately 55 times brighter than the Moon.

Days and nights on the Moon last approximately two Earth-weeks apiece, and the near side of the Moon is the best place to view a “full Earth” phase, during the time when the Sun completely illuminates the Moon’s far side. The Earth, at that moment, appears 13 times larger, 3.4 times more reflective and a total of 43 times brighter than the full Moon does from Earth.

https://medium.com/starts-with-a-bang/ask-ethan-how-bright-is-the-earth-as-seen-from-the-moon-627eb1554ca9


Here is a simulation by NASA of the earth from the moon, from various perspectives

https://www.youtube.com/watch?v=jdkMHkF7BaA


And then, of course, there are the dodgy photos, the photo shoppers with too much time on their hands..!

https://www.google.com/imgres?imgurl=https%3A%2F%2Fp4.wallpaperbetter.com%2Fwallpaper%2F995%2F126%2F341%2Fview-of-earth-from-the-moon-with-a-refreshing-drink-hd-desktop-backgrounds-free-download-wallpaper-preview.jpg&imgrefurl=https%3A%2F%2Fwww.wallpaperbetter.com%2Fen%2Fhd-wallpaper-gpefe&tbnid=0a7Sw_1Z3U0ieM&vet=12ahUKEwirmcK6oODxAhVFSn0KHbjJCaoQMyg1egQIARBU..i&docid=7NsakEQlc3fAGM&w=728&h=455&q=%20earth%20from%20the%20moon&hl=en&safe=images&ved=2ahUKEwirmcK6oODxAhVFSn0KHbjJCaoQMyg1egQIARBU

Posted by: Ric G | Jul 13 2021 14:35 utc | 285

@ricg You expect the earth to look huge and Armstrong said it does not. So? It's a very legitimate question to say 'I don't understand, please explain'. It is not smart to shout 'I don't understand so AHA, gotcha, it is all a lie!'.
Next time you see the moon, try two things, take a picture of it and stretch your arm and cover it with your thumb. It's quite small actually, it just feels big sometimes because of how we process it but the thumb and camera tricks help you work around that. The earth looks 4 times wider than that from the moon, if you stretch your arm (no fat gloves!) and if you take a picture with the same camera, same lense. That is still pretty small.

Posted by: Tuyzentfloot | Jul 13 2021 15:10 utc | 286

@Ric G | Jul 13 2021 14:35 utc | 285

Overall, the Moon reflects only 11% of the sunlight striking it, but the Earth reflects approximately 37% of the sunlight incident upon it. Put this all together, and a “full Earth” as seen from the Moon is about 43 times brighter than the full Moon is as seen from Earth.

Please perform a basic self-check: If you stand at the Apollo 11 landing site at Mare Tranquilitatis and look up at a “full Earth”, what kind of light conditions do you have at the landing site, and why? Does this match the light conditions seen in images and videos from the site?

Days and nights on the Moon last approximately two Earth-weeks apiece, and the near side of the Moon is the best place to view a “full Earth” phase, during the time when the Sun completely illuminates the Moon’s far side. The Earth, at that moment, appears 13 times larger, 3.4 times more reflective and a total of 43 times brighter than the full Moon does from Earth.

Does this match the conditions on 21. July 1969?

Give us a good reason why NASA made sure it didn't.

Posted by: Norwegian | Jul 13 2021 16:06 utc | 287

@vk #277
You keep trying to argue nonsense.
I never said the propaganda value was "worth it" - I said the USSR leadership believed it was and this is well documented in historical archives.
Your ongoing attempts to retroactively justify other people's past actions is stupid and pointless.
The Soviet Union expended enormous resources for this exercise - at a time when 20m+ of its people has just died in WW2 and their economy was in a shambles due to fighting on and around many of the most productive industrialized areas in Russia.
It is not for me to say if this enormous expense is justified - but it is utterly ridiculous to say that it was not an enormous expense which certainly forced opportunity cost losses elsewhere.

Posted by: c1ue | Jul 13 2021 16:09 utc | 288

@Ric G #281
The era of the slide rule was World War 2.
NASA had computers in the 1960s.
IBM had been creating computers since 1949 - and had created a bunch for NASA in the 1950s and 1960s IBM historical site
As I noted earlier - my own father had first hand contact with a few of these computers.

Posted by: c1ue | Jul 13 2021 16:13 utc | 289

S | Jul 13 2021 12:38 utc | 283

The coms link is quite meaningless. Musk's fantasies involve not just being able to recover and reuse the second stage, but to do this carrying payloads at a greatly reduced rate. The space shuttles made a number of flights but total cost of the program worked out at around 1.5 billion per flight.

When you see space-x make a pronouncement that they have made a breakthrough in propulsion technology (as in halving the weight of fuel and thrust unit) then it may become feasible.

Posted by: Peter AU1 | Jul 13 2021 16:21 utc | 290

ciue 289

Yes they had computers but they were clumsy, and often filled a room, and they had to be cooled. I suspect that most of NASA's calculations at that time would still have been checked on a slide rule?
And the computing power that they could fit onto a moon lander would have been amusing in our present era!


Here is the Changi 5 moon mission from 2020.

Chinese video 2020

https://www.youtube.com/watch?v=7JGCp8SS9BM

https://en.wikipedia.org/wiki/Chang%27e_5

The moon lander landed on the moon on December 1, 2020.
The ascender left to return to the orbiter on December 3, 2020

The electronics and systems on the Chang'e 5 lunar lander were expected to cease working on 11 December 2020, due to the Moon's extreme cold and lack of a radioisotope heater unit. However, engineers were also prepared for the possibility that the Chang'e 5 lander could be damaged and stop working after acting as the launchpad for the ascender module on 3 December 2020, as turned out to be the case.[36]

(I seem to remember reading that the Changi 5 ascender could only stay on the moon for a short time as it could not handle the extreme temperatures)

Here is Apollo 15, moon buggy and lander on the moon, NASA photos 1971

https://www.google.com/imgres?imgurl=http%3A%2F%2Fwww.nasa.gov%2Fsites%2Fdefault%2Ffiles%2Fimages%2F574954main_GPN-2000-001140_full.jpg&imgrefurl=https%3A%2F%2Fwww.nasa.gov%2Fmultimedia%2Fimagegallery%2Fimage_feature_2020.html&tbnid=EuEIejhVp1mElM&vet=12ahUKEwjzz8O0t-DxAhVOVSsKHdYPCp8QMygCegUIARC0AQ..i&docid=M1nGw0E9P7uKHM&w=3000&h=3000&hl=en&safe=images&ved=2ahUKEwjzz8O0t-DxAhVOVSsKHdYPCp8QMygCegUIARC0AQ

https://www.google.com/imgres?imgurl=https%3A%2F%2Fi.ebayimg.com%2Fimages%2Fg%2F0bMAAOSw4S1cUF13%2Fs-l300.jpg&imgrefurl=https%3A%2F%2Fwww.ebay.co.uk%2Fitm%2F361910199584&tbnid=1ZxdYuqsmXj6KM&vet=12ahUKEwi15f65t-DxAhVX7zgGHYJTDM4QxiAoCHoECAAQIQ..i&docid=EOr_RpkCNN9DcM&w=300&h=239&itg=1&hl=en&safe=images&ved=2ahUKEwi15f65t-DxAhVX7zgGHYJTDM4QxiAoCHoECAAQIQ

I find it perplexing??? Why was it so easy 50 years ago, and so tricky now?

Posted by: Ric G | Jul 13 2021 16:23 utc | 291

@c1ue | Jul 13 2021 16:13 utc | 289

The era of the slide rule was World War 2.
NASA had computers in the 1960s.

Apollo had a computer on board as well, the Apollo Guidance Computer. See this fascinating lecture about that computer (video) The 1969 Apollo Guidance Computer

Posted by: Norwegian | Jul 13 2021 16:24 utc | 292

@Ric G | Jul 13 2021 16:23 utc | 291

Why was it so easy 50 years ago, and so tricky now?

I have already pointed out in this thread that it wasn't easy 50 years ago, please don't repeat that unfounded claim.

Please answer the questions I posted @287

Posted by: Norwegian | Jul 13 2021 16:28 utc | 293

@Ric G | Jul 13 2021 16:23 utc | 291

Here is Apollo 15, moon buggy and lander on the moon, NASA photos 1971

Yes.

Posted by: Norwegian | Jul 13 2021 16:32 utc | 294

To the commenter S, who hasn't bothered actually reading my subsequent comments in this thread.

About That 'flight plan' with the FCC for the 'orbital' flight of 'starship.'

The distance from Texas to Hawaii, flying eastbound, is about 25,000 km. The flight duration stated in that 'document' you linked to gives a total flight time of 5,400 seconds, which is exactly 1.5 HOURS.

The second stage engines cut off at 520 seconds, at which point it will have reached its maximum velocity. If we subtract that, plus another 500 seconds for descent, it leaves ~4,400 seconds of 'orbital flight to cover 25,000 km.

That's an 'orbital' velocity of 5.7 km/s, which is actually NOT orbital velocity. It's short by more than 2 km/s, or about 30 percent slower.

In simple terms, that ~4,400 seconds of flight time at 'orbital' velocity is exactly 73.3 MINUTES of flight time, to cover 25,000 km.

By comparison, an actual orbital flight at 7.9 km/s will make a complete orbit of the earth's 40,000 km circumference in a time of 84 minutes.

Maybe you could explain the difference? So that we can take your word for it that this is indeed an 'orbital' flight. [Which doesn't actually make even a single orbit?]

Also note we have not accounted for the distance flown over the ground in those 1,000 seconds of ascent to maximum velocity, and descent from there---which are going to be substantial, and would be subtracted from the 25,000 km total distance.

Even if the average speed of those ascents and descents is 2 km/s that still cuts the flight distance of that 'orbital' segment to at most 23,000 km.Which drops the 'orbital' velocity down to 5.2 km/s.

Orbital speed, again, is 7.9 km/s.

Btw, if you have any solid information on key numbers for that contraption, like the mass of that 'starship' payload and, crucially, the mass of its fuel carried, I would appreciate hearing it.

Also the mass of that booster stage, fuel mass, number of engines, total thrust etc.

From that 'document,' under 'flight profile':

The Orbital Starship will continue on flying between the Florida Straits.

It will achieve orbit until performing a powered, targeted landing approximately 100km (~62 miles) off the northwest coast of Kauai in a soft ocean landing.

Mmmhmm. And the particulars of the machine are all top secret of course?

As for your comments about my comments about aero-breaking.

Perhaps I should just devote the next month or so of my 'spare' time to make the technical particulars of atmospheric reentry understandable for the layman?

Surely you must realize the enormity of the subject of atmospheric reentry. Yet you say things like:

No chance to do anything? Another incorrect statement.

Doing half of something is not the same as doing nothing.

Okay then. Perhaps YOU could go ahead and explain how atmospheric reentry works? If you don't mind?

Posted by: Gordog | Jul 13 2021 16:33 utc | 295

291 RiC G
It is depressing how you are babbling about stuff you haven't the slightest clue about. Computers in the 60s were certainly not "clumsy", the mainframes had virtualization already, and a program written in Assembler and thoroughly tested could be trusted orders of magnitude more than the Microsoft and Apple shit with shiny GUIs for idiots. Same for Fortran programs if written by competent programmers (Fortran allowed terrible programming, sure, but not closely as terrible as "OOP").

Yes that were no tiny boxes, but they could do a lot in technical and scientific fields. And of course the computers were at the NASA on the ground, not on board of Apollo.

Posted by: aquadraht | Jul 13 2021 21:16 utc | 296


I was not actually knocking slide rules. They were the computer of the day and my father, to me, was a wizard on one. And of course there were computers on the missions, controlling engines, etc.

https://medium.com/tech-is-a-tool/calculating-the-moon-the-slide-rule-13fdb10c52f1

https://medium.com/@jhoward31415/how-the-slide-rule-got-us-to-the-moon-426299ea1f43

https://www.northjersey.com/story/news/2019/07/19/apollo-11-slide-rules/1742820001/

Pickett slide rules flew on five of Apollo missions, a fact that the company crowed about in ads at the time.
In September 2007, Heritage Auction sold the Pickett slide rule that Apollo 11 astronaut Edwin "Buzz" Aldrin took to the moon.
The Pickett Model N600-ES (Eye Saver) Log Log Speed Rule, was 6 inches long with 22 five-inch scales. In 1969, the N600-ES sold for $10.95.
Aldrin's moon-used slide rule fetched $77,675 at auction.

We are also wasting my time and other people's time arguing over trifles which have little interest to any of us!

Obviously I have my doubts about the way the moon landings have been presented to us. I would be happy if NASA said, 'we went to the moon but it was a pretty basic scientific process, only of interest to the die-hards of science, and we had 300 million Homer Simpsons, outside the door, who wanted to see a super bowl show, so we gathered together a heap of footage we had shot on earth, from all our testing processes, and we made a movie out of it. We then displayed the movie onto a backlit screen, with all the TV station cameras setup in front of the screen. And we told them it was live to justify the fact we were spending (8%?)of the nation's budget on our Apollo program. We were trapped by the people's desire for a religious moon shot experience!'

https://www.popularmechanics.com/space/moon-mars/a28401050/how-1969-apollo-11-moon-landing-was-filmed/

The ability to send back clear TV pictures from space was impressively demonstrated during the Apollo 8 mission. The highlight came Christmas Eve, 1968, when Frank Borman, Jim Lovell, and Bill Anders sent greetings some 230,000 miles to Earth. Viewers were amazed and perhaps a bit puzzled. They may have wondered how it was that local programs, beamed with 50,000 watts, sometimes didn’t come in as well as the pictures from the reaches of space. How could a tiny 20-watt transmitter push a good signal so far?


Have you ever seen the video of the Apollo 11 press conference when they returned to earth. They come across as three condemned men sent out to lie to an audience, not three men in a state of exultation after completing a historic adventure.

https://www.youtube.com/watch?v=BI_ZehPOMwI


If you think a wobbly satellite dish, on a moon buggy, was sending live footage back to earth, in real time, then you are having a religious experience, not a scientific experience.

I like listening to a live radio show, based on interviews, and they technically lose the hookup probably once a week, using phones and Skype. And that is in a radio station connected to the planetary grid!


Posted by: Ric G | Jul 13 2021 22:27 utc | 297

@ Norwegian 294

I posted this link to a beautifully crafted, professional photo, supposedly shot by an astronaut, in a moon suit, wearing moon gloves, in a space radiation environment, who then transported the film through the radiation fields of space, to the earth, where it was turned into a photo which you can still order for $30.

https://www.google.com/imgres?imgurl=https%3A%2F%2Fi.ebayimg.com%2Fimages%2Fg%2F0bMAAOSw4S1cUF13%2Fs-l300.jpg&imgrefurl=https%3A%2F%2Fwww.ebay.co.uk%2Fitm%2F361910199584&tbnid=1ZxdYuqsmXj6KM&vet=12ahUKEwi15f65t-DxAhVX7zgGHYJTDM4QxiAoCHoECAAQIQ..i&docid=EOr_RpkCNN9DcM&w=300&h=239&itg=1&hl=en&safe=images&ved=2ahUKEwi15f65t-DxAhVX7zgGHYJTDM4QxiAoCHoECAAQIQ

Not only that, but someone calculated that the astronauts took a beautiful photo, when added together, for every one minute of the Apollo missions. They must have been photographic legends in their own lunchtimes!

The astronauts also squeezed in a lot of kilometres in their electric moon buggy.

The Lunar Roving Vehicle (LRV) was an electric vehicle designed to operate in the low-gravity vacuum of the Moon and to be capable of traversing the lunar surface, allowing the Apollo astronauts to extend the range of their surface extravehicular activities. Three LRVs were driven on the Moon, one on Apollo 15 by astronauts David Scott and Jim Irwin, one on Apollo 16 by John Young and Charles Duke, and one on Apollo 17 by Gene Cernan and Harrison Schmitt. Each rover was used on three traverses, one per day over the three day course of each mission. On Apollo 15 the LRV was driven a total of 27.8 km in 3 hours, 2 minutes of driving time. The longest single traverse was 12.5 km and the maximum range from the LM was 5.0 km. On Apollo 16 the vehicle traversed 26.7 km in 3 hours 26 minutes of driving. The longest traverse was 11.6 km and the LRV reached a distance of 4.5 km from the LM. On Apollo 17 the rover went 35.9 km in 4 hours 26 minutes total drive time. The longest traverse was 20.1 km and the greatest range from the LM was 7.6 km.

https://nssdc.gsfc.nasa.gov/planetary/lunar/apollo_lrv.html

They were also busy collecting 842 lbs of rocks to be brought back in their aluminum/mylar space craft.

Between 1969 and 1972 six Apollo missions brought back 382 kilograms (842 pounds) of lunar rocks, core samples, pebbles, sand and dust from the lunar surface. The six space flights returned 2200 separate samples from six different exploration sites on the Moon.

https://curator.jsc.nasa.gov/lunar/

If I was a betting man I would say that those who accept the moon landing story, as presented to us by NASA, are having a religious experience, and not a scientific experience. And you cannot argue with a religious experience, nor the devotees of the moon landing NASA cult! Leave it to history to record the truth, as time unfolds!

Posted by: Ric G | Jul 13 2021 22:49 utc | 298

@Peter AU1 #290:

The coms link is quite meaningless.

How is it “meaningless”? Gordog has erroneously claimed that the planned flight isn’t orbital; I have provided the link to show that it is. That circular arc from Florida to Hawaii? That’s an orbital flight path.

Musk's fantasies involve not just being able to recover and reuse the second stage, but to do this carrying payloads at a greatly reduced rate.

I am not debating this. My only objection is to Gordog’s erroneous claim that Super Heavy/Starship is “physically impossible”.

Posted by: S | Jul 13 2021 23:08 utc | 299

@Gordog #295:

To the commenter S, who hasn't bothered actually reading my subsequent comments in this thread.

That is true. I only had time to respond to your comment #165 that I took as your answer to my comment #162. I will try to catch up with the rest of the thread.

The distance from Texas to Hawaii, flying eastbound, is about 25,000 km.

SpaceX Launch Facility at Boca Chica Village, Texas is located at N 25.99822, W 97.15732. I have used the third image of the trajectory from the FCC application and Google Maps’ satellite view to estimate the splashdown point to be at approximately N 23, W 160. Plugging these into NOAA’s Latitude/Longitude Distance Calculator, I get 6301 km. Since the Starship is flying eastbound, the distance is then approximately 40075 − 6301 = 33774 km.

If we subtract that, plus another 500 seconds for descent, it leaves ~4,400 seconds of 'orbital flight to cover 25,000 km.

That's an 'orbital' velocity of 5.7 km/s, which is actually NOT orbital velocity. It's short by more than 2 km/s, or about 30 percent slower.

33774 km / 4400 s = 7.68 km/s

Maybe you could explain the difference? So that we can take your word for it that this is indeed an 'orbital' flight.

Yes, I can explain it. The explanation for the difference is that you are sloppy in your calculations and statements.

Btw, if you have any solid information on key numbers for that contraption, like the mass of that 'starship' payload and, crucially, the mass of its fuel carried, I would appreciate hearing it.

See the Wikipedia article and the product page on SpaceX’s website (click left/right arrows to view more specs).

Surely you must realize the enormity of the subject of atmospheric reentry. Yet you say things like:
No chance to do anything? Another incorrect statement.

Doing half of something is not the same as doing nothing.

You said that the drag coefficient of a cylinder is half that of a flat surface. That must mean that the aero-braking is still happening, just not as efficiently as in the case of a flat surface. So the cylinder is actually doing something, and it is incorrect to say that it has “no chance to do anything”.

Of course, as I’ve already mentioned twice, it’s not just a cylinder, there are two pairs of wings/canards. And there’s a thermal protection system: you can see the tiles installed on one of the Starship prototypes in this video.

You still haven’t addressed my main point: how can it be “physically impossible” for Starship + Super Heavy to do what the Space Shuttle + an external tank + SRBs did?

Posted by: S | Jul 14 2021 3:45 utc | 300

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