Comment by pclmulqdq | Hacker News Reader

Comment by pclmulqdq | Hacker News Reader

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The way this often happens with government programs is that one program has to demonstrably deliver the goods before their competitors lose funding. SLS thus far has done better at this than starship. They do this with a lot of military and military-adjacent contracting - they have multiple companies develop a capability, and then theoretically get some choice about which one to buy from as well as having some strategic redundancy.

In many ways, NASA and others have de-risked their heavy lift capabilities by putting together at least two sources. Artemis has sole-source contracts to both SLS and Starship for separate things, but the program is creating two separate heavy-lift vehicles.

Starship has to innovate its way into orbit first (the most recent flight got the altitude for LEO, but not the velocity) and then around the moon to catch up to where the SLS program is today. As far as I can tell, many space folks outside of SpaceX actually have more concerns about whether Starship can deliver on its promises than whether SLS can.

It depends how you look at it. The mission calls for both systems. Making success reliant on two completely different heavy lift vehicles simultaneously, in which the mission fails if either fails, is arguably not de-risking.

Yes if only one succeeds the US will still have one heavy lift system, but that would require massive re-vamping of NASA's planned mission goals.

> the most recent flight got the altitude for LEO, but not the velocity

Starhship could easily have reached true orbit, they deliberately stopped just before it for safety reasons (don't want massive chunk of space junk if something goes wrong during deorbit)

Is that their line? Musk companies have used that excuse a lot when they actually can't do something (see Tesla FSD). During the test flight, they called that orbital insertion was complete after they ran out of fuel (long before reaching orbital velocity), so I'm not buying it.

Also, at that altitude, there's enough drag that you can de-orbit a big metal can pretty easily by simply pointing it in a high-drag orientation. Most LEO satellites do this when their missions are over, and it takes a couple weeks.

Are we talking about the same test flight? They did not "run out of fuel" on IFT 3, maybe you are confusing with IFT 2 from last November?

Yes. "Starship engine cutoff" was called at 26,600 kph at 155 km altitude, when the fuel gauges for both LOX and CH4 on the stream were at 0. That altitude needs 28,000 kph for orbital velocity.

A sister comment mentioned "venting excess fuel," which I don't believe was in the flight plan, but I would believe that the craft was leaking fuel given the clouds of gas around the thing on all the camera views (and the excess rotation in flight). That would explain how starship failed to make orbital velocity and still ran out of fuel.

Presumably, if there was a leak and they fixed it, there wouldn't be any problems getting to orbit. But the fact of the matter is that they didn't reach orbit despite trying (getting into LEO was in the published plan), and the fuel gauges got to 0 before they got there.

It's very possible that the valve between the tanks for the in-flight fuel transfer test (which didn't seem to happen successfully) was broken, so it's not actually a problem with starship at all, but a problem with the experimental setup.

They were venting excess fuel for some time after final trajectory insertion. There's no real question they could have achieved orbit handily.

"First rule of government spending: why buy one when you can buy two for twice the price" - Fictional billionaire R.L. Hadden, in Carl Sagan's "Contact"

The only goods SLS has actually delivered are dollars to Boing execs and inefficient jobs across the country.

Most of the satellites the first launch carried did not work, it can't launch often enough to be a viable general use heavy lift launcher, it costs too much to launch, it's such a rough ride that scientific probes would rather take a few years longer to reach their destination on a smoother ride like Falcon Heavy. It can launch Orion but that's meaningless since Orion can't do anything on its own, and as mentioned earlier, it can't launch often enough to lift a second vehicle for Orion to work with.

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