Hacker News Reader

Comment by cubefox | Hacker News Reader

The VentureStar was very much possible technology, the reason for cancellation was fairly minor.

"Very much" is out of place here. X-33 had 5 risky technologies to prove, and any failure with them could ground the project. Formally they failed when the composite tank structure broke (the liquid gas evaporated and composite layers detached), but even with the proposed fix (a more conservative and less performant aluminum tank) they still had to clear the other problems.

So, Venture Star probably was just "possible technology". Still risky at the time, at the beginning of the millennium.

It clearly wasn't all that minor, the story is always told as if it'd have been fine if Congress just allowed the alternate tanks, but it's worth considering that the work with the aerospikes was still so incomplete and risky, that even now, no serious company will risk attempting them, with the leaders by far in rocket engine tech, SpaceX, opting for the ridiculous complexity of Raptor over aerospikes.

Then besides all that, VentureStar was never going to be able to overcome the issue of rocket SSTOs just not being efficient in Earth gravity. It's just way more efficient and not much more risky to have two stages.

Of course Starship is a better design now, but the VentureStar had a shot a full reusability long before it, and all that with a small fraction of the Cost-plus budget of the Space Shuttle.

The Dream Chaser certainly doesn't achieve full reusability, and it is doubtful whether it is even overall better than Dragon on Starliner.

The point is that it didn't have an efficient (and therefore cost effective) shot at full reusability. That's always been the key issue.

There were plenty of designs for partially or fully reusable spacecraft, none were done in a way to be cost effective. The space shuttle being the poster child for this sort of thing, so expensive to refurbish that being reusable was almost meaningless.

As an SSTO, VentureStar's payload would've been very limited compared to a two stage rocket of the same fuel capacity. The X-33 prototype that was being built was a scaled down suborbital version which doesn't even list a payload amount.

The VentureStar was explicitly designed for low refurbishmemt demands given the failures of the Space Shuttle. The latter was developed by NASA using contractors, which pretty much always results in extremely high costs, e.g. recently with the cancelled NASA space suits or SLS. Even with Hydrogen, I think the full reusability of the VentureStar could have outweighed its high fuel cost, compared to other rockets at the time. They estimated 20 tons to LEO, which would have been more than e.g. Atlas, which wasn't even designed to fly humans, and would have required a capsule that reduces effective payload.

The inventor of the PICA heatshield does not think it was a very possible technology [1].

As evidence, nobody since has tried to revive it.

1 - https://youtu.be/g3gzwMJWa5w?t=460

Reply on news.ycombinator.com