RCgothic

Yeah, there was plenty of discussion of it up-thread, the post I quoted was @tater getting the first mention in.

The hinge fire is news to nobody in this thread who actually reads it instead of doing nothing but post pet theories. Also nice use of a diagram of SN8. The 3rd hinge on SN33 is comfortably above the false ceiling, exactly where we'd expect to see a plumbing leak.

The plumbing. New downcomers in that section. Engines no significant changes.

Thinking about the "don't bother with reuse, just send it expendable because that works" argument just now and realised that something similar is causing me a significant amount of personal frustration at work right now. There's a major intermittent process I'm responsible for designing, and the traditional way of doing things will cost £190-240M GBP (in 2025 terms) over plant life. Spending perhaps a twentieth of that up-front to implement existing tech would allow us to cut that cost by a third (potentially saving £60M GBP in 2025 terms), employ fewer people, generate less hazardous waste, and provide a safer environment for workers. But because it's "only saving a few weeks" when the process actually rolls round every 5 years or so there's a traditionalist block that is being stubbornly obstructionist, and having lost the technical argument, is now using the argument of development time and submission deadlines to try kill the innovation through "process". I.e: "the way we've always done it works, don't bother." SpaceX could abandon their innovation and take the easy way. They've got a 5-10 year tech advantage over their nearest competitors. But they won't keep that lead by abandoning innovation. Full rapid reuse is the holy grail of spaceflight for a reason. Got very limited sympathies for the alternative arguments right now.

Scott Manley thinks the explosion was FTC activation 2-3 minutes after loss of telemetry, on automated detection of deviation from flight corridor. He thinks the FTC was uncalled for in this instance, and only had the effect of spreading the debris over a larger area. Luckily the ship was entering the atmosphere at the time. If FTC detonation had occured in space on an upward trajectory the debris field could have been extremely large. Potentially Starship could have attempted to glide to a pre-programmed safe splashdown, (varying depending on flight stage) although this may not have been possible with a loss of attitude control. All this counter-balanced against the risk of a large un-FTC'd chunk surviving an uncontrolled re-entry.

Where is the ship going to come down I guess is now the question.

They'll have had data up until loss of vehicle, possibly a few moments after IMO. Raptor pi survived a second flight though!

https://bsky.app/profile/sciguyspace.bsky.social/post/3ldjuvm6r6j2c FAA approve IFT-7

It's a sensible idea. Movements of large quantities of propellant are risky, and the ability to stand the crewed module off at a safe distance might be a useful safety feature. They undock and return dragons to the ISS with crew on with moderate frequency, this would be similar.

I think expendable Superheavy is just a case of making SpaceX an offer, plus a bit of time. How much time? Probably not more than any other option.

16 SLS block 2 missions? Plus commercial refilling in cislunar space? (Talking what, 50+ additional flights?) File that under never going to happen. If SLS even gets to 4 flights and block II it will have beaten the odds at this point. It's amazing how 2040 for a crewed landing can be both totally unrealistic and completely devoid of ambition at the same time.

The apollo programme as a whole may have been expensive due to the amortization of the extensive R&D and construction of infrastructure from the ground up, but the marginal cost of Apollo applications missions would have been less than what shuttle ultimately cost and we'd have got a lot more done with 70+t to LEO capability than shuttle managed. The only unique thing I think shuttle truly accomplished was Hubble servicing. But for the savings we could have built another.

You can get a "skip" re-entry without aerodynamic lift on a ballistic trajectory. Just put your track high enough that you'll pass periapsis before scrubbing enough velocity and altitude will start to rise again. When Apollo commentaries talk about missing the entry corridor and skipping off into space, this is what they mean. The capsule will definitely be coming back to Earth in a later pass, just at a time that's potentially beyond the endurance of the capsule and/or at a very non-conducive-to-safe-landing location. Aerodynamic lift allows better control over the trajectory. It might be desirable to keep the path higher in the atmosphere than a pure ballistic territory would allow, e.g. if the heat shield can endure moderate heating indefinitely and your craft has features that don't enjoy g-forces and high drag, such as wings or fins, then it makes sense to scrub off as much velocity high up as possible. But if the heat shield is ablative, a long re-entry can wear it away. So to keep the total heat absorbed low it might be desirable to come in steeper than ballistics would allow. This would have higher peak temperatures and g-forces, but would ablate less material. Another reason to use aerodynamics during re-entry is if the apoapsis is high or interplanetary, there's a lot of velocity to scrub off. A craft might not be able to endure a low enough periapsis to scrub off enough velocity in one pass ballistically. Using aerodynamics can hold the craft down at a survivable periapsis long enough to scrub velocity instead of skipping off. The heat-shield on the Orion capsule was apparently designed for an initial phase of heating, a skip to a higher altitude for a period of cooling, then a final re-entry. It sounds like that design had some flaws when gasses generated by the first phase of heating built up in the heat shield during the cooling phase, and the build up of excess of pressure of those gas pockets popped large chunks off the shield.

I'm cautiously optimistic about Isaacman as administrator. I think he'll be unsentimental about cutting elements that need to be cut and driving forward progress towards a greater goal. I don't think he'll be able to command Polaris missions whilst NASA administrator however.

I don't expect Isaacman to be sentimental about SLS when he takes charge of NASA.

Quite a nice fireball on splashdown. Nominal insertion for Starship though. Relight test in approx 25mins. Not yet that I've heard.

No-go for catch. Aiming for splashdown.

Liftoff! Max-Q!

Cost of those top 18 launches: potentially $18m for 100t *payload* to lunar surface with basically any cadence once produced. Cost of bottom launch: ~$99m not counting expended spacecraft, for ~10t *total* to lunar surface and probably 1/10th as often bottlenecked by production of the bits that have to be expended. Option 1 gets over 100 times as much usefulness accomplished (20 times as much payload 6 times as often, budget limited) on the same budget as option 2, so option 2 can get in the bin AFAIC. Even if the reusable launch misses it's cost target by a factor of *10*, it's still over ten times better than expendable. Purely considering a bid for an SLS replacement: SpaceX can bid as much for Option 1 as for Option 2 per mission because nobody else can undercut them. Assume a 20% profit margin on Option 2. SpaceX makes $20m. For Option 1 they'd make $100m. SpaceX should not bid Option 2 for anything. And they should not accept a cheque to do Option 2 excepting that it doesn't distract from their pursuit of Option 1.

Cool, if all SpaceX wanted to do is send a flag and footprints mission to the moon or *maybe* Mars. And that might be a sensible way forward (for the getting Orion to the moon portion of Artemis before Starship gets rated for lunar returns) if SLS gets cancelled. But that is *not* what SpaceX wants to do. SpaceX wants a permanent base on the moon. They want a city on Mars. They want the ability to brake hundreds of tonnes of mass into orbit of the outer planets arriving off a fast trajectory. And they want all that to be affordable on their own budget. Starship Superheavy expendable can accomplish some useful missions soon in the short term for a reasonable price. But frankly SpaceX would find that to be a distraction from what they actually want to do. If, as a nation, the US has different priorities, then I'm sure SpaceX wouldn't say no to a big cheque. But humanity would advance faster by investing in the long term goals SpaceX are pursuing rather than distracting them with short term dead-end avenues like flag and footprints (again).

SLS was also really good at shaking sensitive scientific payloads to pieces with those enormous SRBs. Nearly every bit of Artemis except the Landers and the EVA suits could be ditched and nothing of value would be lost. Getting rid of Gateway, Orion and SLS would save a lot of money for more regular flights and actual mission hardware.

The fabrication tolerances won't even hold 0.5cm over the whole booster. Thermal expansion/contraction alone would be much larger than that.

I would personally find 0.5m much more credible.

They have a second launch tower nearly ready. Not a big setback if they break the first. Much useful data to learn.

And even so there's no way impact explosion damage outweighs launch explosion damage. The quantities of propellant involved are just so vastly different.