RCgothic

He followed up by saying that there's no great rush to refuel HLS in orbit, it can be done with sequential tanker flights and the boil-off won't be too bad. Propellant transfer is just docking, and docking to other starships is easy - much easier than docking to the ISS which they do regularly.

There's "never done before" and there's "never done before in a rocket engine". For whatever reason there's never been a good enough motive for someone to try and integrate cooling of secondary systems (because regenerative cooling of combustion chambers and nozzles have been implemented since forever) before. Maybe a rocket needs to have a particular mass of fire suppression, number of engines, or level of reusability before advanced integration of instrument lines and wiring inside housings and elimination of flanges makes sense. In my own work I'm bringing together a lot of different things that are fairly common elsewhere but nevertheless equal "never done before in a power plant". The main reason for us at least seems to be that when production of a thing is at a fairly steady rate, the people building power plants go on to build new power plants the same as they've always done, and train their replacements to do what they've always done. When demand for a thing exceeds the resource pool, people with different experiences need to get brought in from other sectors and the combination of experiences often unlocks doing things differently from then on.

Nah, pez dispensers have been a thing for decades, I remember them when I was young. A quick search turned up they've been around since 1927.

Starship: *Fin fails during first true test of re-entry.* "This was clearly Raptor's fault."

I was in a work meeting and only caught the stream as the camera was getting coated in debris and just before the lens cracked. Saw the landing, came on here and started reading back. A fin melted. Wait. What?! Only then went back and rewatched the stream. Can't believe it made it to a successful ocean landing with that!

I feel so bad for Tim.

So the issue with flight 3 boostback and entry burns wasn't anything to do with Raptors, Quelle Surprise. Oxygen line filtration issue and roll control thruster clogging. The video started at the anomaly, later on it goes back and shows the engine firing apparently normally.

Any SLS not used for Artemis is a waste IMO.

For a similar comparison, the first two full flight lunar modules were probably delivered around the end of 1968. LM-1 flew in Jan 68 on Apollo 5, LM-2 became a test article, and LM-3 flew Mar69 on Apollo 9. Earlier LMs that flew were various degrees of boiler plates and test articles (dev). From what I can tell, 75% of the total funds allocated to lunar modules were disbursed by the end of 68. That would put a 2nd flight dev-inclusive cost for Apollo at $15B in 2020 dollars, or $7.5B per flight. That's rather more favourable to SpaceX's starship's $2B. And that's before considering Starship is VASTLY more capable. Over 10x as much downmass, over 35x as much downmass per dollar.

Sure, with dev costs ammortised over only 2 missions it comes out expensive. But I'd keep an eye on how much is contracted for subsequent missions. On the second point there's not a chance in hell any human lander has a dev included cost over 2 missions of just tens of millions. NASA can't even buy a single unintegrated rocket engine for that little. The paperwork alone for crew rating would blow that figure into smaller pieces than Orion's ablated heat shield.

Oof indeed. That definitely deserves a fresh uncrewed test flight IMO. Falcon Heavy should be able to send an Orion boilerplate with the right shape, entry mass, and heat shield on a free-return trajectory around the moon if it doesn't need to send ESM as well. The problem is they don't have a spare Orion hull they can quickly convert, because they're hardware-poor. Shuttle, Apollo, and the earlier spacecraft all had multiple test articles that could be repurposed in situations like this (or even pressed into operational service, like Endeavour was from structural spares). And apparently any solution that involves demounting the Orion for Artemis II and modifying the heat shield will incur at least a year of delay because they're incapable of doing it any faster. It's inexplicable to me why mounting/demounting a spacecraft takes them so long.

I believe Polaris 1 will be a record for number of astronauts simultaneously in depressurised conditions? IIRC ISS and shuttle never had more than two at once. Apollo occasionally had 3 during depressurisations of the command module for stand up EVAs. Polaris will be 4. Unless different national missions randomly had spacewalks occur at once.

Aha! Fixed! It was importing cropped for some reason.

Image won't link properly. Oh well.

There's no such thing as a minimum viable commercial off the shelf lunar lander made from existing parts. And even if there were, SLS couldn't send it. And even if it could, starting from now would only incur huge delays. And even then it'd only get a very very poor excuse for a lunar mission. If value for money is the concern, then the Landers should be at the very bottom of the list of things to change, right behind *gestures at literally every other thing in the Artemis program and very specifically at SLS/Orion*. Any criticism of Artemis on cost grounds that doesn't want HLS but does want SLS is completely devoid of credibility IMO.

Maybe a waterproof robot could take a normal shower after dirty tasks.

I also suspect one of the reasons Delta Cryogenic Second Stage was chosen over Centaur for the basis for ICPS and EUS was the separate tanks make an explosion due to propellant mixing less likely. A lander based on Centaur would go against this philosophy. (So does Starliner on Atlas/Vulcan, but that's not a NASA designed vehicle).

True. But say (impossibly) they were. Then what? What does that SLS-Orion-Apollo do next? What are its stretch goals, what can it achieve? Maybe 12t of down mass every other year, disregarding crew missions? Can't achieve anything lasting that way. It'll get rapidly cancelled after its flag and footprints. The HLS landers are the genuinely useful bits of Artemis. Suddenly the downmass is hundreds of tonnes, multiple times a year. Habs. Labs. Construction equipment. Solar collectors. ISRU. Refuelling stations. Giant surface telescopes. Permanent off-world inhabitation for dozens to hundreds of individuals. Enabling technologies for Beyond Earth/Moon exploration! And the development costs to enable those sorts of plans are essentially peanuts in spaceflight terms. "It's too hard!" Not as hard as closing SLS's 20 tonne mass budget deficit I'd wager. "It'll be delayed!" Not as delayed as any alternative program would be. "It's a waste of money!" This can't possibly be serious.

I'm never going to get on board with paring back Artemis. I want permanent off-world habitation. Single-stack SLS missions are never going to achieve that.

The secret about starship being oversized for Artemis is that Artemis is a customer but Starship has grander ambitions.

Nuclear (and other thermal plants) don't strictly need water for ultimate heat sink. I've seen several proposals for arid areas.

What's the worst thing someone could do with a loose fully charged battery? That's basically the problem with hot swappable battery packs.

I'm completely unconvinced that hybrids are the way to go for most domestic vehicles. The round-cycle efficiency for synfuels is way less than direct electric, and if the plan is to keep burning fossils then that's bonkers. The only relevant use cases IMO are vehicles that need the increased energy density for routine long hauls like trucks, and/or have necessarily tight margins like aircraft. As much as I love my current petrol Mondeo, when it expires my next vehicle will absolutely be full electric (although not a Tesla).

There are a number of things in comics universes that are effectively magic. Like punching or throwing things without equal and opposite reaction. In reality he would leave a brightly glowing fireball, but if he doesn't then just chalk it up as one of his necessary secondary powers

There's no surprise that with how late they started HLS it's not ready, and there's no reason to think anyone else would have done better. That said, HLS isn't the only source of the delays, because even if that was ready to go the space suits aren't. Both programmes started (and restarted) far too late.