RCgothic

By my count Raptor is coming up on half as many launch and in flight ignitions as Rocketlab's Rutherford by the way. I think Raptor is on 224 counting all of those that started and burned for more than a second from Starhopper through IFT4. Rutherford is on about 490 I think?

I don't know who originally started the "Boeing Astronauts Stranded" line, but it's never actually been the case and it seems like a lot of outlets are just copying the lede and running with it.

Europe clearly needs to do something to compete. But even if they put forward a design targeting falcon-like cadence and reusability, by the time it's ready it'd already be obsolete. Needs a much larger rethink than just producing an all-liquid ariane variant. They need an engine that can be produced at a rate of several per day, with better-than-Merlin levels of reusability, and enough thrust to not need solid boosters for assistance. Hydrogen engines are out on poor thrust and difficulty to refurb (tricky h2 seals). Kerolox is out because of coking. So they probably need a methalox engine as a starting point

Because it can't be fixed or adequately preserved and will inevitably disintegrate, posing a hazard to all spaceflight in it's orbit and nearby orbits. Far better to end it decisively.

Superdracos would break the ISS into bits. It'll be standard Dracos.

Speaking of: https://arstechnica.com/space/2024/06/mere-days-before-its-debut-the-ariane-6-rocket-loses-a-key-customer-to-spacex/ Even government payloads not safe for Ariane it seems.

Lol, Europe doesn't have a rocket market anymore. There'll be a few mandatory government payloads and that's it. Ariane 6 won't be competing with Starship because it can't even compete with Falcon.

The header tanks also have helium COPVs for pressurisation. But also it's probably not safe for NASA to sell the ISS. It's a station that's getting gradually more decrepit and can't reasonably be fixed. If a private entity ended up getting someone killed, NASA could be liable.

Sometimes it's acceptable to just accept the remote chance of a fault because covering it off completely would be grossly disproportionate. The chances of a well-designed cable breaking in normal operation are remote. So we're talking fault cases. What sort of faults could be encountered in interplanetary space? Micrometeoroid impact? And the chances of that severing all the strands of a cable are? If the strands are cross-coupled every so often the broken end wouldn't even rebound especially fast. Any strike large enough to take out multiple strands would probably be a LOCA in the far higher probability of striking the main spacecraft anyway. Any other plausible fault cases? I'm struggling to think of any

Also the gas will be colder by the time it reaches the main tank and less useful as pressurant.

SpaceX appear to be preparing a simulated tower catch.

And for all you know a Merlin (most reliable rocket engine in flight hours ever by a long margin) would have exploded in those circumstances as well. Pretty much every instance of engine-out so far on Starship/Superheavy appears to be some form of "rocket failed to provide the engine with acceptable/survivable operating conditions". A rocket needs to be looked at holistically. Is direct exhaust autogenous pressurisation turning out to be harder than expected? Possibly. But heat exchangers are also massive and complicated and need to move enormous quantities of liquid through a phase change, so we may not yet have reached the point where "stick more filters on it" isn't a better solution. For context, each of the steam generators on a nuclear reactor are about half the size of the reactor vessel itself, and there are typically 2-4 of them.

Part two of Tim's interview with Musk is up. Notably it was only the front-right flap that really let go, they can tell by the deployment data. That one was fully deploying, the other 3 more nominally. Also where the tiles were missing on the skirt, seems 2 layers of backup ablative didn't burn through, one layer did but not clear that the steel also failed, might have survived. They don't even need infra-red cameras for seeing the hotspots internally, they glow in the visible spectrum.

Although I have many, many criticisms of Musk, as a chartered engineer myself "not being a proper engineer" isn't one of them. By all appearances he has as much of a grasp of technical details as top engineers for a nuclear power plant. There are many decisions that get made during the design process of any system, and they're not always good ones. Iteration is part of the process. The only difference with SpaceX is that we see the iterations happen publicly in hardware rather than purely in private sim.

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.