RCgothic

Raptor doesn't use ablative cooling. Other than being non-reusable, Ablative cooling is generally negative on performance. The extra mass is heavy and as the nozzle throat erodes the engine loses expansion ratio.

An engine that melts at 340bar and 250tf thrust will be fine at 320 bar and 230tf thrust. And in the mean time the collected data from multiple firings will help them progress a solution.

That's better! Now properly embedded. Basically the remaining wires are going, and aspirationally there'll be a 250tf variant by year end.

https://twitter.com/elonmusk/status/1492050352664887315?s=20&t=DB7zfu9rbVJUilFqa5mORA https://twitter.com/elonmusk/status/1492050572505137161?s=20&t=DB7zfu9rbVJUilFqa5mORA Urgh, these aren't embedding properly.

Yeah, but the rats' nest on R1 was significant. I wouldn't be surprised if R2 were over 10% lighter overall. Edit: For comparison, if Blue Origin were to build a 10 diameter (approx outer diameter of Superheavy outer engine ring) vehicle, they could fit perhaps 12 fixed and 3 or 4 gimbaling engines with a total of 3914tf thrust. That'd barely more than half the mass of a Starship Superheavy stack at the same TWR, and because the ISP is lower and each engine is individually heavier than the equivalent raptor it would be even less capable than that. Raptor is an incredible engine.

Peak raptor thrust in testing of 247tf thus far is a truly ridiculous figure from an engine that size. R2 being significantly smaller than R1 won't hurt the TWR either.

From reading the report, JET first operated in 1997 and one of the results was an issue with the lining. ITER was designed and built off the back of those results. That process took 25+ years. (ノಥ,_｣ಥ)ノ彡┻━┻ But meanwhile JET was still available, so they tore down the lining and tested the new design. It worked. ITER would have been in peril if it hadn't. So not a breakthrough exactly, but a verification of an intended upgrade.

https://arstechnica.com/science/2022/02/heres-what-im-hoping-to-learn-from-this-weeks-starship-presentation/?comments=1 New article on Ars as a primer ahead of the presentation.

It's that time of the month when SLS is delayed another month again. I had been starting to think SLS would launch before Superheavy.

And design and build a payload dispenser that's easy to load and deploy through whatever door they end up with.

That's not exactly encouraging at this point.

The Lunar Starship is still being referred to as HLS in official statements. If the thread is to be renamed I'd suggest "NASA HLS and LETS"

I believe a little bit of ash in the air/in the ground isn't a big deal for landing radar. The main problem for airplanes is ash ingestion by air-breathing engines.

Yep. It doesn't have any internal consistency. Sci Fi writers and effects artists have no sense of scale.

I believe the "official" explanation is that the streaks are interstellar dust interacting with the deflector and warp fields. Warp 9.99 is roughly 10,000 times faster than light. At that speed it'd still take nearly 3.5h to reach Alpha Centauri from earth. 1 star every 3.5h does not a blizzard of warp streaks make. Warp 9.99 is supposed to be *fast* in universe. The Enterprise D cannot acheive warp 9.9 under its own power.

What @Elthy said. Personally I'm torn between: "A big volcanic eruption that cooled the earth would buy us a couple more vital years to get our act together" and: "Any source of short-term cooling will be used by climate denialists to prevent us getting our act together."

I don't think they'll catch over the mount. They'll almost certainly catch to one side.

It's that time of month where SLS is delayed another month again.

No, it would be possible to see by starlight. Just as you would on a desert. The reason why it's generally not possible on a spacecraft is because of the presence of very bright sunlit objects in the frame of the camera. Dynamic range is an issue. But on a spacecraft entirely shaded by a sunshield that wouldn't be a problem. You could see by starlight just fine.

I believe they baselined 25.5m/s for observations, and that would be sufficient for 10 years of observations in random directions (fuel can be saved by momentum-conserving manoeuvres). https://www.reddit.com/r/spacex/comments/r616aw/comment/hqq67z3/ 66.5 m/s were reserved for the first couple of mid-course corrections. Of this budget they've managed to conserve ~38m/s so far. This would imply a life on the order of 25 years, bar any fuel saving exercises. If JWST has 93-150m/s in total then there could be up to another 57m/s available additional (+~20y). Some of this may be consumed in commissioning exercises, but even so this is very good. Initial estimates of 5y life appear to have been extremely conservative!

Another reason is a high water table isn't conducive to flame trenches. I believe they're also trying to get by without a blast deflector, although not sure why given it's a relatively cheap and easy addition.

I think there's a second tile that looks weird about 2/3rds of the way from rear from to top fin, underneath the other one that fell off.

(╯ರ ~ ರ)╯︵ ┻━┻ Welp, I suppose that just guarantees Starship will be ready to fly by the time the environmental review comes through.

LUVOIR-A at 15.1m was baselined for a Starship/SLS B2 Cargo size fairing, so that would be contemporaneous with upcoming vehicles. LUVIOR-B at 8m was baselined for current vehicles. LUVOIR/HabEx as recommended by the decadal survey is smaller still at 6m. So this is going backwards. IMO they should be counting on an 8m fairing minimum (SLS B1B Cargo/Starship) and up to 15m notional fairing.