RCgothic

Won't have a lot of impact. They basically wanted to eliminate a stage separation mechanism which would need to be pretty chunky to push away a 1500t upper stage. First attempt was flip staging, where the booster main engines induce a spin that causes centrifugal force to separate the stages. They would have attempted this on OFT-1, but didn't get that far. There was some confusion on this point due to the loss of control and tumbling. Since OFT-1 they've changed their mind and are now doing hot staging. This could save a little DV as there is no coast phase for Starship, and the repulsion of the booster by exhaust gases could save it a little bit of DV on the boostback burn. The drawback is that the engines, engine bay and interstage take a much harsher beating.

Full stack! Also that's some nice heat shielding under S25. Was S24 the same?

The point being that without foundations such a skin could break under weight of thrust resulting in the pad being excavated and throwing debris at the lunar craft resulting in LOCV.

One plan for lunar landing pads I'd seen was to coat the surface with adhesive. This would be like a thin concrete skin over zero foundations. Yeah, good catch Dr Metzger!

I'd give odds of 4:1 that the FAA approval comes through just when SpaceX need it to, like it has every time so far.

The midbay has been demolished. RIP midbay. Demolition in progress:

Flame trenches are primarily to direct the exhaust away from the vehicle and to prevent damage to the vehicle. Although there are examples of the refractory brick lining of flame trenches being damaged by rocket exhausts, that's an example of the sort of scouring effect SpaceX were expecting and prepared to put up with for one launch. The Russians don't to my knowledge use deluge systems, even for the large rockets N1 and Energia. The pads at LC39 only had a minimal system for Saturn V, and it was upgraded for shuttle because of damage to the vehicle. The exhaust didn't seriously threaten the flame trench which was built for Nova, and the OLM at Boca Chica is taller than the flame trenches at LC-39 by a long way. A large rocket had never before now cracked and excavated its own launch pad foundation through weight of thrust.

Space is hard and even people who know what they're doing won't get it right 100% of the time. Has there ever in history been a case of rocket thrust so great it breaks a foundation before now? No. That was pretty unexpected. Have they fixed that problem? By all observations they've taken the problem seriously and rebuilt the pad so that won't happen again.

The new foundation isn't going to fail again. It's over two meters thick reinforced concrete capped with steel and with many more support pilings than previously. Even absent the deluge system it wouldn't be going anywhere.

Comment on Reddit supposedly from an insider: https://www.reddit.com/r/spacex/comments/15m3r9k/starship_development_thread_48/jxqawab?utm_source=share&utm_medium=android_app&utm_name=androidcss&utm_term=1&utm_content=2

Full duration was ~6s, sounds like at least 31/33 made it that far.

The 6 Apollo landings highlighted:

Booster 9 had a spin prime last night at 8:11pm.

Falcon heavy should be able to send about 20-22t to TLI direct, which is a few tonnes more than F9 has demonstrated. The difference is presumably not insurmountable. But the full 63.5t is probably going to need to include propellant residuals, so no sticking 60t additional stages on top of FH. 20t to TLI is enough to brake 17t into NRHO, which is more than the 13t Orion can ever comanifest to NRHO. SLS Block 2 Crew could technically comanifest about 16.5t to TLI, but it would result in a rather radical flyby manoeuvre. SLS Cargo is never going to be a thing. SLS is overpriced for crew, nevermind cargo, and the crew program can't spare any. So the biggest payloads it's ever going to loft are going to be comanifested alongside crew. Whilst these could technically be wider than a falcon payload, all the illustrated comanifest payloads I'm aware of would fit on a Falcon. In fact I think FH is sending two of these at once. So the only remaining niche of SLS is "doesn't need a propulsion module on the payload" as if such modules weren't common and robotic docking wasn't a solved problem that doesn't need an extra $3.5B and an astronaut crew mission. And all of this presupposes no LEO rendezvous (FH 32t to TLI) or Superheavy (150+t to TLI).

We absolutely could have built an LEO rendezvous lunar architecture around F9/FH/Delta IVH/FH/Vulcan/NG. And it turns out that's actually what they're doing for the 2 HLS Landers, so SLS is completely redundant. Just attach Orion or preferably an uprated dragon or starliner to one of the HLS transfer stages and be done with it.

Having a further thought, 127 is the maximum number of games in 8 rounds if every team loses once in the first 2 rounds, but the maximum number of rounds is greater. 2 rounds to eliminate 32 who lost twice. 2 more rounds to eliminate 16 2 more rounds to eliminate 8 2 more rounds to eliminate 4 2 more rounds to eliminate 2 Best of 3 rounds to eliminate the last 1 because neither team has lost until the final. The maximum number of rounds to played by the winning team is 13 and the total number of matches is still 127. Crazy that it comes out to the same number of matches, but now I think about it further I guess it has to. Everyone has to lose twice except the winners who may or may not lose once. That's 126 or 127 matches.

R1 is 32 matches. 32 teams lose but are not eliminated. R2 is 32 matches. 32 teams can lose and not be eliminated. Now every team has lost one and a standard elimination ensues. R3 eliminates 32. R5 eliminates 16. R6 eliminates 8. QFs eliminates 4 SFs eliminates 2 F eliminates 1 Total matches are 127 max. I'm not sure what relevance the 10 at a time has except to extend the time this takes.

The tarp is just to keep dust and similar out of the deluge system whilst they're working, it's not especially significant.

It's been reported on Reddit that Booster 9 has been photographed with its hot stage ring installed. Credit to RGV Aerial Photography.

As a nuclear power plant engineer I didn't continue reading past the fictional material. But IRL the answer is: no. Fusion involves getting at least one positively charged nuclei going fast enough that it can overcome electrostatic repulsion and get close enough to another nucleus that the very short ranged nuclear strong force can come into play. Incidentally the reason is easier to use deuterium and tritium for fusion is that they the highest mass to charge ratio of any element and are therefore the easiest to get to collide. Beyond this there are no shortcuts.

A few days ago now SpaceX filed the IFT mishap report. There's no particular detail reported about what's in it or what corrective actions need to be taken before the next flight. https://www.google.com/amp/s/arstechnica.com/space/2023/08/let-the-review-begin-spacex-takes-another-step-toward-launching-starship-again/amp/ To recap here are the areas I think need improving: 1) The pad didn't withstand launch. This is the area that's had the most obvious improvements in foundations and deluge system. 2) FTS didn't work as planned. The next flight will have longer det cord and more FTS units. 3) Hydraulic failure of TVC. B7 was the last booster to use hydraulic TVC, is electric from here on out. 4) Engine/plumbing reliability. They're always working on it. Possibly some ways still to go with recent static fire aborts, but it's not clear B9 is the latest state of the art or had the most recent raptor versions, so it's hard to read too much into. Even if they're not the nearest however, the B9/realtor combos will need to be good enough for flight. 5) Engine shielding/isolation. Apparently the engine protections were patched onto B7, and B9 and later are better. If there is a problem in flight like with B7 it should be better contained.

I can see the tweet that's linked but it won't load any others on my mobile browser which is 99% of how I view the internet.

Care to enlighten those of us without X?

The engine plumes won't directly impinge on the centre of the spray pattern. The water does get to full height before engine ignition, but if it isn't a problem before ignition it won't be after a supersonic flow is acting like a repulsor.

Yes, I've calculated each phase of flight separately. It takes ~8.5t of propellant to get Orion/ESM/lander through LLOI starting from 43t wet (SLS B2 Crew's max advertised TLI throw). Orion/ESM needs some margin for free flight, docking, rendezvous, mid course corrections (both ways). Call it ~100m/s and that uses 0.7t of prop. 4.4t is needed to get Orion/ESM through TEI. That's 13.6t in total, which is an 4.6t extra the ESM needs to carry above its 9t design value. An extra 4.6t of propellant needs ~400kg extra tank mass to support that, and that's been added to the 17.5t original dry mass to give 17.9t, the figure I've used in each phase of flight. And there's also some sums to make sure a 11.5t 2-stage lander can land and return. Lander gets ~2t of non-engine & propellant tank mass to support comms, power, and a single astronaut. Landing needs more margin than SSTO and rendezvous/docking which nominally takes 1730m/s each way. For safety either Orion or the lander ascent stage should be capable of being the active vehicle during rendezvous and docking.