Exoscientist

Actually, that relight lasted only about 2 seconds. We don’t know if the relight was planned to last that long or SpaceX ended it early or it ended itself because it failed. If SpaceX wants to prove the Raptor can relight reliably they need to redo another Starship landing test and ensure you get relights with no engines leaking fuel and catching fire for the full length of an actual burn. As I said SN15 still had a fuel leak and engine fire on relight. Bob Clark

You can’t ignore a major issue for Raptor engine reusability. If the Raptor can not be made to relight reliably then reusability absolutely can not work. After SN15 test where it managed to land without exploding, SpaceX called the landing tests successful even though there was still a fuel leak and fire on relight, and conducted no more landing tests. Based on the Starship landing tests, a Raptor always leaked fuel and caught fire after a relight. Based on actual SuperHeavy/Starship flights a Raptor always fails at some point after relight, whether or not a fire and RUD occurred. In fact, SpaceX still has not proven the Raptor can reliably relight while in flight without failing. Bob Clark

It should be noted the Starship during tests of the landing procedure, that at least one Raptor always leaked fuel and caught fire. Note even in the last two shown here, SN10 and SN15, there were engine fires on landing. For SN10 the engine fire led to the vehicle exploding a few minutes after landing. For SN15 the fire was extinguished before it caused an explosion. SN15 was called a “successful” landing test because it did not explode. But a Raptor still did catch fire also during this test requiring a relight. And SN11 experienced a catastrophic explosion after a fuel leak and engine fire after engine relight: . Bob Clark

Yes, but the losses during reentry were quite substantial. By the way it might be possible to get a Starship that doesn’t even need thermal tiles. The idea is you could have wing loading, vehicle weight per wing area, so small that reentry speed is reduced sufficiently that the metal skin can survive the reentry heating by itself. See discussion here: Reentry of orbital stages without thermal protection? UPDATE: 7/1/2019 https://exoscientist.blogspot.com/2019/06/reentry-of-orbital-stages-without.html BUT for this to happen you would need Starship to have the quite low dry mass speculated upon by Elon of only 40 tons: Bob Clark

Actually, we do know definitely that the engines did not all relight during the landing burn for the booster. That proves something went wrong at this relight, and the damage could even have occurred during the first relight during boostback except that burn was not long enough to cause loss of vehicle. If something goes wrong with the engines during flight, and it is a known problem to have occurred before during testing the first thing to suspect is that same issue is occurring again. Bob Clark

Congratulations to SpaceX on successful ascent firings of both stages. However, Angry Astronaut noted, it is likely the problem of the relight of the engines of the booster for landing was due to the hot staging method. Another possibility is the Raptors has had continuing problems on relight during the Starship landing tests where one or more Raptors leaked fuel and caught fire. Even the landing test called successful, one of the Raptors still leaked fuel and caught fire. I just saw that SpaceX has decided not to try the engine relight test during the Starship return, which does support the idea there are still problems on relight of the Raptors. Bob Clark

Yes. The plug nozzle, variously called the aerospike and aeroplug, was known about since the early days of the space program. Bono’s innovative idea was to use to it deal with the heating during reentry. The plug nozzle then to Bono had two benefits. It would improve engine performance for a SSTO, or a near-SSTO that used drop tanks, whose engines had to fire efficiently from sea level all the way to orbit and would solve the problem of the reentry heating for that stage returning from orbit. It was the reentry thermal control purpose for the plug nozzle for which Bono was granted the patent. If you look at the interviews of Andy Lapsa of Stoke Space such as by Everyday Astronaut and NasaSpaceflight it is this purpose for which Stoke Space is praised for their “innovativeness”. My opinion, Phil Bono should have been given credit for this innovation. Bob Clark

China will launch giant, reusable rockets next year to prep for human missions to the moon. News By Jennifer Nalewicki( livescience.com ) published 2 days ago China's new jumbo-size, reusable rockets are part of the country's plans to send humans to the moon by 2030. https://www.space.com/china-reusable-rockets-human-moon-missions This rocket the Long March 10 can get 70 tons to LEO, or 27 tons to TLI. The article only mentions this rocket doing a circumlunar flight but it might actually be able to launch a manned lander mission Robert Zubrin with his Moon Direct plan noted a manned lunar mission could be launched by the Falcon Heavy: Op-ed | Moon Direct: How to build a moonbase in four years Robert ZubrinMarch 30, 2018 https://spacenews.com/op-ed-moon-direct-how-to-build-a-moonbase-in-four-years/ Key for his plan is using a “lunar exclusion vehicle” (LEV) of ca. 12 ton gross mass that is hydrolox powered as a lunar ascent vehicle. This would require near zero-boiloff tech, but Zubrin thinks this is doable with current tech. Zubrin would also use a larger hydrolox stage for the lander descent stage at ca. 40 ton size, a bit smaller than Centaur V, that could deliver either the 12 ton manned LEV that could return to Earth orbit, or 12 tons of cargo one-way to the lunar surface. Quite notable about his plan is the manned flights it would require a single Falcon Heavy stage as the launcher to get the hydrolox in-space stages to LEO. The FH has a payload capacity of 63 tons to LEO. So an only 63 ton launcher could get the required in-space stages to LEO, which could then do a manned round trip flight to the lunar surface. This small size for the launcher is coming from the fact the in-space stages are so much lighter being powered by hydrolox. The Falcon Heavy is not man-rated so you would need an extra man-rated launcher like the Falcon 9 to get the astronauts to LEO. But the Long March 10 would be man-rated so could carry the astronauts to orbit. So it could do a manned landing mission in a single launch if hydrolox lander stages like in the Zubrin plan were included. Bob Clark

I noticed those Australian patents didn’t mention Bono’s name. I looked at Stoke’s U.S. patents. They also didn’t mention Bono’s name. In academic circles, you write a thesis or research work. You present it as your own work, but it was copied from another author or researcher. In academic circles, that is commonly ascribed a word beginning with the letter “p”. But suppose that earlier author is long dead and his copyrights expired. Should it still be ascribed the “p” word? Bob Clark

By that argument SpaceX should never have developed reusable boosters. Some such as ULA’s Tory Bruno are still saying its not worth it. Bob Clark

Actually it is worth it. Rather than the expensive and uncertain development of a full-flow staged combustion engine, they could accomplish the same thing far more cheaply by using the same multiple thruster around a central plug technique they are using for the upper stage, except with dense propellants. BUT this time they would actually use the altitude compensating effects of the plug nozzle. SpaceX has been developing the FFSC Raptor since 2016, and it is still not reliable enough to be considered an operational engine. It is said the SuperHeavy/Starship development cost has been in the range of $5 to $10 billion. Note then typically for a new launcher development using a new engine, the engine development costs make over half the entire development cost of the rocket. So likely SpaceX has spent billions overs those years since 2016 developing the Raptor. Bob Clark

My point is he did use the altitude compensating effects of the plug nozzle to improve performance. The increase in performance also applies to two-stage vehicles because it increases the performance of the first stage. See Bono’s ideas for SSTO discussed here: One Giant Leap: Philip Bono's ROMBUS. Updated: May 17, 2023 https://www.spaceflighthistories.com/post/rombus In any case, it is considered bad form in academic circles to take credit for something thought up by someone else. Bono is now long since dead, and his patents have expired. Undoubtedly though, Stoke Space in seeking funding believed it more attractive to their prospective funders to pass off Bono’s ideas as their own to get higher estimation of themselves in the eyes of the potential investors. Bob Clark

I’m a little annoyed with Stoke Space they didn’t credit Phil Bono who came up with the idea of using a plug nozzle for thermal shielding during reentry: https://twitter.com/rgregoryclark/status/1677672260159561729 By not crediting Bono they are missing a key aspect of his proposal: Bono wanted to actually use the altitude compensating effect of the aerospike/aeroplug. Stoke Space is ignoring that aspect of his proposal. But by ignoring that they are missing a key advantage of this type of nozzle: the aerospike/aeroplug is even more effective for first stages. Their plan is to use standard, fixed bell nozzles on the first stage with full-flow staged combustion engines: https://www.stokespace.com/rocket/ But actually altitude compensating nozzles such as the aerospike, among many other different kinds and types, can get even better performance than staged combustion engines and are far cheaper. Remember SpaceX with billions of dollars at its disposal still hasn’t gotten the Raptor to operate reliably. Since Stoke is already using a multi thruster plug nozzle for its upper stage, Stoke could be making concurrently a multi thruster plug nozzle for the first stage, except dense propellant rather than the hydrolox used on the upper stage. In fact since dense propellants are easier to work with than hydrolox, the first stage could even have been ready earlier than the upper stage. Robert Clark

The first listed call for proposals called THRUST! seeks proposals for staged combustion engines. But in point of fact altitude compensation can accomplish the same thing at far lower cost: Altitude compensation is more efficient than staged-combustion engines. https://exoscientist.blogspot.com/2024/02/altitude-compensation-is-more-efficient.html Bob Clark

A counterintuitive result: partially reusable SuperHeavy/Starship can get same price per kilo as fully reusable one IF an expendable Starship can get 40 ton dry mass: SpaceX should explore a weight-optimized, expendable Starship upper stage. https://exoscientist.blogspot.com/2024/03/spacex-should-explore-weight-optimized.html This is because of two reasons: 1.)a 40 ton expendable Starship compared to a 120 ton reusable one means you get 80 tons extra payload, and 2.)making the first stage reusable is more important because, like with the Falcon 9, the first stage makes up 2/3rds of the cost anyway. cf., https://twitter.com/elonmusk/status/1111798912141017089 Bob Clark

Looks like India will have the next manned space program beating the Europeans: Bob Clark

Looks like India will have the next manned space program, beating the Europeans: Bob Clark

By “next” manned launcher, I mean the next space agency in the world to achieve manned spaceflight after the Russians, Americans, and Chinese. By the way, I looked up the Apollo Command capsule and found that the capsule itself without the service module only weighed 5,800 kg. The Apollo service module provided the propulsion for entering and exiting from lunar orbit and wouldn’t be needed for missions just to LEO: COMMAND MODULE Crew size: 3 Length: 3.5 m Maximum diameter: 3.9 m Habitable volume: 6.17 m3 Total mass: about 5,806 kg (structure 1,567 kg; heat shield 848 kg; reaction control system 400 kg; recovery equipment 245 kg; navigation equipment 505 kg; telemetry equipment 200 kg; electrical equipment 700 kg; communications systems 100 kg; crew seats & provisions 550 kg; crew mass 216 kg; misc contingency 200 kg; environmental control system 200 kg; propellant 75 kg) Reaction control system thrusters: 12 x 410 N propellant: NTO/MMH specific impulse: 290 s total impulse: 257 kNs L/D hypersonic: 0.3 Power: Ag-Zn batteries; 3 × 40 Ah each, 28 V DC; 3.4 kWh; inverters produced 115 V AC Environment: pure oxygen at 340 mbar http://www.braeunig.us/space/specs/apollo.htm Also, surprising is how little mass is required for the environmental control system, at only 200 kg out of the 5,800 kg. Bob Clark

Friday’s H3 test launch was a success. This H3 version used two core engines and two solid side boosters. But JAXA also plans a version with three core engines and no side boosters. This all-liquid version will have a payload of 4 tons to SSO, sun-synchronous orbit. Payload to LEO is generally 50% to 60% higher, so the 3 engine no SRB H3 will have approx. 6 tons to LEO capability. This would have the capability of launching a Gemini class capsule to LEO, which had a 3.8 ton mass. An all-liquid H3 for a manned launcher would not have the safety issues of using solid rockets. Europe and India are racing to have the next manned orbital launcher. Japan should join the race. Bob Clark

So far three companies seem to be in the lead for the European cargo capsule, the Nyx capsule leading in its development. The Exploration Company was already well into development of their Nyx cargo capsule before the ESA announcement. They plan to launch a 20% scale version on the Falcon 9 this year, with a full scale version to be launched in 2026: News European startup gets $44 million for space station transportation vehicles Jason Rainbow February 2, 2023 https://spacenews.com/european-startup-gets-44-million-for-space-station-transportation-vehicles/ If the launch in 2026 succeeds, I think there is little doubt a crewed capsule development will follow. Keep in mind my thesis is a manned capsule can be developed at a few hundred million dollar range as can a cargo capsule IF following the private funding commercial space approach. The cargo capsules being considered by ESA will have heat shields. Delivering cargo to a space station the cargo capsules will also already have thermal control: when opening the capsule you don’t want space station crew exposed to freezing cold air after the cargo craft is in space for days. Then as far as environmental control for a manned version you just need to add CO2 scrubbers and seating. Then additionally you need to add the launch escape system. The cost for such a pressure-fed rocket system, well less than a full size orbital rocket, would probably be in the tens of million dollars range as privately financed by the commercial space approach. As a point of comparison the development of the Falcon 1 an actual orbital rocket was only about $90 million by following the private financing commercial space approach which included the development cost of the Merlin engine, a more advanced pump-fed engine then the pressure fed Superdracos. Bob Clark

ESA appears now to have a serious aim of progressing to manned spaceflight: ESA Astronaut Samantha Cristoforetti to Lead Agency’s LEO Cargo Return Initiative By Andrew Parsonson - February 8, 2024 In a LinkedIn post published on 7 February, Cristoforetti explained that while her dreams to become an astronaut, participate in a spacewalk, and serve as Commander of the International Space Station had all come true, one big dream remained. “I dream of Europe having its own spaceship, like the US, Russia, China, and soon, India,” wrote Cristoforetti. “I dream of international crews flying to space not only on private US vehicles but also on European ones.” Cristoforetti went on to explain that she had been given the opportunity to be a part of fulfilling this dream by leading the team implementing the LEO Cargo Return Service initiative. https://europeanspaceflight.com/esa-astronaut-samantha-cristoforetti-to-lead-agencys-leo-cargo-return-initiative/ Robert Clark

Key question is how much will they charge for commercial customers? The subsidies will have to be used to reduce the prices charged for commercial customers. Robert Clark

The ESA programs Andrew Parsonson wrote about described here: They are taking suggestions for how to accomplish them. Bob Clark

Rereading that article by Andrew Parsonson. I think he is referring to the methane-fueled Ariane Next program, not a supposed all hydrolox-Vulcain engine version. But interestingly, such a methane-fueled launcher might cost 50% that of the Ariane 6, and thus be competitive with the Falcon 9 prices: Bob Clark

ESA has put out a call for a commercial cargo capsule: ESA to start commercial cargo program Jeff Foust November 6, 2023 https://spacenews.com/esa-to-start-commercial-cargo-program/ They discuss they want a crew capsule to be developed also as a follow up to the cargo capsule. The cargo capsule is expected to be ready by 2027 to 2028. The Maia launcher of MaiaSpace is a Falcon 1 class vehicle using the Prometheus methane-fueled engine. It is expected to make its first test launch in 2025. Now, consider this: the low cost approach to development of SpaceX is well known now, cutting 90% off development costs. Not generally appreciated though is the SpaceX rapid development approach. They went from the first successful test launch of the Falcon 1 in 2008 to the first launch of the Falcon 9 only two years later in 2010. Then I advise MaiaSpace not just emulate the low cost private financing approach of SpaceX but also follow their rapid development approach. If the Maia is successfully launched in 2025, then an upgraded Falcon 9 class version could be ready and launched two years later in 2027. This will be about the time when the cargo capsules will be ready. One more suggestion. SpaceX and now multiple other space startups have shown privately financed launchers can be developed at 1/10th the cost of the usual government financed approach. But SpaceX and Orbital Sciences, now Orbital ATK, showed also with their Dragon and Cygnus cargo capsules respectively, that cargo capsules can also be developed by the private financing approach at 1/10th the cost of the government financed ones, for only a few hundred million dollars. But when SpaceX developed the crew Dragon they took funding from NASA. Suddenly, the development costs ballooned to the billion dollar range. I’m saying it’s because NASA was paying for it that the development costs grew that high. A crew capsule instead following the private financing approach also can be developed at costs in the few hundred million dollars range. Then my suggestion to the European companies developing the cargo capsules is to follow the private financing approach of SpaceX, and also concurrently develop crew capsules privately financed. They each can be developed at costs at the few hundred million dollars range. Then both cargo capsules and crew capsules can be developed by the time when MaiaSpace can have a crew capable launcher ready by 2027. I believe Europe has well enough technical knowledge to advance their own launchers and capsules. The Ariane 5 for many years was the leading launcher for commercial satellites. It was supplanted by the Falcon 9 because SpaceX took the low cost private financing approach and focused on reusability. Europe is now recognizing that is the way to cut costs. My opinion, the new European start ups focusing on the commercial space approach and on reusability will be competitive to the Falcon 9. Note also in regards to capsules, the Cygnus capsule was actually built in Italy by Thales Alenia. Bob Clark