Exoscientist

Flames can be seen coming out at the location of the aft flap hinge. The relative location of the hinge can be seen here: It appears to be below the rear tank dome and somewhat above the engines. This though doesn’t mean the leak and fire didn’t originate at the engines, but it could be that the flames become visible there outside because the hinge was the easiest point for the flames to escape. SpaceX should release any imaging inside the engine bay while the engines are firing. Bob Clark

I would say SpaceX doesn’t want to release images damaging to the idea the Raptors are reliable. For instance it still it did not release images of what happened at the end of the ocean touchdown of the booster IFT-4, when it was clear it exploded. And it has not said anything about the Raptor that exploded on the booster during the IFT-4 landing burn. It could dispel concerns the Raptor is still leaking and catching fire by releasing engine bay views of the booster and ship while the engines are firing, most specifically during the booster landing burns and the ship burns in this last flight. By the way, that Elon is apparently so sanguine about fires appearing in the engines bay in Starship raises questions if it is indeed the case fires arise in the engine bay during the booster landing, but SpaceX doesn’t care because they are “controlled”, so far. Bob Clark

There was no other reason for responding to this specific post of yours than you mentioned Discord. So I wanted to find out if that question was discussed on there. I don’t know which specific Discord forum this is. It wasn’t related to the cost issues. I’d like SpaceX to release those engines views it has available during the Starship engine firing, not just before, that clearly would be important for diagnosing the origin of the leak. Bob Clark

What’s the scuttlebutt on Discord and on Forum.NasaSpaceflight.com about the origin point of the leaks in the Starship in the last flight, the engines or the plumbing? If it were the engines then that is concerning because leaking Raptors was a focal point from the FAA after a prior failure in regards to items SpaceX needed to fix. The Raptors should not be still leaking fuel and catching fire this late in their development. There is no doubt that SpaceX knows the origin of the leaks. During the prior tests of the Starship landing procedures there were cameras in the engine bay that were able to image leaks when they occurred: What Happened to Starship SN11? | SpaceX Starship SN11 Test Flight & Explosion Cause Analysis. https://youtube.com/clip/Ugkx5eG9w2IgvyX_3yKJea8kUCbYcrNHpF1F?si=OYbJQXNgy-CbuguI There is no doubt such cameras are still in the engine bay during the Superheavy/Starship test flights. Bob Clark

This employment posting suggests they are considering 9 engines: Bob Clark

Bob Clark

It’s pretty clear they need to bump up the thrust. The easiest way to do that is add engines. SpaceX adds and subtracts number of engines to either stage of SuperHeavy/Starship like it’s a walk in the park. Increasing thrust to an engine in contrast involves significant engineering work. I wonder if Blue Origin didn’t go with 9 engines from the start just because they didn’t want to be seen as copying SpaceX. In any case, the low 25 ton payload they have now is probably because of that low TWR. If they want their planned 45 tons reusable, they’ll need that thrust upgrade. Bob Clark

FAA grounds SpaceX’s Starship after midflight explosion, reports property damage on Turks and Caicos. PUBLISHED FRI, JAN 17 20251:46 PM ESTUPDATED 6 HOURS AGO. SpaceX initially published a statement on its website Thursday that Starship debris fell “into the Atlantic Ocean within the predefined hazard areas,” seemingly contradicting the FAA’s explanation for why a “Debris Response Area” was activated. As of Friday morning, the latest SpaceX statement did not include that specific language. The company’s website said more broadly that “any surviving pieces of debris would have fallen into the designated hazard area” after the failure. The FAA, in response to CNBC’s request for clarification on whether Starship debris landed outside the predefined hazard area, reiterated that its “information is preliminary and subject to change.” SpaceX did not respond to a request for comment. https://www.cnbc.com/2025/01/17/faa-grounds-spacex-starship-reports-property-damage-in-caribbean.html Bob Clark

I like this review of the Raptors by Ultimate Steve: I agree with him that an engine not starting or not completing its burn counts as an engine failure. In addition to those he mentions, it is almost a certainty that a Raptor actually exploded during the landing burn on IFT-4, but SpaceX still has not come clean on this: Given that SpaceX has not been open about what happened during this prior landing burn, and given the Raptors prior history of leaking fuel and catching fire in flight, I consider it likely the flames seen shooting out the sides of the booster during both tower catches actually arose from Raptor fuel leaks. Consider, that giant 25 meter, 80 foot, tongue of flame shooting up the side of the booster during the prior catch was quite surprising and puzzling. Yet, SpaceX has said nothing about it. It's like they are acting like it never happened. That doesn't inspire confidence that it was something planned. Robert Clark

Flames were seen shooting out the side of this booster like during the last booster catch. Everyone ASSumes it’s just venting. But nobody asks SpaceX and SpaceX ain’t telling. ( And we all remember the warning about what can happen when you ASSume.) In view of a Raptor leaking fuel and exploding on the ship on this flight, and Raptors previously leaking fuel and catching fire in flight, the question should be asked: were the flames seen shooting out the sides of the booster during landing burns, including ones without a catch attempt, due to fuel leaks on the Raptors? A little vignette when it does come out there were fuel leaks during the landing burns, and these things always do come out: Space journalists: Why didn't you say fuel leaks were the cause of the flames shooting out the side of the booster during the landing burns? SpaceX: you never asked. Bob Clark

New Glenn must be underpowered as indicated by its too slow lift-off acceleration. NasaSpaceFlight commenters during their livestream said it so slow they thought it might not even complete the launch. Mystified why Blue Origin would even field it when they must know from the start they would have to upgrade engine thrust or number of engines. They should have done that from the beginning. The 4.51 million pound thrust in the first image is 2,050 tons, or 290 ton thrust per BE-4 engine, a 16% upgrade over the current BE-4’s 250 ton thrust. Upgrading to 9 engines using the current BE-4’s would be a 28.5% upgrade in total thrust. I’d go for the 9 engine upgrade. Gives even greater capability when you also upgrade BE-4 engine thrust, possibly reaching Saturn V 100-ton to LEO capacity. It could do single launch Moon missions.

Agree or disagree: it was a mistake for SpaceX to follow the failed N-1 approach to testing Starship. A Raptor failed both on the booster and on the ship, and on the ship one failed catastrophically. How many total test flights needed now just to make orbit with high payload? 10? A dozen? How many total to prove Raptor reuse reliability? 15? How many total to prove orbital refueling? 20? In contrast standard industry practice is to construct a separate, full test stand to do full up, full thrust, full duration testing. Done this way at least Starship could be doing expendable flights already by now, and with paying customers. Even Raptor reuse reliability could have been tested on the full test stand, providing a faster route to Starship reuse. The comparison of the Superheavy/Starship to the N-1 rocket has been claimed invalid as N-1 rocket engines could not be tested individually, whereas the Raptor engines are. But note a key fact: even when tested, Raptor engines still fail at high rate: SpaceX should withdraw its application for the Starship as an Artemis lunar lander. It is my contention the attempt of SpaceX trying to reach a 2025 deadline to have the SH/SS flying and with multiple successful test flights completed puts undue pressure on its normal safety procedures. For that reason my opinion is it should withdraw the Starship for consideration as a lander for the Artemis III lander mission. http://exoscientist.blogspot.com/2023/08/spacex-should-withdraw-its-application.html Robert Clark

Traditionally in the industry, individual stages are tested for full up, full mission length, full power burn on the test stand. Bob Clark

Thanks for that. That’s a pretty detailed appraisal of the test flights in regards to the Raptor. I have mentioned this before, but I really do not like this approach SpaceX is taking by testing Raptors all together for full mission burns only in flight tests. The typically way this is done in the industry is you construct a separate test stand for the full stage burn. And you test that over and over until you are confident all engines can burn reliably for the full lengths of the full mission burns. A separate full up test stand is an extra expense, but these now 7 test flights without an operational paying flight yet aren’t cheap either. An estimate is ca. $100 million construction cost for Superheavy/Starship, so ca. $700 million just in construction costs. When you add on operational costs this could total over $1 billion. A full up test stand would not have cost that much. Bob Clark

The proof is in the pudding, as they say. Two key things to look out for is how well the single reused engine performs on this flight, and how many engines from this flight will be reused on the following one. Robert Clark

IF it is scrapped would that include the engines? That would not speak well toward Raptor reusability. Bob Clark

But the one being now flown is essentially the same as flown last time. It would be a great proof of of reusability if the same engines were used. Bob Clark

There appears to be only two possible reasons for this: either the Raptor is not as reliable for reusability as thought or it was damaged during the landing burn. Bob Clark

That was for a crewed mission to another star system, tens of trillions of kilometers away. But the primary focus of this new research is for missions still in the Solar System, 1/10,000th the distance, with cubesat-like probes. Here’s the published report by Rene Heller et.al.: Low-cost precursor of an interstellar mission. René Heller1,2, Guillem Anglada-Escudé3,4, Michael Hippke5,6, and Pierre Kervella7 ABSTRACT The solar photon pressure provides a viable source of thrust for spacecraft in the solar system. Theoretically it could also enable inter- stellar missions, but an extremely small mass per cross section area is required to overcome the solar gravity. We identify aerographite, a synthetic carbon-based foam with a density of 0.18 kg m−3 (15 000 times more lightweight than aluminum) as a versatile material for highly efficient propulsion with sunlight. A hollow aerographite sphere with a shell thickness εshl = 1 mm could go interstellar upon submission to solar radiation in interplanetary space. Upon launch at 1 AU from the Sun, an aerographite shell with εshl = 0.5 mm arrives at the orbit of Mars in 60 d and at Pluto’s orbit in 4.3 yr. Release of an aerographite hollow sphere, whose shell is 1 μm thick, at 0.04 AU (the closest approach of the Parker Solar Probe) results in an escape speed of nearly 6900 km s−1 and 185 yr of travel to the distance of our nearest star, Proxima Centauri. The infrared signature of a meter-sized aerographite sail could be observed with JWST up to 2 AU from the Sun, beyond the orbit of Mars. An aerographite hollow sphere, whose shell is 100 μm thick, of 1 m (5 m) radius weighs 230 mg (5.7 g) and has a 2.2 g (55 g) mass margin to allow interstellar escape. The payload margin is ten times the mass of the spacecraft, whereas the payload on chemical interstellar rockets is typically a thousandth of the weight of the rocket. Using 1 g (10 g) of this margin (e.g., for miniature communication technology with Earth), it would reach the orbit of Pluto 4.7 yr (2.8 yr) after interplanetary launch at 1 AU. Simplistic communication would enable studies of the interplanetary medium and a search for the suspected Planet Nine, and would serve as a precursor mission to α Centauri. We estimate prototype developments costs of 1 million USD, a price of 1000 USD per sail, and a total of <10 million USD including launch for a piggyback concept with an interplanetary mission. https://www.aanda.org/articles/aa/pdf/2020/09/aa38687-20.pdf From the scaling indicated there, it appears the mass scales by the areal size of the sail, i.e., by the square of the diameter. So a 100 meter wide sail, would have a sail mass of 2.3 kg and a payload mass of 22 kg. Bob Clark

A good question. His idea needs to be tested in the lab. If I’m to make a guess, the side of the smaller sail facing the Sun is non-mirrored so has low light pressure pushing it away from the Sun, but the side facing the larger main sail is mirrored. And more importantly that larger main sail focuses all it’s light onto the smaller sail in concentrated fashion. Bob Clark

In that Robert L. Forward conception of using reflected light from the main sail to slow down a smaller sail at the destination, he also included the possibility of using the same method to actually *return* from the far destination. Imagine getting returned samples from ‘Oumuamua, the Jovian and Saturnian moons, and Pluto! However, there is a sticking point in using this method in the case we’re considering here. Forward was imagining it for laser propelled propulsion. In that case you can focus the reflected light that is coherent and collimated. But for our scenario we’re using solar light which will be non coherent and uncollimated. It may not be possible to get the highly focused light at long distances in this scenario. It might be we can carry a laser to do it but that may be too heavy. There may be other light weight methods to do it. An intriguing possibility: IF it did work, then could it be used to do staging by sending focused light from the main sail *forward* to a smaller sail ahead of it? Then we could increase the speed multiple times by doing multiple staging. Bob Clark

The Starship HLS plan for Artemis may be even more complex than thought. It may require two refueling depots, the known one in low Earth orbit plus another one in an elliptical high Earth orbit: SpaceX seeks a single FCC license for multiple future Starship missions, including commercial/Starlink launches and Artemis. Filing shows some technical details about HLS lander, indicating it may require a 2nd refueling in an elliptical Earth orbit. [FCC filing link](https://licensing.fcc.gov/cgi-bin/ws.exe/prod/ib/forms/reports/swr031b.hts?q_set=V_SITE_ANTENNA_FREQ.file_numberC/File+Number/%3D/SATLOA2024121800288&prepare=&column=V_SITE_ANTENNA_FREQ.file_numberC/File+Number), most of the technical details is in the [Technical Annex](https://licensing.fcc.gov/myibfs/download.do?attachment_key=32702913) &nbsp; 1\. The filing covers launch, reentry and in-space operations in the following orbits: * LEO: circular orbit with altitude between 181km and 381 km, all inclinations. This would be the deployment orbit for Starlink and the orbit for HLS LEO depot. * Elliptical Earth Orbit: perigee is between 181km and 381 km, apogee is between 10,534km and 150,534km, inclination between 28 and 33 degrees. Filing refers to these as MEO/HEO but technically they're transfer orbit to circular MEO/HEO. This would cover GTO and transfer to MEO such as orbit of GPS satellites, although the filing didn't mention these. It did mention that this will be the Final Tanking Orbit (FTO) for crewed lunar mission where HLS lander will receive a 2nd propellant transfer. * Translunar Injection (TLI), Lunar orbits (NRHO, LLO) and lunar descent/ascent/surface: These would be for Artemis missions &nbsp; 2\. Communication bands used by Starship * UHF and IEEE 802.11ac 5.8 GHz band: Used for communication between HLS lander and EVA suits on the Moon. I believe these are required by NASA. Range is up to 2km. * S band: Most communication is in this band, including ship to Earth, ship to ship/depot, ship to Orion/Gateway, etc. HLS lander and depot will also use this band to communicate with NASA's TDRSS satellites in Final Tanking Orbit. * Ku band: This is used for radio communication between Starship and Starlink constellation, however it's only usable below 300km. * Ka band: Used by HLS lander for direct to Earth communication &nbsp; 3\. Technical details about HLS lander * As said above, a 2nd propellant transfer from depot to HLS lander may be required in an Elliptical Earth Orbit. Note that someone apparently with sources [mentioned this a few months ago on twitter](https://x.com/Jenakuns/status/1821914964220899650): "Starship HLS conducts 2 refuelling's; 1 in LEO, then a second one in an elliptical orbit to get the architecture delta v down. That's the reason why launch count doesn't line up with wet mass/payload ratio." * HLS lander will carry 4 dual-band (S/Ka) gimbaled parabolic reflector antennas, one in each quadrant. Exact location of these antennas is not disclosed. * HLS lander will carry 2 lunar landing radar in the 35.5-36 GHz band. It'll be activated 4km above the lunar surface and run for approximately 5 minutes until landing. There were [FCC Special Temporary Authority filings for testing this radar on an airplane as early as October 2021](https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=current&application_seq=111132&RequestTimeout=1000), call sign is WT9XBJ. https://www.reddit.com/r/SpaceXLounge/s/hEDBg96kBk Bob Clark

Robert Zubrin has made this point numerous times: https://x.com/robert_zubrin/status/1374861051490000896?s=61 https://x.com/robert_zubrin/status/1725747455247979000?s=61 https://x.com/robert_zubrin/status/1278300197664120833?s=61 https://x.com/robert_zubrin/status/1256718751619145728?s=61 https://x.com/robert_zubrin/status/1256574624202018819?s=61 https://x.com/robert_zubrin/status/1256571091100725249?s=61 https://x.com/robert_zubrin/status/1192796619894185987?s=61 https://x.com/robert_zubrin/status/1192785320011415552?s=61 https://x.com/robert_zubrin/status/1192444670191624192?s=61 https://x.com/robert_zubrin/status/1178265541342941184?s=61 https://x.com/robert_zubrin/status/1127195497964478464?s=61 https://x.com/robert_zubrin/status/1127283625366568961?s=61 And finally: Bob Clark

It might be Robert L Forwards idea of reflecting back the light from the main sail to a smaller sail would allow you to slow down the smaller sail to stop at the destination. A problem though is Dr. Forward intended this for the case of laser propulsion where the reflected light could be focused onto the receiving sail. This might not work for the non coherent light from the Sun. However, actually for the solar gravitational lens it still works as long as you are on a line extending out from the SGL so you may not need to slow down for that case. Bob Clark

The Parker Solar Probe recently survived its closest flyby of the Sun at only 0.04 AU. This gives confidence that the proposal to achieve high speed of a solar sail using a close flyby of the Sun using the ultralight, but high temperature material aerographite can work: Interstellar Sails: A New Analysis of Aerographite by Paul Gilster | Sep 27, 2023 | Sail Concepts | https://www.centauri-dreams.org/2023/09/27/interstellar-sails-a-new-analysis-of-aerographite Such a solar sail could reach a speed of 2%c, 6,000 km/s, using this close flyby. At this speed it could reach the solar gravitational lens(SGL) at 550 AU in only 6 months, and ‘Oumuamua in only 11 days(!) The implications are stunning. Aerographite is an existing material. Then this means we currently have this capability. Telescopes placed at the solar gravitational lens(SGL) would have the ability to amplify the images of an Earth-sized exoplanet by 100 billion times. It could resolve continent-sized features on such a planet. ‘Oumuamua is an interstellar object whose unusual motions led some to speculate it could be of artificial origin. Then we now have the capability to directly observe Earth-sized exoplanets in other star systems and to determine features on an interstellar object that came into our solar system which may have been artificially produced. Bob Clark