Exoscientist

Scott Manley did a calculation that the required impactor would be relatively small size so that a Falcon 9 could launch it. The problem is the asteroid’s velocity and position are not precisely known so the impactor’s needed speed and direction are not precisely known. Because of uncertainty in position and velocity might want a high payload launcher to get large number of impactors with range of trajectories to give high likelihood of correct impact velocity and direction. If using Starlink satellite-like impactors, can use onboard thrusters to do fine adjustments on approach. From Grok: Query: How many Starlink satellites would the SpaceX Starship be able to carry? Response: The SpaceX Starship is designed to carry significantly more Starlink satellites than the current Falcon 9 rocket. According to information available on the web, Starship is expected to carry: •V2 Starlink satellites: Around 400 satellites per launch, as mentioned in SpaceX's plans for deploying the second-generation Starlink satellites. •V3 Starlink satellites: Plans indicate that Starship could launch over 100 V3 Starlink satellites in a single flight, with each launch adding about 60 Tbps of capacity to the Starlink network. These numbers reflect the increased payload capacity of Starship compared to the Falcon 9, which has been launching batches of 50 to 60 V1 satellites or fewer for the larger V2 Mini satellites. Bob Clark

One problem is the FAA won’t require a mishap investigation when it should. From the FAA: "The three approved exceptions include: failure of the thermal shield during high-heating; the flap system is unable to provide sufficient control under high dynamic pressure; and the failure of the Raptor engine system during the landing burn. If one of these scenarios occurs, an investigation will not be required provided there was no serious injury or fatality, no damage to unrelated property and no debris outside designated hazard areas." An engine exploding in flight is a very serious failure mode. But SpaceX managed to convince the FAA as long as the public wasn’t endangered a mishap investigation wasn’t necessary. This was a mistake because it allows the engine explosions not to be discussed by SpaceX like they never happened. For example, on IFT-4 an engine exploded during the booster landing burn. Why? SpaceX doesn’t have to say. SpaceX doesn’t even have to admit it happened. But if the FAA has no idea why it happened, as it required no explanation from SpaceX, how does it or the public know it won’t happen during the tower catch? Bob Clark

NASA safety panel is not happy the approach NASA is taking to the Artemis missions: Safety panel urges NASA to reassess Artemis mission objectives to reduce risk. by Jeff Foust February 1, 2025 https://spacenews.com/safety-panel-urges-nasa-to-reassess-artemis-mission-objectives-to-reduce-risk/ The ”risk” being discussed is not just safety risk but also the technical risk of such a complex approach. The negative review is not all due to the Starship HLS lander but a big chunk of it is. Bob Clark

7? B.C.

Does it involve 6 figures? Bob. Clark

That might be the explanation. Only SpaceX can say for sure, but instead SpaceX “takes the fifth”. It’s a combination of reasons that lead one to question if SpaceX is being fully forthright on the reliability of the Raptor: 1.)A Raptor actually exploded on IFT-4. But SpaceX has not “come clean” on that. 2.)Elon Musk’s explanation of the Starship explosion on IFT-7 raises the possibility the large plumes seen shooting up during the Superheavy landing burns were due to engine bay fires. 3.)SpaceX told the FAA the Superheavy would tip over and float after ocean landing. Instead they always exploded. 4.)The Raptor has to do 3-burns for reusability, but SpaceX hasn’t tested this a single time at full mission burn times, wait times, and power levels. 5.)For these reasons, the FAA should require SpaceX to release any and all videos of the engine bays of both stages while the engines are firing, most specifically during restarts: The SpaceX Raptor engine is still of unproven reliability. https://exoscientist.blogspot.com/2025/01/the-spacex-raptor-engine-is-still-of.htm Bob Clark

Actually not a Blue Origin fan over SpaceX. Let me give you an analogy. My wife and I are fans of the show American Greed. Often we marvel at the complexity of the schemes the fraudsters go through to acquire their wealth. We frequently ask, if they could do all that, they could become wealthy just doing it honestly. That is similar to how I feel about SpaceX. It began at the very beginning from how they described their testing. Why call a little 7 second burn “full duration”? Every other space company has done short burn time tests before and they just call them that: tests of that short burn time. They reserve the term “full duration” for tests that are supposed to emulate an actual flight at its full flight burn time and full flight power level. The only reason I could think of for SpaceX wanting to use the term for such short burns was to give an unwarranted inference as to the Raptor reliability. The Apollo missions were the most spectacular successes in the history of spaceflight, while the Soviet N-1 rocket provided the most spectacular failures. Why on Earth then would you choose to follow the N-1 approach of testing in flight? Again the only thing I could think of is following standard industry practice where you had to do full up(all engine), full flight burn time, and full power level burns, that considering the large number of engines, the Raptor would have shown frequent test shut downs if not outright engine explosions. Testing in flight allows test flights before the Raptor was ready according to usual industry standards. When a Raptor exploded on the booster landing burn on IFT-4 SpaceX never acknowledged it happened and never provided an explanation. SpaceX managed to convince the FAA that as long as the public was not endangered then SpaceX didn’t have to provide mishap reports. That was a mistake on the FAA’s part because it allowed SpaceX to continue to imply the Raptor is a reliable engine. The ramifications of that mistake by the FAA continues onto other test flights. SpaceX told the FAA the booster would survive intact and float after ocean touchdown and tip over. Instead, it always exploded. Why, when SpaceX said it would survive intact? Since the public was not endangered, SpaceX didn’t have to provide any explanation. However, we can get a clue from IFT-4. The Raptor fire and explosion during the landing burn likely damaged the vehicle integrity, so it couldn’t survive the tip over intact. Since the Raptor has a tendency to leaks and fires likely this also happened during booster ocean touchdowns even when no explosion was apparent during the landing burns. The flames seen shooting up the sides during the landing burns for flights 5,6, and 7 provide support for this. So what have we seen so far? Of the 7 test flights, 5 of the 7 had either Raptor explosions or full stage explosions. And on the two tower catch flights, flames were seen shooting up the side of the booster. Why did these flames happen? SpaceX hasn’t provided an answer. In fact, SpaceX hasn’t even acknowledged they even happened. Since the public was not endangered SpaceX doesn’t have to provide an explanation. This illuminates further why that mistake by the FAA of not requiring mishap reports could have negative consequences. If an investigation had been required, it may have become apparent the Raptor still has a tendency to leak and catch fire. If the Raptor continues to leak and catch fire in flight then at some point this will result in danger to the public. In fact IFT-7 may have been an example of this. To insure the Raptor does not still have a tendency to leak and catch fire the FAA should require SpaceX to release any and all video of the engine bays of both stages while the engines are firing. Bob Clark

That’s the point. There is a hurry. We’re in a race with China to return to the Moon. If Elon wanted to take to the 2050’s perfecting his Mars rocket to get to Mars, it’s his money he can spend it in any unwise fashion he wishes. But we are now dependent on it for strategic reasons so the increasing delay has strategic repercussions. A NASA safety panel also is not happy the approach NASA is taking to the Artemis missions: Safety panel urges NASA to reassess Artemis mission objectives to reduce risk. by Jeff Foust February 1, 2025 https://spacenews.com/safety-panel-urges-nasa-to-reassess-artemis-mission-objectives-to-reduce-risk/ The ”risk” being discussed is not just safety risk but also the technical risk of such a complex approach. The negative review is not all due to the Starship HLS lander but a big chunk of it is. Bob Clark

Of the 7 test flights, 4 of them had vehicle explosions of one or both stages. That’s nothing to brag about in comparison to the N-1 that used the technology of 50 years ago. You could even argue it should have been 5 of 7 because on IFT-4 a Raptor exploded during the landing burn of the booster, which otherwise would have caused vehicle explosion if not for the steel construction. It might take now 15 to 20 test flights to get all of high payload, reusability, and orbital refueling all operational and rated for human spaceflight. All this could have been avoided by following standard industry practice of doing full up(all engines), full mission length, and full power static testing of stages. They would already be flying expendable version now at the highest payload capacity of any rocket ever made at ca. 250 tons and with paying customers. And this also could do single launch Moon and Mars missions, NOW. None of this agita of China beating us in a return to the Moon. And none of this impractical approach of launching a flotilla of 5 Starships to Mars for a single manned mission to Mars. Remember each of them requires 5 refuelings; some estimates even say as many as 10, So it would mean at least 30 Superheavy/Starship launches, and perhaps as many as 55, for a single Mars mission. In contrast Robert Zubrin worked out 30 years ago, subsequently confirmed by NASA, that the Mars Direct approach could do a Mars mission with two Saturn V-class launches. Then the expendable Superheavy/Starship at ca. 250 ton capacity could be doing single launch missions to Mars now. Note the all-up static testing also would have allowed engine reusability to be perfected in a shorter time frame. The success of partial reusability of the Falcon 9 suggests this also could be attained for the Superheavy once expendable version was up and operational. Since the biggest chunk of the cost of a rocket is the first stage, as demonstrated by Falcon 9, just doing partial reusability on the SH/SS would have resulted in great cost saving. Bob Clark

Could Blue Origin offer its own Moon rocket? Estimates of the propellant load on the New Glenn commonly are in the range of 1,150 tons. However, making a comparison of the size of the tanks to those of the Superheavy booster it’s capacity could be estimated as 1/2.6th that of the Superheavy. (Image Credit Ken Kirtland) https://x.com/kenkirtland17/status/1761481624548511916?s=61 Since the maximum capacity of the Superheavy tanks is ca. 3,600 tons, the New Glenn booster tanks can be estimated to have a maximum capacity of 3,600/2.6 = 1,380 tons. With tanks filled to this maximum capacity though it would need higher thrust to lift-off. Given the thrust upgrades already planned by Blue Origin for New Glenn, running a delta-v calculation suggests it could get in the range of ca. 100 tons to LEO, a Saturn V class launcher. But 100 tons to LEO, i.e., Saturn V class, is commonly given as the launch capacity needed for a Moon rocket. Then New Glenn could possibly serve as a single launch Moon rocket. Remarkably, Blue Origin as soon as next month in March plans to launch a lunar cargo lander to the Moon, the Blue Moon Mk1. At ca. 21 ton mass and 3 ton payload capacity, this could actually serve also as a manned lander if given a 3 ton crew module. The far larger Blue Moon Mk2 multi-billion dollar manned lander would be unnecessary. Could Blue Origin offer it’s own rocket to the Moon? https://exoscientist.blogspot.com/2025/01/could-blue-origin-offer-its-own-rocket.html Bob Clark

That would be true if there were no issues of a danger to the public. But with the IFT-7 explosion public safety issues have arisen. A hypothetical scenario: suppose during the IFT-7 investigation the FAA finds Raptors commonly leak and catch fire during their landing burns, but SpaceX is able to contain the fires with fire shields and fire suppression. Do you think the FAA would keep that information from the public? Do you think the FAA should keep that information from the public? By the way, with so many airplanes having to be diverted after the IFT-7 explosion the NTSB may get involved in the investigation. The NTSB is much more hands on with their investigations than the FAA, which commonly let the companies themselves do the investigating. Bob Clark

Thanks for that impressive review of the Raptor tests. I can say confidently that nobody outside of SpaceX has examined the data on the Raptor tests firings in that detail. In fact, probably many in the propulsion division at SpaceX would find this data review useful. You should definitely post it to the NSF forum and that Discord server on Starship you mentioned. You raised a possible explanation for the lack of testing in this data specifically of the actual 3-burn times of an actual mission that perhaps they were done earlier than in this data set. Perhaps. But that would mean they would be on Raptor 1’s. But Raptor 2 and the upcoming Raptor 3’s operate at higher pressures and thrusts. It would be essential to run these tests as well on the later incarnations. Another possibility you mentioned is perhaps they found if a engine ran successfully for a short time that is sufficient to qualify it for running at the full burn time times. I can’t rule that out. But also we need to consider the possibility that the reason some of these static tests were at short burn times was because indications were the engines were getting so far out of nominal that they had to be shut down. This happened multiple times during the flight tests for instance. When I say SpaceX is giving an inaccurate portrayal of Raptor reliability I don’t mean they are providing invalid telemetry. I mean in a more basic sense. We know in at least one case in the later test flights, IFT-4, that a Raptor exploded during a landing burn. But SpaceX has not acknowledged it or explained it. Given the prior instances such as during the tests of the SpaceX landing procedure of Raptors leaking fuel and catching fire leading to subsequent explosions, it seems quite likely that leaks and fires also occurred on the IFT-4 flight before that engine exploded. Since the Raptor does have this known tendency to leak and catch fire, the possibility still obtains that the plumes seen shooting up the sides of the booster during the landings burns could be due to such leaks and fires. In this regard it is quite notable in the ocean landing of the Starship in IFT-5 flames were seen shooting out of the side as well. See at about the 12 second point in this video on the right side: https://youtu.be/t-2Wj0NyKQY?si=9KJ-r16nmbfjpoek Previously, SpaceX made the argument to the FAA that mishaps investigations were not necessary if no danger to the public was involved. But now we have an instance in IFT-7 that potentially a danger to the public could have arisen from a Starship explosion. SpaceX has made a preliminary appraisal the explosion was due to a failure in the plumbing, not the engines. Perhaps. But given the Raptors tendency to leak and catch fire, the FAA should require SpaceX to release any and all videos of the engine bays in both stages when their engines are firing to be sure. Bob Clark

Thanks for that link to data on Raptor tests. Do you know what format that’s in, Excel or otherwise, to make it more readable? It looks like mostly dates and durations times, then it might not be able to be extracted whether there were restarts involved. This video gives a review of Raptor static tests: 1000 Starship Engine Tests (on a graph). https://youtu.be/I6GJVvwUEGk?si=RfFVmEEpLUQc9NOl The author concludes the Raptor is reliable, but notes there are some oddities such as the relatively low percentage of burn times matching that of actual mission length burns. If there were burns that were full length and matched the 3-burn durations of an actual mission, I would think he would have mentioned that. But I’ll ask him to be sure. Searching on YouTube provides no examples of Raptors testing for the actual 3-burn durations of an actual mission. There are several that show Raptor restarts but none of the lengths for an actual mission. There were also examples cited on twitter with great fanfare of Raptor restarts such as the 34 burn one, but none with the 3-burn durations of an actual mission. About the evidence for Raptor reliability based on the actual test flights, I am dubious that the total of all three burns needed for both stages have been as pristine for the Raptor as portrayed by SpaceX. A major example is the exploding Raptor on IFT-4 during the booster landing burn. That is a major failure not just a Raptor refusing to light, or the burn time having to be cut short. Yet SpaceX says nothing about it, like it never happened. But not mentioning it gives the impression the burns on that flight were successful, thus giving an unwarranted assumption of the Raptor reliability during flight. There still remains also the issue of the underlying cause of the large plumes seen running up the side of the booster during the landing burns. There must be a reason why SpaceX doesn’t want to discuss it. The FAA should require SpaceX to release the footage of the engine bay during the burns of both stages to ensure in fact fuel leaks are not a common occurrence for the Raptor. Bob Clark