Copyright 2025 Robert Clark
The post below was written back in August last year. Back then any criticism of the approach Elon Musk was taking to develop the Superheavy/Starship was verbotten. Now with two successive failures of Starship upper stages for the very same reason, people are starting to ask tough questions about the development of the Starship:
SpaceX Needs A New Mini-Starship To Land Humans On The Moon And Mars.
By Kevin Holden Platt, Contributor. Kevin Holden Platt writes on space defense…
Mar 17, 2025 at 11:33pm EDT
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“Our approach today has a very low probability to match the ‘before 2030’ milestone for landing humans on the Moon,” Daniel Dumbacher, who formerly served as Deputy Associate Administrator of NASA’s Human Exploration and Operations Mission Directorate, in charge of the Artemis lunar landings, testified at the hearing.
While he didn’t mention the fiery breakup of SpaceX’s Starship during its January flight demo, Dumbacher, now a professor in aeronautical engineering at Purdue University, said that the ship’s need to be refueled with super-cooled liquid oxygen and methane in low Earth orbit via multiple dockings with still-to-be-developed tankers - a complicated operation that has never been tested - before each flight to the Moon involves an assemblage of complex technologies that might not be perfected within the next five years.
“We might have to build a lander - we might have to scale down the current lander,” Dumbacher told the House, “so that we get to that 2030 landing.”
To avert potentially spiraling problems with testing the colossal Starships during the countdown to this new Moon quest, he said, “I’d get myself a simplified lander - so that I can get to the Moon - that does not require multiple launches.”
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https://www.forbes.com/sites/kevinholdenplatt/2025/03/17/spacex-needs-a-new-mini-starship-to-land-humans-on-the-moon-and-mars/
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Why SpaceX Needs a True Chief Engineer.
Copyright 2024 Robert Clark
Elon Musk has said that early on when there was still uncertainty if SpaceX would be viable they tried to get a Chief Engineer, but nobody good would come. Musk then designated himself as Chief Engineer.
Now they could get anyone they wanted as a Chief Engineer. My opinion, SpaceX should have as a priority to get a good Chief Engineer.
SpaceX seems to want it make a point of ignoring the lessons of Apollo. When they were building their first launch tower for the SuperHeavy/Starship they were told they needed a flame trench All large launchers use a flame trench. But SpaceX, and more specifically, Musk thought they could do without it:
For some reason, Musk became convinced early on that he did not want the launch tower to have:
*A flame-diverter or flame trench to redirect the blast from the booster’s engines
*A water deluge system to dump a massive amount of water around the launch tower during liftoff
The launch facilities at Kennedy have both of these. Even the launch pads used for the much smaller Falcon 9 have both a flame trench and a water deluge. They help to protect not just the launch pad, and the surrounding area, they also help to reduce the noise. Which sounds trivial, but that noise is energy. That’s what broke up the concrete under the Starship Stage Zero, not the fire. That’s what sent car-sized chunks flying in all directions.
A flame diverter and a water deluge would have greatly reduced, or even eliminated, the damage to the area around the pad. They would have prevented the blow back of debris that damaged Starship before it even left the ground. It might have headed off the whole cascade of events that resulted in that button being pressed 4 minutes into the flight.
We don’t have to guess about whose decision it was not to implement these systems, because Musk already said he decided to skip these systems over the recommendations of his engineers. Musk even had a preview of what was going to happen, as past test flights of the upper stage also resulted in significant spalling of concrete structures and damage to at least one of the ships. He just made them try different kinds of concrete.
The parts for a water deluge were actually on site, ready to install, but Musk decided to forego that installation—likely so he could enjoy the pun of launching his super-joint on 4/20. Which was something Musk had joked about doing months ago.[1]
We know now the result of that poor engineering choice with the launch pad being essentially destroyed, with concrete blocks being thrown hundreds of meters away.
Then, on top of that SpaceX made another inexplicable architecture choice from the beginning. The Apollo program and every other large launch system always constructed a full-up test stand to test all the engines of a stage at once. Instead of taking that approach, SpaceX chose to take the approach of the ill-fated Soviet N-1 rocket of only testing all the engines together during an actual flight. The N-1 became famous in the industry for its explosive failures. Instead of following the approach of the Apollo program of spectacular successes, they chose instead to follow the approach of the N-1 of spectacular failures.
This has important consequences. It might be hard to believe but we still do not know if all the Raptors together on the SuperHeavy can fire at full thrust for the full length of time of an actual mission.
The first test flight resulted in 8 of the 33 engines failing, some in actual explosions. A failure rate of 25%. Observers noted that all the concrete debris being thrown up could have damaged the engines. Elon in an interview however said there was no evidence the concrete being thrown up could have damaged the engines in a way to result in the failures.
SpaceX then was in a bad position. Either the poor engineering choice of not using a flame diverter caused the engine failures, or the engine themselves had such poor reliability that they failed all on their own.
SpaceX in defense of the Raptor reliability might argue there were no failures on the SuperHeavy engines during the ascent for test flights 2 and 3. However, taking note of the slow acceleration of the booster during ascent for these flights, there is very good reason to believe they achieved this reliability by throttling down the Raptors, perhaps to only 75%, [2].
This puts the lack of full-up, full thrust, full duration test burns in sharp relief. This last, of “full duration”, is another way SpaceX deviates from standard industry practice and even terminology. In preflight test burns of the SuperHeavy SpaceX runs these burns for perhaps 5 to 10 seconds, then refers to these burns as “full duration”. In the industry “full duration” is used to mean “full mission duration”. They are burns of the full flight length and full flight thrust and are meant to give confidence to the launch company and importantly to potential customers as well that the engines can run reliably on an actual flight.
Then because SpaceX has not done this with the SuperHeavy, SpaceX’s most important customer NASA has no idea if the Superheavy’s full complement of Raptors can be run reliably at full thrust and full duration of an actual flight. I’m asserting that SpaceX by calling their short burns of only a few second length “full duration” is obscuring this fact.
This again goes to my point of why SpaceX needs a true Chief Engineer. A Chief Engineer should have the persona of a scientist. A scientist, at least a good one, should be scrupulously forthright even on their own research. Instead of Elon Musk proudly boasting how great are the thrust levels of the Raptor engine and how much greater it will be in future versions, a true Chief Engineer would give a more realistic and accurate appraisal. A true Chief Engineer would say something of the nature of,
“The Raptor has reached very high maximum thrust and chamber pressure levels. However, we are working to improve its reliability when run at those levels. Right now when run at 75%, we are at the desired levels of reliability. We are confident though we can reach the needed reliability when run at 100% power and full mission duration.”
Instead of that, Elon Musk as Chief Engineer displays the persona of a PR maven.
NASA Must Know What the True Specifications Are.
My assertion has been SpaceX was intentionally throttling down the Raptors on the booster after the first test flight to improve reliability, [2]. This fact can be regarded as confirmed by the fact the SuperHeavy/Starship has drastically reduced payload capacity than first planned. Elon has stated the payload is only in the 40 to 50 ton range at full reusability when the initial estimate was 100 to 150 tons. If you run the numbers for calculating delta-v it is mathematically impossible for the SH/SS to have a payload that low with the dry mass and engine specifications SpaceX has publicly released. This means either the dry mass numbers or engine numbers or more likely both are significantly worse than what has been released by SpaceX.
NASA must know this. The kinds of calculations known in the industry as delta-v calculations are standard methods of estimating a launch vehicles payload capacity. NASA might be of the opinion that the specifications of a company’s launch vehicle are proprietary and should not be released by them publicly, but NASA has a $4 billion contract with this company to provide an essential component of a multi-billion dollar project being funded by the public, the lunar lander.
It’s a debatable point if NASA should require SpaceX to reveal the true numbers for a project funded by billions of tax-payers dollars. But I don’t think it unreasonable for the public to require NASA to answer the question of whether the low payload capabilities of the SH/SS are what they were expecting at this point in the program, since it is the public that is providing that funding.
Multiple Architecture Mistakes in the SuperHeavy/Starship.
It is irritating for those of us as observers of the space program for decades for SpaceX to simply dismiss the successes of the Apollo program, like Apollo was just some blip in the history of spaceflight. This dismissal is not just of Apollo but of standard industry knowledge. So SpaceX didn’t want to use a flame diverter, and didn’t, and still will not, construct a full-up, all engine test stand for full thrust, full mission duration tests.
But some of the mistakes SpaceX has made in the SH/SS development are just weird. It is standard industry knowledge that you have to have a physical mechanism for separating stages during staging. But SpaceX wanted to do it simply by flinging the upper stage away from the lower stage. Fortunately, they rectified that poor engineering decision with the hot-staging method now used, a method long known to be effective.
On the second test flight they vented oxygen on the second stage while the engines were still firing. Sometimes, you’ll vent propellant from the second stage once it has reached orbit to prevent the possibility of explosion, possibly harming other spacecraft already in orbit. But venting propellant while the engines are firing is a big no-no because of the possibility that itself will cause an explosion, as did indeed happen.
Pressurization gas taken directly from exhaust gases from the pre-burners??? The method used to pressurize the tanks is known as autogenous pressurization. This means the propellant itself is used to pressure the tanks rather than using separate gas such as helium for the purpose. This has been used successfully before with other engines such as the SSME’s. But the other times it was used heat exchangers were used to heat the propellant to pressurize the tanks. Placing exhaust gases directly into the tanks is a very poor engineering approach. Aside from the risk of causing an explosion, there is also the fact the exhaust products contain water and CO2. When these contact directly the cryogenic propellant directly they will tend to freeze. This is bad because the frozen ice or CO2 can then clog the engine inlet valves, as did indeed happen.
SpaceX Taking The Wrong Approach to Reusability.
SpaceX’s approach to reusability is ill-conceived. SpaceX was spectacularly successful in first getting an expendable Falcon 9 then gradually working towards a reusable booster. But instead of taking that successful approach, SpaceX wants the entire SH/SS reusable from the start.
SpaceX has the spectacular success of the Falcon 9’s reusability approach right in front of them but they are ignoring it. First, it is known reusability is most importantly done for first stages because they make up the greatest bulk of the cost, plus the fact in going much lower speed they are more easily made reusable and don’t need thermal protection.
But first just get the rocket to orbit successfully as an expendable. The F9 was able to do that and make a profit as an expendable, with SpaceX all the while working towards reusability.
It might be understandable that SpaceX wanted to take the approach they're taking with the SH/SS if their cost for the launches of the SH/SS were like those of the SLS of ca. $2 billion per launch, since they couldn't get customers at that high launch cost. But Elon has said it is only in the range of $100 million per launch.
Then, if you make the first launches expendable, with the much higher payload without the reusability systems, then SpaceX could be making profit on these launches all-the-while working towards reusability like with the F9.
Another reason why you want to get an expendable launcher first is that extra mass on the upper stage for reusability subtracts directly from payload. For that reason, dry mass on the upper stage is treated like gold. Or said another way extra mass added to an upper stage is like throwing away the equivalent mass in gold.
Elon has said an expendable Starship might have a dry mass of only 40 tons:
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Elon Musk @elonmusk Mar 29, 2019
Replying to
@Erdayastronaut and @DiscoverMag
Probably no fairing either & just 3 Raptor Vacuum engines. Mass ratio of ~30 (1200 tons full, 40 tons empty) with Isp of 380. Then drop a few dozen modified Starlink satellites from empty engine bays with ~1600 Isp, MR 2. Spread out, see what’s there. Not impossible.
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But the current reusable version has been cited as weighting 120 tons, tripling the dry mass. An extra 80 tons as added to the dry mass of an upper stage is huge in regards to reducing its capabilities.
To put this in perspective the dry mass of the Falcon 9 upper stage is about 4 tons. If this was tripled for reusability it would be 12 tons dry mass, i.e., an additional 8 tons. The LEO payload for reusable booster F9 missions would shrink from 15.8 tons to 7.8 tons. And quite importantly the payload for GEO missions would shrink to 0.
When you take into account the much lower expendable dry mass of the Starship and the fact you don’t wastefully leave propellant on the first stage unused on ascent, for return to launch site, the expendable SH/SS probably could get ca. 200 tons to LEO.
But remember those launches would still be $100 million per launch. That would be a cost of only $500 per kilo even as an expendable. That’s well less than even the reusable Falcon 9. At such low cost SpaceX would definitely be able to find customers just for the expendable SH/SS.
Again, SpaceX needs a true Chief Engineer. I simply cannot believe that the SpaceX leadership is aware of these numbers. A major impetus of Elon Musk in wanting to build the SH/SS is for manned interplanetary missions. A 200 ton payload capability is huge. With payload this high every SH/SS launch would have a capability of doing single launch missions to the Moon or to Mars, no multiple refueling flights, nor SLS required. With two launch towers and each tower accommodating a launch every month, this means every other week the public would be witnessing launches capable of doing manned launches to the Moon or Mars.
Keep in mind this is a capability we could have literally, like, tomorrow, if SpaceX went for the approach of first getting the expendable rocket, proven so spectacularly to work for the Falcon 9.
For those familiar with doing delta-v calculations this is based on the delta-v’s for doing missions to the Moon or Mars, [3]. But keep in mind this would require giving the SH/SS a 3rd stage/lander.
Again, SpaceX needs a true Chief Engineer. It’s basic spaceflight engineering that to do beyond LEO missions, requiring high delta-v’s, it’s most efficiently done by adding additional stages. But instead of doing that, SpaceX wants to take the approach of doing 10, 15 or perhaps even more refuelings for a two-stage launcher.
Proponents of this approach quote Elon’s dictum, “The best part is no part” in arguing against adding an additional stage. But they forget the second part of Elon’s saying. The full saying is, “The best part is no part. The best process is no process.” Rather than this additional, complicated process of multiple refuelings, it would be far cheaper, safer, and faster simply using that 3rd stage.
And even the complaint of having to construct an entire new 3rd stage is incorrect. It turns out a stage capable of filling the role already exists: the Falcon 9 upper stage. This is already a fully human-rated stage. A 200-ton to LEO capacity is so large it could launch the F9 upper stage to LEO fully-fueled and with additional extra capacity so that the F9 upper stage could perform all the additional burns needed for a round trip to the Moon and back.
For the crew capsule don’t use the overbloated in size and cost Orion capsule. Use the Dragon capsule. It was already designed to have a heat shield capable of withstanding the greater heating for return from the Moon compared to return from LEO. The only extra piece of equipment it would need is stronger communications equipment for communicating from the longer distance from the Moon compared to LEO.
And for the mission to Mars? Again, SpaceX needs a true Chief Engineer. Not only is SpaceX ignoring basic principles of spaceflight, it’s ignoring basic principles period.
For a first flight to Mars that might take years for a round trip, you don’t send 100 potential colonists who’ve never been in space before in accommodations akin to a cruise ship. You send a small crew of professional astronauts who have already experienced months long periods in space.
Imagine if for the first Apollo flights the architecture was to send 100 lunar colonists consisting of people who had never been in space before. Apollo would have never taken place under that design.
Then for a first flight to Mars, also add on a 3rd stage akin to the Falcon 9 upper stage, and a small habitat of ca. 10 tons size for a crew of 3 to 4 astronauts for the 6 to 8 month flight to Mars. For the return trip you follow the Mars Direct approach of generating the return propellant on Mars, and have air, food, water, and supplies for the stay on Mars and the return flight already in place on Mars beforehand.
Article In Nature Concludes Starship Missions To Mars Not Feasible.
The SpaceX plan is to send 100 colonists to Mars per mission. The authors of this paper conclude this is not feasible:
About feasibility of SpaceX's human exploration Mars mission scenario with Starship.
volume 14, Article number: 11804 (2024)
A major issue the paper discusses is the power requirements for producing the propellant on Mars by ISRU. Robert Zubrin has also discussed this problem and estimated it would take 10 football fields worth of solar panels or a nuclear power plant sent to Mars to generate the needed power:
Elon Musk’s Plan to Settle Mars
February 22, 2020 4:30 AM
Note that simply using a small habitat for 3 - 4 astronauts and small third stage a la the Falcon 9 upper stage, makes the power requirements drastically lower and makes the mission doable in a single flight.
2.)Did SpaceX throttle down the booster engines on the IFT-2 test launch to prevent engine failures?
