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Spacenut:
I think they fixed most of that in the last Block 2 flight, the one after the flight where the picture in post 2243 came from. The explosive burn-through into the engine bay seems unique to that one flight. Although, whether that was caused by a deliberately-missing tile or not, has never been made clear, as far as I can tell.
They also added something (not clear what) to the flap-body joint where the burn-throughs had been happening, and I noticed that there was no flap sheet metal damage visible during that last ascent. The previous pictured flight showed some kind of aft edge sheet metal damage during the ascent right after liftoff. So they changed something there, too. It is just entirely unclear what that something was.
Bob:
There's a lot more going on with inert mass than just scale and material. Most of it is not publicized or made clear. But by the time Block 2 flew, they found they had to add a lot of stringers and frames inside the propellant tanks than they had used on Block 1. They also changed the shape of the aft dome to which the engines are mounted, making it more conical, if memory serves. That also requires additional framing not to bend-toward-round when the tank is pressurized, and to avoid crippling-collapse with the higher engine thrusts (and they are higher!).
Both of you:
Something else real-world to consider: the ballistic coefficient would be lower by a factor of about 87% if reentry were made dead broadside, exposing the largest possible blockage area to the oncoming stream. But they cannot do that! Dead broadside, there is too much reentry plasma (thousands of K effective) getting into the engine bay. They fly reentry at about 60 degree angle of attack as the compromise that limits plasma intrusion into the engine bay, while at the same time presenting the largest possible blockage area to the hypersonic flow. You'll notice that when the hypersonics are over and the hot plasma danger is no more, the belly-flop maneuver really is flown just about dead-broadside to the relative wind, for the biggest-possible drag area. It shows as a near-horizontal axis while flying almost straight down.
GW
From CBS News website 2-20-2026 (my take on it appended at the end):
NASA's new chief rebukes Boeing, space agency over problem-plagued Starliner mission that left astronauts stuck in space for months
By
William Harwood
Updated on: February 19, 2026 / 8:10 PM EST / CBS News
An independent review of the first — and so far, only — piloted flight of Boeing's troubled Starliner spacecraft concluded that the test represented a potentially life-threatening "Type A" mishap resulting from multiple technical problems and management miscues, NASA officials said Thursday. The findings prompted NASA's new chief to make openly critical comments about his own agency and Boeing.
"This was a really challenging event and...we almost did have a really terrible day," said Amit Kshatriya, NASA associate administrator. "We failed them."
He was referring to now-retired astronauts Barry "Butch" Wilmore and Sunita Williams, who were launched in June 2024 expecting to spend eight to 10 days in space. They ended up remaining in orbit for 286 days, hitching a ride home aboard a SpaceX Crew Dragon capsule in March 2025 after NASA ruled out landing aboard the Starliner.
NASA Administrator Jared Isaacman, who took the reigns of the agency in December, said NASA will continue working with Boeing to make the Starliner a viable crew transport vehicle, adding that "sustained crew and cargo access to low Earth orbit will remain essential, and America benefits from competition and redundancy."
"But to be clear, NASA will not fly another crew on Starliner until technical causes are understood and corrected, the propulsion system is fully qualified and appropriate investigation recommendations are implemented," he said.
He made the comments as the agency was releasing the results of a months-long independent investigation of the Starliner mission. The panel's report cited a long list of management failures and technical issues that were not fully understood at the time, but were still considered acceptable for flight.
The panel concluded the problems experienced during the mission were representative of a "Type A mishap," meaning an unexpected event that could have resulted in death or permanent disability, damage to government property exceeding $2 million and the loss of a spacecraft or launch vehicle.
Isaacman said the eventual cost of the Starliner's woes exceeded the $2 million threshold "a hundred fold."
"Starliner has design and engineering deficiencies that must be corrected," he said. "But the most troubling failure revealed by this investigation is not hardware. It's decision-making and leadership that, if left unchecked, could create a culture incompatible with human space flight."
Isaacman said the investigation revealed pressure within NASA to ensure the success of the agency's Commercial Crew Program, which is based on having two independent astronaut ferry ships. That advocacy "exceeded reasonable bounds and placed the mission the crew and America's space program at risk."
"This created a culture of mistrust that can never happen again and there will be leadership accountability," Isaacman said.
The report quoted unnamed personnel saying things like, "There was yelling in meetings. It was emotionally charged and unproductive."
Another said, "If you weren't aligned with the desired outcome, your input was filtered out or dismissed."
Yet another told the panel, "I stopped speaking up because I knew I would be dismissed."
Equally troubling, according to one NASA worker quoted in the report, "NASA wasn't blaming Boeing, but everybody else was. [...] You know, it's our program. We're responsible too. Nobody said that. And nobody within NASA [or outside of NASA] has been held accountable. Nobody. We're 11 months after it happened, and there's been no accountability at all, from any organization."
Isaacman promised that "lessons will be appropriately learned across the agency and there will be accountability."
In the wake of the space shuttle's retirement in 2011, NASA awarded multi-billion-dollar contracts to Boeing and SpaceX in 2014 to build independent ferry ships to carry astronauts to and from the space station. SpaceX, awarded an initial $2.6 billion contract, has now launched 13 piloted Crew Dragon flights for NASA and seven purely commercial missions.
In contrast, Boeing, awarded an initial $4.2 billion contract, ran into multiple problems during an unpiloted Starliner test flight in 2019 that eventually required a second crew-less test flight before Wilmore and Williams were finally launched on June 5, 2024, on what has been the ship's lone crewed test flight.
The trip to space atop a United Launch Alliance Atlas 5 rocket went smoothly and the crew successfully docked with the International Space Station the next day. But the capsule experienced multiple helium propulsion system leaks along the way and several maneuvering jets did not produce the expected thrust.
"During the rendezvous and proximity operations, propulsion anomalies cascaded into multiple thruster failures and a temporary loss of six-degree-of-freedom control," Isaacman said Thursday. "The controllers and the crew performed with extraordinary professionalism ... and docking was achieved.
"It is worth restating what should be obvious," he said. "At that moment, had different decisions been made, had thrusters not been recovered or had docking been unsuccessful, the outcome of this mission could have been very different."
Williams and Wilmore downplayed the malfunctions during the flight, which was originally expected to last about eight days. But NASA and Boeing ended up extending their stay in orbit, carrying out weeks of tests and analysis to determine whether the Starliner could be trusted to safely bring its crew back to Earth.
By August 2024, Boeing managers were convinced engineers understood the problems and the crew could safely come home in the Starliner. But NASA managers ruled that option out. Instead, they decided to keep the astronauts aboard the station until early 2025 when they could hitch a ride back to Earth aboard a SpaceX Crew Dragon ferry ship.
To make that possible, a Crew Dragon was launched in September 2024 with just two astronauts aboard instead of four as originally planned. That freed up two seats for Wilmore and Williams after the SpaceX crew completed their six-month stay in space.
The Starliner, meanwhile, successfully made an uncrewed return to Earth in September 2024 even though, the investigation report revealed, additional propulsion problems left the craft with no available backup options had another failure occurred.
The mission, "while ultimately successful in preserving crew safety, revealed critical vulnerabilities in the Starliner's propulsion system, NASA's oversight model and the broader culture of commercial human spaceflight," the investigation team concluded.
The panel issued 61 formal recommendations "across technical, organizational, and cultural domains to address these issues before the next crewed Starliner mission."
"The report underscores that technical excellence, transparent communication, and clear roles and responsibilities are not just best practices, they are essential to the success of any future commercial spaceflight missions," the team said. "The lessons from CFT must be institutionalized to ensure that safety is never compromised in pursuit of schedule or cost."
For its part, Boeing said in a statement the company had made "substantial progress" on corrective actions "and driven significant cultural changes across the team that directly align with the findings in the report."
"NASA's report will reinforce our ongoing efforts to strengthen our work...in support of mission and crew safety, which is and must always be our highest priority. We're working closely with NASA to ensure readiness for future Starliner missions and remain committed to NASA's vision for two commercial crew providers."
------
My take on it:
This report understates, but confirms, my contentions about NASA management culture valuing money and schedule (which is also money) above crew lives. It is quite apparent that NASA management never learned the lessons of the two lost shuttle crews. Or if any of them did, they no longer work there.
This report also confirms something not common knowledge up to now: that Butch and Sunita’s Starliner experienced even more propulsion problems during its unmanned return from the ISS, leaving no backups.
It would appear that Jared Isaacman might do some “housecleaning” among NASA management. He at least talks like it, in this report. We will see if he really does. However, it does concern me about him that, so far, he shows no sign of concern over a flawed heat shield flying crewed on Artemis-2, and the same flawed design being built for Artemis-3.
It would also appear, based on this report, that Jared Isaacman wants Boeing to properly “fix” Starliner, so that he has a second capsule to use, going to ISS. If it were me, I’d plow that money into Dreamchaser instead. But that is just me.
I would very strongly recommend to NASA that they fly Dragon with all 7 seats installed, even when only flying crews of 4 to the ISS. With the extra 3 seats, up to 3 astronauts in trouble at a time, could hitch a ride home with any full-size Dragon crew sent to ISS, that is coming home. Having that capability is simply far more important than the weight of the 3 seats, or any egress time issues associated with them. But, that importance assessment is true only if you value lives over money!
GW
Bob:
Check your email. I was able to rerun the entry study for circular LEO at Earth. I sent you a pdf file.
GW
Bob:
I think the 40 ton inert figure for Starship is unrealistic in the extreme. Myself, I never heard him say anything under 80 tons. But as far as I know, Block 1 was in the vicinity of 120 tons. And it has grown since then, about 6 meters longer.
I thought you were asking about Mars entry, which is why I looked at that. It's easy enough to run the spreadsheet here at Earth. I can use most of the same inputs, just the Earth atmosphere model. And Earth entry from low circular orbit would hit the atmosphere at about 7.9 km/s. One variation could be deleting the payload weight, on the assumption it was delivered on-orbit. That still leaving landing propellant aboard, though.
I am not familiar with the X-33 metallic shingle thing. But I do know that one of the last two Block 2 Starship flights had at least some "metallic tiles" which were apparently iron-based or iron-containing. These apparently experienced high rates of oxidation, resulting in the "rust-color" staining seen on the vehicle.
GW
Harold:
I haven't yet had a chance to go back and look at what I did trying to land 40 tons of payload 1-way into Mars. If memory serves, and it may not, I did not like my final results. The harshest constraint seemed to be getting enough thrust to fit the space in the vehicle, and second-harshest was protecting those engines during entry.
Riding out in the open behind a heat shield exposes you to the same effective temperatures the heat shield sees, just at an order-of-magnitude-or-so less scrubbing velocity on surfaces, and pressures near atmospheric ambient at extreme altitudes. The heat shields see more scrubbing at much higher pressures, which is why those heating rates are so much higher.
GW
Bob:
Check your email. I ran the entry study you suggested, using the entry spreadsheet available for free download right off the links here on the forums for the "orbits+" course materials. I sent you a pdf document of what I did. I looked at 120 mt, 160 mt, and 40 mt inert dry masses, but I added 100 mt payload and 20 mt landing propellant to those masses. I also used a block 3 length of 56 m.
That's about a factor-2 range of ballistic coefficient, and all 3 showed peak heating at about 35-40 km, and 6 to 6.3 km/s speeds. Using the entry old rule-of-thumb that is about 10% accurate, effective temperature deg K is numerically equal to speed in m/s. It falls between about 6000 and 6300 K, for all 3 configurations.
The amount of plasma radiation heating varied by about a factor of 2 across that range of ballistic coefficients. The altitude at end of hypersonics was around 10-16 km, highest at the lowest ballistic coefficient. Not much else varied at all, not even the speed and altitude for peak heating.
I did find that plasma radiation stagnation heating dominates by far, quite unlike at Earth. I did NOT do the heat transfer balance trying to determine where the tile surfaces might equilibriate. But since the driving temperatures are about the same, the equilibrium temperatures might not be that much different, despite the crudely factor-2 difference in heating rates.
GW
Rob:
I have no way to contact Jared Isaacman directly. All I can do is write a paper letter to him at NASA headquarters. He will not see it, some staffer will. And THAT is the problem. No one but that staffer will see it, and he/she will shit-can it. I had the very same problem writing to his predecessor with the heat shield "fix" almost 2 years ago now.
Rob & Harold:
What I eventually did was send the heat shield stuff to a former colleague whom I found out was working at NASA. He took it to the thermal protection group in Houston, and verified to me that they got it, and that they pretty much agreed with it!
My friend has since retired, so that doorway in, is now closed! After that, I never heard another peep out the heat shield group in Houston, and never from anybody else inside NASA, either.
Those are the verified facts. What follows is informed speculation.
That heat protection group in Houston took it to the Artemis managers, who promptly shit-canned the notion, and ignored the NASA engineers. For them, it was either the Apollo hand-gunning that they did on Orion EFT-1, or else do exactly what they did on Artemis-1. Exclusively! And they saved tons on money doing it the Artemis-1 way. My way to "fix" this fell way outside that either/or thinking. It was NEVER considered at all!
Does that sound hauntingly familiar?
As in the NASA (and Thiokol) engineers who argued against Challenger launching so cold? And the NASA engineers who wanted an inspection of Columbia's wing, either from an EVA, or from ground photography, or both? Both sets of engineers were ignored by management, who arrogantly (and as it turned out ignorantly) assumed that "they knew better". Both times! Many years apart!
Which is EXACTLY why I SIMPLY MUST CONCLUDE that NASA management culture learned absolutely NOTHING from the loss of 2 shuttle crews! Despite the billion-$ inquests and almost-2-year-delays after each one!
GW
I just followed a link on today's AIAA Daily Launch to a Space.com article on the Orion heat shield for Artemis. This was a reporter summarizing the latest press release from NASA, explaining why they do not think Artemis-2's heat shield will show spalling. They think deleting the skip and second heat pulse will prevent the spalling and cratering.
Most of us who actually did insulation work with ablatives DO NOT think so! NASA ran some tests and went to the same kinds of analyses to "prove" they were eliminating risks, the same stuff that failed to predict what happened to Artemis-1's heat shield.
The most disturbing thing about the press release is that they intend to build the Artemis-3 heat shield the very same way as Artemis-1 and Artemis-2, despite that landing being at least 2 years away. That mission cannot fly until (1) there is a reliable lander ready to fly crewed, and (2) their Gateway space station is in place around the moon (since SLS/Orion block 1 cannot get into and out of low lunar orbit).
They have 2 years to figure out a way to put the hex into the bonded Avcoat tiles. I gave them the way to do that over a year ago, and I know for a fact their heat shield group in Houston got it! There is NO EXCUSE not to do it, or else revert to the hand-gunned Avcoat into hex cells that worked on Orion EFT-1 and all of Apollo.
This is top level managers not listening to engineers within and outside the agency, valuing money above lives. The very same flaw that killed 2 shuttle crews!
GW
I never said it didn't.
The same criteria and soil bearing strength numbers apply to both the moon and Mars. Only the local weights are different, and only by approximately a factor of 2.
What I see routinely presented to the public in these press releases is not just wrong, but wrong by orders of magnitude.
GW
I've since learned the GEM 63XL solids do not have thrust vectoring. At least that is not the problem!
From the pictures I have seen, it is impossible to really tell whether the burn through and leaking plume occurred at the nozzle-case joint, the nozzle throat region, or somewhere in-between. It did not appear to be somewhere down on the supersonic expansion bell.
There have been 4 Vulcan flights. Two have had booster anomalies attributed to nozzle problems. The other one supposedly "lost its nozzle" entirely, whatever that really means.
All I can say is that somebody somewhere in the conglomerate that is Northrup-Grumman, specifically its solid motor outfit (which is one of the old large motor contractors from when I worked in that business decades ago), is not paying enough attention to adequate thermal ablative protection in that joint or in that nozzle throat approach design.
With aluminized propellants and AP oxidizer, you are looking at chamber temperatures approaching 6000 F, with a high solids content (mostly aluminum oxide particulates and droplets, in the exiting stream. This thermal environment is way worse than anything the liquid boys have ever seen, even when they tried hydrogen with fluorine at Santa Susanna back in the 50's and early 60's. It's worse in some ways than entry heat shields. Even today.
And a lot of that knowledge was engineering art that was lost in the mass layoffs of the huge industry drawdown about 1993-1996, after the Soviet Union fell apart.
I do have to wonder, though, if NASA insisted on yet another idiotically-dangerous multiple-O-ring "seal" at the nozzle to case joint.
GW
They still have not thought rough-field landings through, because they have never, ever made one! There are few alive today who ever really did. The young crowd today seems blissfully unaware of what it takes to make a rough-field landing on soft ground, with a rocket vehicle making a powered landing. The exception seems to be Firefly. Their design, which worked on the moon, appears to be inspired by what worked decades ago with Surveyor, Apollo, Viking on Mars, etc.
Lunar regolith might be a tad stronger than Martian regolith because the lunar particles are sharp and the Martian ones are not. But the difference is of order factor 2, not orders of magnitude. Both regoliths resemble nothing so much as sand dune sand here on Earth. The presence of scattered rocks within that do not touch provides no reinforcement whatsoever. Earthly sand dune sand is listed in most Earthly foundation design references as having an allowable bearing pressure of 1 to 2 US tons per square foot = 0.1 to 0.2 MPa. The failure pressure is factor 2 to at most 2.5 above that allowable. Those are VERY LOW values to deal with!
When landing, your vehicle is lightweight, unless it is to take off again. Whatever that local-gravity weight is, there are dynamics of touchdown, and off-angle effects leading to one pad touching first. Both require factoring up the static weight by a factor of 2, for a transient landing pressure under the first pad of 4 times what the static value would be. None of those dynamics affect takeoff, the pads see only the static weight, until the vehicle lifts off. But if you are refilling propellant locally, as is often proposed now, that weight is the full max takeoff weight. Which may be some 5 to 7 times the near-empty weight at touchdowndown.
I see nothing in the HLS illustration to show any recognition of those pad bearing pressure issues. I also see nothing in the illustration to suggest any cognizance of the risk of coming down on uneven ground, which is actually depicted nearby, in the illustration, and not as bad as some actually seen during Apollo! The cg is about halfway up the vehicle, with the weight vector hanging from it. If that vector points to a location on the surface outside the polygon defined by the landing pads, the vehicle WILL fall over (and explode)! And that is if there is zero horizontal speed at the moment of touchdown! If there is horizontal speed, the lead pad will dig-in and "trip" the vehicle, even if the weight vector falls well inside the polygon.
I see no cognizance in any of the press release illustration from SpaceX (or anybody else) about these issues and risks. The same ones that twice tripped-up Intuitive Machines on the moon, and the Japanese lander, too.
The criteria to avoid this have been known since the early 1960's. (1) Min dimension of the pad polygon must be greater than the cg height. (2) Make sure the transient bearing pressure under the pads is closer to the allowable bearing pressure than the failure pressure on landing, and similar for the static bearing pressure, for takeoff. (3) Tip the pads on spring mounts inward a little, so that the lead pad won't dig in so easily if you touch down with some horizontal speed. (4) Make sure that you can hover just above the surface, for a significant time, so that whatever is controlling the vehicle during the landing can "see and avoid" uneven high-slope ground, big boulders, and cavities or other holes.
And, also since the early 1960's, if you do not have test data for the target regolith, presume it is like Earthly sand dune sand, and use the lower range of values.
Only parts of this were ever formally written down. This was mostly the engineering art that was known among those who actually did those landings decades ago. Most of them are dead now. Apparently very little of this art was passed-on, and what of it was passed-on, was lost over the time since.
GW
Spacenut:
Did you see the paragraph in the linked report that described how they fixed the leaky seals? By going to a material that better resists NTO?
Q: If the better material was known in the first place, then why did Boeing use something different? Ans -- cheaper.
What does that tell you about the thrusters? Think "cheaper" might have something to do with those troubles, too?
Certainly did for the B-737MAX debacle. And there's a couple of other airplanes Boeing is in deep kimchee with troubles. One is the 777-X, the other is the new USAF tanker. All built by the same Boeing. As is the SLS core stage.
GW
Should not be a surprise. Money talks.
His SpaceX and Tesla baseline incomes come from government contracting. He is being paid to land people on the moon, if he can. He IS NOT being paid by anybody to go to Mars. If he defaults on his moon landing commitments, he will lose far too much credibility to be a major space contractor anymore, to NASA or DOD. That is "default" by not doing what he promised to attempt. "Failure" by not being able to do it, is a different issue.
GW
Whether the Starship really will be cheaper to launch than a Falcon-9 or Falcon-Heavy is still debatable. That answer CANNOT be known until experimental flight testing and design changes are done. Be aware that SpaceX is talking about an even larger Block 4, while the somewhat-larger Block 3 still has yet to fly at all! Block 2 pretty much worked mostly right in the last two experimental flight tests.
The change from "block to block" is somewhat closer to a new design than just a minor variation on an old one. Always has been, always will be. That's just the inherent nature of vehicle developments and the experimental flight tests to "prove them out".
The cost question also depends upon how big your crews are. If 3-7, a Falcon-9 or Falcon-Heavy and Dragon makes very good sense at ~ $90 M/(3 to 7) for $12-30M per seat. That may look like a high seat price, but if all you are flying is a small crew, that's a small portion of your overall mission cost.
If you are flying a big crew 20+, then you would need more than one Dragon, and something big like Starship makes a lot more sense to shoot them all up there in one launch. Per seat price? Nobody can know yet!
Early exploration does NOT need big crews! That comes later when you do some sort of experimental base where you can prove out and verify that you really can start to "live off the land". That capability will NOT be the case in the first explorations, and it will still NOT be the case, when you first set up that experimental base. That is inherent.
Let's just say I am extremely skeptical of the "$10 M launch cost" some have been bandying about for Starship. I rather think $100 M is a better wild guess! But it is ONLY a wild guess! NOBODY has anything any better than a wild guess! Not Musk, not ANYBODY! $100M / (20+) is under $5M per seat. Still a small portion of any real mission cost.
GW
from the AIAA email newsletter "Daily Launch" for Thurs 2-12-2026:
-----
Spaceflight Now
Vulcan suffers solid rocket booster problem during USSF-87 launch
ULA said an issue affected one of the four solid rocket boosters that helped propel its Vulcan rocket into space Thursday on a mission for the United States Space Force. Despite the problem the rocket, making only its fourth flight, continued on its planned trajectory, the company said. The rocket thundered away from pad 41 at Cape Canaveral Space Force Station at 4:22 a.m. EST but less than 30 seconds into the flight, there appeared to be a burn through of one of the nozzles on a Northrop Grumman-built graphite epoxy motor (GEM) 63XL solid rocket boosters (SRBs).
-----
My take: This is not the first such issue with this solid's nozzle. Somebody is not paying enough attention to the highly-erosive ablative insulation environment approaching and through the throat of a solid rocket nozzle. Whether out of ignorance or being too cheap is not knowable from this. If you complicate the design by adding thrust vector capability, you raise the odds of such burn-through or nozzle-loss failures, I do know that!
Reinforced rubbers do not hold up in the high shear flow. It takes hard silica phenolic plus a graphite throat insert, and that does NOT deflect to vector the nozzle bell! You have to deflect to vector out near the full case diameter where the scrubbing fluid shear, to get the rubber to hold up. Even then, you must do that deflection while still holding the full compressive thrust load aligned where you want it. Vectoring a solid rocket is a bad thing to attempt.
GW
Here's variation on what KBD512 suggested. Put together a reusable electric-drive transfer vehicle that is 2-way capable and reusable. Do this in LEO where humans can build the thing from docked modules like the ISS was. Load it there, too. Spiral it out unmanned to an orbit outside the outer Van Allen belt, say 60,000 or 70,000 km out. That's where you send the crew to board it, and to recover them coming home.
But, you do not need a Starship to do that!
Falcon-Heavy with a Dragon has plenty of dV to take a crew of 4 to 7 (there are up to 7 seats in the capsule) across the belts quickly to board the ship there. It's not rated for usefulness beyond about 6 months, but I bet it could be. That's your emergency bailout capsule coming home. Falcon-Heavy also has the dV to fly up empty and bring a returning crew of 4 to 7 home. Once the reusable orbit-to-orbit craft is built, all you have to do is resupply it. It might be just about as easy to spiral in to LEO uncrewed for that, since the dV to LEO is only about 7.8 km/s + loss coverage, while the dV to 60-70,000 km circular is near 10.5 km/s + loss coverage + circularization.
Starship might be more appropriate for larger crews, but remember, its first and best role is as a transport to LEO, without any refueling tanker flights at all. Why use a big vehicle when a smaller one will serve? Just build some sort of tug based in LEO, which would require a lot fewer tanker flights to keep supplied if it is smaller than a Starship, and let it push a small hab about the size of Skylab at the most, for transporting crews quickly across the Van Allen belts. Just keep the tug and hab in LEO, based there.
The orbit-to-orbit interplanetary (or lunar) transport, ought to have spin gravity. Crews will be out there a long time, especially spiralling in and out at the moon or Mars. It will need a solar flare storm shelter, too. The rest of that stuff (the ordinary rockets and capsules) is short-term zero-gee stuff.
If we are going to send Dragons (or similar) out beyond the Van Allen belts, we will need better forecasting for solar weather, lest an unanticipated event kill a crew needlessly. And we will need a station in LEO at which to assemble things and to fill them up with mission propellants. It would seem likely one station could perform both functions.
All that being said, I am wondering why we would even consider sending tall, narrow Starships with landing legs and pads that are inherently too small, to the moon or Mars, before big, flat, hard-surfaced paved landing pads have been constructed. That's the fatal shortfall in Musk's vision. And don't kid yourself, it is a fatal shortfall.
GW
Same is true returning home, too! You have to cross the Van Allen belts fast, then either decelerate into orbit or do a free return. You cannot kill your crew trying to spiral-in slowly with electric.
GW
Void:
You cannot use electric propulsion to take humans from Earth orbit to Mars. Electric propulsion is extremely low thrust/low acceleration. It takes a month or two, maybe three, to spiral out through the Van Allen radiation belts. That long an exposure is a fatal dose for any crew.
You need to cross the Van Allen belts in only a day or so, something known since just before Apollo. That takes high-thrust chemical or nuclear rockets to get significant vehicle acceleration. You need around 0.1 to 0.5-ish vehicle gee capability to make that happen. Electric is typically under 1/10,000 gee.
The departure dV from Earth orbit onto the transfer trajectectory to Mars (or the moon, or anywhere else out there) is the biggest dV by far! If you have to use chemical (or nuclear) for that, then why bother with electric?
My point: there is a whale of a lot more to worry about than just Isp, when looking at travel to Mars, or the moon, or anywhere else. Focusing on only one aspect is a guaranteed trip down the wrong path.
GW
From AIAA's daily Launch email newsletter for Mon 9 Feb 2026:
Wall Street Journal
SpaceX Delays Mars Plans To Focus on Moon
SpaceX has put off a mission to Mars planned for this year, shifting its focus to a long-promised lunar voyage for NASA. The rocket company told investors it will prioritize going to the moon first and attempt a trip to Mars at a later time, according to people familiar with the matter. The company will target March 2027 for a lunar landing without humans on board, another person said.
GW
1. You have to have a way to do entry, descent, and landing. There just enough atmosphere to cause significant peak entry heating, but not enough to do subsonic touchdowns with wings or chutes. It's pretty much propulsive touchdown. With a heat shield at least during entry, and preferred to be retained if the craft is to be used more than once.
2. When you touch down, you must have either a smooth, flat, hard plain, or a vehicle short and squat enough not to tump over, if a landing leg hits a big boulder or a small ravine, or if you touch down on ground that is strongly-sloped locally. Whatever is flying the craft must be able to perceive such hazards and react real-time to avoid them, or else you must design the craft to cope with the worst cases as if you were flying blind. There are criteria that historically worked on the moon and Mars: (1) the polygon defined by the landing pads has a minimum dimension, which must be greater than the height of the center of gravity above the surface, (2) the landing pads have to be large enough to lower the bearing pressure created by a factored-up weight, so that the anticipated soil bearing strength is not exceeded, (3) tip the pads inward a few degrees on spring loading, so that the lead pad cannot dig in and tump you over, if you have horizontal speed at touchdown, and (4) you need the throttleable thrust for thrust/weight equal 1 to hover, for significant time, before attempting the final touchdown, so as to give whatever is flying the vehicle time to see the hazards and avoid them.
3. It would help if the crew cabin were close to the bottom of the craft to limit how far a crewman might fall when using stairs or ladders. The issue with a short fall in lower gravity on the moon or Mars is more about suit punctures and busted visors. Tractor rocket configurations lend themselves to this, plus easing the thrown debris problem. If you are tall and narrow with the crew cabin forward, you risk a very long, fatal fall. Even if you have a powered elevator of some kind.
4. Must limit thrown debris if there is to be anything at all on the site besides the landing vehicle itself! The rocket blasts striking the surface divert sideways, but still moving at very significant speeds measured in km/s. Any rocks, grit, sand, and even dust will get thrown outward at pretty close to that diverted rocket plume velocity. While the gas plume velocity slows as the plume(s) rapidly spread(s), once accelerated, the thrown debris does NOT slow down! Even small pebbles are quite dangerous at km/s speeds!
5. Once down, you must be close enough to straight upright to ensure that a takeoff that does not "fall over" too fast for the thrust vectoring to counter. That has to be built into the landing legs, most likely. Leg-adjust to level the grounded vehicle. Likely hydraulic, possibly electric. Probably NOT manually-operated!
6. When doing the early exploring, it is likely that the site is unoccupied by any assets other than perhaps pre-positioned supplies sent 1-way. Even so, thrown debris is a big risk, if it destroys the supplies your small exploration crew were going to live on. Early exploring is all about finding out what is really there, where exactly it is, roughly how much and what quality it is, and some notion of what is required to get at it. It is NOT about tinkering with in-situ life support or propellant manufacture or anything like that! At least not as a priority objective. That comes later at an experimental base site. Supplies and propellant must have come from Earth to support the early exploration crew for a stay of short-to-modest length (days or weeks). Not months! Not years! They will need a truck with a real drill rig on it, and they will need suits supple enough to work that rig like real oil field roughnecks. They can "camp out" in the landing vehicle for a surface habitation.
That's my two cents' worth.
GW
I finally found enough public information to understand what the heat shield tiles on Starship really are. They are a less expensive and more producible variant of TUFROC tiles used on X-37B. A lot of the savings comes from the fact that the same size and shape tile covers most of the ship, unlike the Shuttle or the X-37B.
These are a modified carbon-carbon composite type outer material, which has some sort of ceramic materials incorporated, which is tougher and higher temperature-capable than alumino-silicate ceramics. It is higher thermal conductivity than low-density aluminosilicates. The lower layer is low-density fibrous (in some way) alumino-silicate ceramic, which has the low thermal conductivity needed to keep the backside temperature down in a thin two-layer title.
I do NOT know exactly how these materials are made. But I have seen the black upper layer atop the white lower layer in photos of these tiles being installed on the pins, over a thin layer of some "ablative" that is a backup for lost tiles.
What they learned from flights 10 and 11 was that the alternative "metallic" tiles (whatever they were) were not reliable because of unexpectedly-high oxidation, and that they needed some sort of gap filler between the tiles. So they are going with this two-layer carbonaceous ceramic atop low density alumino-silicate (a variation on the TUFROC notion).
The gap filler has turned out to be some sort of crushable paper wrapping around each tile. I am only presuming that the excess paper sticking out of the gaps gets trimmed off during the installation process.
It is also my impression that the tiles are redundantly attached, with both adhesives and those pins. The pins may (or may not) stick up into the outer layer.
Sorry, but I am unable to pin it down any better that that! Not privy to internal specifications and data!
GW
Follow-up to post 60. I found another article that gave more information. There were two sets of hydrogen leaks during the wet dress rehearsal. The first was in the connections between the rocket and the infrastructure around it, very similar to the leaks seen during the Artemis-1 wet dress rehearsal. These were fixed the same way as Artemis-1. Then a second set of leaks appeared. I had the impression that these were inside the vehicle. The article said they "did not understand" those leaks, and shut it down at that point.
This is a Boeing-built first stage core having propellant leak problems. So did the Starliner capsule that stranded 2 astronauts on ISS. I think I might see a pattern here: being too cheap damages quality, causing unreliability. Same corporate management mistake as what caused the 737MAX disasters. If I am right, the odds of killing the crew while riding the SLS just got higher.
GW
Follow-up to post 59. I see also that Artemis-2 will now not launch until March at the earliest, since the propellant load rehearsal found hydrogen leaks. Reportedly, these were in the connections between the rocket and the launch pad structure, not the rocket itself. As I recall, the last SLS launch was delayed for the very same reason. So it looks like the leak problem might be chronic.
Meanwhile, I ran across this about severe solar flare activity:
From Space.com via AIAA’s Daily Launch email newsletter for 3 Feb 2026. Note that the “flare” is the burst of electromagnetic radiation that travels at the speed of light. The coronal mass ejection “CME”, if any, is the slower-moving mass of particles that constitutes the actual radiation exposure hazard. The bigger those are, and the more direct the impact upon “something”, the higher the radiation exposure that “something” receives. With big CME’s around, this might not be a good time to put crews out past Earth’s magnetic field in a spacecraft. Quote:
Sun unleashes extraordinary solar flare barrage as new volatile sunspot turns toward Earth
News
By Daisy Dobrijevic published yesterday
A rapidly growing sunspot has fired off at least 18 M-class and three X-class flares in just 24 hours, including an intense X8.3 eruption.
The sun has erupted in a relentless barrage of powerful solar flares over the past 24 hours, firing off at least 18 M-class flares and three X-class flares, including an X8.3 eruption — the strongest solar flare of 2026 so far. Solar flares are ranked by strength from A, B and C up to M and X, with each letter representing a tenfold increase in energy — meaning X-class flares are the most powerful explosions the sun can produce.
The culprit is sunspot region 4366, a volatile active region that has grown rapidly in just a few days. The flurry of activity began late Feb. 1 and has continued into Feb. 2, with multiple M-class and X-class flares erupting in quick succession. The prolific region appears to be far from finished. Spaceweather.com described the region as a "solar flare factory", warning that its rapid growth and magnetic complexity make further eruptions highly likely.
The X8.3 solar flare peaked at 6:57 p.m. EST (2357 GMT) on Feb. 1, unleashing a blast of extreme ultraviolet and X-ray radiation that ionized Earth's upper atmosphere. The flare triggered strong R3 radio blackouts across parts of the South Pacific, with shortwave radio disruptions reported across eastern Australia and New Zealand, according to NOAA's Space Weather Prediction Center.
Scientists are closely watching for signs of any coronal mass ejections (CMEs) that could follow these powerful flares. Early analysis of a CME linked to the recent X8.3 eruption suggests that most of the solar material is likely to pass north and east of Earth, with only a possible glancing blow expected around Feb. 5, according to NOAA's Space Weather Prediction Center.
If those glancing impacts materialize, they could briefly elevate geomagnetic activity and increase the chances of auroras at high latitudes. However, forecasters stress that it is too early to know whether conditions will be favorable, as much depends on the CME's speed, direction and magnetic orientation.
It's also possible that more eruptions are still to come. Sunspot AR4366 remains highly active and continues to rotate into an Earth-facing position, raising the chance that future eruptions could launch CMEs more directly toward our planet. NOAA forecasters say they expect more exciting space weather activity from this region in the coming days.
Solar flares are powerful explosions from the sun that emit intense bursts of electromagnetic radiation. They are ranked in ascending strength from A, B, C and M up to X, with each letter representing a tenfold increase in intensity. X-class flares are the strongest eruptions and the number following the X indicates how powerful the event is. Today's flare was measured at X8.3, putting it high in the upper tier of solar outbursts.
--- end quote
GW
Cosmic ray exposures in the inner solar system more-or-less in the vicinity of Earth vary between 24 and 60 REM per year, varying more-or-less sinusoidally with the nominally-11-year sunspot cycle. High solar activity is the lower value of cosmic ray exposure. Exceeding slightly the 50 REM/year exposure standard (twice that of Earthly workers in nuclear plants) increases the risk of cancer late in life beyond about 3%. 60 REM/year in a peak year is just not that much a risk!
The killer is solar flare events, not cosmic rays! Those occur erratically, though more often during high sunspot years, and they comprise an enormously-larger huge flood of much less energetic particles than cosmic rays. They can vary from 1 REM per hour to 10,000 or more REM per hour. Such exposures are a few to several hours long. Not the whole trip!
The older astronaut high-exposure limits are no more than 25 REM accumulated in any single month, and no more than 50 REM accumulated in a single short event. Somewhere near 200-300 REM accumulated in a short event is about a 50% chance of dying quickly from severe radiation sickness, and 500 REM accumulated in a short event is pretty much a 100% chance of dying quickly.
The outdoor fallout after a nearby fission bomb explosion is somewhere near 5000-50,000 REM per hour, for a few days after the event. That stuff requires feet of lead or yards of earth (and concrete) for adequate shielding.
However, solar flare radiation, being far less energetic particles than cosmic rays, is far easier to shield! It only takes about 15-20 gram/cm^2 worth of shielding on your craft's hull to adequately protect from a high-end solar flare event, such as what occurred in 1972 between two Apollo missions to the moon.
Cosmic rays are not impacted very much by any shielding we might use, but it is known that the lower the molecular weight of the atoms in the shielding materials, the lower the secondary radiation shower intensity produced by scattering events hitting atoms in the shielding. That's why you do not want metal shielding for cosmic rays!
Cosmic rays are just NOT the fatal problem! Anyone who points to that as a show-stopper is lying! The solar wind, and especially solar flare events, are! That exposure really does build up over time toward some kind of career exposure limit. The old one was 400 REM max lifetime accumulation, reduced by age and gender. There was a formula for that. NASA published this stuff, decades ago.
I do hear that those older astronaut exposure limits have recently been reduced some, but that is small change compared to what I am talking about! And the truly high-exposure limits have been known since the atmospheric atomic tests in Nevada in the 1950's, not to mention the two Japanese cities that were A-bombed in 1945. Only the really low-dose exposure limits were found in the decades since.
GW
The Artemis-II mission was delayed because of cold at Cape Canaveral. I don't know any details about the delay, but the reason (cold, just below freezing soak-out) is comparable to what killed Challenger back in 1986. That decision on NASA's part is unsurprising, since the SRB's on this launch vehicle are basically a 5-segment form of the Shuttle 4-segment SRB's. It would be incredibly stupid to make the Challenger mistake twice!
I am not sure how accurate this is, but one posting I saw on LinkedIn had an animation of the orbit Artemis-II is "going to use" (supposedly, anyway). It launches into an ellipse that apogees somewhere in or between the two Van Allen belts, then figure-8's around the moon (like Apollo, but further out from the moon), before making a free return and entry. There has to be a perigee burn to get from the ellipse onto the lunar transfer trajectory, but no other burns, other than course corrections.
If true, these astronauts will spend more time (twice or more) exposed to Van Allen belt radiation than the Apollo astronauts ever did. This is a high solar activity year. From what I read, that increases the radiation exposures from the Van Allen belts (it does decrease cosmic ray exposure outside Earth's magnetic field).
Notice also that I said nothing about the Orion heat shield risk. That is well covered in other postings. Peak convective heating occurs at about half the entry interface speed, which is near escape in a free return from the moon. Convective heating rate varies roughly as speed cubed. Plasma radiation heating rate varies by an exponent of 6 or more with speed. The effective plasma temperature in degrees K is crudely numerically equal to speed in m/s. You decide if flying a known-to-be-defective heat shield with a human crew was a "good risk to take".
GW