You are not logged in.
I see that SpaceX has pushed the next Starship/Superheavy launch off into May. No reason has been given that I know of. But I suspect this one is different enough from the block 2 version that flew previously, that it is taking them longer to make sure they think it is ready to fly. THAT is why Musk time and real time differ by about a factor of 3.
GW
Today's "Daily Launch" from AIAA finally brings up the heat shield issue facing Artemis-2 as it heads to re-entry. The link was to a Scientific American article of some kind. Not all the supposed facts quoted in it were correct, but the concern over char cracking leading to the shedding of chunks of char was correctly pointed out.
Myself, I think the odds are good that the crew will come home just fine. Where I differ with NASA is that I think the same damage seen on Artemis-1 will happen to Artemis-2's heat shield, despite switching to a non-skip, single heating pulse entry. It might be less than what happened to Artemis-1, or it might not. But if ANY chunks at all get shed, then NASA was wrong and I was right!
GW
The lowered static temperatures obtained in the supersonic expansion of a De Laval nozzle are intimately associated with the supersonic speed. As soon as the stream slows down by any means whatsoever, it rewarms. If dead still, it is at its stagnation temperature. Unlike pressure, you ALWAYS recover the full stagnation temperature, no matter what. Ttot = Tstatic * (1 + const * Mach^2) where constant = (gamma - 1)/2, and for air, gamma = 1.4 is usually a very good model.
I ran into that many years ago with ingested cooling air for the electronics in a towed decoy. Once we started looking at supersonic speeds, the cooling air started getting hot. You may capture it at high speed relative to the decoy, but you must slow it down very slow relative to the decoy in order to use it for anything at all.
The missile seeker guys also ran into this decades ago, missiles being mostly supersonic, even by the early 1950's.
GW
They probably have enough on their plate trying to get Starship working acceptably well at all, plus they have a contract that is all-but-in-default for an expendable version that is to be a lunar lander. It's too early in the flight tests to be criticizing their decisions about what to spend their money and their efforts upon.
None of the projected numbers (masses, dollars, anything) are "real" until those tests are successfully completed, and they are actually still somewhat bogus, until actual operational experiences have been obtained. That's just real life!
My guess is that they will have at least another test loss or two, before Block 3 Starship and Block 3 Superheavy are actually flying into orbit and fully-recovering. That's what you get when you operate with youngsters under age 40 and no "old hands" to impart the engineering art.
The art is the undocumented knowledge passed-on, on-the-job, one-on-one, from old hand to newbie. It is about 50% of the essential knowledge in production work, and much more than that, in development work, which this Starship stuff is. Art is the stuff not documented in project reports, because nobody wanted to pay for all that writing. SpaceX's youngsters have to learn that art the hard way, by failing a lot, in tests. Their track record is not hard to understand, at all. It was the same with the Falcon series, starting with almost going bankrupt before they got Falcon-1 to fly.
GW
Too bad nobody is looking at MCP anymore. They are choosing habitat and suit pressures too high for it. Some are approaching 8 psia in the oxygen suit! Such are not necessary.
Paul Webb's MCP test prototypes in the 1960's amounted to vacuum-protective underwear with an oxygen helmet plus a small backpack that had only oxygen plus a CO2 absorber in it. No need for cooling equipment, you just sweat right through the garment into vacuum. Cooling by evaporation guaranteed! The whole shebang weighed 85 pounds., although you would need protective outerwear over it, for the thermal and mechanical hazards, maybe another 5 lb. 10 lb at the very most.
His final prototype was very limber, even more than the SpaceX suit. It operated near the old Apollo suit pressure of 3.2-3.5 psi (170-190 mmHg in his reports), although that gas pressure is only in the helmet and tidal breathing bag! The clothing is unpressurized by gas at all, just a tight fit exerting mechanical pressure upon the body. The old partial pressure suits worked the same way, but they did not apply pressure as evenly, and they did not pressurize hands and feet at all. Webb did.
I've seen the film of the test subject wearing Webb's MCP rig, pedaling a bicycle ergonometer inside at vacuum tank at a simulated 87,000 feet, which is more than 4 miles above the vacuum death point! He was in there for 30 minutes and had no problems, unlike the old partial pressure suits, which were limited to 10 minutes max before fluid edema into uncompressed zones started hands and feet swelling.
Think about it: vacuum protective underwear, over which you wear whatever mechanical/thermal protective outer you need for the job at hand. Easily launderable, too!
And if you run your two-gas habitat atmosphere as 43% (by volume) oxygen (the rest nitrogen), at 43% of a standard atmosphere, the fire danger oxygen concentration driving chemistry rates is the same as sea level pressure air at 70 F, the oxygen partial pressure is equal to air somewhere below 8000 feet (2500 meter) for no risks of chronic altitude sickness and no risks to childbirth, and the nitrogen pressure is low enough compared to oxygen suit pressure that you need zero pre-breathe time, all the way down to suit pressures of only 3.0 psia (155 mm Hg)!
Below 3.0 psia suit pressure, there are tissue dry-out and bleeding problems in the airway and lungs, although cognition can be maintained down to about 2.0-2.5 psia (100-130 mm Hg). You just don't want more than a few minutes' exposure, that low! I have a similar, not-as-easily-remembered, habitat atmosphere that will do no pre-breathe down to 2.9 psia (150 mm Hg) suit pressure, and yet still meet the life support and fire danger criteria.
MCP suits at 180 plus or minus 10 mm Hg, and "rule-of-43" habitat pressure. Easily-launderable space suits. Lightweight backpacks. No heavy cooling systems. Very flexible allowing almost any human activity. And it worked fine in ground tests, more than 6 decades ago. Looks like a match made in heaven to me!
GW
Spacenut: what I am looking at is only nominally two 8 ft x 8 ft x 40 ft containers. These could be rescaled a little bit.
GW
I'm not using a standard shipping container, they are too heavy, designed for ship-handling loads a space delivery item will never see. I'm looking at something the size of a standard shipping container, which is 8 ft x 8 ft x 40 ft.
GW
My letter to Isaacman should be in a staffer's hands by about today. The handout I sent him is already posted over at "exrocketman".
GW
update 3-13-2026: the handout on ramjet ablatives overlapping with heat shields is titled "Ramjet Data Re: Heat Shields", posted 1 March 2026 at http://exrocketman.blogspot.com. Search code 01032026.
From the AIAA "Daily Launch" email newsletter for 3-10-2026:
Space
Incoming! 1,300-pound NASA satellite will crash to Earth on March 10
NASA's Van Allen Probe A will crash to Earth on Tuesday (March 10) after nearly 14 years in orbit, according to the Space Force's current best estimate.
-----
The window USAF projects is + or - 24 hrs from about 7 PM (not sure if eastern or central or what).
GW
Update 3-11-2026: It came down this morning early, reportedly over the "Eastern Pacific region", which does not pin it down very well. There is a second up there, not expected to enter until the 2030's, although that was the original expectation on this one. The pair was operated until out of attitude control/maneuvering fuel, with no way to safely dispose of them. THAT has to change!
Update 3-12-2026: today's "Daily Launch had this AP News headline summary:
AP News
Old NASA science satellite plunges back to Earth
An old NASA science satellite plunged uncontrolled from orbit and reentered over the Pacific on Wednesday. The U.S. Space Force said the Van Allen Probe A came in west of the Galapagos Islands.
GW
From the AIAA "Daily Launch" email newsletter for 3-10-2026:
SpaceNews
First Starship V3 launch slips
SpaceX is pushing back the first launch of the latest version of its Starship vehicle even as NASA is asking the company to accelerate work on a lunar lander version of the vehicle. In a social media post early March 7, Elon Musk, founder and chief executive of SpaceX, announced that the first flight of version 3, or V3, of Starship would be “in about 4 weeks.” Four weeks from March 7 is April 4.
-----
GW
From AIAA “Daily Launch” email newsletter 3-9-2026, just the summary of an ARS Technica article:
ARS TECHNICA
With Gateway likely gone, where will lunar landers rendezvous with Orion?
Last week, NASA Administrator Jared Isaacman unveiled a major shakeup in the Artemis Program. The changes focused largely on increasing the launch cadence of NASA’s large SLS rocket and putting a greater emphasis on lunar surface activities. Days later, the US Senate indicated that it broadly supported these plans. Which lander will be used to take astronauts down to the lunar surface from an orbit around the Moon and back up to rendezvous with Orion?
-----
My take:
The rumors have proved to be true. Gateway is essentially out, SLS Block 1B and Block 2 are out, and there will only be a slight upgrade to SLS Block 1 with the Centaur-5 replacing the Interim Upper Stage (the second stage of Delta-4). Artemis will rendezvous with landers and do its landings from some lunar orbit that the SLS Block-1 can reach with Orion atop it. That is likely some elliptic capture orbit, but nobody is talking about that yet. We will see whose lander “gets there” first. That will be the one they use.
Isaacman is trying to do it “right”. We will see if he can change the NASA culture back to crew lives valued more than schedule and money. He has made noises like that, but as yet I have seen no change at NASA. Artemis-2 will fly with the same flawed heat shield that surprised everyone on Artemis-1. Artemis-3 is already being built to the same flawed design. Sooner or later, the odds will bite them with that, just like they did with the flawed SRB O-ring joint design with the space shuttle.
GW
From AIAA “Daily Launch” email newsletter 3-9-2026, following the link to a Spaceflight Now.com article:
NASA contract confirms selection of ULA’s Centaur 5 as new upper stage for the SLS rocket
March 7, 2026 Will Robinson-Smith
NASA officially selected United Launch Alliance’s Centaur 5 as the upper stage for its Space Launch System rocket starting with the Artemis 4 mission, scheduled to launch no earlier than early 2028.
The Centaur 5 was developed as the upper stage of ULA’s Vulcan rocket. The launch vehicle flew four times since its debut in January 2024 and the upper stage performed well across all flights.
The news, disclosed in contract documents published on Friday, comes one week after NASA Administrator Jared Isaacman announced that the agency would move towards a “standardization of the [Space Launch System rocket] fleet to… a near-Block 1 configuration.”
“The idea is we want to reduce complexity to the greatest extent possible,” Isaacman said during a briefing at the Kennedy Space Center on Feb. 27. “We want to accelerate manufacturing, pull in the hardware, and increase launch rate, which obviously has a direct safety consideration to it as well.”
Originally, NASA planned to launch the first three missions for the Artemis program using ULA’s Interim Cryogenic Propulsion Stage (ICPS), a modified version of its Delta 4 Cryogenic Second Stage, and then transition to the Exploration Upper Stage (EUS), built by Boeing, beginning with the Artemis 4 mission.
NASA, under Isaacman’s leadership, decided to move away from those plans due to cost and schedule overruns.
Long before this decision, Tory Bruno, ULA’s President and CEO at the time, was asked during a reporter roundtable in December 2024 about how the company would handle a theoretical change in the architecture for the SLS rocket. The question came up a month after President Donald Trump was elected to a second term, which sparked discussions of whether or not the SLS plans at the time might change.
“The Exploration Upper Stage is a very, very large upper stage. It’s much larger than the Interim Cryogenic Upper Stage that we’re providing now. It’s larger than a Centaur 5,” Bruno said. “If the government wants to change something in the architecture of SLS, they would tell us and we would tell them what we could do.”
That ‘what if?’ scenario is now reality.
In its procurement statement, NASA said its intention is to issue a sole source contract to ULA, meaning it’s the only upper stage being considered for this new iteration of the SLS rocket. An eight-page supporting document from NASA’s Marshall Space Flight Center (MSFC) in Huntsville, Alabama, was published to document the reasoning for its decision.
Among the stated reasons are the decades-long heritage of the RL10 engine, which has matured over time; the ability of the Centaur 5 to use the interfaces available on the Mobile Launcher 1 (ML1) along with the propulsion commodities of liquid oxygen and liquid hydrogen; and the experience of ULA’s teams working with NASA’s Exploration Ground Systems (EGS) at the Kennedy Space Center and elsewhere in the country.
They also noted that with the Centaur 3 upper stage achieving certification to launch humans as part of the Commercial Crew Program, there are a lot of common features with the Centaur 5.
“This approach leverages current support infrastructure and will use, with relatively minor modifications, an existing ULA upper stage,” NASA said. “All other alternative solutions fail to meet the performance requirements, would require significant modifications to hardware that is still under-development, or would require the development of new hardware that does not currently exist.”
NASA also said a time constraint to this decision caused them to select ULA as its sole choice.
“The NASA Kennedy Space Center (KSC) need date for processing is projected to be nine months prior to a launch,” NASA said. “Award to another source would cause unacceptable delays to current launch schedules.
“These delays would derive from the procurement process, on/off ramping of new contractor personnel, the potential need for reworked activities, as well as efforts necessary to satisfy SLS technical and programmatic drivers.”
The other upper stage that may have been in contention was from Blue Origin’s New Glenn rocket. Besides not having the previously stated advantages from NASA’s perspective, the agency also expressed concerns with the modifications needed to adopt Glenn Stage 2 for the ML1.
“Using the NGUS would require significant modifications to both the stage and the EGS infrastructure. For example, using NGUS would require relocating the Mobile Launcher Crew Access Arm and modification to the upper stage umbilical retraction mechanism,” NASA said.
“The stage could be shortened to meet VAB height constraints but would require full scale development and testing to qualify the stage for the shorter configuration. Full scale testing/requalification would result in unacceptable schedule impacts and additional cost risk to the SLS Program.”
What happened to the Exploration Upper Stage?
The original plan to use an EUS-enabled rocket would’ve enabled what NASA called “more ambitious missions” to the Moon, given that it would allow for the delivery of up to 11 metric tons more mass to the lunar surface under the Block 1B configuration as compared to the ICPS-powered Block 1 rocket.
However, a 2024 report from NASA’s Office of Inspector General found that, despite the SLS Block 1B being in development since 2014 and moving the first flight from Artemis 3 to Artemis 4, it continued to be behind schedule due in part to what the OIG called “quality control issues” at the Michoud Assembly Facility (MAF) in Louisiana.
“We project SLS Block 1B costs will reach approximately $5.7 billion before the system is scheduled to launch in 2028,” the report stated. “This is $700 million more than NASA’s 2023 Agency Baseline Commitment, which established a cost and schedule baseline at nearly $5 billion.
“EUS development accounts for more than half of this cost, which we estimate will increase from an initial cost of $962 million in 2017 to nearly $2.8 billion through 2028.”
The mid-2024 report also noted that at the time, delivery of the EUS to NASA was “delayed from February 2021 to April 2027.” That put the Artemis 4 flight, then projected for September 2028, to become further delayed.
Back in late September 2025, Spaceflight Now spoke with Sharon Cobb, the Associate Program manager for SLS at Boeing, about the Artemis 2 mission as well as the progress on the EUS.
“We’ve been working very diligently on Exploration Upper Stage. I was just at MAF last week and was able to see the liquid oxygen tank has been welded and tested,” Cobb said. “We’ve also got barrels in work there that are about to be welded for the flight unit. The LOX tank is a structural test article. So, we’re making really good progress on developing that Exploration Upper Stage.
Like with the core stage that launched the Artemis 1 mission, the plan was to perform what’s called a ‘green run’ with the EUS at NASA’s Stennis Space Center in Mississippi. That would include a full fueling of the upper stage and a full duration static fire test of the four RL10 engines as well.
Presumably, with this new direction for the SLS rocket, that will no longer take place, though NASA hasn’t specifically commented on what will happen with the EUS hardware currently in flow.
-----
My take:
This is the second of 3 postings regarding Isaacman’s major shakeups at NASA
GW
-----
From AIAA “Daily Launch” email newsletter 3-9-2026, following the link to a Space.com article:
NASA wants to accelerate its Artemis missions to the moon. It will need to drop some big hardware to do it.
By Josh Dinner published 3 days ago
Some major projects might be left half complete after this latest shakeup.
NASA Administrator Jared Isaacman recently announced a significant restructuring of the Artemis program, and how the agency intends to return astronauts to the moon.
The new plan shortens the time between missions and redraws the map of which launches will achieve various program milestones. Nothing will change for Artemis 2, which may lift off in a matter of weeks, carrying four astronauts on a 10-day flight around the moon and back to Earth. Every mission after Artemis 2, however, has been adjusted.
The programmatic shuffle is rendering parts of the old Artemis plan obsolete, leaving major ground hardware half-built and an uncertain future for the Gateway moon-orbiting space station under development.
Isaacman announced the changes during a press conference on Feb. 27, citing unacceptable wait times between missions for Artemis' Space Launch System (SLS) rocket and an increased risk of relying on unproven technologies to carry out mission-critical objectives like landing astronauts safely on the lunar surface.
The Artemis 2 SLS is currently undergoing repairs in the Vehicle Assembly Building (VAB) at NASA's Kennedy Space Center in Florida, with a potential rollback to its launch pad in time for a launch window that opens April 1. Artemis 2 will bethe first crewed flight of the Orion spacecraft and the first return of astronauts to lunar space in more than half a century. Under the previous framework, it was meant to be followed by Artemis 3 in 2028, which would carry out the program's first moon landing with astronauts aboard SpaceX's Starship vehicle.
For Artemis 4, NASA planned to upgrade to the SLS Block 1B, which features a design powerful enough to launch elements of the Gateway space station intended for lunar orbit. Beginning with Artemis 4, NASA aimed to use the Gateway outpost around the moon for deep-space science and as an orbital layover stop where Orion and the program's lunar lander could dock to transfer crews headed down to the surface. Gateway, however, is nowhere to be found in any of NASA's recent Artemis updates.
Under NASA's new plan, there will be no SLS Block 1B. In the hope of shortening launch cadences from the current 3.5-year interval to the desired 10 months, SLS is being standardized into a single configuration. Instead of relying on SLS' current Interim Cryogenic Propulsion upper stage, NASA is reportedly considering converting United Launch Alliance's Centaur V upper stage for use on SLS for all Artemis launches after Artemis 3.
The revised Artemis program is now targeting 2027 for the launch of Artemis 3, but instead of landing on the moon, the mission will fly to low Earth orbit for rendezvous and docking maneuvers with either or both of the Artemis program's contracted moon landers — SpaceX's Starship and Blue Origin's Blue Moon spacecraft — depending on their relative readiness for orbital missions.
NASA partnered with SpaceX for Starship to serve as the lander for Artemis 3 and 4 and contracted Blue Moon for Artemis 5. But the agency is now signaling that it's ready to fly Artemis 3 with whichever lander can be made safely available when launch time rolls around.
With Artemis 3 turned into a lunar landing stepping stone around Earth, Artemis 4 has been tapped as the program's first crewed landing on the moon, which NASA still hopes to accomplish in 2028, with a possible second moon landing that same year on Artemis 5.
It's a major reshaping of Artemis' original mission progression, but the plan has been purposed to maximize both crew safety and NASA's chances of success, according to Isaacman. The shakeup doesn't come without some sacrifice, though.
Gateway's fate remains undetermined under NASA's new plan. Many components of Gateway are already in various states of assembly, but there is now no rocket to launch some of them once they're ready and no missions yet assigned to rendezvous with the proposed outpost. Congress advanced a revised NASA authorization bill on Wednesday (March 4) that supports many of Isaacman's proposed changes to the Artemis program, but only requires he brief lawmakers on Gateway's status within a few months' of the bill's passing.
If Gateway is on the chopping block, as seems likely, there is potential for its existing hardware to be repurposed for use in a possible base on the lunar surface, which has been a longstanding component of the Artemis program's goals and NASA's vision for a sustained human presence on the moon. One of the revisions in the authorization bill even grants the NASA administrator the freedom to "repurpose, reprogram, reconfigure, or reassign existing programs, platforms, modules, or hardware originally developed for other programs" in order to ensure that the space agency's Artemis goals are successful.
-----
My take:
This is the first of 3 postings regarding Isaacman’s major shakeups at NASA.
GW
-----
The thing is wearing out. The Zvevda module cracks and leaks are only one example. Sooner or later there will be a catastrophic failure in some module, causing a fast depressurization, and death of the crew. The longer this thing's mission is extended, the more likely such a fatal event is likely to occur. Simple as that!
The problem here is NOT how long the ISS can fly, it is that replacements for it have been delayed too long already. Corporate business is OK with that delay, greedy as they are; the problem has been inadequate government setting of goals for that corporate business arena by letting appropriate contracts. And that is mostly Congress's fault, but substantially partly the administration's fault, across multiple administrations.
GW
I had not seen your Flight 11 photo with the reddish oxide stain before. I only ever saw the other one.
But there was a lot less of it than Flight 10. On both, it seemed to come from some locations on the belly, not so close to the nose. Where they deliberately left off tiles, perhaps?
GW
From AIAA “Daily Launch” for 3-4-2026, following a link to Spacnews.com, a Jeff Foust article dated 4 March:
WASHINGTON — Workers have completed repairs to the helium pressurization system in the upper stage of the Space Launch System, keeping a potential April launch of the Artemis 2 mission on track.
In a March 3 statement, NASA said engineers traced a blockage in helium flow in the Interim Cryogenic Propulsion Stage, or ICPS, to a seal in a quick-disconnect line feeding helium from ground equipment into the stage. The seal had become dislodged, blocking helium flow.
Technicians removed the quick-disconnect fitting, reassembled it with the seal properly positioned and reinstalled it. Tests confirmed that helium was flowing into the stage after the repairs.
The quick-disconnect line was one of the leading suspected causes of the blockage, along with a check valve inside the stage. NASA said Feb. 21 that neither issue could be addressed at the launch pad, requiring the agency to roll the vehicle back to the Vehicle Assembly Building for repairs.
While addressing the helium issue, workers also performed maintenance on other parts of the SLS. That included replacing batteries in the core stage, ICPS and boosters, as well as replacing batteries in the rocket’s flight termination system ahead of end-to-end testing required by the Eastern Range.
NASA also said it is replacing a seal in a line that feeds liquid oxygen into the core stage. That seal is separate from those in liquid hydrogen lines that caused leaks during a wet dress rehearsal in early February and were replaced at the pad. NASA did not disclose why it is replacing the liquid oxygen seal, as there were no reports of leaks during the two fueling tests conducted last month.
NASA said the repairs and maintenance keep the vehicle on schedule to roll back out to the pad later this month for a launch attempt in early April. Two-hour launch windows are available on the evenings of April 1, 3, 4, 5 and 6 during the next launch period. The following opportunity opens April 30.
The agency did not disclose when it plans to roll the SLS and Orion spacecraft back to the pad. At a Feb. 27 briefing, Lori Glaze, acting associate administrator for the Exploration Systems Development Mission Directorate, said teams would need “at least a week and a half or so” at the pad after rollout to complete preparations for a launch attempt.
-----
My take:
The Helium valve seal displacement problem sounds similar to, but not quite the same, as the bad helium valves in Starliner. This was the interim upper stage of the SLS in which this occurred, which is old Delta-4 hardware acquired when Boeing absorbed McDonnell-Douglas. The oxygen seal wasn’t leaking, but got replaced in the first stage core anyway, for unspoken reasons. The first stage core is a Boeing in-house design. Most of the replacements were actually various batteries that were too long past being fully charged.
I've also seen some statements elsewhere from Isaacman, somewhere, about "standardizing" the SLS rocket configuration. There was no clue what that meant, but I suspect it might mean there will only ever be an SLS block 1, with the interim upper stage.
GW
Well, they need to use something thicker, maybe. In tactical, we used no carbon composites. Those came later. We used silica phenolics, with the fiber lay oriented 45 degrees downstream. We used dense graphite throat inserts, underlaid with a variety of lower density carbon materials or else ablatives. Sometimes we used carbon-phenolic for nozzle entrance structures, driven there by the "saw cut effect" of flow coming out of a slot in the grain design hitting the nozzle entrance structures.
If I were N-G's solid motor outfit, I'd be looking more at tougher and thicker ablatives, and the old test data that support them, than in the new computed-generated nonsense. Computers happily process faulty inputs as good inputs, and the answer "credibility" looks the same. They need to talk to some of the old pencil-and-paper engineers, before all are dead.
GW
There was no orange staining on 11. It was flight 10 that had both the white near the nose, and the orange staining all over the heat shield.
GW
There's no reason you cannot mix up a batch of novolac polymer with microballoons (that is what Avcoat is) to load into an extrusion press instead of a hand-held caulking gun.
The thicker the char layer, the more important the porosity becomes to let the pyrolysis gases out. But no matter what, you need reinforcing fibers that connect that char to the virgin beneath. That is how you resist fluid scrubbing shear trying to tear chunks of char out, and also how you resist pyrolysis gas pressures trying to blow chunks off (so they need the hex put back into their bonded Avcoat tiles).
NASA mangers have "determined" that a change to entry profile will reduce the blow-off pressure. The same basic models on the computers told them that as failed to predict the cratering in the first place. They totally ignored the risk of fluid shear scrubbing forces ripping out chunks. And that shear rip-out is something I saw with insulators in ramjet combustors. It is quite the real effect.
GW
What I think I see for an object of the size and shape as Starship, is quite a difference in peak heating during 7.5 km/s entry at Mars (off a fast interplanetary trajectory), versus 7.9 km/s entry at Earth (from low circular Earth orbit). At Earth, convective heating is modest due to the large radius of the vehicle, while plasma radiation heating is virtually nil. At Mars, convective is comparable to Earth, but plasma radiation heating is an order of magnitude larger, again due to the large radius of the vehicle.
Now, you can resist such heating either by ablation, or by refractive thermal re-radiation, or some of both. You want to minimize conduction into the interior, in either case. Things that can resist the mechanical forces tend to be dense. That opens up the path for conduction inward. It puts you to looking at metallic or hard ceramic tiles, but with some sort of lower-thermal-conduction layer underneath, to re-limit the conduction inward. High density ALWAYS correlates with high thermal conductivity.
SpaceX attempted some metallic tiles (not all of them) on Flight 10. They did not like the fast oxidation rates that they saw, which stained that heat shield orange. They went back to ceramic tiles in Flight 11, which worked. I do not know what that ceramic was. But it is dense and hard, and requires a low-conductivity ablative layer underneath. The low conductivity stops the inward conduction. The ablation capability provides the backup burn-through protection for a lost tile.
I see nothing at all from SpaceX that would address what is needed to make rough-field landings on soft ground. Moon, Mars, both are dominated by both softness and roughness.
GW
I see various reports about shakeups at NASA and changes to the Artemis moon program, following the shellacking NASA management took in the outside safety report.
Isaacman is talking about making Artemis 3 an in-orbit rendezvous and docking test with whatever lander shows up. But he is also talking about increasing the flight rate and adding missions.
I don't think anything is yet settled. But they really need to properly fix that heat shield. Artemis 3 is being built with the same flawed design.
GW
A paperwork trail does not stop nozzle insulation burn-throughs in solid rockets. It merely verifies what was built. Adequate ablative type, thickness, and fiber orientation are what stop the burn-through.
There were good paperwork trails for Apollo-1. For Challenger, for Columbia. The one for Challenger terminated in an attempted coverup at the inquest hearings. There was a good paperwork trail for the Artemis-1 heat shield (and now Artemis-2 and -3). There is a good paperwork trail for the new USAF tanker that still cannot do its design mission. There was a partly-faked paperwork trail for the B-737MAX. Shall I go on?
GW
Spacenut:
I quite agree that nested headers inside main tanks is better. For one thing, the main tank around the header can become almost-a-thermos-bottle, limiting evaporation losses.
But, SpaceX had to put the headers in the nose to get acceptable cg position for entry and descent, especially if no payload was aboard far forward.
GW
There was another article in the AIAA "Daily Launch" for Thurs 2-26-2026 about how the USSF/USAF is viewing the Vulcan booster problem that occurred recently. The summary below the title did not reflect the actual article content and point. That point is this: there will be no further military launches on Vulcan until the booster anomalies (there have been 2 of them out of 4 flights) have been resolved.
Everybody in USSF/USAF and at both Boeing and Lockheed (who comprise ULA), is now looking in Northrup-Grumman's direction. N-G owns the last remaining big solid motor fabrication facilities in the US.
In my day, there were enough contractors for there to be serious competition, both at tactical (lots of competitors) and strategic (not so many) sizes. At least in the tactical business, we knew how to reduce solid motor failure rates to under 1 in a million, and still make profit. If you did not do that, you could not compete successfully.
Isn't monopoly wonderful?
I have to wonder if some sort of a market share tax might forestall the agglomeration of companies into these rather unproductive monopolies without the expense of thousands of lawyers for active enforcement.
GW
From the AIAA "Daily Launch" for Thurs 2-26-2026:
Aviation Week Network
NASA Leadership Lapse Compromised Safety In Starliner Crew Flight Test
Historically, the type of roasting that NASA received from independent teams investigating the 2024 Starliner Crew Flight Test would follow a fatal accident—one triggered not only by technical failings but also by agency safety blind spots. In the case of the Boeing CST-100 Starliner Crew Flight Test (CFT), NASA averted disaster, but its leadership’s lapses were as chilling as the mischaracterizations and missteps that led to the 1986 Challenger and 2003 Columbia space shuttle accidents.
-----
My take: nice to see that not only do lots of folks in positions of power agree with me, but also with my assessment of just how severe those leadership failures really were.
GW