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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
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.
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The window USAF projects is + or - 24 hrs from about 7 PM (not sure if eastern or central or what).
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.
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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?
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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.
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My take:
This is the second of 3 postings regarding Isaacman’s major shakeups at NASA
GW
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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.
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My take:
This is the first of 3 postings regarding Isaacman’s major shakeups at NASA.
GW
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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.
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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.
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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
The "standard" Block 2 (about to become Block 3) Starship does its deorbit burn and its flip-and-landing burn on the propellant in the header tanks, so SpaceX says. They also said that those were transferred to the main tanks in the Block 2 design to make the landing burn. (Note that there is really nothing "standard" about Starship until all the experimental flight testing is successfully done.)
That transfer from headers to main tanks may or may not still be true in Block 3, as I saw in some illustrations plumbing direct to the engines from the header tanks. Those header tanks hold something like 20-25 tons at most, not anything like 100 tons! The ship explodes upon toppling over in the Indian Ocean, because not all of that 20-25 tons was used to make the landing. There are still fuel and oxidizer aboard when it falls over and breaks open.
I do not know of any variants yet being seriously considered except the HLS and some sort of propellant tanker. And that will likely be true until after the next round of Block 3 flight tests are done! Then it gets bigger yet again in the Block 4 design, which must again be proven in test before it can be considered as a viable prototype for any sort of real mission work. Excepting maybe HLS and the tanker, any other variants must wait until everything through Block 4 has been tested and found adequate.
As for the ballistic coefficient of a Block 2 or Block 3 Starship, the hypersonic drag coefficient of a round cylinder dead broadside to the wind is about 1.20 based on the cylinder blockage area, coming from my old Hoerner "drag bible". The drag coefficient of a flat plate normal to the wind in hypersonic flow is about 1.84, based on its blockage area. Same data source. I took a good guess for the effects of the pointed nose, and for the relative blockage areas of body and flaps, and determined a CD = 1.22 on a blockage area of just about 462 sq.m normal to the wind.
Starship does NOT enter normal to the wind, it enters at a nominal angle of attack of 60 degrees, although that varies some about that nominal angle. Thus the normal blockage area is not actually normal (90 deg) to the wind, it is about 30 deg off. That's no big impact on CD, but the effective blockage area is 462 sq.m times a cosine factor of 0.866 for that angled entry.
I used Bob's numbers of 120, 160, and 40 metric tons for the inert mass of Starship, even though I thought (and still think) the 40 ton figure is ridiculously unrealistic. To that I added 20 tons landing propellant, and 100 tons payload at Mars, and I added the same 20 tons of propellant and 0 tons of payload at Earth. That puts mass-at-entry 240, 280, and 160 metric tons at Mars, and 140, 180, and 60 metric tons at Earth.
I did entries at Mars at 7.5 km/s off a fast trajectory, and 2 deg below horizontal. I did entries at Earth at 7.9 km/s out of low circular LEO and 2 degrees below horizontal.
That's where my numbers came from! They should be pretty good, as good as the masses at entry are. The whole thing turned into a sensitivity study with ballistic coefficient the independent variable. The low inerts are ballistic coefficient roughly half those of the heavier values.
GW
"Building things in orbit is still a very future wish list item."
But that is EXACTLY how the ISS was built over 30 years ago! Docking together stuff sent to orbit. The only requirement to do that was the arm on the shuttle to hold things where you wanted them to go, instead of using thruster thrusts. That docking thing is the primary reason there is an arm on the ISS today.
ISS is in the wrong high-inclination orbit to go anywhere else without huge plane-change dV's. But a station in a low inclination orbit does not suffer that problem. Simply equip it with multiple arms, and you can assemble lots of things by docking, by nuts and bolts, by clamps, perhaps even by welding. Just hold the items together in the right position with the arms. If any of this is manual work, the EVA astronauts "stand" attached to other arms. Demonstrated decades ago on the shuttle servicing Hubble and others.
Add another truss section out there with propellant tanks attached to it, and plumbing and power routed inside the truss, and you have a refueling facility as well. Use my rotating-vanes tanks, and transferring cryogenics becomes as easy as handling storables. And there is no reason you cannot also stockpile the gases used by electric propulsion as propellants.
All of which makes space tugs possible for sending and receiving things using high-elliptical capture orbits. It takes at the very least a refueling capability to do that, and even SpaceX is talking about a Starship variant that stays on orbit as a refueling facility, to be kept filled with propellants brought by other tankers, propellants stored on orbit for other craft to use.
The same tug stages that can go onto, and back off of, an elliptic orbit, based from low circular LEO, can also go get depleted satellites for their refilling at the station, and then putting them back where they were before. Even geosynch is less challenging than an elliptic capture orbit that goes more than halfway to the moon. Some of this might be done remotely, some of it might be manned. So what?
We not only could do this today, we could have done most of this at least 30 years ago! My rotating vane tank would make cryogenics transfer a lot easier (and faster) than by using ullage thrust, which disturbs your orbit. That did not exist 30 years ago, but the arms and ullage thrust did!
And a "tug" is just any convenient stage of adequate dV and payload capability, plus a guidance and control rig, and maybe a place for a crew capsule on manned missions, sent up there and kept filled for use on many different missions.
There not a reason in the world why this could not be done, except government and corporate "not invented here" prejudices. With my spinning-vanes tank approach for cryogenics, ALL the critical enabling technologies now exist to make this very practical!
GW
From AIAA’s Daily Launch email newsletter for 2-23-2026:
NEW YORK TIMES
Problem With Artemis Rocket Is Likely to Delay NASA’s Moon Mission
A day after NASA officials optimistically said they were on track to launch astronauts around the moon early next month, a problem with the rocket’s upper stage will require rolling it off the launchpad for repairs.
My take on it:
“Upper stage” would refer to the interim upper stage that was the Delta-IV upper stage. That is something Boeing builds. The pattern really is complete.
GW
That's the latest thing I was looking at. It would be assembled from components shipped up to LEO. I might use 1-way/1-shot solids for the dV onto the Hohmann trajectory, and have NTO-MMH do the course corrections and "fine-tune" the speed getting onto that trajectory.
If the departure stage is to be recovered, I would use LOX-LH2 for departure, and NTO-MMH for course corrections and for capture back into an extended ellipse about the Earth. The transfer trajectory would be an ellipse past Mars with exactly a 2 year period. One would need a tug from LEO to go get that transfer stage and bring it back to LEO.
A space station with assembly facilities and refueling facilities would be perfect for this. It needs to be a low-inclination orbit for this, to reduce the dV's going anywhere beyond Earth orbit. At 53 deg, the ISS orbit is totally wrong for that purpose.
GW
There you go, you heard it from me and you heard it from Oldfart1939. We both quoted the same news article, I think.
GW
From what I have read, we have not been told whether the helium problems were in the core rocket or the spacecraft and its service module.
The Europeans built the service module. Lockheed-Martin built the capsule. Boeing built the SLS core stage, and until it was retired, the upper stage of Delta-IV which is the second stage of SLS. The SRB's do not use helium at all. 2 of the 4 things that use helium are built by Boeing, and the helium problem was also one of two near-fatal difficulties for the Dreamliner, also built by Boeing.
See the pattern here? The odds favor the helium problem being either in the 1st or second stages of SLS.
GW