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Wasn't sure where to put the various pieces of this, so I put the whole thing here. There are several items of interest to correspondents on these forums.
From AIAA’s “Daily Launch” for Thurs 2-27-2025. The longer form of the article is on the Ars Technica site, but this short blurb tells the tale.
ARS TECHNICA
Long-time advocate of SLS rocket says it’s time to find an “off-ramp”
One of the Republican space policy leaders most consistently opposed to commercial heavy lift rockets over the last decade—as an alternative to NASA's large SLS rocket—has changed his mind. "We need an off-ramp for reliance on the SLS," said Scott Pace, director of the Space Policy Institute at George Washington University, in written testimony. He issued the statement in advance of a hearing about US space policy, and the future of NASA's Artemis Moon program, before a subcommittee of the House Committee on Science, Space, and Technology.
NEW YORK TIMES
Intuitive Machines’ Athena Lander Launches on Journey to the Moon
Intuitive Machines landed a robot on the moon last year. Can the Houston company do it again, but keep the spacecraft upright this time? The company’s second lander, named Athena, launched on Wednesday evening on a SpaceX Falcon 9 rocket from NASA’s Kennedy Space Center in Florida. It is now on an arcing path to the moon.
FLYING MAGAZINE
FAA Advises Boeing 757 Freighter Operators to Evaluate Cargo Doors
The FAA has issued a Special Airworthiness Information Bulletin (SAIB) advising operators of Boeing 757-200 freighter planes to be aware of an “airworthiness concern” regarding the main deck cargo door opening while in flight. The bulletin, issued Friday, stated that this concern is not an unsafe condition that would warrant airworthiness directive (AD) action, though FAA investigations into the matter are still ongoing.
My take on the B-757: this one has been out there for decades. It is far more likely this is a wear-out issue than it is some sort of design flaw.
AVIATION WEEK NETWORK
SpaceX Details Starship Mishap Findings, Changes For Next Test
SpaceX has made design changes to the Starship launch system for its eighth flight test in response to the spectacular breakup of the upper stage during its most recent test, which it believes was caused by a harmonic response that stressed the onboard hardware, leading to a fire and loss of the vehicle.
This paragraph was the first paragraph of the longer article on Aviation Week’s site, with the rest of it copied and reproduced here. My take is that there has been some sort of flying airframe-related problem that does not show up in the ground tests, at McGregor, or static fires at Boca Chica. This is the sort of surprise that often happens once you get to flight test. Here is the rest of the article:
The next flight could happen on Feb. 28, pending regulatory approval, SpaceX said on its website. The objectives set for the test include Starship’s first payload deployment, which it failed to achieve last time, and reentry experiments geared toward returning the upper stage to the launch site. SpaceX will again aim to replicate the success it has had twice in catching the Super Heavy booster first stage.
“Several hardware and operational changes have been made to increase reliability of the upper stage,” the company said. Those include changes to fuel feedlines connecting the vacuum engines, propellant temperature changes and a new operating thrust target.
In its Feb. 24 mishap report, SpaceX said: “The most probable root cause for the loss of ship was identified as a harmonic response several times stronger in flight than had been seen during testing, which led to increased stress on hardware in the propulsion system. The subsequent propellant leaks exceeded the venting capability of the ship’s attic area and resulted in sustained fires.” The unpressurized attic is the section between the bottom of the liquid oxygen tank and aft heat shield.
SpaceX said the first indication that something was going wrong came about two minutes into the burn of the second stage when a flash was detected near one of the six Raptor engines. Sensors then detected a rise in pressure, suggesting a leak. Two minutes later another flash occurred, sparking sustained fires in the attic. Five of six Raptor engines then shut down and communications with the vehicle was lost 8 min. 20 sec. into flight, SpaceX said.
Three minutes after contact was lost the vehicle broke apart. “Post-flight analysis indicates that the safety system did trigger autonomously, and breakup occurred within Flight Termination System expectations,” SpaceX said.
The company said it subsequently performed a 60-sec. static fire with the Starship due to fly in the upcoming test. It involved different thrust levels and Raptor configurations to try and replicate and address the issues that led to the mishap.
SpaceX said additional changes being made to reduce flammability include adding more vents and introducing a new purge system utilizing gaseous nitrogen to reduce propellant leak risk. “Future upgrades to Starship will introduce the Raptor 3 engine, reducing the attic volume and eliminating the majority of joints that can leak into this volume,” it said.
In the next flight, SpaceX plans to deploy four Starlink simulators sized to replicate the next-generation of its low-Earth-orbit communications satellite system. The upper stage will also aim to relight a Raptor engine while in space. The company also aims to collect data on the upper stage’s heat shield. “Starship’s reentry profile is designed to intentionally stress the structural limits of the upper stage’s rear flaps while at the point of maximum entry dynamic pressure,” SpaceX added.
The Super Heavy booster also sports new features, including a more powerful flight computer, upgraded power and upgraded power and network distribution.
Robert Wall
Robert Wall is Executive Editor for Defense and Space. Based in London, he directs a team of military and space journalists across the U.S., Europe and Asia-Pacific.
GW
From AIAA’s Daily Launch email newsletter for Wednesday 2-19-2025, and found at 10:30 AM CST, there was a link to this Space.com report:
Boeing plans to lay off hundreds of employees working on NASA's SLS moon rocket: reports
News
By Sharmila Kuthunur
published 17 hours ago
Boeing notified employees it is planning to issue layoff notices "to align with revisions to the Artemis program and cost expectations."
Boeing is preparing to issue layoff notices to roughly 200 employees working on the Space Launch System (SLS) — the massive rocket central to NASA's flagship Artemis program — as it braces for the possibility that its contracts with the space agency may not be renewed after they end in March.
Of the approximately 400 positions Boeing initially considered cutting by April "to align with revisions to the Artemis program and cost expectations," the company managed to preserve half of the jobs after daily talks with NASA, Boeing's Vice President and program manager for the SLS rocket, David Dutcher, notified employees in an email last week, according to Bloomberg.
The news of layoffs, first reported by Ars Technica on Feb. 7, comes as six space industry representatives advising President Donald Trump and Elon Musk say they want the duo to cancel the SLS program — or at least phase it out over several years, Reuters reported on Wednesday (Feb. 12).
The development of SLS, for which Boeing is the primary contractor, has cost $23.8 billion between its inception in 2011 and its first Artemis test flight that occurred in late 2022. The megarocket is neither reusable nor inexpensive: it can launch only once every two years and costs an estimated $4.1 billion per launch, making it effectively unaffordable for future Artemis missions.
YOU MAY LIKE
• Jeff Bezos' Blue Origin laying off 1,000 employees: reports
• Boeing considers selling its space business, including Starliner: report
Critics often argue Musk's SpaceX could accomplish missions to the moon at lower costs with its reusable Starship vehicle, which is undergoing test flights in preparation for the Artemis 3 crewed mission, currently scheduled for 2027. Historically, however, SLS and Orion spacecraft development has received substantial funding from a broad coalition; the program supports more than 69,000 jobs nationwide as of 2019.
But critics contends that the rocket's costs and slow pace of development mean it should go the way of the space shuttle. "Regarding space, the Artemis architecture is extremely inefficient, as it is a jobs-maximizing program, not a results-maximizing program," Musk wrote in a post on X on Dec. 25. "Something entirely new is needed."
NASA itself has not yet officially noted any changes to its Artemis program. At the SpaceCom conference in Florida last month, Kirk Shireman, who is the Orion program manager at Lockheed Martin, said NASA's current approach to Artemis remains effective despite criticism regarding costs and delays, according to a report by SpaceNews.
"What we need to do is tell the people in the new administration and anyone we can talk to this about is, hey, the fastest way to get humans back on the moon is to stay the course," Shireman said, according to SpaceNews.
"Things take a long time to build and certify and, if you throw them away every four years and start over, that's probably the slowest and most expensive thing we could do."
Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: community@space.com.
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My take: this is confirmation of what I already found. The number of layoffs has dropped to half that in the first reports.
As to why Blue Origin is laying off, that’s another thing to be chased down.
GW
And this is the entire text of my posting in post 503 of Meta New Mars/GW Johnson postings .....
Major news from AIAA’s “Daily Launch” email newsletter for Monday 2-10-2025, with link to a longer Ars Technica article that reproduced here. The 1st 3 paragraphs were in the “Daily Launch”.
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Boeing has informed its employees of uncertainty in future SLS contracts
The White House has not made a final decision yet on the large rocket
By Eric Berger, senior space editor at Ars Technica, 7 Feb 2025
The primary contractor for the Space Launch System rocket, Boeing, is preparing for the possibility that NASA cancels the long-running program.
On Friday, with less than an hour's notice, David Dutcher, Boeing's vice president and program manager for the SLS rocket, scheduled an all-hands meeting for the approximately 800 employees working on the program. The apparently scripted meeting lasted just six minutes, and Dutcher didn't take questions.
During his remarks, Dutcher said Boeing's contracts for the rocket could end in March and that the company was preparing for layoffs in case the contracts with the space agency were not renewed. "Cold and scripted" is how one person described Dutcher's demeanor.
Giving a 60-day notice
The aerospace company, which is the primary contractor for the rocket's large core stage, issued the notifications as part of the Worker Adjustment and Retraining Notification (or WARN) Act, which requires US employers with 100 or more full-time employees to provide a 60-day notice in advance of mass layoffs or plant closings.
"To align with revisions to the Artemis program and cost expectations, today we informed our Space Launch Systems team of the potential for approximately 400 fewer positions by April 2025," a Boeing spokesperson told Ars. "This will require 60-day notices of involuntary layoff be issued to impacted employees in coming weeks, in accordance with the Worker Adjustment and Retraining Notification Act. We are working with our customer and seeking opportunities to redeploy employees across our company to minimize job losses and retain our talented teammates."
The timing of Friday's hastily called meeting aligns with the anticipated release of President Trump's budget proposal for fiscal-year 2026. This may not be an entire plan but rather a "skinny" budget that lays out a wish list of spending requests for Congress and some basic economic projections. Congress does not have to act on Trump's budget priorities.
Multiple sources said there has been a healthy debate within the White House and senior leadership at NASA, including acting administrator Janet Petro, about the future of the SLS rocket and the Artemis Moon program. Some commercial space advocates have been pressing hard to cancel the rocket outright. Petro has been urging the White House to allow NASA to fly the Artemis II and Artemis III missions using the initial version of the SLS rocket before the program is canceled.
Critics of the large and expensive rocket—a single launch costs in excess of $2 billion, exclusive of any payloads or the cost of ground systems—say NASA should cut its losses. Keeping the SLS rocket program around for the first lunar landing would actually bog down progress, these critics say, because large contractors such as Boeing would be incentivized to slow down work and drag out funding with their cost-plus contracts for as long as possible.
On Saturday, a day after this story was published, NASA released a statement saying the SLS rocket remains an "essential component" of the Artemis campaign. "NASA and its industry partners continuously work together to evaluate and align budget, resources, contractor performance, and schedules to execute mission requirements efficiently, safely, and successfully in support of NASA’s Moon to Mars goals and objectives," a spokesperson said. "NASA defers to its industry contractors for more information regarding their workforces."
Long-delayed and expensive
Friday's all-hands meeting indicates that Boeing executives believe there is at least the possibility that the Trump White House will propose ending the SLS rocket as part of its budget proposal in March.
The US Congress, in concert with senior leaders at NASA, directed the space agency to develop the SLS rocket in 2011. Built to a significant degree from components of the space shuttle, including its main engines and side-mounted boosters, the SLS rocket was initially supposed to launch by the end of 2016. It did not make its debut flight until the end of 2022.
NASA has spent approximately $3 billion a year developing the rocket and its ground systems over the program's lifetime. While handing out guaranteed contracts to Boeing, Northrop Grumman, Aerojet, and other contractors, the government's rocket-building enterprise has been superseded by the private industry. SpaceX has developed two heavy-lift rockets in the last decade, and Blue Origin just launched its own, with the New Glenn booster. Each of these rockets is at least partially reusable and flies at less than one-tenth the cost of the SLS rocket.
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My take:
I was expecting to see Starliner cancelled before SLS, but it may work out to be SLS first. We will see if Trump’s sowing chaos can overcome the entrenched pork-barrel politics of powerful Senators. Meanwhile, even the Artemis moon program itself could possibly be on the chopping block. That was definitely hinted in the Ars Technica article, in the 7th of 12 paragraphs.
Copy below of an email sent to Tahanson43206 2-17-20265, regarding SLS reusability. I’ve already posted elsewhere about SLS cancellation. Boeing gave its SLS team their legally-required 60-day notice of cancellation layoffs just the other day.
I don't think the mix of older and younger workers at Boeing could be re-trained very expeditiously to work the reusability problem. Their habits are ingrained fairly deep, and I seriously doubt there has been any change to the corporate culture. That takes a major shakeup that Boeing hasn't had yet. All they've done so far is lose $billions from their bad management culture. Which has been there, about 3 decades now, ever since the takeover/merger with McDonnell-Douglas. That took place as McDonnell-Douglas becoming Boeing, but at the cost of using some of their top corporate managers as a majority of the new merged management. McDonnell-Douglas was a target for merger/takeover precisely because those managers had already run it into the ground.
As for reworking the SLS hardware into reusable hardware, you might do that with the engines and maybe some of the avionics units, but it's just about impossible with the stage/tankage hardware. You don't just rework it, you mostly end up replacing it, or you pay a huge operating cost. The Falcons fly back with aluminum structure because they do 3 burns, not just two! With aluminum, you have to be doing no more than about Mach 2.5 to at most 3, when you hit the atmosphere, which requires the "entry burn". You'll notice nobody else besides SpaceX is doing that, not yet, and even SpaceX no longer does it with their Superheavy booster. It takes a lot of propellant to do the return burn, then the entry burn takes at least as much propellant as the landing burn, probably more. You really cut into payload capability with 3 burns instead of 2. It's an exponential mass ratio thing with the rocket equation.
BlueOrigin eliminated the return burn with their New Glenn, planning on recovering on a ship downrange instead. That saves a lot of propellant and payload capability, but you pay for it with the costs of the returning of the ship with the stage on it, and on handling the spent stage at both ends of that ship journey.
Nobody that I know of is yet proposing the "right thing to do", which is to land the stage downrange somewhere, reload it with propellants there on the surface, and then fly it back to the launch site. You need only hard-surfaced large (really large !!!) landing pads to do that, you don't really need SpaceX's catch towers. Just put the landing legs on your stage, the way Blue Origin already does, which is the simpler brute-force solution. Pad construction is comparably cheap. If you do it "right", you only have to do it once.
If you can divert a bit cross-range after staging, to touch down on dry land downrange somewhere, you don't even need the special ship to land upon. If you have the proper landing pads in place, the landing legs don't have to be so large and heavy (we already saw that with the early Starship-only flight tests). You only need big heavy legs to do rough/soft-field landings. Boosters are uncrewed; so ditching failures in the sea is an easy option for them.
Even I could get the FAA to agree to a plan like that! There are simply fewer failure modes.
GW
(1) first crossing is a few weeks before second cross. I don't know the number, but the orbital perihelion is actually inside Venus, so it is moving quite quickly along the near-sun part of its orbit.
(2) the public is "fixated" on blowing it up because of the movies "Armageddon" and 'Deep Impact". The asteroid defense community has only 3 credible approaches: (1) gravity tractor which only works with years of warning, (2) a series of small impactors under the (found to be bad) assumption that small impactors won't disrupt rubble piles, and (3) nuclear explosives alongside to heat spallation from the adjacent surface. As it turns out, even the small impactors can disrupt rubble piles, and certainly the nuclear explosives would.
(3) in the case of 2024 yr4 we won't get the chance to recover anything, if it actually turns out to be a collision in 2032. Right now the odds are estimated to be 2+% of a collision then, but the uncertainty in the actual orbit determination overwhelms that. The right answer is just "we don't really know, but there's a significant risk". S-type are silicate minerals with other-metal admixtures, much like igneous and metamorphic rocks here. Stuff like magnesium and aluminum silicate. It takes a whopping amount of heat energy just to melt such rocks, much less heat them further to the point of dissociating the minerals. Once dissociated, how do you separate out what you want from the melt pool? We don't even do that here, except with high-grade ores, which these are not. I honestly see very little value in such materials.
The C-types are the same silicates with some carbon-bearing minerals included, and maybe even some straight carbon mixed in. Again, it takes a whopping amount of heat energy to melt the rocks, and a lot more to cause any dissociation. Same lack of value relative to the whopping energy to dissociate them, plus the difficulty of separating what you want from the melt pool. I must question the value of these bodies as “resources”.
It is the rare M-types that might be valuable in some way. Those are solid "rocks", not loose rubble piles, made of iron alloyed with mostly nickel, and some other metals. That is NOT a recipe for steel, there's too much nickel and way too little of the other alloying metallic elements. It would need the "right" small carbon addition to be a steel. However, it is a resource for iron and other metals.
More (3) All this refining is done in a very hot melt in something resembling a traditional blast furnace (a technology dating back almost 2 centuries now), except that the only blast furnaces we know how to build would NOT work in vacuum and zero-gee. You use an oxygen lance to burn out what you don't want in the mix, including excess carbon.
This is not done in electric arc furnaces, those only do scrap re-melts. And the energy costs of all these processes are truly enormous.
Finish up (3) The upshot here is that small chunks of M-type asteroids could be cut free and shipped home, for refining down here on the surface where we actually know how to do it. But with all the steel scrap available for the re-melt processes in electric furnaces, why bother?
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As for mining volatiles like water ice, CO2 ice, methane ice, etc, you will NOT find any of that in, or inside, the main asteroid belt, except in the very largest such bodes like Ceres and Vesta. The smaller ones have all been dried out by solar radiation heating in vacuum over geologic time. That includes Phobos and Deimos, too.
There will be increasing ice content as you move outward from the sun, past the main asteroid belt. Some at Jupiter, more at Saturn, etc. By the time you reach the Kuiper belt, there's more ice than mineral in these bodies. The comets come from there, but get dried out a bit by their repeated close solar passes over geologic time.
GW
I see a serious typo in the quoted Wikipedia article: 100 Kpa is NOT 105 Pa, it is 100,000 Pa. The 5 should be an exponent. Such an egregious error raises doubt about the accuracy of the whole article.
As to the claim that STP was revised from 1 atm to 1 bar in 1982, I very seriously doubt that! I have seen nothing in any of the science journals, textbooks, or other on-line resources making that claim. The ICAO standard atmosphere that the airlines use has sea level surface pressure at 1 atm, not 1 bar. The ICAO standard day is identical to the old US 1962 standard day to to about 60,000 feet altitude. The standard sea level pressure has been 101.325 KPa = 14.696 psia = 760 mmHg for centuries. Why screw that up? The air pressure is 1.000 bar about 500 feet up. That is NOT sea level!
Check that article again, someone may have since corrected it. I've seen bad stuff posted in Wikipedia before, usually someone corrects it fairly soon.
I also doubt the validity of the change claimed by the linked site for confirmation, because that would goober up the ideal gas law and about 3 centuries worth of thermodynamic tables, not to mention most of the knowledge in most thermodynamics texts and chemistry books. I have no idea who they are, or who the so-called council is that supposedly made the change.
There's more than enough disinformation out there is all of life's other venues. We don't need any disinformation within science.
GW
2024 yr4 is classed as a Type S ("stony") or perhaps type L asteroid, based on the spectrum of its reflected light. Type C's (and the very similar comet nuclei) that we have been to with probes are all rubble piles, not monolithic objects. The comet nuclei are partly cemented together by internal ice that has not evaporated away yet. The asteroids have all been loose dry rubble piles. Type S are similar, likely also loose dry rubble piles, although some of the particles could be a bit bigger. Only the type M ("metallics") seem to be monolithic objects.
If you put too big a "push" onto a loose rubble pile, it will come apart into a cloud of objects resembling nothing so much as a shotgun blast. We already saw this in action at "Didymoon" with the NASA impact test, which very nearly disrupted "Didymoon". It lost a cloud of boulders and cobbles that we could see (and presumably a whole cloud of smaller things we could not see), and it visibly changed shape, in addition to being deflected slightly.
The "push" can be an impactor, or it can be vaporization induced by a very bright light. Both produce a reaction force due to the cloud of ejecta suddenly moving away. Conventional or nuclear explosives have very little of a pressure blast wave. There is no such thing as a "shock wave" in vacuum. Planting a bomb inside an asteroid would actually do very little. You have to explode it alongside, and vaporize a chunk of adjacent surface, which flies away into space, producing a reaction force on the asteroid in the other direction. On a rubble pile, it takes very little such reaction force to entirely break up the body into a cloud of debris. NASA's Dart impactor was very small compared to "Didymoon".
If you disrupt the body into a shotgun blast too close to Earth, all the debris hits Earth, but it just hits all over its surface instead of in one location. You actually do more damage that way. You have to do this far out, in order for the debris cloud to spread in diameter far beyond Earth's diameter, before you do less damage.
2024 yr4 has an ellipse that crosses Earth's orbit in two places. It is the second crossing at which both the asteroid and Earth will be there at the same time in 2032. Your only chance to reach it with some payload is to launch that payload after the first crossing, and hope to get there before the second crossing. Time is very short to do that, and the debris cloud will not have time to spread out much by the time of the second crossing. If you disrupt it, you kill more people than would have died if you did nothing.
My point: there is NOT time to accumulate the effects of a bunch of "small pushes" that do not disrupt the asteroid. My other point: based on the "Didymoon" experience, we do not understand yet what actually constitutes that "small push" below the disruption point.
Now here's the killer: we have rockets that could reach 2024 yr4 just about the time of threatened impact, and we have nuclear warheads. But we do NOT have the right guidance and control avionics and software for such a mission, and we do NOT have the right kind of warhead fusing for such a mission. And we lack the spacecraft design to carry them. It is very likely that none of this could be developed and tested in time to be used. It's only 9 years away.
The hell of it is, things have changed very little since I attended the asteroid defense conference in Granada, Spain, way back in 2009. Only the recent asteroid probes and impact test are new since then. We still do NOT have the right avionics, software, and warhead fusing to attempt any such deflection missions! And we still do NOT know how a small a push is needed not to disrupt a rubble pile! Although the "Didymoon" DART test suggests that is a lot smaller than anyone wants to believe.
GW
I found a news article and posted it in Meta New Mars, in the "GW Johnson postings" thread. It would seem that the threat of SLS cancellation is real enough that Boeing executives gave the required 60-day notice of impending layoffs to their SLS employees.
GW
Major news from AIAA’s “Daily Launch” email newsletter for Monday 2-10-2025, with link to a longer Ars Technica article that reproduced here. The 1st 3 paragraphs were in the “Daily Launch”.
---
Boeing has informed its employees of uncertainty in future SLS contracts
The White House has not made a final decision yet on the large rocket
By Eric Berger, senior space editor at Ars Technica, 7 Feb 2025
The primary contractor for the Space Launch System rocket, Boeing, is preparing for the possibility that NASA cancels the long-running program.
On Friday, with less than an hour's notice, David Dutcher, Boeing's vice president and program manager for the SLS rocket, scheduled an all-hands meeting for the approximately 800 employees working on the program. The apparently scripted meeting lasted just six minutes, and Dutcher didn't take questions.
During his remarks, Dutcher said Boeing's contracts for the rocket could end in March and that the company was preparing for layoffs in case the contracts with the space agency were not renewed. "Cold and scripted" is how one person described Dutcher's demeanor.
Giving a 60-day notice
The aerospace company, which is the primary contractor for the rocket's large core stage, issued the notifications as part of the Worker Adjustment and Retraining Notification (or WARN) Act, which requires US employers with 100 or more full-time employees to provide a 60-day notice in advance of mass layoffs or plant closings.
"To align with revisions to the Artemis program and cost expectations, today we informed our Space Launch Systems team of the potential for approximately 400 fewer positions by April 2025," a Boeing spokesperson told Ars. "This will require 60-day notices of involuntary layoff be issued to impacted employees in coming weeks, in accordance with the Worker Adjustment and Retraining Notification Act. We are working with our customer and seeking opportunities to redeploy employees across our company to minimize job losses and retain our talented teammates."
The timing of Friday's hastily called meeting aligns with the anticipated release of President Trump's budget proposal for fiscal-year 2026. This may not be an entire plan but rather a "skinny" budget that lays out a wish list of spending requests for Congress and some basic economic projections. Congress does not have to act on Trump's budget priorities.
Multiple sources said there has been a healthy debate within the White House and senior leadership at NASA, including acting administrator Janet Petro, about the future of the SLS rocket and the Artemis Moon program. Some commercial space advocates have been pressing hard to cancel the rocket outright. Petro has been urging the White House to allow NASA to fly the Artemis II and Artemis III missions using the initial version of the SLS rocket before the program is canceled.
Critics of the large and expensive rocket—a single launch costs in excess of $2 billion, exclusive of any payloads or the cost of ground systems—say NASA should cut its losses. Keeping the SLS rocket program around for the first lunar landing would actually bog down progress, these critics say, because large contractors such as Boeing would be incentivized to slow down work and drag out funding with their cost-plus contracts for as long as possible.
On Saturday, a day after this story was published, NASA released a statement saying the SLS rocket remains an "essential component" of the Artemis campaign. "NASA and its industry partners continuously work together to evaluate and align budget, resources, contractor performance, and schedules to execute mission requirements efficiently, safely, and successfully in support of NASA’s Moon to Mars goals and objectives," a spokesperson said. "NASA defers to its industry contractors for more information regarding their workforces."
Long-delayed and expensive
Friday's all-hands meeting indicates that Boeing executives believe there is at least the possibility that the Trump White House will propose ending the SLS rocket as part of its budget proposal in March.
The US Congress, in concert with senior leaders at NASA, directed the space agency to develop the SLS rocket in 2011. Built to a significant degree from components of the space shuttle, including its main engines and side-mounted boosters, the SLS rocket was initially supposed to launch by the end of 2016. It did not make its debut flight until the end of 2022.
NASA has spent approximately $3 billion a year developing the rocket and its ground systems over the program's lifetime. While handing out guaranteed contracts to Boeing, Northrop Grumman, Aerojet, and other contractors, the government's rocket-building enterprise has been superseded by the private industry. SpaceX has developed two heavy-lift rockets in the last decade, and Blue Origin just launched its own, with the New Glenn booster. Each of these rockets is at least partially reusable and flies at less than one-tenth the cost of the SLS rocket.
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My take:
I was expecting to see Starliner cancelled before SLS, but it may work out to be SLS first. We will see if Trump’s sowing chaos can overcome the entrenched pork-barrel politics of powerful Senators. Meanwhile, even the Artemis moon program itself could possibly be on the chopping block. That was definitely hinted in the Ars Technica article, in the 7th of 12 paragraphs.
GW
You can use really lightweight thin gas bags, if (1) they contain no net pressure relative to the atmosphere, and (2) they do not have to provide any other structural strength function. Such were in the dirigibles, since before WW1.
The US Navy blimps from WW2 into the 1950's had the gas bag as the airframe, using slight net internal inflation pressure to make it hold its shape, despite the air loads from the fins, the thrust loads from the engines, and the gravity loads of carrying the gondola car. This is part of why they were smaller than the 800-ft-long class dirigibles. That's the biggest they could make the blimp gas bag and still tolerate the weight that results from the necessary bag thickness at the necessary internal overpressure (which is larger the bigger you attempt to design).
As for the lift force, that is the difference between the weight of the volume of gas in the gas bags, versus the weight of air in the same bags, at the same pressures and temperatures. The density of the lifting gas, all else being equal, is proportional to its molecular weight, pressure and temperatures being otherwise equal. That density comes from the ideal gas law: density = P * Vol*MW/(Runiv*T).
The weight of your gas bags, your gondola car, your engines, and your fins, must be subtracted from your gas bag lifting force, with whatever is left over being your payload capacity.
GW
Excellent posting Kbd512. Thanks.
The basics of stealth and detection have not changed since I worked in aircraft countermeasures 4 decades ago. What has changed are the technologies for achieving stealth. And I agree, the focus has been on radar stealth, almost but not quite to the exclusion of IR and visual stealth.
The four prototype B-1A bombers were not all that stealthy, it being mostly in the shapes of the metal skins. The B-1B bombers had less nose-on radar signature, but were just as large or larger at about 45 degrees off the nose as the B-1A's. For penetrating dense air defenses at low altitude, the most common aspect at missile launch is nearer 45 degrees than nose on. Achieving lower nose-on signature cost them air craft performance, because they had to compromise the inlets to achieve it. So, I don't know why it was done that way.
The other B-1B problem persists to this very day. On that design low-altitude penetration of dense air defenses, there are 3 avionics systems that must all operate, or else you end up a smoking hole in the ground. One is the navigation system. Another is the threat warning and countermeasures system. The third is the robotic piloting that enables flying a large craft very close to the ground at transonic speed. USAF did the systems integration on this one, not Rockwell. And if you turn on all 3 systems, they interfere with each other and crash. 2 OK, 3 no. Avionics were 2/3 the price of the program, and they could not afford to tear it all out and start over, so it was never fixed. Which is why the B-1 fleet has never been used in penetrating dense air defenses at low altitude. They have to stay away from that mission like the plague.
The stealth skin technology used in the B-2 and F-117 are older, comprising only the carbon composite skins, without the fancy coatings used on metal-skinned aircraft. The older F-117 was designed before the radar boys knew how to compute the reflection patterns from curved panels. That's why it was faceted so weirdly. They only understood how to calculate the return from flat panels. The facets and the extreme wing sweep caused very serious aerodynamic deficiencies in handling. By the time the B-2 was being designed, they knew how to handle curved panels, so that aircraft only has to overcome the aerodynamic control risks of flying wings. The biggie is not to deep stall it, because if you do, there is no recovery. This has been known since the fatal crash of an XB-35 in the late 1940's that killed USAF test pilot Glen Edwards. That's who the base is named for.
The bare epoxy carbon-fabric materials turned out to have a stealth-loss vulnerability associated with salt getting into the pores in the material. Once contaminated, it's no longer stealthy, and it was not possible to clean those pores of that salt. This is why the B-2 was never flown out of Diego Garcia, while the B-52's and B-1's were. It is also really a big part of why the Navy A-12 replacement for the A-6 Intruders was cancelled (salt spray very common on carrier flight decks!). The other two reasons were cost, and past negative experience trying to land tailless aircraft on carrier decks with the F-7U Cutlass (whose nickname was "widowmaker").
I suspect there's ways around the contamination issue now. But I haven't worked in that business since the mid 1980's, so I do not really know.
GW
There is, and never was, any serious threat of Fentanyl from Canada, crossing the northern US-Canada border. There is, and was, such a threat crossing the southern border with Mexico, but that that threat is of the same order of magnitude as the threat of US arms crossing that same border into Mexico to fuel the cartels.
Failing to take those facts into account are a systematic error on the part of right-wing, and far-right-wing, media on the internet and social media, that are totally unpoliced for truth.
GW
Beware of faked-up weight statements. They lead you astray very quickly in the rocket equation, due to its exponential nature.
Also beware of rocket equation estimates without vehicle acceleration capabilities being explored. That will also lead you astray very quickly.
As for the topic of this thread, yes, f course the Blue Origin New Glenn could be a moon rocket. It is roughly a Saturn-5-class vehicle. It would require a spacecraft cluster more like what we used on Apollo, than anything to do with Orion and its undersized service module propulsion.
The real problem is NOT technical, it is mostly Senate pork-barrel politics and the lobby power of entrenched old space interests. Note that SpaceX is transforming in slow motion into the new "old space". Musk has gotten close enough to Trump to accelerate that a bit. Which is why Bezos and the rest are also chumming up, both within and without the space industry.
GW
This from AIAA's "Daily Launch" email newsletter for 1-31-2025:
SpaceNews
Safety panel reports progress in Starliner investigation
Boeing and NASA are making “significant progress” on addressing issues seen on a test flight of the company’s CST-100 Starliner spacecraft last year, an independent NASA safety panel says, although key problems with the spacecraft’s thrusters remain unresolved. Paul Hill, a member of the Aerospace Safety Advisory Panel (ASAP), said at a Jan. 30 public meeting that the committee was briefed on the status of the investigation into Starliner’s Crew Flight Test (CFT) mission recently.
xxx
My take:
Note the words "key problems with the spacecraft's thrusters remain unresolved". You don't go with the cheapest designs and components when you are handling NTO. There's more than 6 decades world-wide experiences that say so, quite clearly. With improper valve seal materials that swell, and improper designs that allow NTO and moisture to coincide, you are asking for trouble, and that is exactly what happened. The "cheap" also showed up in the helium leaks. The thruster subsystem needs to be redesigned "from scratch" and done right, or Starliner will never be reliable enough to certify for human flight.
Boeing is not going to do that, they are already very deep in the red with Starliner, amidst all the other losses for not doing their main airliner business right instead of cheap. You are literally watching the slow-motion end of Starliner. That "cheap instead of right" approach is a top management fault, as we all know, that has persisted and taken full effect all across the corporation over about a 3 decade period. They are actually considering selling off their entire space business, possibly even their share of ULA, per what I put in post 133 just above.
GW
The Hindenburg did not catch fire and crash because of the hydrogen, it caught fire from a static spark near a thunderstorm, because its fabric covering was a nitrate (!!!) dope (mostly nitrocellulose in solution) whose colorant was a low-grade off-mixture thermite. The hydrogen just made the fire a bit brighter. But the same crash-and-burn would have occurred had it been filled with helium! And the insurance company in Germany that insured it, knew that, way back in 1937 right after the crash, but kept that secret for decades.
The US Navy had some big Hindenburg-class airships using helium: the Shenandoah, the Akron, and the Macon. All were eventually destroyed by the high winds associated with violent thunderstorms. Torn apart and crashed, but not burned. Such storms are common all over North America, one of the stormiest places there is, for such violent thunderstorms. But not the only place where they occur.
The Navy had a better track record with its semi-rigid and much-smaller blimps. Fewer of these were destroyed by storms, mostly by the simple expedient of staying the hell away from storms. The commercial Goodyear blimps are similar in size and construction.
The lesson of history there is two-fold: stay smaller with the semi-rigid blimp design which is more maneuverable, and (2) stay well clear of stormy weather.
GW
All new engines have serious teething troubles. They take hundreds of tests and years of work to resolve. The more radically different the engine is, the more teething troubles there will be. That is the lesson of history.
Raptor is a lot more radical than Merlin. I am not surprised the teething troubles have surprised SpaceX. I would anticipate that Blue Origin is going to run into the same thing with its engines, too. Probably already did, they tested in secret out at their west Texas site.
The same thing is true of tank constructions, heat shields, and all sorts of vehicle design features. Failures are normal. The earlier you bump into them, the cheaper they are to fix. The expensive SpaceX way to fix them in full scale flight tests, is entirely driven by the young age of their staff and the high turnover rate they have, despite claims otherwise. The engineering art was not passed on from the older workers, because there aren't any. Older workers cannot physically withstand the chronic 70-80 hour weeks demanded. And that art is substantially over 50% of the knowledge needed in development work.
As for getting hung up on short-burn tests at the launch site, I think Bob is mistaken about claiming they don't test adequately. They do, here, in McGregor, where everything that flies is tested first. I hear Raptor tests all the time. Durations are often in the 2-4 minute duration. Some of them are ignited near full power. The ones fired on the tower stand are a lot louder (being way up in the air), but create no steam cloud, since there is no water deluge at the tower stand, only the two surface stands.
My question for Bob: if they test full duration at McGregor, why test full duration again on the launch stand? You shorten life when you do that.
That being said, I think Bob is right about all the leaks and fires in the engine bay on the booster and upper stage vehicles. Handing easy-to-leak methane is almost as bad as handling hydrogen, and no one has ever done that at feed pressures exceeding 4000 psi before. I am entirely unsurprised they have been having problems. Especially since they 3-D print much of the engine and its plumbing. 3-D printed metals are now as strong as their wrought counterparts, but they still lack wrought ductility. Which means they crack easier, especially during the shock of a near-full-power start.
Von Braun only had wrought metals when he did the V-2 in the 1940's, but he still had to learn the hard way not to start its engine at near full power. We do better now, but it is still an easily-avoided risk.
GW
Adding logarithms is literally multiplication, by definition, in mathematics. That is quite literally how a slide rule works, and has worked, for over 300 years.
GW
A thick material of low stress capability supports the same force as a thin material of high stress capability, all else being equal. But, mechanical instability is the more important factor, by far, compared to material compressive stress capability, in vessels subjected to external pressure. I rather doubt your AI has any understanding of that, because most people do not.
Actually, I doubt any AI has any "understanding" of anything, because AI is just high speed computation coupled with trained imitation. There is no intelligence there, only imitation. "Artificial intelligence" is actually an oxymoron.
GW
External pressure on a vessel is different from internal pressure, because with external, there is a sort of mechanical instability that causes collapse, not just the compressive stress exceeding some allowable. That is unlike internal pressure, which has no mechanical instability to it.
That being said, it is possible to withstand enormous pressures with relatively ordinary materials in small sizes. As a graduate student 5+ decades ago, I used a very thick wall 300-series Austenitic stainless steel tubing for a probe into a hypersonic wind tunnel. This tubing was used routinely by the geology folks at internal pressures around 37,000 psi (2517 atm, 2550 bar).
In my application, the pressures were nowhere near that high, but the bending stresses were very, very high indeed, during wind tunnel start as the shock waves blew by. It worked OK. That's another mechanical instability case, by the way. Ordinary hypodermic tubing would string out flat along the wall of the wind tunnel. This much thicker-wall stuff survived those forces in the elastic range, actually. We had no permanent deformations test-to-test.
GW
There's "hard to weld" and there's "hard to weld". The old 17-inch thick battleship armor on the Iowa-class ships was welded with very high-power arc welders and great big welding sticks. The "V" joint to do that was 17 inches wide and 17 inches deep, so it took a lot of passes at about a quarter inch per pass to fill that V. But it was non-hardened mild steel and ordinary welding stick materials, just larger ones than most people have ever seen.
You have to use the "right" stick material with each different kind of metal. Mild carbon steels all use the same kinds of rods (there's more than one), and there are different kinds intended for the Austenitic stainless steels. Neither application involves heat-treated materials, like the Martensitic stainlesses and the maraging steels. Those heat-treated alloys are almost impossible to weld after heat-treating. No arc welding or torch welding works. Spin inertia welding and electron-beam welding do work, to some extent, but it ain't easy. Those materials are far better welded first, then heat-treated afterward.
As for ductility, that goes inversely hand-in-hand with hardness, for just about any metal you want to name. If it's hard and strong, it has little ductility, and vice versa. It it has little ductility, the consequences of a failure at pressure can be extremely disastrous! You cannot have both in any real-world metal materials. For applications where "heavy" is not a killer problem, you go with high ductility and lower strength specifically to limit failure consequences. Where "heavy" is a "killer", you have to go for strength, and accept the consequences of failure (and try to design around them). That's why fatigue failures in airplanes kill more people at a blow than fatigue failures in bridges and buildings and ships.
I'm no materials expert myself, but I do know enough about it to talk with real experts quite intelligently. I had to be able to do that, in order to lead new product development design teams effectively. Narrow specialists don't do so well at that.
GW
There is an ASTM specification for the denatured ethanol product known as E-95. It specifies very dry ethanol at under 0.5% water, and 5% denaturant, specified to be unleaded gasoline or an alkylate precursor.
What you blend depends upon the application. The E-85 product sold for motor vehicles can vary quite a bit, driven by the vapor pressure / cold start issue you cited. It can be as low as E-70 in the winter, usually pretty close to E-75. It's usually very close to E-85 per the name in warm months.
Most of the ASTM-spec unleaded gasolines sold for motor vehicles range from E-0 to E-10. There at least were some moves to let E-15 be sold, maybe done in some locations, but most not. Experimentally, I have run production vehicles on E-20 to E-35 as drop-in fuels for about 20 years now. If there were a problem with that, I would know about it by now. There is not. EPA feared damage to catalytic converters, but I have found extended life, by the solvent action cleaning the soot buildup off the catalyst beads. I also found extended engine life, traceable to reduced carbon deposits.
As for the airplanes, the STC's specify E-95 or gasoline, not blends. There is no water-induced phase separation problem that way, because you drain and replace to switch fuels. Although, I came up with a simple and reliable field test for detecting phase separation risks for blends, too! With E-95, you solve the cold start problem with a start fuel canister, mounted on the engine side of the firewall. Connect the primer to it instead of the main tank, and put gasoline (any grade) in the start canister. That solution is reliable, and it is in the STC's (Piper Pawnee and Cessna 152).
The only difference you ever see in an E95-or-avgas STC'd airplane is the mixture control. Lean-out is the same. Full rich is to the panel on E-95, but only about halfway to the panel on avgas. If you are used to setting mixture by the sound and behavior of the running engine, there is no problem with that. Amateur pilots need a mixture control stop when operating on gasoline (it's just a clip you put on the rod). I talked to the FAA about that, and it went into the STC for the C-152 trainers STC'd for E-95 or avgas.
With blends, you have to avoid phase separation risks and you would have intermediate full rich mixture control positions between E-95 and avgas, reflecting blend strength. That has never been STC'd, but it worked fine experimentally, with experienced pilots who are used to managing mixture by ear and feel. Key: you don't just unthinkingly always slam it all the way forward. You instead move it slowly, and perceive the effects as you move it. Requires a change of habit handling the mixture control.
The biggest problem with ethanol in airplanes is not really water separation (given my field test), but materials compatibility. The aviation manufacturers never transitioned to ethanol-tolerant materials the way the automotive manufacturers did decades ago (for unleaded gasoline, which has always had one or another alcohol in it). Most fuel bladders are urethane, and cannot handle ethanol. The few neoprene bladders can (as was in the Pawnee). If there are plastic parts in the metering devices or fuel pumps, those are usually not compatible with ethanol, unlike automotive equipment.
We did not use ethanol in gas turbines. We did biodiesel-Jet-A blends in those, up to 30% biodiesel. This was an experimental program directly overseen by the FAA. I came up with a 7-month plan to put a Beech King Air A-90 into "experimental" for the testing, and return it to "standard" category afterwards, which had never before been done by the FAA. The exposed engine required a hot section overhaul to verify no damage, so we exposed the weakest engine that needed to be overhauled soon, anyway.
I got the whole program done in 5 months, including flight tests to around 20,000 feet. Freezepoint was the limiting factor. But biodiesel rejuvenates old, stiff fuel bladders, which pleasantly surprised us and the FAA. No change to emissions, but the sooting on surfaces downstream of the exhausts was far easier to clean off. I did find one blend that had no freezepoint trouble. It had military potential. All this took place 1996-1998, at Baylor U.
Oops, sorry, wrote the years down wrong. Baylor U was 1997-1999. Was still in Minnesota 1996 and first part of 1997.
GW
I have run VW engines, Lycoming IO-360's, and a Lycoming O-54 and an IO-54 on E-95 denatured ethanol, neat. I got the STC to do that in a Piper Pawnee with the 540, along with the airframe STC, long ago while working at Baylor U. All these engines test as 5-15% more power with the same or lower cylinderhead temperatures, running on ethanol. That's a measurable increase in the energy conversion efficiency, which I measured directly on a dynamometer with the IO-360.
The specific fuel consumption is higher ion ethanol, but not as high as you might think from heating value ratio or stoichiometric air/fuel ratio, by around a factor of 2 less increase. That is the result of the higher energy conversion efficiency, verified on the dyno, ground static tests, and in flight. My dissertation verified all this, and suggested the sootless ethanol flame as the reason. With no soot to radiate the hardware from the flame, less energy goes into the hardware as waste heat. It has to go into higher gas pressure on the pistons instead. There is nowhere else for it to go.
After that, I experimented in cars with road tests of ethanol and ethanol blends. I got exactly the same results in one VW beetle that I got in the airplanes, on neat ethanol. The conversion was easy in the old technology (carbureted, with simple battery ignition): adjust the jets for the higher fuel/air, add intake heat to get the ethanol to vaporize, and advance the spark timing by about 30 degrees.
With stiff blends, there were no mods, it was a simple drop-in fuel. But I found an upper limit, where power dropped and fuel consumption skyrocketed. This was like a light switch at about E-42. It happens when the ethanol with the longer ignition delay suddenly "takes over control" of the ignition in the cylinders. I had winter cold start troubles become significant at about E-35, which is really the maximum I would recommend. You won't be able to statistically distinguish an ethanol blend in your performance and fuel mileage all the way up past E-35. It's trading higher conversion efficiency for lower heating value, just about 1 for 1.
GW
Those docking ports go on the center module at the spin axis. There can only be two, located coaxially with the spin axis, on either side.
Docking to a spinning object is quite possible, as was depicted long ago in the movie "2001 A Space Odyssey". The vehicle approaches close, makes sure it is lined up with the spin axis exactly, not off to one side just parallel to it. Once in position, it spins up to match spin, then moves in and docks. Undocking is even easier: once clear, you de-spin, the you can go anywhere you want.
GW
I haven't seen anything in the technical journals about a General Atomics breakthrough in fuel element temperature capability. A lot of press releases turn out to be more fiction than fact. We'll see.
I do know the operating temperature in the old NERVA was lower, leading to a hydrogen temperature into the nozzle actually cooler than the flame in a hydrogen-oxygen chamber. It was the low molecular weight of only hydrogen that gave NERVA its higher Isp. I'd be surprised (but pleased) if that were no longer the case.
This is one of the first internet media postings I have ever seen that correctly identifies solar flares as the lethal radiation threat. It does not correctly connect the 20 g/cm^2 shielding figure with the solar flares, though. And that 20 g/cm^2 does not have to be aluminum, as the video claims. That 20 g/cm^2 can be 20 cm thick water at sp.gr = 1. A thickness of 7.4 cm of aluminum provides the same 20 g/cm^2. 2.5 cm of stainless steel provides the same 20 g/cm^2.
For coarse-woven fabrics of H-C fibers with significant porosity (void fraction), the specific gravity would be near (0.3 vol fraction solid) * (1.3 fiber sp.gr) ~ 0.4 ish, and so about 50 cm thickness would provide the same 20 g/cm^2. That's about what the inflatable being tested at the ISS has.
Thicker is more radiation shielding that also can serve as thermal insulation and as a meteoroid shield, too. Bigelow is now gone, but they were going to use fabric layers totaling 100 cm thick on their B-330 inflatable. I'm not yet sure what Sierra Nevada is doing with its inflatables.
Nearer a meter thick, you can intersperse a couple of metal foil layers in the outer fabric layers, to enhance the meteor shielding, and still contain the secondary radiation shower from cosmic rays hitting the metal, inside the thick layers of low atomic weight atoms that are the fibers. That's also better for cosmic rays, which violate the exposure standards (as unshielded) only for 2-3 years near solar minimum. The rest of the solar cycle, cosmic rays do not exceed the exposure standards. With more than 20 g/cm^2, inside the inflatable, you still do not quite exceed the exposures even in the worst years near solar minimum, even though most (but not all) of the cosmic rays still get through.
Solar flares can happen anytime during the solar cycle, but tend to be more numerous in near solar maximum years. The 20 g/cm^2 figure shields those very well, according to NASA's old radiation website, where I got the older exposure standards. Those are mostly the same protons as cosmic rays, just moving a lot slower, and therefore far more easily shielded.
GW
News reports that I have seen indicate that the FAA is demanding failure investigations from both SpaceX for the loss of its Starship, and Blue Origin for failing to land its booster on the ship.
GW