Can the Artemis SLS booster and its Orion capsule fly again. More than likely. It's just as we're approaching a year and a half after the first Artemis lunar flyby mission, NASA still doesn't understand why the heat shield on the Orion capsule had damages that the models didn't predict.
This topic first showed up as soon as the recovered Orion capsule was
inspected and was
made public around March of '23. Like the Apollo capsules and really most everything except for the
Shuttles and the few other vehicles using ceramic tiles, the Orion capsule
uses ablative heat shielding.
"During inspections there were more variations across the heat shield than we expected," said Howard Hu, the Orion program manager for NASA. "Some of the charred material ablated away differently than what our computer models, and what our ground testing, predicted. More of this charred material was liberated during reentry than we had expected."
When an ablative shield burns away differently than the models say, that investigation is about as serious as it gets. The Orion capsule was never in any danger, and a crew onboard would have been safe, but that's no excuse to stick with a model that may be lying. That's too much like saying your Russian Roulette game with a revolver hadn't killed you the first time so it must be safe. Like the Russian Roulette, what happens the next time it reenters?
Amit Kshatriya, who oversees development for the Artemis missions in NASA's exploration division, said Friday that the agency is still looking for the root cause of the heat shield issue.
Engineers have performed sub-scale heat shield tests in wind tunnels and arc jet facilities to better understand what led to the uneven charring on Artemis I. "We’re getting close to the final answer in terms of that cause," Kshatriya said.
NASA officials previously said it is unlikely they will need to make changes to the heat shield already installed on the Orion spacecraft for Artemis II, but haven't ruled it out. A redesign or modifications to the Orion heat shield on Artemis II would probably delay the mission by at least a year.
One of the possible approaches to resolving this problem is to determine if small modifications to the flight's path - how the reentry happens - could be instituted.
On Artemis I, Orion flew a skip reentry profile, where it dipped into the atmosphere, skipped back into space, and then made a final descent into the atmosphere, sort of like a rock skipping across a pond. This profile allows Orion to make more precise splashdowns near recovery teams in the Pacific Ocean and reduces g-forces on the spacecraft and the crew riding inside. It also splits up the heat load on the spacecraft into two phases.
The Apollo capsules didn't do that. They just plunged into the atmosphere and reentered directly. There are other
approaches to reentering and NASA wants to understand how the Orion heat
shield would perform during all of the possible reentry trajectories for
Artemis II.
There are other issues from the Artemis I mission that need to be addressed before it flies its next mission.
After its Artemis 1 flight, technicians inspect the heat shield anomalies on the Orion capsule. Image credit: NASA/Skip Williams
So Sanger was potentially right about skipping in the atmosphere for the Nazi's Antipodal Bomber (launched on a sled with a version of the A-4 rocket.)
ReplyDeleteAs to the heat shield, what's so damned hard about fixing it? If memory serves me, the first Dragon came back with more wear on the heat shield and SpaceX had a new design in less than a month or two, tested in another month, then launched pretty darned quickly after that.
The other issues? What incentive does anyone on a 'cost-plus' contract have to do work quickly and correctly? Come on, man, it's the 21st Century and we've been doing heat shields and valves and issues with wiring since the 1940s.
The big thing about cost-plus is you get paid to spin your wheels and go down every non-productive path you can think of. It economically incentivizes being inefficient. When it's fixed price, you concentrate on what's most likely to get you your answer so you can "get 'er done" and get back to making money.
DeleteTonight's SpaceX launch up the road was a doubly significant launch. First, it was launching European Galileo satellites - someplace I read said the ESA has never let non- Europeans even see their Galileo satellites, but since the ESA doesn't have any rockets that can fly, "who you gonna call?" ... Second, the Booster, 1060 flew its 20th mission, but the payload and trajectory required they burn up every drop of fuel so none was left to land. They threw 1060 away, like they were ULA or something.
Amortize the price of B1060 and, whew, how cheep was that booster and how much pure profit did SpaceX make?
DeleteAnd the Euros, who have stiffed SpaceX for years, had to come, hat in hand, to SpaceX. And SpaceX was nice enough not to charge them an 'arse-hat' surcharge.
As to cost-plus, geez, this, this is how you get eternal programs that don't produce anything.
And if you're gonna start blaming SpaceX on delays on Starship, remember it was Blue Origins that kept using lawfare against SpaceX because nobody at NASA trusted BO to make a lunar lander within the next 20 years (of the beginning of the contract.) Sure, SpaceX used that time to do a lot of infrastructure work (which included a bunch at the Cape that they subsequently destroyed or sidelined,) but SpaceX has shown that they can work on infrastructure and Starship at the same time. How far ahead would the HLS and Starship overall be if BO hadn't tied their hands?
Considering that BO's HLS is years down the line and nobody's seen testable prototypes yet, but that was under previous management, so...
I like your description of the odds.
ReplyDeleteTo their credit, unlike NASA of the 1990s, they aren't going "Let's just go ahead and see what happens, because heaven forfend we should jigger the schedule for a paltry thing like crew safety."
ReplyDeleteAlmost like someone there has rediscovered that the point of the mission is to accomplish the mission.
What a refreshing development. Hopefully no one in senior management needing smelling salts.
The ablative model they use is FAR more accurate than the AGW model they are using to destroy the country.
ReplyDeleteWow. Now THERE is a true statement, Mark.
DeleteI wonder if the issue is how the material reacts to a heating followed by cooling cycle. In a direct entry, the temperature profile just continuously increases. In a skip entry, that curve has peaks. This could loosen bonds in the material.
Any engineering model is orders of magnitude more accurate than those AGW models. I still say, "wake me up when you can model clouds correctly."
DeleteThey intend to have you DEAD before that happens!
Delete"They threw 1060 away, like they were ULA or something."
ReplyDeleteI imagine SX used the old booster and charged the EU the cost of a new replacement. It's just good business.
Well, the cost of the new booster comes from somewhere. They've charged more for missions when the booster gets discarded all along (IIRC and if what I recall is true).
DeleteI suppose that no matter how big the booster there will always be launches that max it out. Might happen with Starship too.
DeleteInteresting that it costs less to buy SX a new booster than to donthe re-usable thing, twice.
Gee, NObody charges for new and utilizes a used one if they can.
DeleteI had to go into the N-cell reactor compartment to do a calibration on a load cell for their fuel rod overhead crane, and it was hot as hell in there - I had 7 minutes to get the job done. 3-1/2 minutes and I was done with time to spare...BTW, that's my ENTIRE lifetime exposure, I could never go back in there. Not without glowing, at any rate.
I had the Fluke test meter wrapped in 1/8" lead sheeting with a window flap over the readout and another over the controls. Shielded test leads, even - it was so hot in there that the miniscule voltages I was reading were affected by the radiation!
Did I mention that EVERYTHING I used for calibration (even hand tools) were now considered "hot" and were thrown away once they entered the cell? That's policy, no exceptions. So, we bought brand new test gear and tools and used our old stuff (still calibrated, don't worry!) to do the job. Heck, even *I* had to undergo a full-body radiation scan before and after the job. But I didn't get thrown away...
THAT was an interesting job. I have several more stories about this particular one, but that's for another day and topic.
Back in the early '70s, a father of a friend worked construction at one of the nuclear power plants in Florida, Turkey Point. He's the first guy who told me about some of those requirements and explained that every wrench, screwdriver or whatever they brought in had to be thrown out when they were done, and that tools, gloves and safety equipment were the bulk of the "radioactive waste" that was being talked about. Technically true but not what people would think of when they heard that term.
DeleteThe heat shield R&D is still underway, but Boeing has started laying off SLS R&D personnel (and others).
ReplyDeleteSeems a bit early, after a just a couple of launches, but I guess the schedule is slipping to the right, and they don't want to pay people to sit around for years.
It's good business sense, Boeing is in the red, but, if they need these guys back, it'll be tough, a lot of institutional knowledge will be walking out the door..
I seriously doubt those people will be needed again, if you catch my drift.
Delete