Orion Discussion Thread 2

[woods170]

Paul Hill Leading Independent Review Board on Orion Heat Shield

https://spacepolicyonline.com/news/paul-hill-leading-irb-on-orions-heat-shield/

From that article: "NASA is determined to understand what happened on that mission, which used a “skip-return” trajectory, and how the heat shield might respond to other types of trajectories."

Is the skip-return profile a suspect cause in the unexpected degradation of the heat shield. Does the skip put the vehicle through a thermal heat-cool-heat cycle?

Yes.

[StraumliBlight]

Zero. Today's NASA doesn't have the gonads to make such a late change.

NASA did redesign the heat shield after EFT-1 and 3D-MAT is new (the project was started in 2012).

[woods170]

Zero. Today's NASA doesn't have the gonads to make such a late change.

NASA did redesign the heat shield after EFT-1 and 3D-MAT is new (the project was started in 2012).

Did you bother to actually read the two links you included in your post?

1. The heat shield "redesign" after EFT-1 was basically nothing more than cutting up a monolithic Avcoat heat shield into a Avcoat heat shield consisting of multiple blocks. But the TPS material itself remained the same: Avcoat. Which proves my point: NASA didn't have the gonads to switch to PICA when the EFT-1 mission showed that the structural performance of the monolithic Avcoat heat shield was less than desired. Of note: Avcoat was never designed to be used in a heat shield consisting of blocks, unlike PICA.

2. 3D-MAT was not developed to replace Avcoat, but as a material to replace the less-than-adequate original compression pad TPS. To give you an idea: 3D-MAT covers only 2% of the Orion primary heat shield. The other 98% is Avcoat.

[whitelancer64]

Remind me, what was the reason for rejecting PICA?

Avcoat performed slightly better in testing. IIRC the two were pretty much even performance wise, but Avcoat showed less cracking on curved edges. This decision was made back in ~2008 or so.

[StraumliBlight]

NASA wants clarity on Orion heat shield issue before stacking Artemis II rocket

Potential solutions to the heat shield issue for Artemis II include altering the spacecraft's trajectory during reentry or making changes to the heat shield itself. The latter option would require partially disassembling the Orion spacecraft at NASA's Kennedy Space Center, something that would probably delay the launch date from September 2025 until 2027 at the earliest. Another alternative could be to do nothing and fly the Artemis II mission as is.

"The entire trade space is open," Koerner said. "But as far as the actual Artemis II mission, right now, we're still holding to the September ’25 launch date, knowing that we have still a lot of work to do to close out the heat shield investigation.”

[panjabi]

NASA wants clarity on Orion heat shield issue before stacking Artemis II rocket

Potential solutions to the heat shield issue for Artemis II include altering the spacecraft's trajectory during reentry or making changes to the heat shield itself. The latter option would require partially disassembling the Orion spacecraft at NASA's Kennedy Space Center, something that would probably delay the launch date from September 2025 until 2027 at the earliest. Another alternative could be to do nothing and fly the Artemis II mission as is.

"The entire trade space is open," Koerner said. "But as far as the actual Artemis II mission, right now, we're still holding to the September ’25 launch date, knowing that we have still a lot of work to do to close out the heat shield investigation.”

Pretty damning article, if you read between the lines. With the "lessons" from Starliner seeping in, you may see an uncrewed Artemis II. Except in this case, it is the taxpayer picking up the ridiculous costs, while Lockheed laughs all the way to the bank. This is what happens when you label projects as national prestige projects. Now Lockheed is in a position where THEY benefit from an uncrewed Artemis II launch, as that probably gets them another Artemis mission down the line.

[DanClemmensen]

NASA wants clarity on Orion heat shield issue before stacking Artemis II rocket

Potential solutions to the heat shield issue for Artemis II include altering the spacecraft's trajectory during reentry or making changes to the heat shield itself. The latter option would require partially disassembling the Orion spacecraft at NASA's Kennedy Space Center, something that would probably delay the launch date from September 2025 until 2027 at the earliest. Another alternative could be to do nothing and fly the Artemis II mission as is.

"The entire trade space is open," Koerner said. "But as far as the actual Artemis II mission, right now, we're still holding to the September ’25 launch date, knowing that we have still a lot of work to do to close out the heat shield investigation.”

Pretty damning article, if you read between the lines. With the "lessons" from Starliner seeping in, you may see an uncrewed Artemis II. Except in this case, it is the taxpayer picking up the ridiculous costs, while Lockheed laughs all the way to the bank. This is what happens when you label projects as national prestige projects. Now Lockheed is in a position where THEY benefit from an uncrewed Artemis II launch, as that probably gets them another Artemis mission down the line.

One little problem: it also makes an alternative more attractive. It might Give NASA a powerful justification for opening a bid for a commercial service to replace (or "augment") SLS/Orion.

[panjabi]

NASA wants clarity on Orion heat shield issue before stacking Artemis II rocket

Potential solutions to the heat shield issue for Artemis II include altering the spacecraft's trajectory during reentry or making changes to the heat shield itself. The latter option would require partially disassembling the Orion spacecraft at NASA's Kennedy Space Center, something that would probably delay the launch date from September 2025 until 2027 at the earliest. Another alternative could be to do nothing and fly the Artemis II mission as is.

"The entire trade space is open," Koerner said. "But as far as the actual Artemis II mission, right now, we're still holding to the September ’25 launch date, knowing that we have still a lot of work to do to close out the heat shield investigation.”

Pretty damning article, if you read between the lines. With the "lessons" from Starliner seeping in, you may see an uncrewed Artemis II. Except in this case, it is the taxpayer picking up the ridiculous costs, while Lockheed laughs all the way to the bank. This is what happens when you label projects as national prestige projects. Now Lockheed is in a position where THEY benefit from an uncrewed Artemis II launch, as that probably gets them another Artemis mission down the line.

One little problem: it also makes an alternative more attractive. It might Give NASA a powerful justification for opening a bid for a commercial service to replace (or "augment") SLS/Orion.

There are a pair of very famous mathematical equations dating back to ancient antiquity, that refute your argument.

NASA < Pork addicted Congress critters
NASA << Lobbyist powered Old Space

[russianhalo117]

NASA wants clarity on Orion heat shield issue before stacking Artemis II rocket

Potential solutions to the heat shield issue for Artemis II include altering the spacecraft's trajectory during reentry or making changes to the heat shield itself. The latter option would require partially disassembling the Orion spacecraft at NASA's Kennedy Space Center, something that would probably delay the launch date from September 2025 until 2027 at the earliest. Another alternative could be to do nothing and fly the Artemis II mission as is.

"The entire trade space is open," Koerner said. "But as far as the actual Artemis II mission, right now, we're still holding to the September ’25 launch date, knowing that we have still a lot of work to do to close out the heat shield investigation.”

Pretty damning article, if you read between the lines. With the "lessons" from Starliner seeping in, you may see an uncrewed Artemis II. Except in this case, it is the taxpayer picking up the ridiculous costs, while Lockheed laughs all the way to the bank. This is what happens when you label projects as national prestige projects. Now Lockheed is in a position where THEY benefit from an uncrewed Artemis II launch, as that probably gets them another Artemis mission down the line.

One little problem: it also makes an alternative more attractive. It might Give NASA a powerful justification for opening a bid for a commercial service to replace (or "augment") SLS/Orion.

There are a pair of very famous mathematical equations dating back to ancient antiquity, that refute your argument.

NASA < Pork addicted Congress critters
NASA << Lobbyist powered Old Space

This is straying from the intended topic. The direction this conversation is heading is geared towards space policy.

[deltaV]

Potential solutions to the heat shield issue for Artemis II include altering the spacecraft's trajectory during reentry or making changes to the heat shield itself. The latter option would require partially disassembling the Orion spacecraft at NASA's Kennedy Space Center, something that would probably delay the launch date from September 2025 until 2027 at the earliest.

Maybe NASA should get started on a backup plan of buying a Dragon heat shield, which is supposedly designed for lunar return, modified for Orion's larger diameter and mass. NASA could do the slow and relatively inexpensive step of issuing an RFP now and only spend serious money if they end up deciding the current heat shield isn't fixable. Adapting a space-proven heat shield could be faster, cheaper, and safer than fixing Orion's novel heat shield if finding a root cause for the spalling continues to be difficult.

[DanClemmensen]

Potential solutions to the heat shield issue for Artemis II include altering the spacecraft's trajectory during reentry or making changes to the heat shield itself. The latter option would require partially disassembling the Orion spacecraft at NASA's Kennedy Space Center, something that would probably delay the launch date from September 2025 until 2027 at the earliest.

Maybe NASA should get started on a backup plan of buying a Dragon heat shield, which is supposedly designed for lunar return, modified for Orion's larger diameter and mass. NASA could do the slow and relatively inexpensive step of issuing an RFP now and only spend serious money if they end up deciding the current heat shield isn't fixable. Adapting a space-proven heat shield could be faster, cheaper, and safer than fixing Orion's novel heat shield if finding a root cause for the spalling continues to be difficult.

The quickest way to use a Dragon heat shield in this application would probably be to replace the Orion capsule with a Dragon capsule. Still not quick, but IMO much quicker than actually replacing the Orion heat shield. There lots of serious problems with trying to use Dragon here, but the problems with a new Orion heat shield are probably worse. It would be relatively inexpensive to test a Dragon heat shield by launching a Dragon on an expended F9 or even an FH into a high orbit. In Artemis terms, even risking the loss of a Dragon capsule is cheap.

[sdsds]

The quickest solution is to use the Artemis 2 mission to gather additional data on how the Orion heat shield behaves during reentry. That doesn't require the Artemis 2 mission to include a return from cislunar distance. Split the Artemis 2 mission objectives across two SLS launches, i.e. Artemis 2A and Artemis 2B. Fly the 2A mission to retire heat shield risk, and also other risks. (ECLSS, radiation, etc.) Fly the 2B mission with the current Artemis 2 profile. This approach requires some clever way of handling the scarcity of ICPS-compatible stages.
https://forum.nasaspaceflight.com/index.php?topic=60070.msg2618247#msg2618247

[DanClemmensen]

The quickest solution is to use the Artemis 2 mission to gather additional data on how the Orion heat shield behaves during reentry. That doesn't require the Artemis 2 mission to include a return from cislunar distance. Split the Artemis 2 mission objectives across two SLS launches, i.e. Artemis 2A and Artemis 2B. Fly the 2A mission to retire heat shield risk, and also other risks. (ECLSS, radiation, etc.) Fly the 2B mission with the current Artemis 2 profile. This approach requires some clever way of handling the scarcity of ICPS-compatible stages.
https://forum.nasaspaceflight.com/index.php?topic=60070.msg2618247#msg2618247

I assume the first of these two missions is uncrewed. I that case, it's really Artemis 1B.

[freddo411]

Potential solutions to the heat shield issue for Artemis II include altering the spacecraft's trajectory during reentry or making changes to the heat shield itself. The latter option would require partially disassembling the Orion spacecraft at NASA's Kennedy Space Center, something that would probably delay the launch date from September 2025 until 2027 at the earliest.

Maybe NASA should get started on a backup plan of buying a Dragon heat shield, which is supposedly designed for lunar return, modified for Orion's larger diameter and mass. NASA could do the slow and relatively inexpensive step of issuing an RFP now and only spend serious money if they end up deciding the current heat shield isn't fixable. Adapting a space-proven heat shield could be faster, cheaper, and safer than fixing Orion's novel heat shield if finding a root cause for the spalling continues to be difficult.

I really like this idea.   I'll add that if they put this out for bid they could specify a test flight with lunar return like entry speed for the new heat shield.

A slight scaled down heat shield may suffice for the test.  ( 4.5 meters vs 5 meters )

 

[Jim]

Potential solutions to the heat shield issue for Artemis II include altering the spacecraft's trajectory during reentry or making changes to the heat shield itself. The latter option would require partially disassembling the Orion spacecraft at NASA's Kennedy Space Center, something that would probably delay the launch date from September 2025 until 2027 at the earliest.

Maybe NASA should get started on a backup plan of buying a Dragon heat shield, which is supposedly designed for lunar return, modified for Orion's larger diameter and mass. NASA could do the slow and relatively inexpensive step of issuing an RFP now and only spend serious money if they end up deciding the current heat shield isn't fixable. Adapting a space-proven heat shield could be faster, cheaper, and safer than fixing Orion's novel heat shield if finding a root cause for the spalling continues to be difficult.

I really like this idea.   I'll add that if they put this out for bid they could specify a test flight with lunar return like entry speed for the new heat shield.

A slight scaled down heat shield may suffice for the test.  ( 4.5 meters vs 5 meters )

 

Doesn't guarantee that you will get SpaceX

[sdsds]

The quickest solution is to use the Artemis 2 mission to gather additional data on how the Orion heat shield behaves during reentry. That doesn't require the Artemis 2 mission to include a return from cislunar distance. Split the Artemis 2 mission objectives across two SLS launches, i.e. Artemis 2A and Artemis 2B. Fly the 2A mission to retire heat shield risk, and also other risks. (ECLSS, radiation, etc.) Fly the 2B mission with the current Artemis 2 profile. This approach requires some clever way of handling the scarcity of ICPS-compatible stages.
https://forum.nasaspaceflight.com/index.php?topic=60070.msg2618247#msg2618247

I assume the first of these two missions is uncrewed. I that case, it's really Artemis 1B.

Were I NASA Czar, I would put a crew of 2 on it and call it a Crewed Flight Test.
The currently plan has the first use of Orion ECLSS in a elliptical Earth orbit and if all seems well that same vehicle commits to supporting the crew of 4 for ~8 more days. The 2A mission has the first use of Orion ECLSS in LEO, followed by an apogee raising burn that might commit the crew of 2 for ~4 days. Successful completion of that looks like risk reduction for the Artemis 2B mission. Similar logic applies to exposing the crew to solar particle radiation (assuming the 2A orbit apogee is high enough).

[DanClemmensen]

The quickest solution is to use the Artemis 2 mission to gather additional data on how the Orion heat shield behaves during reentry. That doesn't require the Artemis 2 mission to include a return from cislunar distance. Split the Artemis 2 mission objectives across two SLS launches, i.e. Artemis 2A and Artemis 2B. Fly the 2A mission to retire heat shield risk, and also other risks. (ECLSS, radiation, etc.) Fly the 2B mission with the current Artemis 2 profile. This approach requires some clever way of handling the scarcity of ICPS-compatible stages.
https://forum.nasaspaceflight.com/index.php?topic=60070.msg2618247#msg2618247

I assume the first of these two missions is uncrewed. I that case, it's really Artemis 1B.

Were I NASA Czar, I would put a crew of 2 on it and call it a Crewed Flight Test.
The currently plan has the first use of Orion ECLSS in a elliptical Earth orbit and if all seems well that same vehicle commits to supporting the crew of 4 for ~8 more days. The 2A mission has the first use of Orion ECLSS in LEO, followed by an apogee raising burn that might commit the crew of 2 for ~4 days. Successful completion of that looks like risk reduction for the Artemis 2B mission. Similar logic applies to exposing the crew to solar particle radiation (assuming the 2A orbit apogee is high enough).

The OIG report says that the heat shield is questionable. How can they justify sending crew on a mission that tests a modified heat shield for the first time?

[sdsds]

The OIG report says that the heat shield is questionable. How can they justify sending crew on a mission that tests a modified heat shield for the first time?

OIG says the Artemis 1 Orion survived reentry at lunar distance velocity with no damage to other parts of the spacecraft. After the 'skip' reentry NASA saw degradation of the heat shield they weren't expecting, which rightly set off an investigation.

A test pilot takes many risks. The goal of the program is to keep the sum of those risks tolerable. So they would do the analysis. They would show that for a direct reentry from ~0.5 LD the likelihood of the heat shield failing to protect the spacecraft is almost nil. Lower than parachute deploy failure risk. Lower than on-pad anomaly risk. Lower than abort during ascent risk. Lower than ECLSS failure risk. Lower than propulsion failure risk. Etc.

And with the additional data gained from the test flight they might even be able to approve, with that same level of confidence, a LD return velocity with direct reentry mission profile. All without any heat shield modification required.

The challenge would be to show that the total LOC risk for two missions (2A/2B) was lower than the LOC risk for a single Artemis 2 mission as currently planned.

[sdsds]

On several occasions recently I've noticed expressions of ... concern ... that Orion as built may not be capable of supporting 'eyeballs-out' maneuvers where Orion is docked nose-to-nose with a stage providing propulsion for e.g. trans-lunar injection.

Orion in its original design supported that because the Ares V Earth Departure Stage would be propelling Orion (and Altair) through TLI. And later Altair would be providing propulsion for LOI. Did the requirement somehow get de-scoped, or does Orion retain that capability?

[woods170]

On several occasions recently I've noticed expressions of ... concern ... that Orion as built may not be capable of supporting 'eyeballs-out' maneuvers where Orion is docked nose-to-nose with a stage providing propulsion for e.g. trans-lunar injection.

Orion in its original design supported that because the Ares V Earth Departure Stage would be propelling Orion (and Altair) through TLI. And later Altair would be providing propulsion for LOI. Did the requirement somehow get de-scoped, or does Orion retain that capability?

Orion, as built has only limited capabilities for supporting "eyeballs-out" maneuvers. Not so much caused by the CM, but by the limits of the SM.
When ESA "adopted" the SM, not all requirements of the original CxP 606/607 design iteration were adopted in the design of the CSM. Quite a bit of stuff was descoped to keep the design within the limited available ESA budget. It also assumed no lunar lander, which had already been defunded in the later stages of the disaster that was CxP.