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91
Meanwhile, NASA has regulations for its professional astronauts:

pLOC <1/500 during ascent
pLOC <1/500 during EDL
pLOC <1/270 during a six-month mission, after factoring in MMOD and other on-orbit hazards.

1/500 for each of launch and EDL is almost certainly what NASA would expect, and I'd be surprised if SpaceX didn't hold itself to the same standard for private missions.  There's too much downside and not enough upside to do anything else.
SpaceX might be able to reach these numbers without massive re-design, basically taking advantage of all the low hanging fruit.

For SH failures, use the second stage as an escape pod.  This should work except in those cases where the SH quickly goes KA-BOOM.  But a more gentle failure should be more likely - liquid engines seem to fail less violently, and SpaceX should have significant data on Raptor failures from their testing program, and as long as one steerable engine is running the first stage can cooperate by keeping stable and not instantly disintegrating from aero forces.  For example, this approach would have worked fine on the recent New Shepard failure.  Various relatively minor changes might be required - stronger stage separation pneumatics, better shields between the booster's steerable engines (to keep one engine running for stage stability after second stage departure), new software for both stages, and so on.  But no major design effort.

Similarly, many second stage boost failures, and landing failures, could be addressed by (a) trying to make sure an engine failure does not take out all the engines, and (b) a serious software effort, and testing, to make sure the second stage does the best it can with whatever engines remain, and (c) always have legs on crewed missions, so any dry land will do (and even a gentle water landing might be OK - this can be tested).

If SpaceX can get the raw reliability to 99% (about where F9 is now), and handle 4 out of 5 failures without loss of crew, then they could meet the above requirements without huge changes. 
92
https://blogs.nasa.gov/artemis/category/orion-spacecraft/

Quote
Shortly after acquiring signal with the Deep Space Network’s Canberra ground station at 12:41 a.m. CST, Orion experienced an issue with a power conditioning distribution unit (PCDU), in which four of the latching current limiters responsible for downstream power were switched off. These lower-level switches connect to the propulsion and heater subsystems. Teams confirmed the system was healthy and successfully repowered the downstream components. There was no interruption of power to any critical systems, and there were no adverse effects to Orion’s navigation or communication systems.
93
I think that is a safe bet that Artemis III will be delayed by a year, from 2025 to 2026, given that Artemis I was delayed by a year, from 2021 to 2022. The delay of launching Starship to orbit by more than 6 months also contributes to that delay.

I noticed that Axiom's contract ends on July 8, 2026 which leads me to believe that the suits won't be ready before that time either.

https://forum.nasaspaceflight.com/index.php?topic=53612.msg2437302#msg2437302

NASA said that it would update the dates after Artemis I is completed.
We do not know if the Starship slip will affect the Artemis III slip. It depends on what is on the critical path (PERT/CPM strikes again...) My guess: SLS/Orion is still critical path and Starship is not, at least not yet. However, If SLS/Orion were not slipping and the spacesuits were not slipping, then Starship HLS would be on the critical path.

Someone from NASA (I forget who) mentioned that slip in the orbital mission as a potential delay to HLS-Starship. I am pretty sure that it has a direct impact.
Do you have a pointer to a PERT chart for the Artemis program? In my experience with complex projects, you don't find out what was really on the critical path until the post-implementation project review. My experience is with far smaller projects, though.

I had assumed that the uncrewed HLS demo has very few non-SpaceX dependencies and could be used as a relatively "clean" milestone.
94
Mission elapsed time 18 days, 20 hours, 14 minutes.

Orion's distance from the Earth is 223,943 miles. Distance to the Moon now only 19,635 miles.

95
Advanced Concepts / Re: Medusa concept using chemical explosives
« Last post by Beratnyi on Today at 02:03 am »
[snip]

No matter how efficient your heat transfer, your exhaust velocity can never exceed the limiting value determined by the total amount of energy available.
I will cite as an example the Spitfire fighter, in which the amount of heat entering the radiator was equal to the amount of energy driving the propeller. However, the thrust from the radiator was negligible and barely covered its air resistance, and all because of the temperature of the antifreeze in the region of 100 degrees Celsius.
There is not only energy density, but also energy quality.

Yes, we all know how waste heat (vs useful energy) works.

I can guarantee you the Spitfire didn't violate the Conservation of Energy either.  :D
The quantity and quality of energy are two different things!

I know.

At the Spitfire, a megawatt of heat passed through the radiator, but even a cutlet on it would be impossible to fry. At the same time, a 1 kilowatt burner can easily fry a kebab.

I fail to see how this relates to your original proposal, or to my criticism.

My criticism was that you can't violate Conservation of Energy, so total energy still matters. Nothing about the Spitfire changes that.
For example, we have a substance with an energy density of 10 MJ per kg. We can release this energy in a second and get a temperature of 3000 degrees, or we can release this energy in an hour and not even get warm. And hypothetically, we can release this energy in a nanosecond and get millions of degrees. In all three cases, the energy density is the same, but the rate of its release is different. Speed is what matters, which is why the temperature in the center of a nuclear explosion is so high, because the detonation velocity is thousands of times higher than that of any chemical explosive, and not at all because of the energy density.
96
Advanced Concepts / Re: Medusa concept using chemical explosives
« Last post by Twark_Main on Today at 01:59 am »
Spitfire

...

kebab

"Hey I heard u like Spitfires, so I made a Spitfire spit fire at ur spit."
97
Advanced Concepts / Re: Medusa concept using chemical explosives
« Last post by Twark_Main on Today at 01:55 am »
[snip]

No matter how efficient your heat transfer, your exhaust velocity can never exceed the limiting value determined by the total amount of energy available.
I will cite as an example the Spitfire fighter, in which the amount of heat entering the radiator was equal to the amount of energy driving the propeller. However, the thrust from the radiator was negligible and barely covered its air resistance, and all because of the temperature of the antifreeze in the region of 100 degrees Celsius.
There is not only energy density, but also energy quality.

Yes, we all know how waste heat (vs useful energy) works.

I can guarantee you the Spitfire didn't violate the Conservation of Energy either.  :D
The quantity and quality of energy are two different things!

I know.

At the Spitfire, a megawatt of heat passed through the radiator, but even a cutlet on it would be impossible to fry. At the same time, a 1 kilowatt burner can easily fry a kebab.

I fail to see how this relates to your original proposal, or to my criticism.

My criticism was that you can't violate Conservation of Energy, so total energy still matters. Nothing about the Spitfire changes that.
98
Advanced Concepts / Re: Medusa concept using chemical explosives
« Last post by Beratnyi on Today at 01:49 am »
[snip]

No matter how efficient your heat transfer, your exhaust velocity can never exceed the limiting value determined by the total amount of energy available.
I will cite as an example the Spitfire fighter, in which the amount of heat entering the radiator was equal to the amount of energy driving the propeller. However, the thrust from the radiator was negligible and barely covered its air resistance, and all because of the temperature of the antifreeze in the region of 100 degrees Celsius.
There is not only energy density, but also energy quality.

Yes, we all know how waste heat (vs useful energy) works.

I can guarantee you the Spitfire didn't violate the Conservation of Energy either.  :D
The quantity and quality of energy are two different things! At the Spitfire, a megawatt of heat passed through the radiator, but even a cutlet on it would be impossible to fry. At the same time, a 1 kilowatt burner can easily fry a kebab.
Energy density refers only to the amount of energy available to you, not its quality.
99
I think that is a safe bet that Artemis III will be delayed by a year, from 2025 to 2026, given that Artemis I was delayed by a year, from 2021 to 2022. The delay of launching Starship to orbit by more than 6 months also contributes to that delay.

I noticed that Axiom's contract ends on July 8, 2026 which leads me to believe that the suits won't be ready before that time either.

https://forum.nasaspaceflight.com/index.php?topic=53612.msg2437302#msg2437302

NASA said that it would update the dates after Artemis I is completed.
We do not know if the Starship slip will affect the Artemis III slip. It depends on what is on the critical path (PERT/CPM strikes again...) My guess: SLS/Orion is still critical path and Starship is not, at least not yet. However, If SLS/Orion were not slipping and the spacesuits were not slipping, then Starship HLS would be on the critical path.

Someone from NASA (I forget who) mentioned that slip in the orbital mission as a potential delay to HLS-Starship. I am pretty sure that it has a direct impact.
100
Advanced Concepts / Re: Medusa concept using chemical explosives
« Last post by Twark_Main on Today at 01:44 am »
[snip]

No matter how efficient your heat transfer, your exhaust velocity can never exceed the limiting value determined by the total amount of energy available.
I will cite as an example the Spitfire fighter, in which the amount of heat entering the radiator was equal to the amount of energy driving the propeller. However, the thrust from the radiator was negligible and barely covered its air resistance, and all because of the temperature of the antifreeze in the region of 100 degrees Celsius.
There is not only energy density, but also energy quality.

Yes, we all know how waste heat works (or more accurately, doesn't).

I can guarantee you the Spitfire didn't violate the Conservation of Energy either.  :D
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