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One obvious missing capability to turn the Option A LSS into Option B is the ability to refuel in cislunar, which is how the LSS becomes reusable. 
Don't they also need some way to inspect/test the vehicle before reuse? That seems to me to be the biggest missing piece--although it provides a great reason to have a crew at Gateway. :-)
There is no hard requirement in Option B for reuse of the HLS lander. The requirement is for "sustainable" access to the moon, meaning (more or less) one or more times a year for not too much money. The original NASA reference lander has three elements: transit, descent, and ascent, and only the ascent element was reusable in its Option B. The Starship HLS system has three elements: Depot, Tanker, and HLS. The tanker and Depot are reusable and the HLS is not very expensive, so even if it is expended  the system still meets the sustainability requirement. It is probably cheaper to expend it than to refuel it, but the big problems for reuse are reprovisioning and loading new large cargo. Provisioning and cargo are easy to load on a new HLS on Earth, much harder to transfer in space (cislunar, LEO, or other).

HLS is "not very expensive" because much of it is built from standard Starship parts in a high-production SpaceX factory.

Starship HLS also increases sustainability by eliminating most separate cargo missions. Cargo missions have generally been assumed to be one-way anyway.

It might make sense to reuse Starship HLS if SLS/Orion is retired and HLS conveys the crew from LEO to the Lunar surface and back.
The cost of the LSS is the crew habitat and other LSS crew related addons to the basic SS. A basic SS hardware may be easily as low as $50M. But an LSS hardware is likely to run at greater than $150M. NOTE here is that a depot and a BEO tanker would be at the close to a basic SS costs. Thus such to use an LSS at least 3 times will gain significant savings overall for surface missions of $50 to >$100M on each mission. Which can say a lot about a stripped down oneway cargo hardware to cost ~$75M for the cargo SS that delivers about 75 to 100t of cargo to the surface.

Even using a throw away tanker vs a Lunar Depot you would still save money by just reusing the LSS 3 to 5 times. You could even refuel the LSS for return to LEO so it could be loaded for next mission and still save money. Such that initially only Tankers are thrown away until its possible to return EDL the Tanker from Lunar orbit. Once that happens an additional ~$50M is saved per mission.
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Similarly if for whatever reason the peak temperature reached is higher than planned, temperatures will rise on the inner side of tge heat shield, and again Stainless will perform much better than Aluminum.

Which, again, doesn't matter since neither one will survive entry temperatures if the heat shield is compromised or if the entry is otherwise off-nominal.

One of the shuttles lost a tile and survived reentry (STS-27) because it happened to be over an antenna mounting plate rather than the normal aluminum skin. The loss of a tile isn't necessarily fatal if the underlying substrate is robust enough. Stainless steel is much better than aluminum in this regards as evidenced by the lack of need for lee side TPS on SS.
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Advanced Concepts / Re: Using shaped charges as a rocket engine
« Last post by Barley on Today at 06:43 pm »
As far as I can see you have rediscovered solid fuel boosters.
There is a difference between detonation and burning.  Go look at the rotating detonation engines thread.
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Orion spacecraft’s return powered flyby of the Moon:

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Encke and Kepler Craters.

Luna 7 crashed not far from this region of the Moon.

Just a quick clarification - that is indeed Kepler at the bottom of the image, with the bright rays.  But the other two prominent craters are Marius and Reiner.  See all the bumps - those are the Marius hills.  Encke is very faintly visible in the Kepler ray system.


True, I grabbed the wrong screenshot by accident. That is indeed Marius and Reiner. The Marius Hills are also visible in the image.
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Encke and Kepler Craters.

Luna 7 crashed not far from this region of the Moon.

Just a quick clarification - that is indeed Kepler at the bottom of the image, with the bright rays.  But the other two prominent craters are Marius and Reiner.  See all the bumps - those are the Marius hills.  Encke is very faintly visible in the Kepler ray system.
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The idea is that when the heat shield is partly compromised, an underlying steel structure will last a lot longer than an underlying aluminum one.
Which is irrelevant if they both fail.
Yes, obviously. I assume the discussion is about the cases where details means one or the other has a larger chance of surviving.
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The temperature at the structure will not be that of the outer skin, so the ability to withstand elevated temperatures really matters.
Since the skin is the structure, I don't know what this means.
Not on the side covered in TPS, the glass coating on the TSP is the outer skin with regard to heating.
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Similarly if for whatever reason the peak temperature reached is higher than planned, temperatures will rise on the inner side of tge heat shield, and again Stainless will perform much better than Aluminum.
Which, again, doesn't matter since neither one will survive entry temperatures if the heat shield is compromised or if the entry is otherwise off-nominal.
This is the same as saying that reentries are impossible and meteorites do not exist since temperatures during reentry are far above the vaporization temperature of all known materials...
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NASA posted photos earlier of recovery practice using an Orion mock-up
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The idea is that when the heat shield is partly compromised, an underlying steel structure will last a lot longer than an underlying aluminum one.

Which is irrelevant if they both fail.

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The temperature at the structure will not be that of the outer skin, so the ability to withstand elevated temperatures really matters.

Since the skin is the structure, I don't know what this means.

Quote
Similarly if for whatever reason the peak temperature reached is higher than planned, temperatures will rise on the inner side of tge heat shield, and again Stainless will perform much better than Aluminum.

Which, again, doesn't matter since neither one will survive entry temperatures if the heat shield is compromised or if the entry is otherwise off-nominal.
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Any chance this could be changed to an UPDATES only thread so we're not constantly getting bombarded with speculation and opinion?
There is already an Updates only thread: https://forum.nasaspaceflight.com/index.php?topic=55711.0
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