SpaceX Super Heavy/Starship (BFR/BFS) - Earth to Deep Space / Re: Starship On-orbit refueling - Options and Discussion« Last post by oldAtlas_Eguy on Today at 06:49 pm »
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.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).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. :-)
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.
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.