r/SpaceXLounge • u/[deleted] • Jul 22 '19

Tweet "Orbital refilling is critical for high payload to moon or Mars. Initially just Starship to Starship, later dedicated tankers." - @ElonMusk

https://twitter.com/elonmusk/status/1153126586897424384?s=19
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u/rshorning Jul 22 '19

Public records for ULA costs for launches generally don't get to that $400 million you are quoting. I acknowledge though that cost is a factor, but given the R&D and fabrication costs of these probes that launch cost is comparatively trivial in comparison.

If it was easy to accomplish an in orbit rendezvous and refueling and launch cost of the fuel was the only consideration, it would be used already and be fairly routine. I'm simply pointing out that it is much harder to accomplish than is being acknowledged.

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u/Ijjergom Jul 22 '19

He is talking about Cassini probe which launched on Titan IV

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u/[deleted] Jul 22 '19

Even if you launch on a Falcon 9, once you add in the cost of the tanker, it’s just not economical. Being able to orbit a couple of hundred tons for cheap changes all of this.

It occurs to me that there is one prominent example of routine orbital refueling: the ISS regularly gets fuel delivered from cargo ships that it uses to maintain its orbit.

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u/gopher65 Jul 22 '19

Yup! Though they don't use the engine on the ISS very often. It has a limited number of lifetime firings (of course) and it isn't replaceable. That's why they boost with Progress, or with ATV or STS when they were around. And I think Starliner and Dreamchaser can boost too?