In article ,
says...

"Jeff Findley" wrote in message
...

I heard helium, because while lift isn't important, mass most certainly
is. And at the same volume and pressure, helium masses less than
nitrogen. The mass of the molecule doesn't enter into the ideal gas
law:

P*V = N*R*T

Jeff
Fair point. And I believe they already have helium tanks on board, just use
those as part of the supply.

They do, to pressurize the kerosene and LOX tanks for the Merlin engine.
Adding another gas would complicate pad operations (only a bit, but
still).

I'm glad they're working on upper stage recovery. My guess is that
BFR/BFS will take a bit longer than Elon's aspirational schedule
products. As such, Falcon 9 and Falcon Heavy will remain the workhorses
of SpaceX for many years to come. Anything they can do to cut their
costs increases the cash they can funnel into BFR/BFS development.

Same goes for Starlink. That needs to be developed, built, and launched
quickly in quantity for them to maintain the number of satellites that
goes with their FCC agreement. That's a "use it or lose it" type of
thing. You can't apply for and be granted bandwidth and just "sit on
it". You have to use it. Improving Falcon 9 and Falcon Heavy reuse
will help keep costs down for launching Starlink as well.

Jeff
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