9 thoughts on “More Propellant Depot Commentary”

1. Over 70 percent of conduction an exploration mission beyond low earth orbit is fuel

   I believe this statement to be wrong. Or possibly right if you take into account the wasted fixed cost of NASA. First, the actual cost of fuel can be assumed zero. The real fuel cost is getting it to orbit. That’s the actual mission start to anyplace and even with free fuel that cost is over 90% of almost any mission to anywhere.

   Let’s say 50mt cost $100m to orbit. If your ship is 50mt you need about ten times that in fuel or $1b to send it one way. It’s much more if you want to come back. The actual cost of the fuel itself is lost in the noise.

   Fuel depots have a large potential to cut this cost and become an economic driver. Lunar oxygen by itself becomes a profitable private venture as soon as ships are in orbit and going places.

   1. Isn’t the point that over 70% of IMLEO is propellant?

      1. If somebody weighed 300 pounds it would be technically correct to say over 200 pounds, but it would give a wrong impression.

2. I see some people rendering “SLS” as “Senate Launch System”.

   If it were to be used to launch the Senate, it might be worth the expenditure. Ideally it would skimp on re-entry provisions.

   1. I call it the “Stupid Launch System” although I’d be willing to launch the Senate on a one-way voyage to anywhere to get rid of them.

      1. That joke never gets old irrelevant.

         1. Sadly true.

3. Interesting idea: the Dragon capsule as a LOX tanker …

   http://engineerinprogress.blogspot.com/2011/10/ideas-that-might-hold-water-or-at-least.html

   (And I wouldn’t be at all surprised if that was one of the things that were factored into Dragon’s design …)

4. Here at the CRASTE Conference, Dave Cheuvront of NASA JSC just delivered a presentation on propellant depots as a game-changing, disruptive technology. The main thesis was that it changes space system operations from “mass scarce” to “mass abundant” propositions. And the resulting saving in development cycle time and cost, and the increase in margins that come from not wringing every ounce of inert weight from a design, dwarf any supposed drawbacks from lower reliability. It was a first-class job.

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