Re:Recording of aerospace executive's speech leads to his re...
by mikeash on Friday March 18, 2016 @09:23AM
(#11311582)
Why does 15-20% (and it's more like 5-10%) make it dumb?
What matters is how much you can put into orbit. RTLS hits you with a 30% payload penalty, a normal barge landing is about a 15% penalty, and a crazy hail-Mary attempt like SES-9 is somewhat less.
If your payload is under that threshold then the only downside to it is the extra cost of fuel and support. Both are completely minimal. For example, SpaceX's next ISS supply mission has plenty of margin for an RTLS landing. A Dragon stuffed full of cargo still weighs less than what Falcon 9 can put into the ISS's orbit and land back at the launch site afterwards. For a little bit of extra fuel, you can potentially save a rocket stage worth tens of millions. That doesn't sound dump to me.
For those few payloads that can't tolerate that penalty, they can fly the rocket expendable. It's still one of the cheapest out there even if they don't recover it. Or they can fly it on Falcon Heavy, which if recovered is cheaper than an expandable Falcon 9.
The only big unknown right now is the cost of refurbishing a recovered first stage so it can be ready for another launch. That's what made the Space Shuttle cost so much more than it was supposed to. It sounds good so far, but until they're doing this on a regular basis we can't know for sure.
What matters is how much you can put into orbit. RTLS hits you with a 30% payload penalty, a normal barge landing is about a 15% penalty, and a crazy hail-Mary attempt like SES-9 is somewhat less.
If your payload is under that threshold then the only downside to it is the extra cost of fuel and support. Both are completely minimal. For example, SpaceX's next ISS supply mission has plenty of margin for an RTLS landing. A Dragon stuffed full of cargo still weighs less than what Falcon 9 can put into the ISS's orbit and land back at the launch site afterwards. For a little bit of extra fuel, you can potentially save a rocket stage worth tens of millions. That doesn't sound dump to me.
For those few payloads that can't tolerate that penalty, they can fly the rocket expendable. It's still one of the cheapest out there even if they don't recover it. Or they can fly it on Falcon Heavy, which if recovered is cheaper than an expandable Falcon 9.
The only big unknown right now is the cost of refurbishing a recovered first stage so it can be ready for another launch. That's what made the Space Shuttle cost so much more than it was supposed to. It sounds good so far, but until they're doing this on a regular basis we can't know for sure.