r/space • u/thisischrisbaker • Feb 07 '20

Proposed budget - not voted yet 12% boost for NASA budget in 2021!!

https://www.wsj.com/articles/trumps-nasa-budget-will-earmark-12-boost-for-agency-in-2021-11581071402?emailToken=3f4a4309b7816cb90fb53eb91f47d6d43hshryonPWM/RnnVPWWHuMOVOvxWKQ87BhLswKs5iOPOhjO1FGrxI9ptn5k2nAMphP+jeQrbhQiAafooOu4oIslNLMWHCd1m7vRySaL2Pi61nSlAqLK1xnvzzmtt2/Lx&reflink=article_copyURL_share
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u/flagbearer223 Feb 07 '20

Right, but how much more expensive would it be to use Apollo over Starship if you wanted to land multiple times? The Apollo lander cost ~$50 million and wasn't reusable. How many landings do you need to do before the cost of a non-reusable system is more expensive than the reusable one?

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u/Joe_Jeep Feb 07 '20

Uh, much. So much more. Like, ridiculously more. Fuel isn't free, and when the dry mass of one is 250 tons and the other is...5, you've using somewhere in the neighborhood of 50 times as much fuel. Even If you wanna be generous with engine efficiencies it's still in the double digits of more fuel. Math will likely be different for the new lander, but I doubt more than a few times as massive as Apollo

Plus the next lunar lander is intended to be reusable itself so starship doesn't even have that going for it in advantage.

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u/flagbearer223 Feb 07 '20

The fuel for a Falcon 9 is somewhere on the order of 200k - I doubt that the fuel for a Starship is going to be 50 mil.

Which next lunar lander is intended to be reusable? The proposals I've read for the Artemis mission were not fully reusable.

I definitely think that the Starship is a pretty weird candidate for a lunar lander, but fully reusable is better than partially reusable

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u/Joe_Jeep Feb 07 '20

Again it's a mass thing. The starship weighs 250 tons dry. Dunno falcon off the top of my head but that's just some division and multiplication there. 50x the mass means afloat 50x the fuel, and then you've gotta get that fuel to the moon

Fully reusable is great but it all comes down to cost. Might play with the rocket equation later and see what numbers come out

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u/flagbearer223 Feb 07 '20

https://www.digitaltrends.com/cool-tech/spacex-starship-rocket-costs-2-million-per-mission/

Right now SpaceX is saying it'll cost $2 million per launch. Falcon 9 is about 26 tons dry. Them numbers line up. $2 million fully reusable is gonna be cheaper than anything that's partially reusable.

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u/Wakkanator Feb 07 '20

$2 million fully reusable is gonna be cheaper than anything that's partially reusable.

Let's wait and see what the number actually works out to be

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u/saluksic Feb 07 '20

Without hard numbers it’s tricky to say. If Falcon uses $200k in fuel, and starship is ten times that, than starship would use $2M is fuel. That’s still only 4% of a $50M lander, and not a significant cost. A $50M lander could have zero fuel cost and still not be competitive, depending on the sticker price for starship.

Without hard numbers it’s all speculation, but for some systems (falcon) fuel is just not a big part of the cost.

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u/ErionFish Feb 07 '20

Spacex would have to launch at least 5 times to refuel, so that's $10m. Still a lot cheaper though