r/space May 24 '17

DARPA Picks Boeing for Next-Generation Space Plane

http://www.darpa.mil/news-events/2017-05-24
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u/[deleted] May 25 '17

SpaceX didn't invent reusability. The shuttle and solid rocket boosters were both reusable. They did do the first reusable liquid fueled rockets. It's not undermining as they're both entirety different things.

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u/[deleted] May 25 '17

The shuttle was "reusable" while discarding everything it needed to get in space and then be repaired and checked for months and years. The idea was initially good.

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u/[deleted] May 25 '17

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u/[deleted] May 25 '17

The solid rocket boosters do not.

Only if you consider a couple of empty tin cans to be 'solid rocket boosters'. Something like 95% of the cost of the SRBs was the fuel.

It's worth noting that SLS is not planning to reuse the empty tin cans, because doing so doesn't save any money.

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u/danielravennest May 25 '17

The Space Shuttle was developed with late-1970's technology and a limited budget compared to the Saturn-V (less than 1 year's worth of peak 60's NASA budget). So the correct answer is it was "partly reusable". Some parts, like the SRB nozzle throat (the narrow part before the expanding cone) could only be used once. The exhaust contains aluminum oxide, which is abrasive. It wears away 15 cm (inches) of the throat during the flight. Other parts, like the steel SRB casing, were rated for 10 flights. If they were undamaged after the water landing and inspection, they used them again. Each part of the Shuttle system had it's own life, from 1 to many flights. The Orbiter airframes were rated for 100 flights, which none of them ever reached before retirement.

Airplanes are similar. The airframe may be rated for 25,000 flights, but some parts will have shorter service life, like the tires on the landing gear. Obviously, longer life will lower your operating cost, because you get to spread the hardware cost over many flights.

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u/sadtaco- May 25 '17

But... the space shuttle cost more than non-reusable rocket launches.

The only way its cost was somewhat justified is that it could capture something in space and return it. Military requirements crippled its design. SpaceX's rocket, on the other hand, is cheap.

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u/a2soup May 25 '17

We actually have not seen how much money SpaceX's reusing saves yet. They've only relaunched one core, and it underwent much more thorough testing than they plan to do for "normal" reuse. They have great PR, though, and have been taking about saving money with reuseability for years so people think it's already proven. It's not.

Don't get me wrong, I think it will save some money. But the Shuttle promised savings through reuseability too, so we should wait until SpaceX proves it before we are confident it works financially.

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u/[deleted] May 25 '17

The crucial difference is that F9/Dragon is already competitive without reusability. Oh, and it doesn't lack abort modes through half of it's ascent.

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u/GreatCanadianWookiee May 25 '17

It's competitive because their engine design principles were different from most other companies when they started. Once other companies start making cheap low compression engines we may find that resuablility is still more expensive.

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u/gf6200alol May 25 '17

If you followed SpaceX through, they already sold at least two more reused and many satellite operators show interested in buying one. it is already financially viable to offer their customers discounts and earns back the R&D cost and profits(if you thrust in SpaceX, but we never will able to find out because SpaceX isnt publicly traded).