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Comment by nextparadigms | Hacker News Reader

In a recent interview, Elon Musk was saying how we wouldn't have airplane travel the way we have today if the airplanes wouldn't be reusable.

He was saying that to point out that this is how reusable rockets should revolutionize space travel, in a way just as big.

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Hmm, well, but it's interesting that the US went down that road and built an unreliable "reusable" spacecraft that had a high failure rate and had be largely reconditioned at high expense after every flight. Meanwhile, the Russians are using an incrementally improved capsule design from the '60s that's simpler, cheaper, and safer.

I'm not saying that a true reusable speacecraft wouldn't be revolutionary. And maybe it's possible with '10s tech in a way that it wasn't in the '70s. But picking "reusable" as a goal in and of itself, rather than using metrics like reliability or cost per pound to orbit, seems like a dodgy business.

The shuttle had wings, Falcon 9 / Dragon does not. That's also why it had expensive/brittle tiles rather than ablative shielding, was strapped on sideways, had solid rocket boosters to handle the added weight, and didn't have an eject capability. Also all of its stuff splashed at parachute speed into the sea. The shuttle wasn't so much reusable as rebuild-able. By contrast this SpaceX concept looks like it could pretty much be stacked back up, fuelled and re-launched.

The Shuttle had to have a lot of design compromises to get the political support needed for funding the program. NASA didn't have any need to haul satellites into polar orbit, but the Air Force thought that it might be useful so the Shuttle ended up having far more payload space and delta-V than it needed for the missions NASA ran. Of course, most of those excess capabilities ended up not ever being used except for the repair of the Hubble, but they made the Shuttle far more expensive and less reliable.

When it comes to spacecraft Fuel is cheap manpower is expensive.

The Americans built the first ever reusable spacecraft but they never really stuck with one design. Just about every shuttle was slightly different which resulted in slightly improved performance, reduced safety, and dramatically increased costs. They then kept using them well past the designed lifetime which once again radically increased the costs. All while flying them a minimum number of times each year.

How cheap is the fuel? Say, a space shuttle? I've heard a launch costs $450 million, but it doesn't say if it was fuel alone.

In U.S. dollars in the year 2000, it came to about $16 of fuel per pound of payload launched. We had a homework assignment to figure out that number in our propulsion class at the University of Washington.

Shocking. The rest of that $10k per pound is amortized launcher costs and operations. (If you include the initial R&D, it goes up to something like $50k per pound.)

The shuttle was a truly immoral launch vehicle.

That's incredible. You should do a blog post about that. It's really fascinating and I don't think is been published anywhere.

The marginal cost on a Space Shuttle launch is actually rather low--a few tens of millions if we kept up with the original launch rates (less than the cost of a Falcon 9h!).

Also, no work was ever done to bring down operational costs. In fact, such costs ballooned as the program dragged on, despite numerous design studies showing ways to reduce them.

While the shuttle was technically 'reusable', it required a lot more retooling between flights than simply putting more fuel in the tank. It was a _very_ complicated machine, and invariably needed to have various components and consumables replaced after every flight.

It's supposed to be on the order of one to two percent of the program cost, depending on exactly what fuel you use and how often you fly.

jfruh, I disagree with you there. By setting the goal of reusable and reliable he could change the cost structure in a way that would make a fundamental improvement in financing of space missions.

The rest of the video make no sense with rockets helping for reentry. Why not just use pilot guided shoots?

By setting the goal of reusable and reliable he could change the cost structure

But there's the assumption, isn't it? Actually two: that reusable will be cheaper, and that reusable and reliable can go together.

I'm certainly not saying they can't -- I am, quite literally, not a rocket scientist -- but the Space Shuttle program was the triumph of the idea that "Of course it'll be cheaper if we can re-use the vehicle." Which didn't work out in practice for the reasons outlined upthread. My point is that a space program should pick the goals of "This should get people up and back safely and cost $X a launch" because those are measurable. Maybe the best way to do that is with a reusable vehicle! But to make reusability a goal in and of itself, due to a sentimental attachment to the kind of vehicles we used to travel by sea, seems silly.

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