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Comment by avar | Hacker News Reader

> This is basically how SpaceX seems to operate: rather than optimizing a single part of the system (like trying to get the most efficient engine), they try to optimize from a systems level.

They're optimizing for "real" reusability, as in eventually aiming for airline-like turnarounds. None of the earlier engines you noted were reusable except the RS-25, and given how long it took to turn the Shuttle around one could argue it doesn't really count as "reusable" in sense SpaceX is aiming for.

Aiming for reusability and ease of maintenance leads to different optimization paths, in particular we should expect that any one component is going to be less powerful, it'll need to account for wear & tear, not use once and crash it into the ocean.

But raw performance on a single trip doesn't matter much if you can just deliver the same payload in two trips to orbit instead.

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> and given how long it took to turn the Shuttle around one could argue it doesn't really count as "reusable" in sense SpaceX is aiming for.

Not just the time but the cost, if you take the figure of how much the space shuttle program cost, and divide it by total number of flights (including the two lethal ones), it cost somewhere between $900 million to $1.1bn every time the thing launched. It was very far from the early 1970s dream of an economically reusable spacecraft.

Indeed, the space shuttle was so expensive it burned up much of the rest of NASAs budget-- keeping that disastrous, failed program running is why NASA doesn't have manned spaceflight capability at the moment.

Well, from an outsider perspective, the SLS/Orion program is pure pork. Nobody holding the purse strings cares whether the thing ever flies. Heck, probably they even prefer if it never flies (always just a few years and tens of billions in the future); a failed launch is potentially politically catastrophic.

> But raw performance on a single trip doesn't matter much if you can just deliver the same payload in two trips to orbit instead.

Except that you're doubling the cost if you have to do two trips.

You just need twice as much methane. So just have PF Chang’s catered and you’re back in orbit in a couple hours.

If you throw away the rocket, sure, you're doubling the cost if you have to do trips.

If the rocket is reusable, then the vehicle cost gets amortized over the total number of trips, and the per-trip cost gets closer to just the cost of fuel (hopefully at least an order of magnitude less than a new vehicle+fuel on each flight).

Fuel and oxidizer is 2-3 orders of magnitude less than the cost of an expendable rocket.

Entirely valid point, but doubling 1% of the cost of a single use system is still pretty good, comparatively speaking.

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