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SpaceX is attempting a huge feat in spacecraft engineering. It is seeking to land the first stage of its Falcon 9-R rocket on a floating platform at sea. Normally this would end up at the bottom of the ocean. If successful, SpaceX will shake the rocket launch market, by shaving millions of dollars off launch costs.
Today’s rockets are one shot wonders. They burn up fuel in a few minutes and splash down into terrestrial oceans, having put their payload on the right trajectory. This is wasteful and that is why scientists have dreamed of building reusable launch vehicles.
The holy grail of rocket launchers is a concept referred to as the single stage to orbit (SSTO) vehicle. The idea is to use a reusable launch vehicle (RLV) which has the capability to deliver a payload to orbit, re-enter the Earth’s atmosphere and land, where it can then be refuelled. The process can then be repeated with a short turnaround.
https://theconversation.com/explainer-why-reusable-rockets-are-so-hard-to-make-36036
(Score: 1) by steveha on Monday January 12 2015, @05:10AM
The article seems heavy on the disadvantages of reusables. Additional weight and complexity to accommodate the reusability is the main one.
I don't buy the "additional complexity" argument. The control software would be more complex and that's about it. What SpaceX is doing is to land the first stage under controlled rocket power; so you don't really need any extra hardware (e.g. parachutes).[1]
But there are two major, major advantages to reusable: cost and reliability.
Cost is obvious. You build this giant rocket stage out of expensive metal alloys, with all the tanks and pipes and rocket engines and computers, and you pay a bunch of people for building it and quality-checking it; and then instead of destroying it you use it more times. Huge cost savings.
Reliability? With a single-use rocket you have to make brand-new rocket parts perfect the first time, and any mistake means your rocket can be destroyed. With reusables you can actually have a test flight, and as the rocket keeps flying you can get a track record of reliability.
One more advantage: once you have a fleet of tested reusable spacecraft, if you have a sudden urgent need to launch something, you can just prep and fuel and go. Right now we are very far from that.
I want to see space travel become boring and routine within my lifetime. That will never happen with single-use rockets, so I'm cheering on any attempts for reliability.
P.S. I have seen a couple of references to the Space Shuttle in comments on this article. Just because the Space Shuttle was insanely expensive and at the same time insanely dangerous[2] doesn't disprove the concept of reusable spacecraft. NASA got to the moon by iteration: fly something, measure how it worked, design something new, repeat. For the Shuttle, NASA attempted to design something in a single generation, and it was far from perfect. (In contrast, look at how SpaceX has been iteratively refining their stuff.) Also, the Shuttle was compromised by a weird requirement to be able to lift heavy things into a polar orbit, so its design favored heavy lift capacity over reusability.
http://en.wikipedia.org/wiki/Space_Shuttle_design_process#Air_Force_involvement [wikipedia.org]
[1] If you didn't plan to reuse the first stage, maybe you could use non-restartable engines and I guess for reuse you probably need to be able to stop them and start them... but I think most liquid-fueld rocket engines are restartable anyway.
[2] By actual statistics, the Shuttle was only two-nines reliable. Wikipedia lists 135 flights; two of those ended in complete destruction of the Shuttle and the deaths of all crew. That's a 1.5% chance of death per flight; if cars or airplanes were that unsafe, few would use them.