Early science-fiction books almost universally portrayed rockets departing from a planet and landing on another (or back where they started from). There was no thought of abandoning almost all the equipment launched off a pad, leaving it to splash down uselessly into the oceans or be burned up on re-entry into the atmosphere. The harsh realities of early space flight made that necessary, of course, but it's always been a very wasteful business.
Elon Musk wants to change that. Flight Global reports:
One of the most ambitious development projects in spaceflight took a giant leap last month when SpaceX achieved a 29s flight to a height of 40m - and safely back to the launch pad - with its Grasshopper rocket, a bid to develop a fully reusable vertical take-off and vertical landing launch vehicle.
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SpaceX chief Elon Musk says Grasshopper is only the first in a series of projects that he hopes will result in 100% reusability for SpaceX vehicles. Speaking at the Royal Aeronautical Society in London in November ... Musk said he hoped to be bringing back the first stage from SpaceX flights "in the next year or two", and promised "soon" to unveil a new version of his Dragon cargo or crew capsule capable of landing vertically, on legs.
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Musk added that his full-reusability timetable was "five to six years", though he confessed that "could be famous last words". Moreover, he said to the RAeS gathering, he expected that as Grasshopper testing continues "there will be a few craters along the way".
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Musk's dream of total reusability promises much when it comes to transforming the economics of ordinary Earth orbit spaceflight. As Musk told the RAeS, the cost of a rocket today is only about 0.3% propellant, with the rest thrown away; in the case of a $60 million Falcon 9 launch, that's less than $200,000 for gas and a lot of money ending up in the sea.
There's more at the link. Recommended reading.
Here's a video clip of SpaceX's latest, 29-second-long test flight of the Grasshopper. It rose 131 feet into the air, hovered, and successfully touched down again on the pad it had just left. A small step, to be sure, but one that had never before been accomplished . . . and, one hopes, a stepping-stone to much greater achievements in future.
Go SpaceX, and thank you, Elon Musk! If you get this right, we'll all owe you an incalculable debt.
Peter
6 comments:
I can't help but wonder what will happen if they get a significant wind vector during landing... And whether the gimbels can overcome the inertial moment arm...
Actually, this has been done before. The DC-X project back in the '90s did this, but NASA (or at least the government) didn't follow up with further testing. I seem to recall the last landing was a bit rough and damaged the landing gear, but I don't think it was catastrophic.
DC-X was intended to be a test program designed to get enough information to develop a larger, single-stage-to-orbit launcher. I think the Shuttle budget was what killed it. Hopefully SpaceX will be able to develop it all the way.
131 feet into the air is kind of where the Wright brothers were. Now we just have to wait 200 years. . .
Single-stage-to-orbit turns out to be a very difficult design problem at best. Depending on specifics, at least 90% of liftoff weight must be fuel. Whatever is left gets divided up among structure, machinery, and payload. Not generally realized is that the majority of launch energy goes into transverse direction, parallel to Earth's surface. On re-entry, that energy comes back out of the vehicle, and if you want a powered landing, the landing fuel counts as part of the orbital payload. It's a really tough problem, and much more practical to leave a trail of used rocket parts. Gravity is a harsh mistress too.
DC-x flew multiple times for its builders, who then turned it over to NASA for further testing. One of NASA's technicians failed to hook up the hydraulic line for one of the landing legs and the DC-X tipped over after landing and was totally destroyed. Go NASA!
Yes , SSTO is hard, but staging is fine if you can recover the various stages. Space-X tried to recover stage 1 of the Falcon 9 without success, but I'll bet they keep trying until it works. and then costs will really drop. The idea is to run it like and airline, not artillery.
Why does it have to be single-stage-to-orbit? Why can it not, at least for now, be a two-stage affair akin to the 1930s Short Brothers Mercury-Maia aircraft?
We'd certainly not be traveling much by air if 80% of the airplane was scrap after a single flight.
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