On 14 September 2011, NASA revealed the design of its new rocket, the Space Launch System. This titanic vehicle may send American astronauts to the Moon, Near Earth Asteroids or even further into deep space.
The SLS is intended to carry NASA’s proposed new crewed spacecraft, the Multi-Purpose Crew Vehicle (MCPV, née Orion CEV) into space. Central to the SLS concept are two liquid-fuelled rocket stages. The first stage is 8.4m wide, exactly the same width as the Space Shuttle’s External Tank. Like the Shuttle two large solid fuel boosters are attached to the sides (in fact these are identical to the Shuttle’s SRBs, the idea is to save development costs by reusing as much Shuttle technology as is feasible) . Initially the first stage has three Space Shuttle Main Engines, but this will be increased to five – ensuring a truly awesome spectacle at launch. (Scott Lowther at the Up-Ship blog has pointed that no new Space Shuttle Main Engines will be built for the SLS, it will use examples looted from museums!) The upper stage will use the J-2X, a modernised version of a rocket engine used in the classic Saturn series.
When introduced in 2017 (a date sure to slip), the SLS should be able to place 70 tonnes into Low Earth Orbit. It is planned to increase this to 130 tonnes eventually, making it the most powerful rocket ever built.
So what is this astonishing vehicle for? Bizarrely enough, the answer is no one knows. The SLS is a solution looking for a problem. It is way too large to support the ISS and anyway the feeling in the US is that supplying the space station is trivial and tedious enough to be left to foreigners and the private enterprise johnnies. If there was a program to return to the Moon, explore the asteroids or ultimately visit Mars the SLS would be very useful- but there are no such programs. True, there are vague and sketchy ideas for these adventures, but NASA has no budget to afford them and there is little sign that it will any time soon. To outside observers, development of the SLS is a Soviet Five Year Plan-style politically-mandated project aimed to prevent catastrophic job losses in areas where Shuttle components were made (I thoroughly approve of helping to save the jobs of people who actually make things, but is this the right way to do it?)
Don’t get me wrong, giant rockets are very cool and I want to see humanity expanding across the Solar System, but this seems an odd way to go about it. I hope history will prove me wrong (like if in 500 years time 14 September is celebrated across the Solar Federation as SLS Day).