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The linchpin of NASA’s entire grand plan to reach Mars with a manned spacecraft by 2030 is the Space Launch System, the proposed most powerful rocket in the world. Without it, the Orion spacecraft that will carry astronauts to the red planet will never actually reach said red planet.
The critical pieces of the SLS have started to come into place, with two substantial steps forward with the actual propulsion behind the SLS – the RS-25 engine.
NASA has selected an engine building company in Sacramento, California, Aerojet Rocketdyne, to rebuild and modernize the RS-25 engine (previously used on space shuttles) for use on the SLS. The contract is worth $1.16 billion, with the modernization of 4 RS-25 engines with the option to build six more flight engines.
The first four missions of the SLS will use the refurbished engines, and will use a total of 16 engines from the scrapped shuttle program. The RS-25 will be tested in early 2016.