NASA Officially Announces the Space Launch System

Last Wednesday NASA officials publicly unveiled the Space Launch System, the new heavy lift rocket that will send astronauts beyond earth orbit, to asteroids, the moon and possibly some day to Mars. As I mentioned in an earlier post, the design has been known for a few months now, but for various political reasons, the project hadn't been officially announced yet.

It looks like the only difference with what had been shown before is the black and white color scheme for the core stage, but according to sources at NASA, this is only for publicity purposes, the actual rocket will sport the usual orange color, like the space shuttle. (the orange color is actually the color of the sprayed-on thermal insulation foam. Any white and black paint on top of that is deemed unnecessary weight and has been dispensed with on all shuttle flights since 1981).

The current plan is to have several variants of the rocket, capable of carrying from 70 mt (metric tonnes) to 130 mt to Low Earth Orbit. Some will carry 4 astronauts astronauts on the Orion Multi-Purpose Crew Vehicle (MPCV) while others will only carry cargo. For comparison, the Space Shuttle only carried ~25 mt of cargo to orbit, and the Saturn V from the Apollo moon program of the 70's carried 120 mt.

The rocket will use two 5-segment Solid Rocket Boosters (SRB) with 3.6 Millions pounds of thrust each, a 30% improvement over the Space Shuttle's 4-segment boosters. The core stage will be a modified 8.4 meter Space Shuttle External Tank fitted with 3 or 5 RD-25 D/E engines (the same engines as the Space Shuttle). The first two flights will actually use engines scavenged from the retired Space Shuttle fleet, with Atlantis's engines used on the first flight, and Endeavour's used on the second flight. After that, they will use RD-25E's, an expendable (and cheaper) version of the RD-25D.

In the long run (think 2020's), the SRBs might be replaced by liquid-fueled boosters.

The first flight of the basic version of the SLS with take place in 2017 and will take an unmanned Orion on a trip around the moon. The first manned flight is scheduled for no later than 2021, but it is hoped that if everything goes well and funding is available it would happen earlier. That mission would involve sending 4 astronauts around the moon (no landing). After that, NASA plans to use the rocket to send Astronauts on a 5 month trip to a Near-Earth Asteroid.

NasaSpaceflight.com has a great article about the technical specs of the SLS, as well as its scheduled missions.