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NASA is funding private spaceflight in the form of the Commercial Crew Program, but that is not the extent of its space ambitions. The agency is also working on a proper long-term replacement for the Space Shuttle known as the Orion spacecraft. The launch vehicle for this vessel is the Space Launch System (SLS), and it’s going to be tested live Thursday, August 13th.

This will be the sixth of seven tests for the SLS RS-25 engine, which won’t actually be fitted on a rocket. It’s mounted on the same A-1 testing rig at NASA’s Stennis Space Center in southern Mississippi that was used for the Space Shuttle program. It’s simply been repurposed for SLS development. So the engine won’t actually be going anywhere, but that allows engineers to carefully monitor its performance close up. Additionally, this is just going to be a single engine test. The final SLS first-stage configuration calls for four RS-25 engines, making it the most powerful launch vehicle in the world.

NASA has fired the SLS engine for 44 minutes across the five previous tests, and Thursday’s test will add another 535 seconds to the total. This test will focus on exploring how the engine performs at different thrust levels, with the throttle being varied as low as 80%. Propellant flow and software performance will also be monitored closely during the test.

If all goes as planned with the sixth firing, there is only one more preliminary design test planned for the RS-25 engine. The next step after that will be to begin integrating the four final engines into the SLS core stage for a full rocket test. The vehicle will be moved to the larger B-2 stand at Stennis for a complete test firing before launch. NASA will also begin testing engines for use in the second SLS launch, an uncrewed mission to lunar orbit (Exploration Mission 1).

SLS and Orion have been pushed back several times, but now there’s near-final hardware for all the core components. The Orion capsule has already been successfully tested aboard an old Delta IV rocket and was recovered after landing. This will be a return to the older Apollo-style missions with a non-reusable launch system and parachute-assisted landings in the Pacific. NASA hopes to launch its first SLS flight no later than November of 2018.

The SLS has enough power to finally take manned spaceflight out of Earth’s orbit and enable missions to Mars or even outer solar system targets like Europa. Of course, there’s a lot more testing that needs to be done before we can safely send astronauts on a multi-year mission to such distant destinations. Whenever we’re ready, it’ll probably be the SLS powering the trip.

Tomorrow’s test will be streamed live starting at 4:30PM EDT on the NASA TV UStream channel. The actual test firing is expected to begin around 5PM.

Read more http://www.extremetech.com/extreme/212049-nasa-to-test-space-launch-system-rocket-engine-thursday-with-live-stream