NASA Successfully Fires Rocket Engine Designed for Deep Space Missions

— -- NASA said it has cleared a milestone in the path to ushering in the next era of human space exploration after successfully firing one of its rocket engines intended for use in deep space missions.

The space agency fired an RS-25 rocket engine for 500 seconds on Thursday.

The engine is one of four powering NASA's Space Launch System, which will provide a combined 2 million pounds of thrust, eventually launching humans on long-haul missions to an asteroid and to Mars sometime in the 2030s, according to NASA.

"We have exciting days ahead with a return to deep space and a journey to Mars, and this test is a very big step in that direction," Rick Gilbrech, director of NASA's Stennis Space Center, said in a statement.

While the engines used for the Space Launch System will be carrying astronauts on deep space journeys NASA has dreamed about for decades, here's the kicker: The engines are actually leftover from the space shuttle program.

NASA and Aerojet Rocketdyne, the contractor for work on the RS-25, ran several tests on the rocket engine last year, focusing on testing the controller "brain" of the engine and to test out different operating conditions, according to NASA.

Aerojet Rocketdyne and NASA plan to continue working together at the Stennis Space Center to carry out further engine tests, NASA said. The first flight for the Space Launch System is expected to happen no later than November 2018.