Watch NASA Test-Fire Its Heavy-Duty Mars Rocket

NASA is betting on its heavy-lifting rocket, the Space Launch System (SLS), to carry astronauts to Mars in the 2030s. But first they need to make sure it can get off the ground.

At 10:05AM Eastern Time on Tuesday, the space agency will fire up the SLS’s main booster for two minutes to see how it performs when its propellant is cold. (Although it’s hot in the Utah desert, where the stationary ground test will take place, the fuel will be cooled to about 40 degrees Fahrenheit.)

This will be NASA’s second time test-firing the booster. The first, in March 2015, tested how the propellant fared at the higher end of its temperature range, at 90 degrees Fahrenheit.

Tuesday’s test will be the last before the rocket’s first real test flight in 2018, which will launch an uncrewed Orion capsule into lunar orbit.

Live coverage of the test begins at 9:30am Eastern.