SpaceX has confirmed that second stage fueling is now underway for the Falcon Heavy rocket, carrying NASA’s Nancy Grace Roman Space Telescope spacecraft from NASA’s Kennedy Space Center in Florida.

Falcon Heavy uses the same second stage and same payload fairings that are flown on Falcon 9.

Falcon Heavy’s first stage consists of three Falcon 9 derived cores, each powered by nine Merlin engines. Together, these 27 engines will lift the Roman spacecraft off the pad. After the side boosters and center core separate, the second stage, driven by a single Merlin Vacuum engine, will continue accelerating Roman toward its destination.

The Merlin engines use RP-1 and liquid oxygen as rocket propellants in a gas-generator power cycle. The two side boosters supporting this mission have different flight histories: one is making its first flight, while the other has supported two previous missions, GOES-U ((Geostationary Operational Environmental Satellite U) and Viasat-3 F3. SpaceX plans to recover both side boosters after today’s launch.

In about 17 minutes, second-stage liquid oxygen loading is scheduled to begin. Engine chill will begin at seven minutes before liftoff.

Launch remains on track for liftoff no earlier than 7:26 a.m. EDT from Launch Complex 39A.

Source: NASA