SpaceX is preparing to launch its Falcon Heavy rocket for the first time in more than 18 months, kicking off what could be a busy time for the vehicle. The mission will loft the ViaSat-3 F3 communications satellite into geostationary orbit. Liftoff is scheduled during an 85-minute window opening at 1421 UTC today, with a backup opportunity on April 28 at 1417 UTC. The last Falcon Heavy mission launched the Europa Clipper in October 2024, and the entire Falcon Heavy system was expended. This time, SpaceX plans to recover both side boosters, landing them simultaneously at Landing Zones 2 and 40 at Cape Canaveral. Both side boosters are veterans: one has flown on 18 Starlink missions, the other on the GOES-U Falcon Heavy mission in June 2024. Today's assignment marks the start of a high-activity period for SpaceX's heavy lifter. If all goes to plan, a Falcon Heavy will send Astrobotic's Griffin-1 uncrewed lander to the Moon in July, and the Nancy Grace Roman Space Telescope could launch as soon as September .…