A previously-used Falcon 9 booster soared to life at California’s Vandenberg Air Force Base on Sunday for its Static Fire test ahead of lifting the fifth set of Iridium-NEXT communications satellites on Thursday, marking the start of a string of Falcon 9 missions lined up for March and April. Liftoff is targeting 14:19 UTC on March 29 to boost the number of Iridium-NEXT satellites in orbit to 50 as the Virginia-based communications company continues pushing toward having the full Iridium-NEXT constellation in operation by the end of summer.

Sunday’s Static Fire test occurred near the opening of the day’s test window at 7 a.m. and was expected to run for seven seconds to exercise the nine previously-flown Merlin 1D engines of Booster 1041, gearing up for its second Low Earth Orbit mission. The booster was first in action for the third Iridium-NEXT mission in October 2017 and successfully returned via a Drone Ship landing in the Pacific Ocean as SpaceX has yet to conduct its first return-to-launch-site recovery from Vandenberg.