SpaceX launches SES-9 satellite


Updated 7:55 p.m. Eastern.

WASHINGTON — After a variety of problems delayed four previous launch attempts, a SpaceX Falcon 9 successfully launched the SES-9 communications satellite March 4, although an attempted landing of the rocket’s first stage on a ship was not successful, as expected.

The upgraded Falcon 9 lifted off at 6:35 p.m. Eastern from Cape Canaveral, Florida. The rocket released the SES-9 satellite into geostationary transfer orbit 31 minutes after liftoff.

The outcome of an attempt by SpaceX to land the rocket’s first stage on a ship about 600 kilometers downrange from the launch site was initally uncertain. Video from the ship was lost at the stage appeared to be approaching, and SpaceX ended its webcast coverage of the launch without providing an update on the status of the landing attempt. SpaceX Chief Executive Elon Musk later tweeted that the rocket “landed hard” on the ship.

While that attempted landing, part of SpaceX’s ongoing efforts to make the first stage reusable, garnered considerable attention, SpaceX had warned leading up to the mission that a successful landing was unlikely. “Given this mission’s unique GTO [geostationary transfer orbit] profile, a successful landing is not expected,” the company stated in the mission’s press kit.

“Didn’t expect this one to work,” Musk tweeted, citing high reentry speeds, “but next flight has a good chance.”

This was the fifth attempt to launch SES-9. SpaceX canceled the previous attempt March 1 several hours before the scheduled liftoff time, citing high upper level winds that would have acted like a “sledgehammer” on the rocket had it flown through them, according to Musk.

Three previous attempts were all delayed because of issues associated with the rocket’s use of “supercooled” liquid oxygen. The Feb. 28 launch attempt was aborted immediately after main engine ignition because of a low thrust alarm. Musk said that the liquid oxygen had warmed during a hold of more than half an hour in the countdown when a boat entered restricted waters offshore.

SES had waited even longer for this launch, as the mission was originally scheduled for launch last fall prior to the Falcon 9 launch failure in June 2015. The Boeing-built SES-9 will operate at 108.2 degrees east in geostationary orbit. The spacecraft’s 81 Ku-band transponders will provide communications services for parts of Asia, Australia and the Middle East.

The next Falcon 9 launch is tentatively scheduled for March 30, carrying a Dragon cargo spacecraft to the International Space Station. NASA officials said March 2 that an exact launch date for that mission would depend on when the SES-9 launch took place.