SpaceX scrubs SES-9 launch again

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WASHINGTON — For the second night in a row, SpaceX postponed the launch of a Falcon 9 rocket carrying the SES-9 communications satellite Feb. 25, citing a last-minute problem with propellant loading.

SpaceX halted the countdown 1 minute and 41 seconds before the scheduled 6:47 p.m. Eastern liftoff of the rocket from Cape Canaveral, Florida. SpaceX manager John Insprucker, on the company’s webcast of the launch, said that launch controllers were “still evaluating” loading during the final minutes of the countdown and decided to stop the launch.

Although the launch window extended for more than 90 minute, Insprucker said that the timing of the hold, so close to the scheduled launch, meant that SpaceX had to call off the launch for the day. A new launch date has not been set, but Insprucker said it would likely be in a “couple of days or so.”

SpaceX previously scheduled the launch for Feb. 24, but postponed the launch more than a half-hour before the launch window opened. The company said in a later statement that it rescheduled the launch “out of an abundance of caution” in order to get the rocket’s liquid oxygen propellant as cold as possible.

The upgraded version of the Falcon 9 uses liquid oxygen cooled to near its freezing point, which increases its density. That is one of several changes SpaceX made to the Falcon 9 to increase the vehicle’s performance and thus its payload capacity. Those changes made it possible for the Falcon 9 to launch SES-9, which weighs about 5,300 kilograms at launch.

The launch attracted considerable attention because it marks the latest attempt by SpaceX to recover the Falcon 9’s first stage by landing it on a ship several hundred kilometers downrange from the launch site. However, the company had deemphasized that in the days leading up to launch, saying that a successful landing was not likely because of the “mission’s unique GTO [geostationary transfer orbit] profile.”

The launch is the second this year for SpaceX, after the Jan. 17 launch of the Jason-3 ocean science satellite on an older Falcon 9 v1.1 from Vandenberg Air Force Base in California. SpaceX President Gwynne Shotwell said Feb. 3 that after the SES-9 launch, the company planned to launch “every two to three weeks” to handle a backlog of commercial and NASA missions.

After this mission, the next Falcon 9 launch, a Dragon cargo mission to the International Space Station, is tentatively scheduled for early April, also from Cape Canaveral.