Third time not the charm for SpaceX with launch abort
The nine main engines at the base of a SpaceX Falcon 9 rocket ignited and began throttling up for launch Sunday evening when a low-thrust alarm triggered a computer-commanded shutdown, a dramatic conclusion to the company's third attempt in a row to launch a powerful SES communications satellite.
Already running four days late because of a temperature-related propellant issues that grounded the rocket last Wednesday and Thursday, the countdown made it to the T-minus one-minute 33-second mark Sunday when a hold was ordered because of a wayward ship in the off-shore launch danger zone.
That issue cleared up and launch, originally planned for 6:47 p.m. EST (GMT-5), was re-targeted for 7:21 p.m. This time around, the countdown made it to zero and the engines began igniting with a rush of fiery exhaust and unexpectedly shut down. Engineers quickly began "safing" the vehicle, depressurizing the propellant tanks and making sure the rocket remained in a stable configuration.
After spending a few minutes troubleshooting the issue in hopes of making another launch try before the 94-minute launch window closed, mission managers ordered the flight scrubbed for the day pending additional analysis.
"Launch aborted on low thrust alarm," SpaceX founder Elon Musk tweeted a few moments after the engine shutdown. "Rising oxygen temps due to hold for boat and helium bubble triggered alarm."
Oxygen temperatures are critical for this version of the Falcon 9 rocket. It is only the second booster upgraded by SpaceX to utilize super-cooled, "densified," propellants that allow the rocket to carry more RP-1 kerosene fuel and liquid oxygen propellant.
The upgraded rocket is critical to SpaceX's long-range plans and the booster successfully flew last December. But a launch attempt for the SES-9 satellite on Wednesday was called off before fueling began because of liquid oxygen temperature issues and another scrub was ordered the next day because of problems completing propellant loading.
It is not yet known when SpaceX will make a fourth attempt to launch the powerful SES-9 communications satellite. The relay station, which will provide video and data services across the south Asia-Pacific region, is the first of three comsats SES hopes to launch aboard SpaceX rockets this year.