Kennedy Space Center – Barely 11 minutes after the spectacular Friday morning, March 1 launch of the SpaceX Falcon 9 rocket and unmanned Dragon capsule bound for the International Space Station (ISS), absolute glee suddenly threatened to turn to total gloom when the mission suffered an unexpected failure in the critical propulsion system required to propel the Dragon to the Earth orbiting outpost.
For several hours the outlook for the $133 million mission appeared dire, but gradually began to improve a few hours after launch.
“It was a little frightening, ” said SpaceX CEO Elon Musk at a Friday afternoon media briefing for reporters gathered at the Kennedy Space Center, commenting on the moments after the glitch appeared out of nowhere.
The situation progressed onto the road to recovery after SpaceX engineers immediately sprang into action and frantically worked to troubleshoot the thruster problems in an urgent bid to try and bring the crucial propulsion systems back on line and revive the mission.
By late Saturday afternoon sufficient recovery work had been accomplished to warrant NASA, ISS and SpaceX managers to give the go-ahead for the Dragon to rendezvous with the station early Sunday morning, March 3.
“The station’s Mission Management Team unanimously agreed that Dragon’s propulsion system is operating normally along with its other systems and ready to support the rendezvous two days after Friday’s launch on a Falcon 9 rocket from the Cape Canaveral Air Force Station in Florida, ” NASA announced in a statement on Saturday, March 2.
A failure to ignite the thrusters within 1 or 2 days would have resulted in unacceptable orbital decay and a quick and unplanned fiery reentry into the earth’s atmosphere, said Musk.
Reentry would cause a total loss of the mission – carrying more than a ton of vital supplies, science gear, research experiments, spare parts, food, water and provisions to orbit for the stations six man crew.
Shortly after the Dragon achieved orbit and separated from the second stage, the solar arrays failed to deploy and the live webcast stopped prematurely.
During the course of the Friday afternoon briefing, Musk and NASA officials received continuous updates indicating the situating was changing and slowly improving.
Musk confirmed that SpaceX was able to bring all four of Dragon’s thruster pods back up and running. Engineers were able to identify and correct the issue, normalizing the pressure in the oxidation tanks.
The problem may have been caused by stuck valves or frozen oxidizer in the lines. Dragon has four oxidizer tanks and four fuel tanks.
“We think there may have been a blockage of some kind or stuck check valves going from the helium pressure tank to the oxidizer tank, ” Musk hypothesized. “Whatever that blockage is seems to have alleviated.”
Three of the four thruster pods must be active before the Dragon would be permitted to dock, said Mike Suffredini, NASA program manager for the ISS. There are a total of 18 Draco thrusters.
NASA's Commercial Orbital Transportation Services: A New Era in Spaceflight - History of International Space Station (ISS) Cargo and Crew, SpaceX, Orbital Sciences, Bigelow
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