The picture perfect docking of the SpaceX Dragon capsule to the International Space Station (ISS) on March 3 and the triumphant ocean splashdown last week on March 26 nearly weren’t to be – and it all goes back to a microscopic manufacturing mistake in the oxidizer tank check valves that no one noticed long before the vessel ever took flight.
Barely 11 minutes after I witnessed the spectacular March 1 blastoff of the Dragon atop the SpaceX Falcon 9 rocket from Cape Canaveral, Florida, everyone’s glee suddenly turned to disbelief and gloom with the alarming news from SpaceX Mission Control that contact had been lost.
Applying the space version of the Heimlich maneuver turned out to be the key. But if you can’t talk to the patient – all is lost.
Right after spacecraft separation in low Earth orbit, a sudden and unexpected failure of the Dragon’s critical thrust pods had prevented three out of four from initializing and firing. The oxidizer pressure was low in three tanks. And the propulsion system is required to orient the craft for two way communication and to propel the Dragon to the orbiting lab complex.
So at first the outlook for the $133 million Dragon CRS-2 cargo resupply mission to the ISS appeared dire.
“The problem was a very tiny change to the check valves that serve the oxidizer tanks on Dragon.” Musk told Universe Today
“Three of the check valves were actually different from the prior check valves that had flown – in a very tiny way. Because of the tiny change they got stuck.”
SpaceX engineers worked frantically to troubleshoot the thruster issues in an urgent bid to overcome the serious glitch and bring the crucial propulsion systems back on line.
“What we did was we were able to write some new software in real time and upload that to Dragon to build pressure upstream of the check valves and then released that pressure- to give it a kind of a kick, ” Musk told me at a NASA media briefing.
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