CRS-2: Dragon’s tantrum subdued following Falcon 9 launch

March 1, 2013 by William Graham and Chris Bergin

SpaceX conducted its tenth launch on Friday, sending the fourth Dragon spacecraft on a mission to resupply the International Space Station (ISS). The launch of CRS-2 (SpX-2) – which also marked the fifth flight of the Falcon 9 carrier rocket – occurred at 10:10 Eastern (15:10 UTC). However, a problem with the Dragon’s thrusters required mitigation.


The problem was noted after Dragon separation, with the anomaly reported at the point Solar Array deployment was expected.

This procedure was delayed due to a problem cited as with the Dragon’s thrusters, which failed to initiate as planned – claimed to be related to a propellant valve.

SpaceX controllers used ground stations to send commands to override the inhibits, with the goal of bringing at least two of the four thruster pods online. This was deemed to be successful, with SpaceX CEO Elon Musk using social media to confirm solar array deployment had been achieved.

However, L2 sources noted only one of the “quads” was working as of 17:00 UTC – around the point the coelliptic burn was scheduled. It was also noted Dragon was not in attitude control at the time. It was later revealed the array deployment was related to thermal conditions and the bonus effect of the arrays stablizing the vehicle’s attitude.

SpaceX and NASA issued a statement at 8pm UTC, confirming ISS rendezvous on Saturday was missed. Dragon will have other opportunities to hook up with the ISS, most likely on Sunday or Monday.

However, SpaceX did confirm they were back to two of the four thrusters, with the remaining two returning to life shortly afterwards. Three thruster pods are required for ISS rendezvous and berthing.

The root cause is still preliminary, but the initial data points to a stuck valve that was resolved by “jackhammering” it open and close to free it, or the potential of a blockage in the associated helium pressurization line.

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