CAPE CANAVERAL, Fla. — A Space Exploration Technologies (SpaceX) Dragon cargo capsule forfeited its scheduled March 2 docking at the international space station after problems with the spacecraft’s thruster rocket pods surfaced minutes after launch on March 1.
At press time, the company was hopeful it would be able to save the mission, and deliver more than 1,000 kilograms of science equipment, spare parts, food and supplies to the six-member station crew.
The 48-metertall rocket blasted off on schedule at 10:10 a.m. EST from Cape Canaveral Air Force Station here and successfully delivered its Dragon capsule into orbit.
“Basically we put the vehicle where we wanted it to go,” SpaceX President Gwynne Shotwell told reporters.
About 12 minutes after launch, however, when the Dragon’s solar wing panels were due to unfurl, onboard cameras showed no activity.
On a Twitter post, company founder and chief executive Elon Musk reported an initialization problem with three of Dragon’s four thruster pods. NASA flight safety rules require at least three pods to be working for the spacecraft to approach the station.
Preliminary analysis indicated a possible blockage in the pressurization system or a stuck valve, he added.
Dragon has 18 thrusters in total, packed into pods of either four or five thrusters.
During a conference call five hours after the launch, Musk told reporters two working thruster pods would provide sufficient power to raise Dragon’s orbit and keep it from plunging back to Earth. Shortly after the call, Musk again turned to Twitter to report that all four thruster pods were operating normally.
Musk told reporters Dragon could conceivably remain on orbit for months. “We wouldn’t keep it up there that long, but I think we would keep it up there at least a month, trying to sort out any issues and get everyone comfortable with an approach to the space station,” Musk said.
NASA’s top human spaceflight official, meanwhile, praised the SpaceX team for displaying grace under pressure after Dragon’s propulsion anomaly.
“They did everything right,” William Gerstenmaier, NASA associate administrator for human exploration and operations, said during the conference call. “They did a phenomenal job of pulling that all together. They showed the patience that it takes to operate in space, to not give up.”
The mission is the second of 12 for SpaceX under a $1.6 billion NASA contract.
A second space freighter, built by Dulles, Va.-based Orbital Sciences Corp. is expected to debut this year.
Preparations for SpaceX’s second Commercial Resupply Services (CRS) mission had included extensive troubleshooting, analysis and testing to determine why a Falcon engine shut down early during launch of CRS-1 in October.
“There was a material flaw that went undetected in the jacket of the Merlin engine, resulting in a breach … causing depressurization of the combustion chamber,” Shotwell told reporters during a prelaunch press conference Feb. 28.
“The flight computer recognized that depressurization and then it commanded shutdown,” Shotwell said.
The Falcon’s eight other engines compensated for the loss of power and the Dragon capsule successfully reached the station. The situation, however, triggered a contract stipulation with NASA that barred SpaceX from restarting the engine, leaving an experimental Orbcomm satellite flying as a secondary payload in a lower-than-intended orbit.
“This vehicle has been designed to accommodate an engine-out. Though you never necessarily want to see it happen, it’s nice that we demonstrated the vehicle as it was designed,” Shotwell said.
She declined to provide details about the material flaw, citing an ongoing U.S. State Department review of SpaceX’s report for export-controlled technical details that would be illegal for the company to publicly release.
“I don’t look good in horizontal stripes,” Shotwell quipped.
“The conclusions they came to, we agree with,” added NASA space station program manager Mike Suffredini.
“Our role as NASA is to sit next to them and work with them and understand the anomaly so that we’re comfortable. We have two options as the customer: We can either put our hardware on that vehicle or not.”
SpaceNews Staff Writer Dan Leone contributed to this story from Washington.
