Update: NASA says glitch delays SpaceX Dragon linkup with space station

Computerworld - After a successful liftoff of the SpaceX Dragon on Friday, the company's engineers were working on a glitch in the spacecraft's thruster system, delaying a Saturday rendezvous with the International Space Station.

NASA reported earlier Friday that three of the Dragon spacecraft's four thruster pods were not working. The problem is caused by a malfunctioning propellant valve.

At 3:30 p.m. ET, the space agency said that while a second thruster pod was brought online, the Dragon spacecraft won't be able to link up with the space station on Saturday as had been planned.

Engineers are working to get two still-malfunctioning thrusters up and running. The spacecraft needs at least three thrusters working to be able to make a series of burns needed to rendezvous with the space station.

The thruster pods enable maneuvering and altitude control.

Shortly after Dragon reached orbit, SpaceX founder and CEO Elon Musk reported on Twitter that there was a problem with the Dragon spacecraft's thruster pods, delaying the deployment of the craft's solar array, which powers it.

"Issue with Dragon thruster pods. System inhibiting three of four from initializing. About to command inhibit override," Musk tweeted. "Holding on solar array deployment until at least two thruster pods are active."

At approximately 11:50 a.m. ET, the Dragon's solar arrays were successfully deployed.

The SpaceX Falcon 9 rocket, carrying the unmanned Dragon capsule, lifted off from Cape Canaveral Air Force Station in Florida at 10:10 a.m. ET today. The spacecraft, was scheduled to rendezvous with the space station on Saturday, ferrying 1,268 pounds of scientific experiments and supplies for the space station crew to the orbiter.

Using a robotic arm onboard the space station, two astronauts are set to grab hold of the Dragon capsule and attach it to the station. The capsule will stay attached for about three weeks, returning to Earth on March 25.

Today's launch is the second of 12 SpaceX flights contracted by NASA to resupply the space station. It also will be the third trip by a Dragon capsule to the orbiting laboratory.

After SpaceX made a demonstration flight in May 2012, it then launched the first official resupply mission last October, delivering 882 pounds of supplies.

Another successful commercial launch is an important milestone for NASA, which now depends on commercial flights since retiring the agency's fleet of space shuttles in the summer of 2011. For the foreseeable future, NASA will need commercial missions to ferry supplies, and possibly even astronauts, to the space station, while the space agency focuses on developing robotics and big engines in preparation for missions to the moon, asteroids and Mars.

Sharon Gaudin covers the Internet and Web 2.0, emerging technologies, and desktop and laptop chips for Computerworld. Follow Sharon on Twitter at @sgaudin, on Google+ or subscribe to Sharon's RSS feed . Her email address is sgaudin@computerworld.com.

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