Space Station Computer Glitch May Require Spacewalk Fix, Delay Cargo Ship Launch

International Space Station as seen from NASA space shuttle.
This image from a NASA space shuttle mission shows the International Space Station in orbit. The space station is the size of a football field and home to six astronauts. Image taken: Feb. 10, 2010. (Image credit: NASA)

NASA is studying a glitch with a backup computer on the International Space Station, an issue that could potentially force astronauts to perform a spacewalk repair and delay the planned Monday launch of a SpaceX cargo ship.

Space station officials announced the glitch late Friday (April 11) after confirming that a backup computer on the space station's exterior was not responding to commands. The computer, known in NASA parlance as a Multiplexer-Demultiplexer, is a backup controller for some robotics systems on the space station.

"The computer outage does not pose a risk to the six crew members aboard the space station," NASA officials wrote in a statement. "ISS [International Space Station] teams are assessing next steps to attempt to bring the computer back online or replace it."

The private spaceflight company SpaceX prepares its unmanned Dragon cargo ship to launch to the International Space Station on its third official supply delivery mission for NASA. (Image credit: SpaceX)

Any plan to replace the backup computer would require a spacewalk by astronauts, NASA officials added. Meanwhile, the primary computer in the affected system is working normally.

The glitch comes three days ahead of the planned launch of a Dragon cargo ship by the private spaceflight company SpaceX on Monday (April 14). The Dragon spacecraft is due to launch from Cape Canaveral Air Force Station in Florida atop a Falcon 9 rocket. It is packed with nearly 5,000 lbs. (2,268 kilograms) of supplies for the station's crew, but can only be captured by the space station's robotic arm.

"The backup [computer] would provide redundancy for robotic systems that will be needed to attach the SpaceX Dragon spacecraft currently scheduled to launch on Monday and rendezvous with the ISS on Wednesday," NASA officials wrote in a statement. "NASA is continuing to work toward a Monday launch.

SpaceX's Dragon launch has already been delayed nearly a month due to unrelated damage to a ground-based tracking radar system used by the Florida launch site that has since been repaired.

Another company, the Dulles, Va.-based Orbital Sciences Corp., has a $1.9 billion contract with NASA for eight cargo missions using its own unmanned Antares rockets and Cygnus spacecraft. The first official Cygnus cargo mission launched in January, with the next one slated for June.

Email Tariq Malik at or follow him @tariqjmalik and Google+. Follow us @Spacedotcom, Facebook and Google+. Original article on

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at:

Tariq Malik

Tariq is the Editor-in-Chief of and joined the team in 2001, first as an intern and staff writer, and later as an editor. He covers human spaceflight, exploration and space science, as well as skywatching and entertainment. He became's Managing Editor in 2009 and Editor-in-Chief in 2019. Before joining, Tariq was a staff reporter for The Los Angeles Times covering education and city beats in La Habra, Fullerton and Huntington Beach. In October 2022, Tariq received the Harry Kolcum Award for excellence in space reporting from the National Space Club Florida Committee. He is also an Eagle Scout (yes, he has the Space Exploration merit badge) and went to Space Camp four times as a kid and a fifth time as an adult. He has journalism degrees from the University of Southern California and New York University. You can find Tariq at and as the co-host to the This Week In Space podcast with space historian Rod Pyle on the TWiT network. To see his latest project, you can follow Tariq on Twitter @tariqjmalik.