NASA restored its communication link with the International Space Station on Tuesday, hours after it was knocked out by a glitch encountered during a computer software upgrade.
Josh Byerly, a spokesman for NASA's Johnson Space Center, told NBC News that the link was restored at 12:34 p.m. ET.
The outage began at about 9:45 a.m. ET, during a planned upgrade for the custom-coded software that NASA uses for command and control as well as voice and data communication with the space station, via the Tracking and Data Relay Satellite system, or TDRS. When the system switched from the primary computer to a backup computer, communications were lost immediately, Byerly said.
During the outage, the station's crew had to rely on Russian ground stations for communications. Those ground stations are in range only when the station is flying overhead, roughly every 90 minutes. "It's just like back in the old days, during Gemini," Byerly said. "We still need those antennas from time to time."
Byerly said NASA astronaut Kevin Ford, the station's commander, received instructions for resetting the computers during the Russian communication passes.
Similar software upgrade problems have occurred before, Byerly said, and engineers are looking into the specific causes for Tuesday's glitch. "It is a problem, but the crew was not in danger," he told NBC News.
More about space station operations:
Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.