The International Space Station regained contact with Nasa controllers in Houston after nearly three hours of accidental quiet, the space agency says.
Officials say the six crew members and station are fine and had no problem during the brief outage.
Nasa spokesman Josh Byerly said something went wrong about 9.45am EST today, (3.45am, NZT), during a computer software update on the station. The outpost abruptly lost all communication, voice and command from Houston.
Communication was restored less than three hours later, Byerly said
"We've got our command and control back," he said.
Station commander Kevin Ford was able to briefly radio Moscow while the station was flying over Russia.
Normally, Nasa communicates with and sends commands to the station from Houston, via three communications satellites that transmit voice, video and data. Such interruptions have happened a few times in the past, the space agency said.
If there is no crisis going on, losing communication with the ground "is not a terrible thing", said former astronaut Jerry Linenger, who was on the Russian space station Mir during a dangerous fire in 1997. "You feel pretty confident up there that you can handle it. You're flying the spacecraft."
Not only should this boost the confidence of the station crew, it's good training for any eventual mission to Mars because there will be times when communications is down or difficult during the much farther voyage, Linenger said.
In the past few weeks the space station had been purposely simulating communications delays and downtimes to see how activity could work for a future Mars mission, Byerly said. This was not part of those tests, but may prove useful, he said.