NASA lost direct contact with the International Space Station Tuesday due to equipment failure, leaving the orbiting laboratory dependent on Russian ground stations for communications with Earth, space agency officials say.

The communications loss occurred at 9:45 a.m. EST (1445 GMT) as flight controllers at NASA's Mission Control at the Johnson Space Center in Houston were sending a software update to the space station.

A main data relay system malfunctioned, and the computer that controls the station's critical functions switched to a backup, NASA officials said in a statement. However, the station was still unable to communicate with the Tracking and Data Relay satellite network that serves as the outpost's link to NASA's Mission Control center on the ground.

All six space station astronauts are in good health, and NASA has reestablished a connection with the station, NASA officials said. The space station is currently home to three Russians, two Americans and a Canadian astronaut.

"Mission Control Houston was able to communicate with the crew as the space station flew over Russian ground stations before 11:00 a.m. EST and instructed the crew to connect a backup computer to begin the process of restoring communications," NASA officials explained. "Expedition 34 Commander Kevin Ford reported that the station’s status was fine and that the crew was doing well."