Scientists lost contact with the Voyager 1 interstellar probe from Oct. 19 to Oct. 24 after a technical malfunction forced the spacecraft’s main radio transmitter to shut down, NASA officials wrote. Engineers have since contacted Voyager 1’s weaker backup transmitter, which had not been used since 1981, while assessing the situation.

“The transmitter shutdown appears to be caused by the spacecraft’s onboard failsafe system, which responds autonomously to problems,” NASA officials wrote in a blog post. “For example, if the spacecraft overloads its power supply, fault protection will save power by shutting down systems not required to maintain the spacecraft’s flight, including the spacecraft’s main radio transmitter,” the team added.

Once the connection is re-established, it may take a few more days or weeks for the underlying problem to be detected.

Interstellar IT

Communicating with Voyager 1 and its twin spacecraft, Voyager 2, is not easy. Currently more than 15 billion miles (24 billion kilometers) from Earth, Voyager 1 is the most distant human-made object in the universe. It takes 23 hours for commands sent from Earth to reach the spacecraft at its current location outside the solar system, and it takes another 23 hours for responses from Voyager 1 to return to Earth.

According to NASA, the current communications error began on October 16, when engineers sent Voyager 1 a command to turn on one of its heaters. While the spacecraft should have had enough power to carry out this command, the command instead triggered Voyager 1’s fail-safe system.

Two days later, when NASA engineers searched for Voyager 1’s answer using the Deep Space Network, a worldwide network of radio antennas used to support interplanetary missions, they were unable to detect a signal from the spacecraft. Later that day, the team finally found Voyager 1’s signal. However, according to NASA, communication with Voyager appears to have been completely lost the next day (October 19).