Voyager 1 sent a signal to Earth through a transmitter that had not been turned on since 1981

Due to problems with the main radio transmitter, the Voyager 1 spacecraft sent a signal to Earth through an auxiliary module that had not been launched since 1981. The portal Space.com reports this with reference to a statement from the American aerospace agency NASA.

Image source: NASA

In mid-October, the interstellar research vehicle encountered problems with its main communications equipment, after which it was automatically transferred to a safe operating mode to save energy. The problem was discovered after a signal was sent via the Deep Space Network (DSN) on October 16 to the vehicle to turn on one of its heaters, and the mission team did not receive a response to this command on October 18.

After sending new instructions to Voyager 1 on October 16, the mission team expected to receive a return signal with data from the device over the next couple of days. Typically, transmitting a signal to a probe located more than 24 billion km from Earth takes about 23 hours. The same amount is required for the device to transmit a signal to Earth. However, on October 18, the mission team did not detect a signal from Voyager 1 on the X-band frequencies using the DSN antennas. This happened due to the fact that the X-band signal turned out to be of less power, since the emergency failure protection system reduced it at the main transmission. The mission team still managed to later receive a signal from the probe, but on October 19, communication with Voyager 1 was completely lost because the probe completely turned off the X-band signal transmitter.

Mission engineers believe that after this failure, the craft’s emergency protection system was activated several more times, which ultimately led to the probe switching to an auxiliary signal transmitter operating in the S-band frequencies. The latter has not been used by the probe since 1981. Considering the fact that Voyager 1 is now much further from Earth than it was 43 years ago, the mission team feared that the signal from Earth would simply not reach the S-transmitter of the device, since the transmitter itself and its antenna use much less power than the X transmitter. However, mission specialists also did not want to risk sending a signal to the X-band transmitter, which could potentially lead to another activation of Voyager 1’s emergency failure protection system. As a result, the signal from Earth on October 22 was sent precisely to the S-transmitter. Two days later, on October 24, the mission team was finally able to restore the communication channel with the probe.

«The shutdown of the [main] transmitter appears to have been caused by an emergency failsafe system, which autonomously resolves problems that the device may encounter. The team is now gathering all available information that can help determine the source of the problem and return Voyager 1 to normal operation,” NASA said in a statement.

Activation of Voyager 1’s emergency crash protection system can be caused by various reasons. One of them, for example, is the possible excessive energy consumption of the device. If this happens, the probe automatically turns off non-key systems to save energy.

Mission engineers are now trying to determine what caused the vehicle’s defense system to activate, given that Voyager 1 should have had enough power to operate the heater. However, the NASA report notes that finding the source of the problem may take several weeks.