The Voyager 1 spacecraft has resumed normal operation after a pause in communication with Earth. It was caused by the shutdown of its main radio transmitter.
Voyager 1 was launched in 1977, and during its years of flight it has traveled nearly 25 billion kilometers away from Earth. This is the most distant object in the Universe made by human hands. The vehicle is gradually approaching the end of its life cycle. Every year, its radioisotope generator produces less and less power, forcing engineers to find various clever ways to conserve it by shutting down various auxiliary systems as well as manipulating heaters.
On October 16, the mission team sent a command to the vehicle to turn on one of the heaters. Although Voyager 1 should have had enough power to execute it, the command triggered the fault protection system. This caused the probe to suddenly turn off its primary X-band radio transmitter, and turn on a much weaker S-band transmitter that was last used in 1981. Because of the spacecraft’s distance from Earth (it is 24.9 billion kilometers away), this shutdown prevented the mission team from downloading scientific data and information about the spacecraft’s engineering status.
Engineers say the fault protection system is programmed to automatically shut down systems that are not essential to keeping Voyager 1 running in order to preserve power to critical systems. The problem is that the probe has shut down all non-essential systems except the instruments a long time ago. Engineers even turned off the heaters for some of the scientific instruments. Surprisingly, they continue to work despite temperatures below what they were tested at.
The team has computer models developed to predict how much energy different systems, such as heaters and appliances, should consume. However, the uncertainty in these models is due to a number of factors, including the age of the components and the fact that equipment does not always behave as expected. This is what caused the system to shut down the main Voyager 1 transmitter.
In early November, the mission team again managed to turn on the X-band transmitter, and from November 18, the spacecraft resumed collecting data from four working scientific instruments. Engineers also calibrated the method used to measure the voltage level on both probes to avoid a repeat of this situation in the future.
We previously covered how NASA had to shut down one of Voyager 2’s science instruments to extend its life.
Provided by NASA
