Voyager 2 was launched back in 1977 not long after the launch of Voyager 1. Both of the spacecraft are in interstellar space, making them the most distant human-made objects from Earth in history. Voyager 2 has encountered a problem, and its fault protection routine has been triggered.
The fault protection routine was programmed into the spacecraft, so it could automatically take action to protect itself if harmful circumstances arise. NASA engineers are still communicating with Voyager 2 and receiving telemetry data from the spacecraft. The team is working on returning the spacecraft to normal operating conditions now.
NASA says that on January 25, Voyager 2 didn’t execute a scheduled maneuver where it rotates 360 degrees to calibrate the onboard magnetic field instrument. Telemetry analysis indicated that the unexpected delay in completing the maneuver left two high electrical drain instruments operating at the same time.
That caused the spacecraft to overdraw its power supply. A fault protection routine designed for such an event triggered and turned off one of the high-power systems. The routine also turned the science instruments back on, but they haven’t resumed tracking data. NASA is reviewing the status of the rest of the spacecraft and working to return it to normal operations.
Over the years since the spacecraft launched, it has lost about 4 watts of power per year. Its power comes from a radioisotope thermoelectric generator (RTG) that turns heat into electricity. The natural decay inside the RTG is why the power level drops each year. Progress is slow as it takes 17 hours for communications to travel to the spacecraft and another 17 hours for it to return, even at the speed of light. It’s impressive that using spacecraft using such old technology continue to operate.