One of the most distant man-made objects in the universe, NASA’s Voyager 2, has suffered a glitch that caused it to consume more power than expected. Launched in 1977, Voyager 2 has followed its sibling Voyager 1 out beyond the bounds of the solar system and into interstellar space.
The problem began on Saturday, January 25, when the Voyager 2 spacecraft was supposed to execute a scheduled rotation maneuver, in which it rolls over 360 degrees to calibrate its magnetic field instrument. But the craft didn’t perform the maneuver, and two systems remained powered on longer than they should have, consuming more power than was intended.
When the craft draws too much from its power supply, automated protections kick in to prevent its power being drained completely. These automated protections turn off non-essential functions, such as the scientific instruments, to preserve as much power as possible.
The problem is that this affects Voyager 2’s ability to perform its science functions, so the engineers are keen to get the craft back to full operations as soon as possible. They are making progress toward this goal, according to an update shared this week: “As of January 28, Voyager engineers have successfully turned off one of the high-power systems and turned the science instruments back on but have not yet resumed taking data,” NASA reported in a blog post. “The team is now reviewing the status of the rest of the spacecraft and working on returning it to normal operations.”
The power supply used by Voyager 2 is a type called a radioisotope thermoelectric generator, which uses the decay of radioactive fuel Plutonium-238 to produce heat which is then converted into electricity. As the Plutonium-238 decays over time, the power the craft can produce drops by approximately 4 watts per year, meaning the engineers have to be increasingly careful with how they budget the available power.
Another challenge for the engineers is the distance between Voyager 2 and Earth. The craft left the solar system in 2018, passing the edge of the heliosphere which marks the end of the sun’s influence on space. Since then it has been investigating the interstellar medium, the vast space between stars. It is now approximately 11.5 billion miles (18.5 billion kilometers) away from the planet, meaning that it takes 17 hours for communications from Earth to reach the craft and another 17 hours for the craft to send a response.
It is estimated that there will not be enough power for any instruments to run by 2025. So throughout the rest of this year and beyond, NASA engineers will attempt to share the limited available power between Voyager 2’s various instruments. We have reached out to NASA for more information about the agency’s expectations for the longevity of the spacecraft and its current scientific work.
But it’s not necessarily the end of the adventure for this trailblazing craft, even once its power runs out and it can no longer communicate with Earth. Eventually, in 20,000 years’ time, Voyager 2 will reach the nearby star Proxima Centauri.
