Voyager 2 power budget change delays next instrument shutdown to 2028
NASA engineers combined power switches on Voyager 2, preserving heat while freeing enough energy to defer a planned instrument shutdown.
By Renata Fuchs · Policy Reporter
· 3 min read
NASA engineers have reworked the Voyager 2 power budget with a coordinated change that has pushed the spacecraft’s next planned science-instrument shutdown to well into 2028. The July 9 reconfiguration matters because it gained electrical headroom without cooling the nearly 50-year-old probe below conditions needed to keep its propellant lines usable, according to Voyager project manager Suzanne Dodd.
The operation, called the “Big Bang,” was not a new power source or a repair. Engineers switched several devices at once, shutting off some powered hardware and replacing it with lower-power alternatives, NASA’s Jet Propulsion Laboratory said. The bundle of changes was designed to preserve heat inside the spacecraft while cutting its electrical load.
How did Voyager 2’s power budget change extend the mission?
Voyager’s constraint is both electrical and thermal. Dodd said that turning systems off one by one could release power but would not leave enough heat to keep propellant lines warm. If those lines freeze, the spacecraft can no longer point its antenna toward Earth.
The combined configuration avoided that trade-off. By changing multiple loads at the same time inside the spacecraft bus, the team aimed to reduce demand while keeping enough electronics operating to maintain thermal conditions. NASA has not identified the specific devices in the public description.
That distinction matters in a system with almost no slack. The spacecraft’s component power records date from roughly 50 years ago, and Dodd said discrepancies measured in fractions of a watt could alter mission decisions. Voyager 2’s available power falls by about four watts a year as its radioisotope power system declines, according to material from NASA JPL carried by ScienceDaily.
Testing took weeks because Voyager 2 cannot be troubleshot live
The team first conducted ground testing and built power and thermal models. It then briefly placed Voyager 2 in the new setting and restored the prior configuration, checking whether the commands worked and whether the expected power draw appeared in telemetry.
Thermal behavior required a longer test because temperatures shift slowly, over roughly 48 hours, Dodd said. In early June, engineers ran the configuration for six hours, long enough to detect a temperature trend while limiting exposure if their model was wrong. A command could take up to 20 hours to reach the spacecraft, followed by another 20 hours for a response to return, turning even a short trial into a multi-day operational cycle.
After the permanent July 9 change, monitoring over the next roughly 24 to 48 hours showed a smaller temperature decline than the model had projected, Dodd said. That result moved the expected shutdown of Voyager 2’s Cosmic Ray System beyond the probe’s 2027 launch anniversary and well into 2028. Dodd characterized that as about two years of delay based on power alone.
NASA’s more conservative public expectation is that Voyager 2’s three active instruments can operate together for at least another year. The difference reflects two measures of the same result: the near-term minimum operating expectation and the projected timing of the next shutdown. A similar change is planned for Voyager 1, which has tighter power margins, while turning previously disabled instruments back on remains under consideration rather than an approved operation.
This story draws on original reporting from The Register.
