Even two-tenths of a watt matters when your spacecraft launched in 1977

Adding a few extra years to Voyager 2's prodigiously long life was the result of an effort that began more than a year ago, as engineers and managers pondered how to eke out a few more watts from the spacecraft's dwindling power supply.

"We came up with the 'Big Bang' idea probably more than a year ago now," recalls Suzanne Dodd, Project Manager for the Voyager project.

"We were looking for ways to extend the lifetime of the mission, which means really extending how long we can operate the instruments." //

"The idea behind the Big Bang… If we were to switch systems and do a lot of power switching all at once within the bus of the spacecraft, we would gain a lot of power and it would still keep the electronics warm, as opposed to when we do it serially (in a series), it doesn't provide enough of the heat input to keep the propellant lines warm."

The approach required careful power and thermal modeling. The draw of each component had been documented, but the figures were nearly 50 years old and might contain some hidden margins. "We're talking about a half a watt, or two tenths of a watt, and that makes all the difference on the spacecraft," Dodd explains.