Voyager 2 is nearly 50 years old, losing about 4 watts of power every year as its plutonium power source fades — and NASA just bought it at least another year of science with an all-at-once power-system swap engineers called the “Big Bang,” performed on a spacecraft with razor-thin power margins and no possibility of physical repair.

Voyager 2 is nearly 50 years old, losing about 4 watts of power every year as its plutonium power source fades — and NASA just bought it at least another year of science with an all-at-once power-system swap engineers called the “Big Bang,” performed on a spacecraft with razor-thin power margins and no possibility of physical repair.

Voyager 2 has no repair port that anyone can reach, no spare spacecraft waiting nearby and no possibility of a technician opening its 1970s hardware. Nearly 49 years after launch, every intervention begins as a command transmitted across more than 20 billion kilometres and ends with a wait of almost two days to learn whether the spacecraft accepted it. This July, engineers at NASA’s Jet Propulsion Laboratory used that narrow connection to rearra…