NASA shuts off long-running instrument on Voyager 1 to keep the probe alive

The switch

Engineers at NASA's Jet Propulsion Laboratory sent commands on April 17 to shut down Voyager 1’s Low-energy Charged Particles experiment (LECP). The instrument has been running almost without interruption since the probe launched in 1977 — nearly 49 years of continuous service — but the spacecraft is running short on power. Turning off LECP is the chosen move to prevent deeper, automatic safing that could be harder to recover from.

Why it mattered

Why give up a sensor that’s been quietly mapping the interstellar medium for decades? Because the twin Voyagers are powered by radioisotope thermoelectric generators that lose roughly 4 watts a year. After almost a half-century, margins are razor thin. During a routine roll on Feb. 27, Voyager 1’s power dipped unexpectedly and engineers worried an undervoltage fault would force the spacecraft to shut down systems on its own. The team acted first — a preplanned, painful triage rather than a chaotic blackout.

The human and technical angle

There’s real poignancy here. The LECP measured ions, electrons and cosmic rays that told us about pressure fronts and particle density beyond the heliosphere. One of the team’s directives, though, was to preserve the mission, not any single instrument. “Voyager 1 still has two remaining operating science instruments — one that listens to plasma waves and one that measures magnetic fields,” said Voyager mission manager Kareem Badaruddin. Those instruments are still sending back unique data from a place no other craft has reached.

What’s next

The LECP shutdown command will take about 23 hours to reach Voyager 1 at more than 15 billion miles away; the shutdown itself will take roughly three hours and 15 minutes. A small LECP motor that helps the sensor scan will remain powered (about 0.5 watts) so the team might bring the instrument back if extra power appears. Engineers estimate the move buys roughly a year of breathing room while they finalize a broader energy-saving maneuver, dubbed “the Big Bang,” intended to stretch the Voyagers’ operational lifetimes as long as physics and plutonium allow.

Sources: nasa.gov, Hacker News