How NASA repaired Voyager 1 from Earth
When Voyager 1 stopped returning readable data, engineers could not replace a chip. They diagnosed the fault remotely and rewrote software locations in a computer launched in 1977.
14 November 2023: a signal without usable data
Earth still received a radio carrier, and controllers knew the spacecraft accepted commands. Science and engineering telemetry was unreadable. The problem involved the Flight Data Subsystem (FDS), which packages data for transmission.
March and April 2024: a memory clue
A requested FDS memory readout showed that about 3% of its memory was corrupted. NASA suspected a single memory chip had failed, but could not determine the exact cause.
18–20 April: code in a new location
The chip could not be repaired physically. Engineers split affected code across free memory and changed references to its new locations. They first moved the engineering-data code on 18 April; readable data arrived on 20 April. At the time, radio signals took about 22.5 hours each way.
May and June: science returns
On 19 May the team sent a command to restore science data. Two instruments responded immediately; two needed more work. On 13 June 2024, NASA reported usable data from all four instruments operating then. That historical count does not describe the spacecraft's present instrument status.