NASA scientists claim to have identified the source of the trouble preventing humanity’s most distant emissary, Voyager 1, from sending back its scientific data. However, finding the problem’s exact location, let alone fixing it, is still proving frustrating. A 45-hour round-trip for messages to get through doesn’t help, nor the fact that only one radio dish, with other calls on its time, is powerful enough for Voyager 1 to hear it over these distances.
Late last year, Voyager 1 started
“The spacecraft is receiving and executing commands sent from Earth; however, the FDS is not communicating properly with one of the probe’s subsystems, called the telemetry modulation unit (TMU),” a NASA
Three months after the problems started, with some of the best engineers in the world working on the problem, it’s still happening.
In a certain sort of science fiction film, this would be a hint Voyager 1 had become sentient and had either gone on strike or was asking for help. In the real world, it reflects the fact that one of the most potent scientific instruments of all time runs on a computer system that was obsolete soon after it launched in 1977.
Voyager 1 has three computers. In a testament to
The FDS takes the data from the spacecraft’s surviving sensors and combines them for sending to Earth through the Telemetry Modulation Unit.
“[The problem’s] likely somewhere in the FDS memory,” Suzanne Dodd, Voyager project manager since 2010, told
“It would be the biggest miracle if we get it back,” Dodd added. “We certainly haven’t given up. There are other things we can try. But this is, but far, the most serious since I’ve been project manager.” Nevertheless, the successful
Those ideas include trying to switch the FDS back to the operating mode it used during its fly-by of the giant planets, in the hope this will reveal where in the memory the problem lies. The usually small Voyager team has pulled in people from other parts of NASA to prepare to do this, but Dodd noted the people they want the most are not available.
“Not to be morose, but a lot of Voyager people are dead,” she noted, leaving the current operators to search through archives that haven’t been kept in the best order. “We have sheets and sheets of schematics that are paper, that are all yellowed on the corners, and all signed in 1974,” Dodd
If, in a real-life version of
Dodd bemoaned the lack of a ground-based simulator that can be used to test commands before they are sent to Voyager 1. She also noted the mission’s declining power supply and other fragile parts means it hasn’t got too long. There’s no point taking the rescue attempt too slowly if it means finding the solution just before the mission fails for a different reason.
Despite the weight restrictions when they were launched, the Voyagers had two FDSs each, but Voyager 1’s backup failed in 1981 (fortunately after it had passed Saturn). At the time, most people at NASA thought Voyager 1 had done its job, since, unlike its twin, it would not be passing by any further worlds.
Instead, both Voyagers have