From more than 15 billion miles away, NASA engineers began repairing a space probe last April that is headed for the constellation Ophiucus, even though it will arrive in some 38,000 years. NASA launched Voyager 1 in 1977 and it has already exceeded expectations, but the space agency hopes to continue receiving data from the probe until at least 2030. Still, after Voyager 1 experienced a computer glitch in November, it began transmitting garbled data (which is not t completely unusual), prompting NASA to initiate these long-range repairs.
After some uncertainty as to whether any of this would work, the fix was made. Even better, when Salon spoke with NASA about the problem of remotely repairing spacecraft, experts were optimistic about their future and what it says about space exploration in general.
To understand why, it is first necessary to analyze what happened to Voyager 1. In November, the spacecraft sent a signal that contained no data. Engineers determined that the problem was either the Flight Data Subsystem (FDS) or the Telemetry Modulation Unit (TMU). In the last week of February, NASA sent a “nudge” to Voyager 1 to prompt the FDS to send data from memory; not only did it succeed, but NASA soon uploaded a separate command that caused Voyager 1 to respond with a full memory read, helping them identify the specific problem with the FDS.
“The team has confirmed that the issue is with the FDS,” NASA Jet Propulsion Laboratory media relations specialist Calla Cofield told Salon. “The chip responsible for storing 256 words of FDS memory has a stuck bit (the code is stuck at 0 or 1), indicating that a component has failed, either due to age or damage to an external particle. This part represents about 3% of the FDS memory. The team will need to relocate part of the software code stored on the damaged chip.”
During the April mission, NASA instructed Voyager 1 to relocate some of the affected FDS software code and redirect references to that code to other locations in the spacecraft’s software.
“On April 20, the team received technical data from the spacecraft indicating that the command was successful,” Cofield said. “All indications are that the spacecraft is fine after five months out of contact.
The team began receiving science data from Voyager 1 again on May 19, and by June, all science instruments on Voyager 1 had resumed sending usable data. Even so, Cofield added that “cleaning [is] still ongoing with the spacecraft.”
Of course, the matter does not end there; Voyager 1 isn’t the only space probe that may one day require repair. There are currently two other space probes that have left the solar system and remain operational, Voyager 2 and New Horizons. In addition, NASA sent two other probes that are now defunct, Pioneer 10 and Pioneer 11. Can the lessons that allowed NASA to repair Voyager 1 be applied to these and other distant spacecraft?
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“All indications are that the spacecraft is fine after five months out of contact.
“The future is not so much about fixes as it is about finding ways around problems,” said Voyager flight team member Bob Rasmussen. “We know several life-limiting factors and have strategies to preserve capabilities as long as possible. However, we cannot predict total failure, so we must deal with them as they occur.”
That doesn’t mean Rasmussen has full faith in NASA’s ability to save the malfunctioning probes. In 2019, the agency had to turn off the heater for Voyager 2’s Cosmic Ray Subsystem instrument to conserve the probe’s power. In April, NASA continued to keep Voyager 2 running by hooking up to a small backup power bank that is used to power the onboard safety mechanism. NASA believes this will keep the craft powered by enough juice so it won’t need to shut down the science instrument until 2026.
Voyager 1 and 2, meanwhile, are always on the verge of a more permanent breakdown. Even if all of their systems work optimally in the future, the spacecraft are still not expected to survive past the 1930s. The fact that they have lasted this long is a testament to the skill and dedication of the 1970s engineers who built them. Unfortunately, there may come a day when more than one of their vital systems simply stops working properly.
“The worst case scenario is that both could fail at any time,” Rasmussen said. “Not all failures are fixable. Many we would never be able to tell what happened because contact would simply stop.”
Rasmussen added that the best-case scenario is that Voyager 1 will operate for another five to ten years. “We have a long-term strategy to gradually reduce performance-degrading activities and to use degraded modes of operation,” Rasmussen said. “But we also know what happens to the best laid plans.
Tragically, June was also the month that Ed Stone, the man who pioneered the Voyager missions and led them for half a century, died. In its obituary for the former director of the Jet Propulsion Laboratory, NASA wrote that Stone was “a pioneer who dared the mighty things of space” and “took humanity on a planetary journey through our solar system and beyond, sending NASA where no space probe had gone before. the ship did not get”.
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