Voyager 1 is still alive and flying more than 25 billion miles into space. However, a computer glitch prevented a special mission support team in Southern California from learning more about the condition of one of NASA's oldest spacecraft.
On November 14, a computer problem occurred that affected Voyager 1's ability to transmit telemetry data, such as measurements from the spacecraft's science instruments or key technical data about the probe's performance. As a result, the team has no knowledge of key parameters related to the vehicle's engine, power or control systems.
"If we bring him back, it will be the biggest miracle. We certainly haven't given up,” Susan Dodd, Voyager project manager at NASA's Jet Propulsion Laboratory, told Ars. "There are other things we can try. But this is the most dangerous because I am in charge of the project".
Dodd became program manager for NASA's Voyager mission in 2010, overseeing a small team of engineers responsible for human exploration of interstellar space. Voyager 1 is the most distant spacecraft ever created, leaving the Sun at 38,000 miles per hour (17 kilometers per second).
Voyager 2, which launched 16 days before Voyager 1 in 1977, is not that far away. It took a more convenient route through the solar system, flying past Jupiter, Saturn, Uranus and Neptune, while Voyager 1 sped up to Saturn, bypassing its sister ship.
Over the past two decades, NASA has devoted Voyager instruments to the study of cosmic rays, magnetic fields, and the plasma environment of interstellar space. They don't take pictures anymore. Both probes traveled beyond the heliosphere, where particles emitted by the Sun are directed into the interstellar medium.
No other operational spacecraft currently explore interstellar space. NASA's New Horizons probe, which flew by Pluto in 2015, is on track to reach interstellar space in the 2040s.
50 years of advanced technology
Voyager 1's latest problem involves the probe data subsystem (FDS), one of three spacecraft computers that works with the central command and control computer and another device that controls attitude and signal handling.
The FDS is responsible for collecting scientific and engineering data from the spacecraft's network of sensors, then combining the information into a single data packet, a binary code with leading 1s and 0s. A special component called a telemetry signal modulator sends a beam. the data returns to Earth behind the 12-foot (3.7 m) Voyager satellite dish.
Data packets sent by Voyager 1 in November showed a repeating pattern of 1s and 0s, as if they were stuck, NASA said. JPL engineers spent the better part of three months trying to diagnose the cause of the problem, Dodd said. He said the engineering team is "99.9% sure" the problem is with FDS, which appears to have problems "synchronizing frames" of data.
For now, the ground team believes the most likely explanation for the problem is corrupt memory in the DSF. However, because the computer is not working, engineers do not have detailed data about Voyager 1 that could lead to the root of the problem. "That's probably in the FDF memory somewhere," Dodd said. "It was returned or slightly damaged. But without telemetry, we cannot determine where the FDS memory is damaged."
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