NASA Solves the Mystery of Why Voyager 1 Was Sending Random Data

UPDATE 8/31: NASA engineers discovered that the probe’s attitude articulation and control system (AACS) had switched to sending its telemtry data through an onboard computer that hadn’t worked for years(Opens in a new window), causing it to become corrupted. This accounts for why seemingly random data was arriving back on Earth.

The problem was resolved by simply asking the AACS to start sending its data through the correct computer again, which it has now done and uncorrupted data is being received once more.

What remains a mystery is why the AACS decided to switch to using the broken computer. NASA suspects it “received a faulty command generated by another onboard computer,” but the Voyager team doesn’t know which one and what fault would cause that to happen (yet).

According to Suzanne Dodd, Voyager’s project manager, ““We’ll do a full memory readout of the AACS and look at everything it’s been doing. That will help us try to diagnose the problem that caused the telemetry issue in the first place. So we’re cautiously optimistic, but we still have more investigating to do.”

Original Story 5/19:
Voyager 1 continues to return science data and otherwise operate as normal, but readouts beamed back to Earth from the probe’s attitude articulation and control system (AACS) don’t reflect what’s happening onboard.

As NASA’s Jet Propulsion Laboratory explains(Opens in a new window), the AACS, which keeps Voyager 1’s antenna pointed at Earth, appears to be in working order. The telemetry data it’s returning, though, is invalid—appearing randomly generated or not reflective of the system’s possible state.

No onboard fault protection systems have been triggered and the spacecraft has not yet entered “safe mode,” nor has Voyager 1’s signal weakened.

“A mystery like this is sort of par for the course at this stage of the Voyager mission,” according to Suzanne Dodd, JPL project manager for Voyager 1 and 2. “The spacecraft are both almost 45 years old, which is far beyond what the mission planners anticipated.” Dodd also points out interstellar space is a “high-radiation environment that no spacecraft have flown in before,” so a few strange events that take some time to explain should come as no surprise.

Voyager 1 became the first human-made object to reach interstellar space in 2013—36 years after leaving Earth. The space probe, launched in 1977 as part of the Voyager program, is currently 14.5 billion miles from Earth, and it therefore takes nearly two days (20 hours and 33 minutes) to send a message and receive a response.

Delay aside, it’s possible the mission team may not discover the anomaly’s source and instead have to adapt to it, Dodd explained. On the other hand, if they do manage to solve the problem, it could be fixed through some remote software changes or by using one of the craft’s redundant hardware systems. In 2017, Voyager 1’s primary thrusters showed signs of degradation, forcing engineers to switch to another set(Opens in a new window) previously used 37 years earlier during the probe’s planetary encounters.

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