Voyager 1 starts making sense again after months of babble

Veteran spacecraft shows signs of sanity with poke from engineers

Engineers are hopeful the veteran spacecraft Voyager 1 has turned a corner after spending the past three months spouting gibberish at controllers.

On March 1, the Voyager team sent a command, dubbed a "poke," to get the probe's Flight Data System (FDS) to try some other sequences in its software in the hope of circumventing whatever had become corrupted.

Readers of a certain vintage will doubtless have memories of poke sheets for various 1980s games. Not that this hack ever used a poke to get infinite lives in Jet Set Willy, of course.

While Voyager 1's lifespan is not infinite, it has endured far longer than anticipated and might be about to dodge yet another bullet. On March 3, the mission team saw something different in the stream of data returned from the spacecraft, which had been unreadable since December.

An engineer with the Deep Space Network (DSN) was able to decode it, and by March 10, the team determined that it contained a complete memory dump from the FDS.

The FDS memory read-out contains its code, variables, and science and engineering data for downlink.

Prior to NASA's announcement, Dr Suzanne Dodd, project manager for the Voyager Interstellar Mission, said in a Pasadena Star-News report that the data being transmitted from the probe was "not exactly what we would expect, but they do look like something that can show us that the FDS is at least partially working."

Dodd was referring to the ones and zeroes streaming from the spacecraft. Previously, the probe's telemetry modulation unit (TMU) had begun in mid-December transmitting a repeating binary pattern as though it was somehow stuck. Engineers reckoned the issue was somewhere within the FDS.

The next step is to study the memory read-out and compare it to one transmitted before the problem arose. A solution to the issue could then be devised.

One of the original Voyager scientists, Garry Hunt, told The Register that engineers at JPL were determined to get communications with the stricken probe working again: "This requires both skills and patience with the long time between communication instructions and response."

The time lag is a problem. A command from Earth takes 22.5 hours to reach the probe, and the same period is needed again for a response. This means a 45-hour wait to see what a given command might have done.

The availability of skills is also an issue. Many of the engineers who worked on the project - Voyager 1 launched in 1977 - are no longer around, and the team that remains is faced with trawling through reams of decades-old documents to deal with unanticipated issues arising today. ®

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