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WHY did NASA probe go suddenly SILENT - JUST as it was about to send pics of remote ice-world?

Unplanned schtumness 'scares' boffins

NASA's New Horizons probe – due to soar past the remote, icy dwarf planet Pluto 10 days from now – gave its handlers a brief fright yesterday by going silent at an inopportune juncture.

Fortunately, contact was re-established after around 80 minutes. NASA added that the spacecraft remained "healthy" despite the anomaly.

NASA announced that New Horizons had lost comms with Earth on 4 July at 2pm EDT (6pm GMT). Immediately after, the US space agency's servers were struggling under the load of people presumably desperate to read the bad news.

NASA explained:

During that time the autonomous autopilot on board the spacecraft recognised a problem and – as it’s programmed to do in such a situation – switched to the backup computer.

The autopilot placed the spacecraft in “safe mode,” and commanded the backup computer to re-initiate communication with Earth.

With comms re-established, the New Horizons probe began transmitting diagnostic telemetry.

The glitch does mean that no scientific data can be collected until everything has returned to normal. But NASA appeared to be confident that it can restore operations before the crucial flyby.

“[F]ull recovery is expected to take from one to several days”, the agency stated, mostly because of the nine-hour delay for communications to cross the 4.9 billion km (3 billion miles) between Earth and New Horizons.

Over at the Planetary Society, Emily Lakdawalla wrote that no optical image downloads were planned for 4 July.

A few pictures for 5 and 6 July might also have been forfeited. However, if everything goes well, "the only result of today's safe mode will be an annoying – but educational – gap in our approach animations", and a non-catastrophic gap in the light curves collected for Nix and Hydra.

"Safe modes are scary and annoying but not uncommon," Lakdawalla noted.

Fingers crossed. ®

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