JHU Pluto probe malfunctions a week before close-up — but it’s OK now

While you were barbecuing, Johns Hopkins scientists were scrambling to re-establish contact with a spacecraft that’s three billion miles away.
On July 4, just days before New Horizons is scheduled to begin its approach to Pluto, scientists lost contact with the probe. The silence lasted for about an hour and 15 minutes, and some scientific data was lost due to the “anomaly” that caused it.

Seeing Pluto – 9 days away, I hope the team gets the @NASANewHorizons probe back working soon! http://t.co/ikZGFKUXRu pic.twitter.com/iNA4fjKjBD

— Chris Hadfield (@Cmdr_Hadfield) July 5, 2015

According to NASA, scientists operating the probe at the Johns Hopkins Applied Physics Laboratory in Laurel lost touch with the New Horizons probe at about 2 p.m. as the probe was conducting an operation to prepare for its fly-by of Pluto. During this time, the probe’s autopilot found a problem, and went into “safe mode” by powering down the main computer, and switching to a backup.
After reviewing telemetry transmitted from the probe’s backup computer to Earth, the scientists found that the loss in contact was caused by a “hard-to-detect timing flaw” in a command sequence. It wasn’t a speedy investigation, as radio signals from the probe take four and a half hours to reach Earth.
Some scientific data was lost as a result of the malfunction. With the approach of Pluto still to come, however, the scientists don’t seem too sad about it.
“In terms of science, it won’t change an A-plus even into an A,” said Alan Stern of the Southwest Research Institute in Boulder, Colo., who is principal investigator for New Horizons.
Operations are expected to be fully restored to normal by Tuesday, July 7, ahead of the spacecraft’s July 14 Pluto fly-by.
The New Horizons concluded a nine-year journey toward Pluto in December, when it was awakened to prepare for the interplanetary photographic excursion. Photos and measurements started coming back in January, but scientists say the July 14 close-up is the main event.
While we wait another excruciating week, here’s a little bit about what scientists have learned from the Pluto photos that have been sent so far: