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Glitch Halts New Horizons Operations As It Nears Pluto
An anonymous reader writes: NASA says their New Horizons probe suffered a temporary communication breakdown on Saturday, 10 days before it's supposed to fly past Pluto. The mission team is working to restore normal communications. "Full recovery is expected to take from one to several days," NASA wrote in a status report on Saturday. "New Horizons will be temporarily unable to collect science data during that time."
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Alan Stern is the director of the New Horizons mission. So no worries. :) You can see that two way communication is in progress here at the Canberra dish.
This was a really minor glitch and will have no impact on the mission as a whole. There weren't even any significant observations planned for today.
(As a side note, the closer we get to Pluto and the more we see of it (dark band at the bottom is around the equator), the more it's starting to remind me of an airless Titan :) )
Dear Lord: One of your creatures may be hurt tonight. Please let it be the other creature.
From T(rather brief)FA:
The “encounter program” includes software to prohibit the very type of automated safe mode that New Horizons executed Saturday afternoon.
“Encounter mode short-circuits the on board intelligent autopilot so that if something goes wrong, instead of calling home for help, which is what most spacecraft do and what New Horizons does during cruise flight, it will just stay on the timeline. It will try to fix the problem, but it will rejoin the timeline because if it ‘went fetal,’ as we say, if it just called home for help, it could miss the flyby,” New Horizons lead scientist Alan Stern told Discovery News before Saturday’s problem.
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I don't have any knowledge specific to this project, but I'll give you my interpretation:
The engineers programmed the on-board software to know approximately what the spacecraft should be doing at certain times. New Horizons uses on-board fuel to spin up so that it can more reliably transmit information back to Earth. However, it cannot take pictures while spinning, so it'll have to spin-down. In an "everything's fine" scenario, there will be set times for it to spin up, transmit its data, spin down, capture more data, etc. That's the default timeline.
In previous spacecraft, if something has gone wrong, then the default response was to "stop and wait for further instructions". The idea was that doing "something" could be worse than doing "nothing" and waiting for a human to figure out the best course of action. In other words, it "went fetal".
Pluto is a tad far away, and signals take about 4.5 hours each way. So, a minimum of 9 hours would be required for a response to a problem, not including engineer problem solving and implementation time. That's long enough that the spacecraft may miss the window of ideal picture taking time while waiting for a response, assuming one ever arrives. What it'll likely do in this case is carry on with the mission, and only after it has acquired the flyby data will it call back home and—in Windows parlance—check for updates.
The article is too scant. Here's a better one.
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UPDATE: NASA issued a statement at about 19:30 PT / 22:30 ET July 5 / 02:30 UT July 6 saying that the cause of the safe mode is understood, and that New Horizons will resume science operations on July 7:
NASA’s New Horizons mission is returning to normal science operations after a July 4 anomaly and remains on track for its July 14 flyby of Pluto.
The investigation into the anomaly that caused New Horizons to enter “safe mode” on July 4 has concluded that no hardware or software fault occurred on the spacecraft. The underlying cause of the incident was a hard-to-detect timing flaw in the spacecraft command sequence that occurred during an operation to prepare for the close flyby. No similar operations are planned for the remainder of the Pluto encounter.
“I’m pleased that our mission team quickly identified the problem and assured the health of the spacecraft,” said Jim Green, NASA’s Director of Planetary Science. “Now – with Pluto in our sights – we’re on the verge of returning to normal operations and going for the gold.”
http://www.planetary.org/blogs...