New Horizons News

Every six weeks or so, New Horizons Principal Investigator (and current head of NASA’s Science Mission Directorate), Alan Stern, writes a column posted on John’s Hopkins New Horizons Web Site, called The PI’s Perspective. I’ve been waiting for this one, because since the last update in early October, the mission deviated a bit from it’s original time line. Stern explains:

We did have a couple of unexpected events during ACO-1. (ed. ACO is Annual Check Out.) One came in early October, when the spacecraft partially lost track of its timeline owing to a very subtle kind of error generated by a command script we’d sent it. The operations team caught this and recovered from it very quickly. It was really a blessing that this subtle behavioral flaw manifested itself now, rather than at Pluto, so we can protect against it. It’s these kinds of idiosyncrasies that our testing and flight operations hope to expose. So, despite the fact it cost us some lost sleep and some cruise science observations, we’re very glad to have learned this lesson.

Yeah – I saw this news just after it happened, in the regular weekly report. It’s a rather expected kind of unexpected problem that comes up regularly in these kinds of environments. He’s being polite, but you can be sure that someone felt like (s)he made a dumb mistake somewhere.

The second unexpected event came just last week, on November 12, when a cosmic ray or some other kind of charged particle caused our main computer to reboot. This is the fourth such computer reboot we have had in flight caused by space radiation bursts. Preflight predictions were for these events to be far more rare than this, and our engineering team is looking into why this is occurring more often than predicted. Fortunately, on the four occasions this occurred, the onboard spacecraft autonomy software performed as planned and recovered New Horizons safely.

Hum… This is happening rather frequently…The first time was even before I left the mission. The middle two times were attributed to Jupiter’s intense radiation belt, but apparently, they’re not satisfied with this explanation any more. Could it be a harbinger of a potential problem? Hope not.

The third and final such event took place on November 16, when the spacecraft’s main computer executed a power on reset (POR) because of a glitch on its power line. Since this was so unexpected, we are analyzing what happened and have decided not to enter hibernation until late December while we analyze the root cause of this anomaly and put in place some software protection against future events. For the next couple of weeks, we’ll monitor the spacecraft three to four times a week using NASA’s Deep Space Network to collect more data.

Eeeechh. This is not good. Perhaps not real bad (yet), but unexplained power glitches really aren’t a good thing when your about six hundred million miles away from home (as the crow flies). I saw the news of this too, last week, in the weekly report and I really forgot to mention it here. I also noted that the spacecraft was not put into hibernation as originally planned.

The mission will be using quite a bit of “Deep Space Network” time in the next few weeks. That’s expensive. Is this the reason that Stern says “Budget constraints will force us to slim down the team in mid-2009, so we need to finish the Pluto planning before many of the Jupiter encounter team members move on to other projects.”? It’s probably a factor. New Horizons was supposed to spend much of it’s flight time to Pluto “sleeping”, relying on its Autonomous Control System and nearly no support from the ground to save years and years worth of FTEs on the budget. And in the spirit of full disclosure, I spent my time testing the autonomy system, as one of those FTEs.

Finally Stern mentions that NH is planning to spend forty weeks in hibernation next year. The spacecraft is behind the Sun (from our perspective on Earth) starting in the middle of December and will be out of touch for just about two weeks. So the plan is to put it to sleep about the first of the year, and keep it there at least until May.

[voice type=demonic, class=”Price, Vincent”]
And then my autonomy system will have complete control over the spacecraft, and THE MISSION IS MINE. MINE! ALL MINE, I SAY!
[laugh type=evil, class=”mad scientist”]
AhhhHAHAHAHAAAA!
[/laugh][/voice]

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