There are numerous risks that spacecraft face when traversing the deep black of space. Since we’ve sent many probes to many locations most of these risks are well known and thus we’ve built systems to accommodate them. Most craft carry with them fully redundant main systems, ensuring that if the main one fails that the backup can carry on the task that the probe was designed to do. The systems themselves are also built to withstand the torturous conditions that space throws at them, ensuring that even a single piece of hardware has a pretty good chance of surviving its journey. However sometimes even all that engineering can’t account for what happens out there and yesterday that happened to New Horizons.
New Horizons is a mission led by NASA which will be the first robotic probe to make a close approach to Pluto. Its primary mission is to capture the most detailed view of Pluto yet, generating vast amounts of data about our most diminutive dwarf planet. Unlike many similar missions though New Horizons won’t be entering Pluto’s orbit, instead it will capture as much data as it can as it whips by Pluto at a blistering 17 km/s. Then it will set its sights on one of the numerous Kuiper Belt objects where it will do the same. This mission has been a long time in the making launching in early 2006 and is scheduled to “arrive” at pluto in the next 10 days.
However, just yesterday, the craft entered safe mode.
What caused this to happen is not yet known however one good piece of news is that the craft is still contactable and operating within expected parameters for an event of this nature. Essentially the primary computer sensed a fault and, as it is programmed to do in this situation, switched over to the backup system and put the probe into safe mode. Whilst NASA engineers have received some information as to what the fault might be they have opted to do further diagnostics before switching the probe back onto its primary systems. This means that science activities that were scheduled for the next few days will likely be delayed whilst these troubleshooting process occur. Thankfully there were only a few images scheduled to be taken and there should be ample time to get the probe running before its closest approach to Pluto.
The potential causes behind an event of this nature are numerous but since the probe is acting as expected in such a situation it is most likely recoverable. My gut feeling is that it might have been a cosmic ray flipping a bit, something which the processors that probes like New Horizons are designed to detect. As we get more data trickled back down (it takes 9 hours for signals to reach New Horizons) we’ll know for sure what caused the problem and what the time frame will be to recover.
Events like this aren’t uncommon, nor are they unexpected, but having one this close to the mission’s ultimate goal, especially after the long wait to get there, is sure to be causing some heartache for the engineers at NASA. New Horizons will only have a very limited opportunity to do the high resolution mapping that it was built to do and events like these just up the pressure on everyone to make sure that the craft delivers as expected. I have every confidence that the team at NASA will get everything in order in no time at all however I’m sure there’s going to be some late nights for them in the next few days.
Godspeed, New Horizons.