It’s true. NASA’s Opportunity rover (aka “Oppy”) is hunkered down under the heaviest part of the worst Martian dust storm seen since before the rovers landed.
I learned a lot yesterday about what’s going on and wanted to share the important highlights:
Oppy is solar powered – the rover’s batteries are recharged using the Sun – and dust storms block out some to all of the Sun’s light. To save power, NASA instructed Oppy to go into low power mode, stop all scientific operations, and only attempt contact with Earth on a defined schedule. Unfortunately, Oppy has missed checking in twice now. The last we heard from the rover was Sunday (6/10/18).
NASA believes Oppy has entered “low-power fault mode”. This is when the charge in the rover’s batteries dip below 24 volts. The only thing that is able to function at that level is the mission clock. Even the rover’s heaters stop working. Essentially the rover is in hibernation mode. The mission clock is programmed to attempt to wake Oppy up every two (Earth) days. If the batteries have enough power, Oppy will wake up and attempt to make contact with Earth. If there isn’t enough power. Oppy will continue to “sleep”.
Eventually one of 2 things will happen. After the storm ends (not expect for weeks or perhaps months) and before all the dust kicked up by the storm settles back to the ground – and on top of Oppy – Sunlight will be able to charge Oppy’s batteries. Assuming they charge enough, Oppy will wake up and be able to communicate with us again. At which point NASA will furious work to recover this rover.
The other possibility is Oppy enters “mission clock fault mode.” This is when the mission clock fails to maintain time. However, NASA engineers and designers are amazing people. Even if the mission clock enters fault mode, it’s not the end of Opportunity. What this means is that the mission clock can’t keep track of “two days” anymore, so it will start randomly attempting to wake Oppy to make contact. The reason mission clock fault is a problem is that without a known schedule of attempted contact, NASA will not know when to be listening for Oppy reaching out to us. If we miss replying, Oppy won’t know what to do with itself.
NASA remains hopeful about Opportunity’s survival. There are 3 strong reasons for this:
1) Oppy has survived a global dust storm before, back in 2007. However, this dust storm is significantly stronger, and Oppy got close but didn’t actually fall into low power fault mode then. As with earthquakes here on Earth, the scale of relating their strength (the Richter scale) is exponential. A level 4 magnitude earthquake is not twice as strong as a 2, it’s 4 times as strong. The same with ratings for Martian dust storms. The 2007 global storm had an opacity level, or tau, somewhere above 5.5. The current storm had an estimated tau of 10.8 on Sunday when we last heard from Oppy, which again is not twice as thick, it’s 4 times.
2) NASA isn’t worried about Opportunity freezing, despite the loss of use of the rover’s heaters. Mars is moving into Summer time which, like on Earth, is significantly warmer than Winter time. And it is well established that Martian dust storms also increase the temperature of the air. NASA has done modelling and testing here on Earth this last week, and strongly believes that the temperature around Oppy will stay well within the rover’s tolerance limits.
3) Spirit – Opportunity’s twin rover, whom we lost in 2010 – survived and recovered from a fault mode back in 2004. So we know it’s possible.
But the one thing that is keeping our hope in check is Oppy’s age. Opportunity is now 14 1/2 Earth years old. Spirit lasted 6 years. Both rovers were designed to last 90 days (roughly 3 months). NASA is likening this to humans by describing Oppy as your 90-something year old grandparent. There’s a whole lot more stress a human teenager can survive compared to a 90-year-old human. The rovers are no different.
For now, Oppy is in a protective “coma”. All we can do is wait.
- https://solarsystem1.jpl.nasa.gov/nnw/telecon-display.cfm?TeleconID=4058 (ONLY AVAILABLE TO LOGGED IN SSAs)