The Mars Exploration Rover (MER) Opportunity landed on Mars on January 25, 2004. The rover was originally designed for a 90 Sol mission (a Sol, one Martian day, is slightly longer than an Earth day at 24 hours and 37 minutes). Its mission has been extended several times, the machine is still trekking after 11 years on the Red Planet.

How it has been working for 11 years? Can anyone explain hardware-related aspects and how smart this Rover is ?

I need to know how this rover is getting services on Mars regarding to hardware related issues?(if any hardware is not working properly, how it can be repair on the Red Planet?)

  • $\begingroup$ I'd be rather suprised if there are any AI elements at all. AI algorithms are very hard to test, can't be proven correct and you really don't want your robot to learn something wrong. It's also under close supervision all the time so it does not have to learn much. $\endgroup$
    – FooTheBar
    Sep 13, 2016 at 8:17
  • $\begingroup$ AI has nothing to do with it. It's all about robust electromechanical design for extreme environmental operation. $\endgroup$
    – Paul
    Sep 13, 2016 at 21:03
  • $\begingroup$ but how is it working too long ? why not affected by time and environment ? Those are the questions in my mind.. $\endgroup$ Sep 14, 2016 at 2:11
  • $\begingroup$ Here is the answer - x3.cdn03.imgwykop.pl/c3201142/… $\endgroup$
    – mactro
    Sep 14, 2016 at 7:30
  • $\begingroup$ Welcome to Robotics Abhishek Tandon, but I'm afraid that questions like this really aren't a good fit for a stack exchange site. We prefer practical, answerable questions based on actual problems that you face. Take a look at How to Ask and tour for more information on how stack exchange works. Also, the Robotics question checklist has good advice on how to write a good question. $\endgroup$
    – Mark Booth
    Sep 14, 2016 at 15:21

1 Answer 1


There are 2 main reasons why the MER is still operating long after it's 90 Sol planned lifetime.

The first is political, strategic, and can be summarized as 'Under promise, over deliver'. When a PI (principal investigator) proposes a high-risk scientific mission like this, they always frame the goals of the project such that their project is viewed successful even when things go wrong. If you say that your project lasted 11 years and then failed, that is one framing. If you say your project lasted 10 years longer than it was designed for, that is another framing of the same information that sounds much better. You can find many NASA projects where things went very wrong but the project was still viewed as successful.

The second reason is statistical. It is difficult to truly understand the details of the quality of the components a machine is built from, and the conditions of operation that a machine will operate in. We can never know exactly how long a machine will operate before failing. But we can use prior experience and statistical calculations to get a pretty good estimate of how long a population of similar machines will operate before failure. A machine like the MER is very complex, and we apply the statistical analysis to each individual part, and all the combinations of the parts. In the end, it is likely that the design engineers actually had 90 Sol of operation as their goal. They would also have had a measure of certainty associated with that. Perhaps it was a 90% chance that the MER would last 90 Sol. Or perhaps it was 99.9%. The higher the certainty required, the more 'over design' is needed to guarantee that.

You can research the term 'design life' to understand better these hardware related aspects.


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