Slashdot Mirror

← Back to Stories (view on slashdot.org)

Mars Rovers Have Incorrect Instruments Installed

Posted by Zonk on from the maybe-they-should-have-given-them-different-paint-jobs dept.

Christopher Reimer writes "The New Scientist is reporting that the twin Mars rovers, Opportunity and Spirit, has instruments installed in the wrong rovers. From the article: 'While the bungle does not undermine the main scientific conclusions drawn from the data collected by the rovers, it is an embarrassing slip-up for a space agency that once lost a Mars spacecraft because engineers mixed up metric and imperial units.'"

10 of 294 comments (clear)

  1. Confusion...Why differing configurations? by Alpha_Traveller · · Score: 3, Interesting
    Creeping errors
    Although their designs are identical, each instrument is unique because of quirks in the materials they are made from. So before the rovers were launched, each instrument was calibrated using known rock samples. The measurements from each rover are then processed using the calibration files, but because of the mix-up, researchers were using the wrong ones. As a result, small errors have crept into the APXS results, affecting measurements of sodium, magnesium and aluminium abundance.
    Perhaps someone can clarify this statement? (Since I am not an engineer, eh?)... I'm wondering why it's so important to have differing configurations for the sensors in the first place. Wouldn't it be wise to collect exactly the same kind of information regardless of how complex if it's all being sent via transmission back to us anyway? Wouldn't it be extremely important to have the exact same configuration on BOTH sensors? I would think the end result would be useful when comparing the chemical composition of any particular area. It would be like hacking off a sensor "at the knees" when you had no significant reason to do so wouldn't it?
    --
    "Love is like pi - natural, irrational, and very important." (Lisa Hoffman)
    1. Re:Confusion...Why differing configurations? by Anonymous Coward · · Score: 5, Interesting

      In the old days, if you bought a carbon +/-10% resistor, you could be assured that it was either -10% to -5% or +5% to +10%, and almost never in-between. The reason? They'd mark the ones that fell between as +/-5% and sell them for more moeny.

      This doesn't work for +/-5% and the next grade (+/-1%) because the parts are built differently.

    2. Re:Confusion...Why differing configurations? by grozzie2 · · Score: 1, Interesting
      You are very right, this is NOT a little 'oopsie'. We dont like the results, but, we found if we add this fudge factor to the experimental readings, the results are more like those we wanted to get. In this case, the fudge factor is to swap the calibration files.

      Makes you wonder what happened to scientific methods, where the results drive the conclusions. I thought the case of fudging the measured data to fit the desired conclusions was limited to 'fixing' high school labs gone awry. I didn't realize it continues all the way up the food chain to researchers gathering raw data from sensors on mars.

      With examples like this, as a high school teacher, you will likely have to adjust how you teach/mark the class. With a prestigious outfit like nasa blessing the idea of fudging the data to fit the desired results, you surely cant mark down students for that concept anymore...

  2. Re:If... by Tethys_was_taken · · Score: 2, Interesting

    Even though the designs of the rovers are identical, the instruments themselves are not. The article says so. Each instrument was calibrated to behave properly in one rover. When the instruments were swapped, the readings from them were incorrect.

    --
    StrayByte.Net
  3. Cat calls from the cheap seats by amightywind · · Score: 4, Interesting

    Let the New Scientist criticize from the cheap seats. It is hard to argue that the rovers have been anything other than a resounding success for over 400 days. I would have hoped /. would instead print the recent story of the Spirit Rover discovering salty soil.

    --
    an ill wind that blows no good
  4. Re:nah... by Anonymous Coward · · Score: 1, Interesting

    Could explain how the solar panels were dusted earlier in the mission...

  5. Re:No big deal... by Aglassis · · Score: 5, Interesting

    "Compared to the fact that the rovers are still running long after they were expected to die, this is a tiny, tiny thing."

    Except for the fact that the same organization that made this error is designing other spacecraft. If they don't get to the root causes of the problem, like the failure of the technicians to properly follow the correct procedure to install the instrument and the failure of any other engineer or management to catch their failure to follow procedure, much larger problems could occur. Lets examine a couple of JPL's problem's in the last couple of years:

    Galileo: High power antenna failed to deploy resulting in a much lower data transfer rate. This was due to technical specifications in the lubrication of the antenna not being reviewed when the project was delayed.
    Mars Climate Orbiter: Burned up because the technical requirements were not met (converting from BES to metric).
    Mars Polar Lander: Lost on landing. Cause is not known. Project team was rushed in accordance with faster, better, cheaper plan.
    Genesis: Failed to deploy parachute and crashed on landing due to technical requirements not being met (backwards specification for G-force meters).
    Mars Exploration Rovers: Software glitch early in mission due to failure to test software for its entire expected lifespan. Instruments swapped due to failure to follow procedure.

    Some things we can get out of this analysis are that the QA was unsatisfactory. Procedures were not followed. Technical specifications were not verified. The culture was rushed (go-fever or product push environment). None of these are small problems, but they also point to much bigger problems: failure of the leadership to properly plan the project so that rushed timelines would not occur. This same culture is building new spacecraft. While JPL is a great agency and they do tremendous and incredible feats, they are not perfect and have lost several spacecraft and have had severe faults in others. These problems did not have to occur and more importantly these problems do not have to occur again in the future.

    --
    Suddenly, the hairy finger of a familiar monkey tapped me on the shoulder. It was time.--G. T.
  6. Re:No big deal... by Anonymous Coward · · Score: 2, Interesting
    Mars Exploration Rovers: Software glitch early in mission due to failure to test software for its entire expected lifespan. Instruments swapped due to failure to follow procedure.

    The Trashy Fucking File System (TFFS) has bitten many projects, and the response from WindRiver is "We can't fix it." Which they can't. They bought TFFS from someone else. And they can't fix it.. for some reason. It's really a pain in the ass and the "loss of a flash file system" happens infrequently enough that it is possible for it to pass QA.

  7. They should have... by chud67 · · Score: 2, Interesting

    ...put Burt Rutan in charge of the mission.

  8. Re:Root Cause by notmuchtosay · · Score: 2, Interesting

    Having taken a class from Squires as these rovers were being built, I know he was very aware of small problems being important. He explained how "small" problems caused failed missions in the past. Such as the previous mention of SI to imperial additionally not "testing as you fly."

    A more complicated mission? Landing two rovers utilizing air bags on another planet isn't complicated enough for you?

    He was the PI but he cannot be expected to observe everyone's work personally. This sort of thing should not need supervising.

    I agree this should have been caught with better testing of full rovers, but the launch windows cannot be merely pushed back. It was a time crunch the rovers and instruments performed well, the analysis was wrong.