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Space Science

Instrument on Mars Rover 'Spirit' Malfunctioning 22

Posted by michael from the get-out-and-fix-it dept.
deglr6328 writes "During the first in-flight checkout of both mars rovers this week it was found that the Mossbauer spectrometer on the first launched "Spirit" Rover was not functioning properly. The instrument is intended to be used on the surface of Mars to examine the composition and magnetic properties of Iron containing minerals in rocks. Mission engineers think they may be able to partially fix the spectrometer before it arrives in January. All other cameras and instruments on both rovers checked out ok."
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Instrument on Mars Rover 'Spirit' Malfunctioning More

Instrument on Mars Rover 'Spirit' Malfunctioning

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  • SSH... (Score:5, Funny)

    by jpsowin ( 325530 ) on Saturday August 09, 2003 @03:39PM (#6656136) Homepage
    I'm sure they'll simply logon to mars.spirit.nasa.gov via SSH and fix it. Recompile the kernel or something. ;)

  • I always wondered... (Score:3, Interesting)

    by neglige ( 641101 ) on Saturday August 09, 2003 @03:43PM (#6656148)
    Mission engineers think they may be able to partially fix the spectrometer before it arrives in January.
    How do they do that?! I mean, they can't reach up there, they can't physically fix anything. They can't turn that screw an inch to the left.

    Please, someone who knows, enlighten me... Can it really be done by making changes in the software (given that this is possible)?

    • Re:I always wondered... (Score:5, Informative)

      by deglr6328 ( 150198 ) on Saturday August 09, 2003 @03:59PM (#6656210)
      I'm not sure exactly how they plan to fix the spectrometer but I'm sure they're not lying when they say it's an option. Remember the Galileo space probe was recently fixed [216.239.51.104] from hundreds of millions of miles away. Since a Mossbauer spectrometer uses a moving radioactive source to take a spectrum I would guess it might be put through it's paces several times to try to work out a glitch(speculation). The Japanese Mars probe with a failing circuit breaker is currently undergoing repairs to fix [space.com] it remotely too.
      • I'm sure they're not lying when they say it's an option

        I didn't say they were lying, I honestly had no clue what they could do :) Thanks for the links, they were quite insightful. The solution for the Galileo probe was:

        Running current though the LED over time can push enough of the doping atoms back into their proper places that the widget will glow again.

        So its seems that one approach is to "stress" the suspected culprit hoping that it will start to work. Like starting up a motor again and again...
        • Another aproach is simply to try to figure out exactly what went wrong, and recalibrate. For instance, in the failed instrument they might have a sample of known copisition. Reading this might give them enough data to 'fix' the thing by massaging data returned from it.

      • Re:I always wondered... (Score:5, Informative)

        by QuantumFTL ( 197300 ) * on Sunday August 10, 2003 @03:26PM (#6660963)
        Note: I work on the Mars Exploration Rovers mission, developing Ground Data Systems software used by the scientists. I'm also completing a degree in Physics.

        I'm not sure exactly how they plan to fix the spectrometer but I'm sure they're not lying when they say it's an option. Remember the Galileo space probe was recently fixed from hundreds of millions of miles away. Since a Mossbauer spectrometer uses a moving radioactive source to take a spectrum I would guess it might be put through it's paces several times to try to work out a glitch(speculation).

        It's really quite amazing what can be fixed remotely, or at least worked around... If there's a significant mechanical problem with the instrument, however, there's not that much that can be done. From what I've heard, the Mossbauer on Spirit isn't currently getting data at full resolution, but they may be able to compensate for that by reprogramming the instrument remotely.

        In case you don't already know, the Mossbauer spectrometer is a rediculously cool instrument. The way it works is the following:

        According to elementary quantum physics, the energy levels of the nucleus are preturbed by the presence of nearby magnetic fields. Because electrons are charged fermions (and thus have nonzero spin), they have a dipolar magnetic field which can interact with the nucleus via hyperfine splitting. Hyperfine splitting is the creation of two or more distinct energy states from a single energy state via spin coupling. As an example, imagine a bar magnet which is held at the top of a one-foot drop. It has a very specific potential energy (in quantum physics energy is quantized and thus exists only in discrete amounts). Now, imagine that a uniform magnetic field is turned on in the lab room, pointing along the Z-axis (up/down). The bar magnet, if allowed to rotate, will want to minimize its energy by aligning itself antiparallel to the magnetic field (remember, opposites attract). To twist it into the "parallel" orientation, energy must be exerted, thus the single energy level of the bar magnet is now two distinct energies (in the quantum case, the difference between energy levels caused by hyperfine splitting is very small, hence the term "hyperfine"). This is a rough analogy to what's going on in the nucleus. Still with me? Good!

        Now, what does this have to do with the spectrometer? Well one of the most important pieces of information we can gather about rocks on Mars is their chemical composition. Most people are aware that Mars' rusty color is due to the high concentration of iron oxides on the surface. From high school chemistry we can remember that metals have multiple valence numbers they can use to bond with other atoms... It turns out that the electron configuration of the different bonds causes the electric and magnetic field from the electrons to vary significantly.... And if the magnetic field is varied, so is the hyperfine splitting! So... the nucleus itself is slightly affected by the valence shell geometry, among other things.

        So, how do we detect these differences in hyperfine splitting? That's where the Mossbauer spectrometer comes into play. The spectrometer contains two pieces of raioactive cobalt-57 (each about the size of a pencil eraser) as sources of gamma-radiation quanta. The cobalt-57 decays into an isotope of Iron with an excited nucleus. The excited nucleus quickly decays, emitting the exact gamma-quanta required to excite another iron nucleus. This gamma radiation exits the instrument and strikes a rock. Inside the rock iron nuclei absorb and re-emit the gamma radiation to be detected by the spectrometer.

        The variations in the energy levels in the iron in different chemical forms are just large enough that the addition of a dopplar shift to the radiation source allows us to detect it reliably. The radiation source slides towards and away from the target at specifically varying speeds, and because the gamma rays energy levels are changed slightly by the dopplar
        • Ah, sorry I forgot to mention in my plug that the newest version of SAP that can be downloaded is called "WITS for FIDO"... Don't let the acronyms fool you, it's essentially an older version of the same program, a flavor designed for "field tests" (simulated mars missions conducted out in remote locations on earth).

          The direct link (in case you have trouble finding it) is: http://wits.jpl.nasa.gov:8080/WITS/fido/index_htm l /releases [nasa.gov].

          The site is a little odd at first but once you get used to it, it's
        • "In case you don't already know, the Mossbauer spectrometer is a rediculously cool instrument..."

          I knew. :-)

          Your post was still very informative though, and the part about the software you're developing for the mission...cool!

          There is something I don't understand however. I thought that since the linewidth of metastable iron 57's hyperfine transition was so incredibly narrow that unless the nuclei are fixed in a crystal and the crystal lattice vibrations(phonons) are quantized by cooling it to cryogenic
        • elementary quantum physics... charged fermions... dipolar magnetic field... hyperfine splitting... spin coupling... energy is quantized... antiparallel... rough analogy... multiple valence numbers... valence shell geometry... gamma-radiation quanta

          Holy crap! I thought a Slurpee [bradfitz.com] brain freeze was bad enough!

          (Although I must admit, once I slowed down enough to read the terms, I really enjoyed the trip. Thanks!)
          • Yeah sorry about that... One of the issues with science is that the precise terminology often obfuscates communication with nonexperts... Not a lot that can be done about it except the creation of (usually cheezy) analogies. As I've been very b usy with my job lately I didn't have time to really formulate the post in the best possible way.

            I'm glad it made sense once you dug into it... that's what's truely important. Writing scientific explainations for a broad audience is extremely difficult and I hav
            • what exactly is "antiparallel"? Is it perpindicular? or something completely different?

              Other than that I've pretty much got the jist of what you were saying. You would have got me with anisotropic, but nth order perturbations and recoilless spontaneous emmissions would have been fine :-)
              • Antiparallel... well when we think of "parallel lines", they are just lines with the same slope. But what about vectors? I mean, if they point the same direction, they are obviously parallel. But what if they point in exactly opposite directions? Clearly the lines they lay on are parallel, but they are not! That would be what "antiparallel" means. Perpendicular is about half as far away from parallel as you can get. Antiparallel is the exact opposite (as the name implies.)

                FYI anisotropic means "h
        • Can I please mod this to "+6 Informative"??
          • Can I please mod this to "+6 Informative"??

            Ha ha ha... thanks but I've already got enough karma ;)

            I wonder though how informative the most really is... that is, how many of the people who read the post were actually informed. ANyone out there not understand what I said, can you tell me what didn't make sense to you?

            I don't think most /.ers have had a course in quantum physics (seems to be many more computer geeks than physics geeks here, unlike somewhere like bottomquark).

            Cheers,
            Justin
        • Great post. I dunno if you work with him, but Dr. Steven Squyers was my professor in college and he was so awesome (he's on the Mars team). His class was one of the best i'd ever taken in my life (also Dr. James Bell, also from Cornell and also involved with some Mars stuff, but not sure if he's on the rovers. he was on the cancelled 2001 Apex mission)
          • I work directly for Steve Squyres at Cornell, and I've also worked with Jim Bell before (although not so much any more).

            Squyres is quite a guy... I really love his management style... he keeps his nose out of things unless there's a big problem, then he dives right in :-D

            I wanna take one of his classes sometime but... doesn't look likely, as I'm so darn busy with everything else.

            Cheers,
            Justin

            P.S. Squyres is the Principle Investigator of the mission, which means he's in charge of the science end of

    • Re:I always wondered... (Score:1, Insightful)

      by Anonymous Coward

      Seems entirely possible that they could fix at least some things in software. It could be something that just requires them to program in some sort of compensation factor. Since they seem to think they can only partially fix the problem, then there may be hardware issues that they can't correct via software.

    • Re:I always wondered... (Score:1, Funny)

      by Anonymous Coward

      Simple. They just have to reroute the secondary plasma inducers through the aft buffer array. Problem solved!

    • Re:I always wondered... (Score:2, Interesting)

      by jwdg ( 676461 )
      Well, the article says:

      The remaining theories focus on an apparent problem in movement of a mechanism within the instrument that rapidly vibrates a gamma-ray source back and forth.

      "The Mossbauer spectrometer on Spirit is working, and even if we don't come up with a way to improve its performance, we'll be able to get scientific information out of the data it sends us from Mars," Squyres said. "But it's a very flexible instrument, with lots of parameters we can change. We have high hopes that over the

  • Regardless (Score:2, Interesting)

    by MacEnvy ( 549188 )
    I think that even if the spectrometer is only partially fixed, it could provide good data to scientists here on the ground - not to mention the dozen other sensors. From other reports (CNN, NYTimes), people are talking about this as "another one of NASA's failures". Not at all, the mission can be 95% successful even without this particular iron spectrometer.

    Go NASA! Kick some ESA ass!

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