back to article Are you aware of the gravity of the situation on Mars? Why yes, say boffins: We rejigged Curiosity to measure it

Brainiacs have today revealed how they rejigged instruments aboard NASA’s Martian rover Curiosity to measure changes in the Red Planet's gravity over its surface. "Curiosity, essentially, has a new science instrument, six and a half years into its mission," said Kevin Lewis, lead author of a published paper describing the …

  1. Anonymous Coward
    Anonymous Coward

    Is there a beer icon?

    Because the folks at NASA deserve one for this.

    Well done!

    Re. hacking accelerometers, do they work better at low temperatures?

    One would assume several effects interact including the "stiffness" of the beam(s) and noise in the measuring

    chips as well as frequency shift taking it outside the preset passband for the on chip filters.

    I might yet be able to put my vintage 2007 PS2 golf game sensor(s) to good use as these are an older type

    with analogue versus digital outputs so some rejigging might make them more sensitive at certain frequencies.

    A good method would be fluctuating the power supply using a feedback PID loop tuned to a harmonic of the on chip

    sensor drive (most likely in the low MHz range)

    1. phuzz Silver badge

      Re: Is there a beer icon?

      You need to have a forum account to be able to use the icons, so here's one for NASA on me >>>>>>

      1. John Brown (no body) Silver badge

        Re: Is there a beer icon?

        You need to have a forum account to be able to use the icons post. You just need to remember to NOT post as AC to use the icons.


    2. John Brown (no body) Silver badge

      Re: Is there a beer icon?

      "One would assume several effects interact including the "stiffness" of the beam(s) and noise in the measuring"

      You just average out and look for change over time. I remember many years ago noticing that my analogue joystick would drift out of centre alignment over time. So I wrote a quick programme to read the X and Y axis and graph it. It wasn't accurate and it wasn't to scale, but the (probably carbom track) pots made decent temperature sensors to at least show relative change over time as the room cooled at night when the heating had gone off. The NASA boffins don't need highly calibrated instruments for this new accelerometer usage, they just need a baseline and ways to filter and use the data showing the changes.

  2. SonOfDilbert

    Cried Alice:

    'Curiouser and curiouser!'

  3. Scott Broukell

    In say hundreds of thousands of years from now I can imagine that some alien species may well visit Mars, find all this rather crude and totally quaint equipment and repurpose all the landers into much sought after chic coffee tables.

    1. cd

      Perhaps a read of The Janitor On Mars is in order...

  4. JimmyPage
    Thumb Up

    Porous, you say ?

    so could hold water ?

  5. bombastic bob Silver badge

    or, once DID hold water. during formation [let's say], and probably not that long ago in terms of mars-a-logical history

    accelerometers read 1G in the direction of gravity (combined sum of all 3 axes on typical 3 axis accel) and so you can use them to determine the orientation of things. Re-purpose to use them to measure gravity differences is pretty smart. I've done coding with the angular position in the past, in that case for a surfboard, and did an interesting "video" of xyz plots to show what was happening over time. I'm guessing they take regular measurements of the IMU, now, and extrapolate the gravity changes from it.

    beer icon, of course!

    1. Tom 7 Silver badge

      I think one of the troubles with scientists is they did not spend enough time playing as children. I used to spend days playing in the dunes near my grandparents in Aberdeen and most of Mars can easily be created with sand and wind alone - no need for water. Its because we have a lot here that we tend to assume its necessary for there to have been some on Mars at some time, but even rocks can flow like a fluid to cause the erosion seem in many places and wind will layer sand to make sedimentary rock.

      The latest theories about earth's water (which doesnt match the isotope ratios of comets in the least) seem to suggest it may have been created in the hot depths of the earth, something that existed in Mars for a billion years leaving 3.5billion years of wind to create most of what we see now.

  6. fourth of three
    Thumb Up

    Push out s/w mods and they WORK

    Kudos to them all.

  7. arctic_haze

    We are so used to g = 9.8 m/s^2

    It would be fun solving school physics problems on Mars with g = 3.7 m/s^2

    1. Mr Benny

      Re: We are so used to g = 9.8 m/s^2

      Not as much fun as chucking a pencil at your mate and watching it go for another 100 metres out the window.

      1. Tom 7 Silver badge

        Re: We are so used to g = 9.8 m/s^2

        Is not golf the correct way to estimate gravity on non-earth bodies?

  8. Binra

    Is Big G truly a universal CONSTANT?

    Is Big G truly a universal CONSTANT?

    We have extrapolated a model of the Universe upon local conditions applying universally.

    Why does G vary on Earth - such as to be replaced by a mathematically mandated 'constant'?

    Note that the remote 'Ultima Thule' is also unexpectedly lacking mass and so also asserted to be surprisingly porous.

    What exactly is gravity and mass? Newton worked out mathematical laws or ratio and relation as describing the force. mass and actions but we do not understand what gravity is or how it operates. I am attracted to the theory that it is a function of dipolar alignments in electrically charged bodies which (like cells) have negatively charged surface relative to positively charged core. IE: Gravity as a weak but locally significant function of The electrical force.

    Ad hoc extensions to a model that does not meet its predictions in empirical observation only serve to make matters dark and lead us into black holes with corresponding budgets to search for the saviour of the MODEL - while a false not only leads astray, but denies the benefits of aligning in a true appreciation - in a broad spectrum of reintegrative alignment back from death by fragmented specialisations under a gov-corps narrative dictate.

    1. G Watty What?

      Re: Is Big G truly a universal CONSTANT?

      Has ' A man from mars' got a new account? Honestly, I was hoping for more insight.


      1. Anonymous Cowtard

        Re: Is Big G truly a universal CONSTANT?

        Do not feed the Binra.

        1. Tom 7 Silver badge

          Re: Is Big G truly a universal CONSTANT?

          We could feed him General Relativity and see if that helps.

  9. oomagoolies


    If they cant neasure gravity on earth who would believe they have a rover on mars that can........?????

    1. John Brown (no body) Silver badge

      Re: hahahaha

      They are not measuring gravity on Mars. They measuring the relative change in the effect of gravity at various altitude.

  10. Anonymous Coward
    Anonymous Coward

    RE. Re. Is there a beer icon?

    Found my ancient accelerometer stash: incidentally some older hard drives have them too.

    The one you want is an ADXLxxx with the metal cap.

    Also very handy for cooling as you can thermal Epoxy it to the Peltier stack and it will then work.

    Not sure if anyone remembers the early ones that came in a very strange package that looked a bit

    like an old DRAM chip but those were da schittz and feratured in an EPE article.

    Sadly these turned out not to be suitable as the thermal insulation ironically was too good.

    Also relevant: looks like dark matter got another blow when it was revealed that some of the early

    positive results were caused by helium leaking into the photomultiplier tubes.

    QI it is then.

    1. Conundrum1885

      Re: RE. Re. Is there a beer icon?

      Also useful: a lot of the early units were used in other devices.

      Charity shops can be a good source and did find my "missing" sensor but not sure if

      the glue is any good as I unwisely used baking soda as an encapsulant.

      If you do run into one of these the sensor looks like a small square puck with LGA pins.

      Be careful with it as they are very delicate and can't take a lot of heat so lotsa flux and preheat

      the board first.

      They are also found on some budget smart phones notably the Pixi 2 / 3.

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