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NASA Space Science

Mars Probe Brings the "Weather Rock" New Respect 144

Posted by timothy from the if-tail-is-wet dept.
radioweather writes "What looked to casual observers like a malfunction, a dangling wire with something on the end, seen in the first photo of the meteorological mast on NASA's Phoenix Mars Lander, actually turned out to be the real instrument. Surprisingly, it is much like the novelty 'weather rock' seen as a novelty gag around the world. The instrument called the 'Telltale' is described as a 'passive wind indicator' and uses an extremely lightweight Kapton tube hanging in Kevlar fiber. Images taken of the instrument will show the deflection of the Telltale due to the Martian wind."
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Mars Probe Brings the "Weather Rock" New Respect More

Mars Probe Brings the "Weather Rock" New Respect

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  • I have this rock (Score:4, Funny)

    by morgan_greywolf ( 835522 ) * on Tuesday May 27, 2008 @10:37AM (#23556891) Homepage Journal
    It picks winner of any sports game, series, etc., everytime, in advance.

    Yours for only 5 easy payments of $19.95!

    The Sports Bookie Rock.

    Get yours now!

  • AOD (Score:5, Funny)

    by Stanistani ( 808333 ) on Tuesday May 27, 2008 @10:38AM (#23556901) Homepage Journal
    Fascinating. This may be the first time 'angle of dangle' could be used in an actual scientific context.

  • Don't you hate it when... (Score:5, Insightful)

    by tiedyejeremy ( 559815 ) on Tuesday May 27, 2008 @10:38AM (#23556903) Homepage Journal
    Don't you hate it when... Simple makes sense?

    • Re:Don't you hate it when... (Score:5, Insightful)

      by krog ( 25663 ) on Tuesday May 27, 2008 @10:40AM (#23556933) Homepage
      The windsock is pretty tough to beat.

      • Re: (Score:3, Funny)

        by tgd ( 2822 )
        Ack, I thought you said WINSOCK and was about to disagree strongly.

    • Re:Don't you hate it when... (Score:4, Insightful)

      by magarity ( 164372 ) on Tuesday May 27, 2008 @10:41AM (#23556975)
      Hate it? Not at all. I love it when a government financed project provides simple yet effective solution.
  • Simon and Garfunkle fans think.. The answer my friend is blowing in the wind...

  • New-old fashioned "Science" (Score:3, Funny)

    by TJ_Phazerhacki ( 520002 ) on Tuesday May 27, 2008 @10:40AM (#23556957) Journal
    Wonder if they included some good old fashioned Dowsing Rods to find water too?

    • Dowsing rods don't detect anything (Score:5, Informative)

      by CustomDesigned ( 250089 ) <stuart@gathman.org> on Tuesday May 27, 2008 @11:24AM (#23557625) Homepage Journal
      A dowsing rod doesn't actually detect anything (even according to practitioners) - it is simply a device to magnify subconscious body language of the operator. The theory is that the human operator detects water via poorly understood senses below conscious awareness. Some dowsers don't bother with the rods, claiming to have trained themselves to become more aware of these senses.

      I know I "see" something like a flash of light whenever someone turns on a fluorescent light with magnetic ballast in another room - so I don't think the idea of additional senses is completely crazy.

      • Re: (Score:3, Insightful)

        by gardyloo ( 512791 )
        Dowsing rods actually do an awfully good job at detecting idiots!

        • Re: (Score:2, Insightful)

          by mopower70 ( 250015 )
          Geez mods! You mark a guy "Funny" who has an extra sensory experience due to the influence of a remote magnetic ballast, and then mod the oldest dowsing rod joke on the planet as "Insightful"? Not sure where you're going with that roll...

      • Re: (Score:3, Funny)

        by SpydeZ ( 1196075 )

        I know I "see" something like a flash of light whenever someone turns on a fluorescent light with magnetic ballast in another room.
        And I thought I was the only one who saw light when someone turn on the lights...

      • I know I "see" something like a flash of light whenever someone turns on a fluorescent light with magnetic ballast in another room - so I don't think the idea of additional senses is completely crazy.

        I know a guy [randi.org] who might be willing to give you a million dollars if you can demonstrate this ability under controlled conditions.

      • Re: (Score:2)

        by achurch ( 201270 )

        I know I "see" something like a flash of light whenever someone turns on a fluorescent light with magnetic ballast in another room - so I don't think the idea of additional senses is completely crazy.

        Actually, that'd probably just be noise from the current spike--sort of like the click you can hear from a speaker in the same circumstances.

    • Re: (Score:2)

      by Gilmoure ( 18428 )
      My uncle doesn't need rods, sticks or wires to find water. He just holds out his hands and witches it. Talking to a civil engineer in New Mexico, am amazed how many business still do water searches this way.
      • I don't either.

        I go to the tap and turn it on.

        It's like magic.

        No, really, to most of the world throughout history, it really is like magic.

        • Re: (Score:2)

          by Gilmoure ( 18428 )
          When it came time to drill a well on my property, he thought it was weird I picked up some geo survey charts and looked at where nearby wells were located. Figured out there was a bunch of decent wells in a line that matched an underground fault and we hit water first try, with a depth right in line with the other wells. It was like magic!
  • Why didn't they put in a lightweight weather vane with a small fan? That way they could tell direction and velocity. With the rock you can basically gauge the initial wind, but once it starts swinging in the opposite direction its practically impossible to tell if the deflection is from an opposing wind or merely the pendulum swinging. It becomes even more useless if there are sudden changes in wind speed/direction since it will just seemingly bounce round in random directions none of which are reflective o

    • Re:Why not a weather vane? (Score:5, Insightful)

      by desenz ( 687520 ) <roypfohNO@SPAMgmail.com> on Tuesday May 27, 2008 @10:48AM (#23557067)
      It definitely wins in the durability department. Dust is a real problem on mars, so wherever that weather vane pivots would have to be sealed up pretty tight.
      • they're called fines and gets into all our equipment, even in the pressure domes you need eye drops and you can just taste the dust. Once the next few water-heavy asteroids come in, the pressure will raise and hopefully the fines will bind to the water vapor volume and form clouds eliminating part of the problem.

    • Re:Why not a weather vane? (Score:4, Interesting)

      by TheRedSeven ( 1234758 ) on Tuesday May 27, 2008 @10:50AM (#23557101)
      From TFA:

      The Telltale consists of a gallows that is mounted on the top of the Meteorological Mast of the Lander. The active element of the instrument is an extremely lightweight Kapton tube hanging in Kevlar fibres. Images taken of the instrument will show the deflection of the Telltale due to the wind. A mirror is mounted below the active part to enable better direction information. (My emphasis)
      The wonderful addition of a high-tech "mirror" allows multiple perspectives that would allow you to detect direction. Looks like some overpaid engineer already thought of this.

      When you're sending something into orbit or further, payload weight is a concern. Cutting weight, moving parts, and simplifying things is generally a good idea on this sort of thing.

    • Re:Why not a weather vane? (Score:5, Interesting)

      by hcpxvi ( 773888 ) on Tuesday May 27, 2008 @10:50AM (#23557105)
      Remember that the surface air pressure on Mars is very small compared to on Earth. So you need a much lighter and more delicate instrument for the air to be able to move it. Anything resembling a traditional weather vane would probably not respond to the tenuous Martian breezes. Even if it worked at first, it might well get stuck after the first of those Martian dust storms blew dust into its pivot. Disclaimer: Yes I am a meteorologist. No, I have not been to Mars or worked on any instrument that went there.

      • Re: (Score:2)

        by Robert1 ( 513674 )
        I think you're wrong on the first point. I feel like it wouldn't be that hard to make a very very lightweight weathervane, maybe even made of foil. I do think you're spot on with your second point though, the pivot would seem to be the limiting factor.

        Thanks for answering the question.

        • Re:Why not a weather vane? (Score:4, Insightful)

          by Profane MuthaFucka ( 574406 ) <busheatskok@gmail.com> on Tuesday May 27, 2008 @11:23AM (#23557601) Homepage Journal
          Great, Now make your nice lightweight fragile weathervane survive 9g's of reentry and almost that amount on launch, plus numerous bumps at various times in the mission.

          Touchdown on the Mars Surface was 5 miles an hour. How hard could it be. Now, crash your Toyota into a wall at 5 MPH and you might find that the 5 MPH bumpers really only work at 4.95 MPH. Oops.

          It's easy to make a lightweight weathervane. It's hard to make a lightweight weathervane, get it to Mars, and still have it in working order.

      • No, I have not been to Mars or worked on any instrument that went there.


        Thanks for clearing that up. I was wondering. :-)

      • Re: (Score:3, Interesting)

        by dargaud ( 518470 )
        I wonder why they don't use a sonic anemometer: precise, works in any conditions and at any wind speed, no mechanical parts and it can take fast readings several times per second to measure turbulence. Yes, I've operated one in Antarctica [gdargaud.net].

        • Re: (Score:3, Insightful)

          by DerekLyons ( 302214 )
          Because a sonic sonic anemometer requires power, calibration, and computer cycles. A windsock doesn't.
    • A weather vane requires a free moving bearing or bushing which would not do well in a dusty/gritty environment like Mars.
    • Two reasons

      1) Reliability, there is bugger all that can go wrong with a tell tale
      2) Weight, a vane and a fan are going weigh grams more than the tell tale and when sending something to Mars those things count.

      Personally I love this sort of engineering you can almost imagine the meeting

      "We've got 5 grams and we need to tell where the wind is coming from"
      "Weather, vane with a fan?"
      "Nope to heavy"
      "Hang on how about just something hanging down from a stick"

      And thus extensive engineering and testing was born (it

    • Re: (Score:2, Funny)

      by Anonymous Coward
      well, the rock can tell you if it is raining outside, foggy, and cold...all from the rocks tactile interface...

      raining, rock is wet
      foggy, hard to see the rock
      cold, rock has ice on it...

    • Re:Why not a weather vane? (Score:5, Funny)

      by Scratch-O-Matic ( 245992 ) on Tuesday May 27, 2008 @11:15AM (#23557501)
      That's why I read Slashdot, so I can find innovative and workable solutions that were dreamed up after five minutes of consideration, rather than wasting time observing and learning about the decades-long efforts of a bunch of idiot engineers who have no friggin idea how to design, launch, navigate, land, and operate an interplanetary exploration robot.

    • Re: (Score:3, Interesting)

      by pz ( 113803 )
      Design choices:

      (a) tell tale: simple; robust to launching forces; reliable; lightweight; works well as long as winds are relatively constant; works poorly if winds are turbulent; gives wind speed AND direction

      (b) weather vane: has moving parts including bearings that require protection from the elements; delicate structure that needs to be made robust to launching forces; heavier than tell tale; works well in any winds, although the mass of vane averages, and therefore can mask, turbulence; unless paired wi

    • Re:Why not a weather vane? (Score:4, Interesting)

      by pz ( 113803 ) on Tuesday May 27, 2008 @11:40AM (#23557883) Journal
      The kapton tube does not swing in response to wind, it just deflects. The stronger the wind, the more it deflects. Imagine that it's a spring. Ever seen a car's radio antenna flex on the highway? Same idea.

      Insects use exactly the same sort of mechanism to detect gentle air movements. This is one reason it's so hard to catch a fly with your hand when the fly has landed somewhere: the air currents generated by your comparatively large and slow-moving hand are easily detected by the fly.

    • Re: (Score:3, Interesting)

      by WebCowboy ( 196209 )

      Why didn't they put in a lightweight weather vane with a small fan?

      Actually a vane and fan is inferior for this particular purpose. This "rock on a string" can be used to determine both direction and intensity of winds just as well, plus it is lighter and mechanically less complex than a vane and fan--important in the very cold and dusty environment on Mars. The rotating parts would more easily wear, freeze or seize up more easily in such an environment.

      With the rock you can basically gauge the initial wind, but once it starts swinging

      If a wind is sustained the rock would not swing. Furthermore sensors and computer analysis of the motion can provide

    • Re:Why not a weather vane? (Score:5, Funny)

      by mazarin5 ( 309432 ) on Tuesday May 27, 2008 @12:27PM (#23558631) Journal

      but once it starts swinging in the opposite direction its practically impossible to tell if the deflection is from an opposing wind or merely the pendulum swinging.
      Because the motion of a simple pendulum is one of the last great unsolved problems in physics?

      • Re: (Score:2)

        by dbIII ( 701233 )

        Because the motion of a simple pendulum is one of the last great unsolved problems in physics?

        Instead of physics here you can use the dark mysteries of the Foucault :)

  • It's called a 'wind sock' (Score:5, Informative)

    by Chris Burke ( 6130 ) on Tuesday May 27, 2008 @10:51AM (#23557123) Homepage
    And they already had enough respect as a simple form of wind indicator. You may have seen one at an airport, for example. It's not a weather rock.

    See, the point, or "joke" as it were, of the weather rock is that it can't actually tell you anything you wouldn't have already known due to your own senses. "If it's wet it's raining, white it's snowing, bouncing and there's an earthquake." But you could tell all those things without the rock... get it?

    A wind sock isn't very sophisticated, but it tells us things that wouldn't have been as apparent without it.

    • Re: (Score:3, Informative)

      by jrumney ( 197329 )
      They're calling it a telltale, which from the description sounds more accurate than windsock, as a telltale is not hollow. Telltales (usually thin strips of nylon, sometimes on smaller yachts just bits of string) are used on the leading and trailing edges of sails to indicate the flow of air over and off the sail.
      • They're calling it a telltale, which from the description sounds more accurate than windsock, as a telltale is not hollow.

        Well they're saying it's a 'tube', which to me implied a hollow sheath of material like a wind sock. Looking at the pictures, it looks like a tube handing from a string, but it's hard to tell if it's hollow or not.

        Either way, it's an actual time-tested instrument, not a joke like the weather rock.

    • A wind sock isn't very sophisticated, but it tells us things that wouldn't have been as apparent without it.

      To elaborate on Chris' comment: A wind sock will "inflate" about half way with about a 7 mph wind speed. It will inflate fully with a 12-15 mph wind speed. It also rotates to indicate the direction of the wind. When observed over time, it can indicate the variability of the wind. For example, is it gusty or is the wind direction frequently changing.

      Simple, but quite effective. One of the last things pilots check for when landing is the wind sock to see if we will need to prepare for a more "stimulatin

  • Telltale's (Score:4, Informative)

    by penguinstorm ( 575341 ) on Tuesday May 27, 2008 @10:53AM (#23557165) Homepage
    Telltales have long been used in sailing. Most sails have some visible.

    http://en.wikipedia.org/wiki/Tell-tale [wikipedia.org]

    That they are incredibly rudimentary and primitive does not diminish their usefullness, provided they're used for what they're meant for. They're not going to predict anything, for example.

    • Re: (Score:3, Informative)

      by Scratch-O-Matic ( 245992 )
      In case anyone is interested, a telltale in sailing is used to properly shape the sail for smooth airflow over the airfoil created by the sail, rather than for determining the direction or strength of the wind.
  • I think I saw this somewhere in a textbook. I believe it was when Spain was looking for a new route somewhere... oh ya! that is in 1600's my bad. They used that to find wind I forgot, NASA=Outdated. I guess they will use Dowsing Rods.
    • You do realize that most airports have windsocks up to help determine current conditions? Or that every single firing range out there has a flag to indicate when it's safe to fire? The people who are actually marksmen (I was, when I was in the military) use the flag as a windsock to determine weather conditions and adjust their firing.

      I'm not saying that there's going to be airports or a firing range set up on Mars. But the point is that there's modern applications for a windsock/telltale/weather vane. They
    • Obviously NASA should use GPS to detect wind.

  • Martian weather forecasting rock (Score:5, Funny)

    by mikael ( 484 ) on Tuesday May 27, 2008 @10:58AM (#23557227)
    Martian weather forecasting rock

    o Rock has dust on it - there has been a martian sand storm

    o Rock is swaying back and forth slighly - a martian sand storm is brewing

    o Rock cannot be seen - there is a martian sand storm

    o Rock is white - there is frozen water on Mars

    o Rock is levitating - There is a UFO with an anti-gravity beam

    o Rock is floating - Rock is in orbit around planet

    o Rock has gone - UFO has been here and removed rock

    • Re: (Score:2)

      by elrous0 ( 869638 ) *
      Bah, rock left when Elvis died.

    • Re: (Score:3, Funny)

      by Luyseyal ( 3154 )
      o Rock has dust on it - there has been a martian sand storm

      o Rock is swaying back and forth slighly - a martian sand storm is brewing

      o Rock cannot be seen - there is a martian sand storm

      o Rock is white - there was a martian sand storm

      o Rock is levitating - caution: martian sand storm

      o Rock is floating - seriously, you guys, martian sand storm

      o Rock has gone - martian sand storm

  • Can't wait... (Score:5, Funny)

    by slashname3 ( 739398 ) on Tuesday May 27, 2008 @10:58AM (#23557235)
    I can't wait for the first manned landing with the first weather report from Mars. "Well it looks kind of windy, hold on, let me take my glove and helmet off so I can lick my finger and hold it up to get a measurement of what direction the wind is blowing...." "POOF!" "ARRRGGGGGG!"

    "Mars base, this is Houston, over"
    "Mars base, this is Houston, over"
    "Damn, I think we lost another weatherman..."

  • Obligatory (Score:3, Funny)

    by FurtiveGlancer ( 1274746 ) <.moc.loa. .ta. .yuGhceTcoHdA.> on Tuesday May 27, 2008 @10:58AM (#23557241) Journal
    Thank you for bringing us this "Telltale tale."
  • We were at the beach Everybody had matching towels Somebody went under a dock And there they saw a rock It wasn't a rock It was a rock lobster!
  • Condition______________________Forecast
    Stone is Wet___________________Liquid Water on Mars!
    Stone is Dry___________________Mars Still a Frozen Desert
    Shadow on Ground_______________Sunny
    White on Top___________________Well, We Did Land At The North Pole
    Can't See Stone________________Dusty, or Phoenix Broken
    Swing Stone____________________Windy
    Stone Jumping Up and Down______Marsquake
    Stone Gone_____________________Aliens
  • So they hung a string from a pole and called it a 'wind-measuring device'

    Yeah, it's great and works really well, but did they really need the 'extremely lightweight Kapton tube hanging in Kevlar fiber'

    How about a bit of fishline?

    No troll, why did they need something so sophisticated? The martin environment is hostile, and the string would need to be awfully light, but why wouldn't a bit of reflective fishline work? It'd hold up pretty well...

    And before I say this, let me say that I think NASA needs to be gi

    • How about a bit of fishline?

      Ever put a match on fishline? - it burns..:

      From the Kapton manufacturers website [dupont.com]:

      DuPont has set a high standard in the polyimide film markets with its durability and performance in extreme temperature environments.

      Use the right material for the job - remember this is rocket science.

    • Traditional fishing line has issues with cold. Dunno about the braided "superlines" that don't stretch... but then those are extremely thin compared to regular line....
    • But how much did they spend on this 'extremely lightweight Kapton tube hanging in Kevlar fiber', that looks like it could be replaced with fishline?

      Kapton and Kevlar are both used in aerospace engineering. Kevlar is often used to sheath fiber optic cables and in composites. According to Wikipedia, Kapton is used as an aerospace (electrical) insulator and plastic structural support in space. Know what? Being aerospace engineers and all, in a lab environment, they might have just had this stuff lying aroun

    • Re: (Score:2)

      by amorsen ( 7485 )

      But how much did they spend on this 'extremely lightweight Kapton tube hanging in Kevlar fiber', that looks like it could be replaced with fishline?
      The instrument was built and paid for by the University of Aarhus in Denmark. Also, I would imagine that the cost of sending things to Mars is rather high, so it could easily be worth it to spend a little more on materials to save on fuel.
  • ...cause it took a CD up with it containing Earth's greatest hits!
    http://fawkes4.lpl.arizona.edu/images/gallery/lg_532.jpg [arizona.edu]

    Either that, or Apple's scored a deal with NASA to lock in the Martian music market...
  • When racing sailboats, every little of winds counts. You can see strong winds coming over the water at a distance, but the ones next to you are difficult to make out. So, you fix small feathers to strong lightweight thread to the fore, side and back stays, and it becomes possible to see the wind as it shifts around. Including watching how your sail impacts the wind. Obviously when the winds are 20-60 mph, nobody will care, but the light 1-15 is very important. It use to makes the difference of wether you ca

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