Mars Probe Brings the "Weather Rock" New Respect
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."
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.
Quite difficult, but it is being planned...
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