Polygons on Mars


The Phoenix Mars Lander arrived safely on Mars Sunday night! This is a particularly big deal because the previous Lander didn’t: the Mars Polar Lander was due to arrive on Mars in December 1999 but, for still-unknown reasons, communications stopped suddenly about 6 minutes before it was due to enter the Martian atmosphere and its exact whereabout remain unknown. (Incidentally, the Polar Lander was part of the Mars Surveyor mission. The other part was the Mars Climate Orbiter, which ran into a little $125 million problem of its own when the teams didn’t translate between imperial and metric units.)

But back to the Phoenix Lander: the Phoenix had no trouble, landed perfectly, and is already sending back pictures. Our newspaper this morning showed the following photo of polygons on Mars:

The newspaper made a big deal about the fact that there were polygons and when I looked at the picture my response was along the lines of, “Umm. Okay.” But then I found NASA’s image page and the caption for this picture explains that this polygonal pattern is “similar in appearance to icy ground in the arctic regions of Earth”. So then I went to My Favorite Source and found this photo from Canada’s Northwest Territories (taken by Emma Pike), where the polygons are more noticeable:

The polygons are formed by water getting in cracks, freezing, and then expanding. When it gets cold enough (-17°C, or close to 0°F) the ice contracts rather than expands, and that leaves even bigger cracks (called ice wedges) for more water to get in, etc. So finding polygons on Mars could be a big deal indeed.

There was also another neat NASA picture of the Phoenix Lander landing:

You can see the parachute and everything! According to the the FAQ page at the University of Arizona:

Phoenix is very grateful to the Mars Reconnaissance Orbiter (MRO) team for that otherworldly picture. It was very, very good math. MRO was moving about 3.4 km/sec (30,000 mph). Phoenix, at the time of parachute deployment, was moving between 700-130 mph.

Hooray for very, very good math and for the Phoenix Lander!


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One Response to “Polygons on Mars”

  1. yehiel Gotkis Says:

    Well, I should keep in mind that many solid structures which passed in their history liquid phase (freezing, crystallization etc.) were subjected to Marangoni-Bernard convectional structuring, which shapes the near surface structure of the liquid, and, after the phase transition occurs, the solid phase formed. Some of the images presented, to my opinion, could be, and most probably were, shaped by the pre-crystallization convective motion in the liquid.


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