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Posted by: pioneer May 7 2008, 01:47 PM

What effect, if any, will the dust devils have on the landing of Phoenix? Do they pose any threat?

Posted by: djellison May 7 2008, 03:12 PM

That statistical likelihood of Phoenix being near a dust devil during landing is so close to zero as being not worth considering.

Even if it WERE to encounter one during landing - it would be during terminal decent under the thrusters, and to be honest, I can't imagine it having much, if any, impact on vehicle dynamics.

Doug

Posted by: dvandorn May 7 2008, 03:21 PM

Also, dust devils are *not* ubiquitous across the Martian globe. They only occur in specific places on Mars where conditions are right for them -- and you can fairly easily tell where they roam, they leave distinctive tracks.

I see no indication of any dust devil tracks anywhere in *any* of the images of Phoenix's landing site. In fact, I don't recall seeing anything resembling dust devil tracks in any of the pictures of any of the *potential* Phoenix landing sites.

I rather get the feeling that worrying about dust devils at a polar Martian site is somewhat like expressing concern over interference by hurricanes during a Soyuz landing in the Kazakh steppes. Yes, you do get hurricanes on Earth -- but never on the steppes. I'm fairly confident in saying that dust devil weather conditions on Mars are similar -- you get them, but not in polar climes.

-the other Doug

Posted by: elakdawalla May 7 2008, 03:32 PM

oDoug, pioneer should probably have posted links to these when he opened the topic so we'd all be on the same page:

http://www.msss.com/msss_images/2008/05/06/

http://www.planetary.org/blog/article/00001416/

I agree that the dust devils pose no specific threat. And they're part of a fairly well understood pattern of the polar response to the coming of spring.

Still, I'm a bit curious to know what the Phoenix team's models say about the amount of dust that is fluttering around in the air, and at what rate it's likely to settle on the solar panels. I don't think dust will pose a problem during the primary mission, but since the life of the lander is strictly limited by power as the Sun sinks toward fall, dust will probably be an important factor in how long the lander clings to life.

--Emily

Posted by: dvandorn May 7 2008, 04:47 PM

Interesting! Says something about the surface conditions that a dust devil can sweep the surface and not change its albedo noticeably...

-the other Doug

Posted by: Stu May 8 2008, 06:59 AM

Hmmm... might mean some interesting sky effects.. a low arctic sun, plus icy clouds, plus dust in the air... might mean some nice solar haloes, sundogs and optical phenomena for Phoenix to observe and send us back pretty pictures of...

Posted by: ustrax May 8 2008, 11:48 AM

Hey Doug where are you? We're live on spacEurope now and your (and all of you guys...) questions are certainly required...