Phoenix mission to Mars will search for climate clues (Forwarded)

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May 21, 2008

Phoenix mission to Mars will search for climate clues

How green is their valley?

By Tony Fitzpatrick

On May 25, 2008, approaching 5 p.m. PDT, NASA scientists will be
wondering: Just how green is their valley?

That's because at that time the Phoenix Mars Mission space vehicle will be
touching down on its three legs to make a soft landing onto the northern
Mars terrain called Green Valley.

Of course, no valley is actually green on the Red Planet. The place got
its name after analysis of images from Mars Reconnaissance Orbiter's
HiRISE instrument. HiRISE can image rocks on Mars as small as roughly a
yard and a half across. Green is the color that that landing site
selection team used to represent the fewest number of rocks in an area,
corresponding to a desirable place to land. Thus, "green valley," a
relatively rock-less region, is a "sweet spot" where the Phoenix
spacecraft will land.

Peter Smith of the University of Arizona is principal investigator for the
mission.

Also playing a key role in the Phoenix Mars mission is Raymond E.
Arvidson, Ph.D., the James S. McDonnell Distinguished University Professor
and chair of the earth and planetary sciences department in Arts &
Sciences at Washington University in St. Louis.

Arvidson has extensive experience in planetary landing operations. He
participated in the two Viking Lander missions in 1976 and has spent the
past four years, first helping select the landing site for the 2004 Mars
Exploration Rover (MER) mission, then guiding the activities of the rovers
Spirit and Opportunity as the mission's deputy principal investigator.
Accordingly, Arvidson is NASA's Phoenix landing site working group chair.
He also is the co-investigator for the Phoenix robotic arm, a crucial
instrument that will collect soil and ice samples; the lead for archiving
mission data, and a key science lead for the first week of surface
operations.

Phoenix will touch down in Green Valley with the aid of a parachute, retro
rockets and three strong legs with shock absorbing footpads to slow it
down.

That's sol (a Martian day) zero.

"We'll know within two hours of landing if Phoenix landed nominally," said
Arvidson. "It will land, deploy its solar panels, take a picture and then
go to bed."

The next day, Sol 1, begins a crucial period of operations for the
mission. Arvidson said, "We'll be checking out the instruments and begin
robotic arm operations within about a week, if everything goes well, and
collect soil and ice samples over the summer for analyses with the
on-board instruments."

Phoenix will dig to an ice-rich layer expected to lie within arm's reach
of the surface. It will analyze the water and soil for evidence about
climate cycles and investigate whether the environment there has been
favorable for microbial life. It also carries a weather station to monitor
changes in the atmosphere. The primary mission is brief, just 90 days.

Martian weather channel

That first tense, exciting, crucial day, four Washington University
students will work with Arvidson at the University of Arizona. Two of
them, sophomore Kirsten Siebach, and junior Rebecca Greenberger, are
Fossett Fellows, a scholarship program established at WUSTL by the late
adventurer J. Steven Fossett. A third, Tabatha Heet, will have just
graduated with a bachelor's degree nine days earlier, and WUSTL doctoral
candidate Selby Cull will be present as well. Thomas C. Stein, a WUSTL
computer systems manager, will work with the Phoenix geology theme group
and also archive data for NASA's Planetary Data System.

The four students are Phoenix Mission documentarians, responsible for
recording all that is done on the mission and for informally naming
geological sites in the area.

Heet played a key role in counting rocks in HiRISE images to enable a safe
landing for Phoenix. She began the rock measurement and counting project
in October of 2006.

Both Heet and Arvidson are excited to have the mission so close at hand
after years of planning.

"It's still very exciting," the veteran Arvidson said. "This is a new
place on an intriguing planet, and we can't wait to see what we'll find."

[NOTE: A video supporting this release is available at
http://news-info.wustl.edu/tips/page/normal/11767.html ]