[meteorite-list] NASA's Phoenix Lander Might Peek Under a Rock

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon, 22 Sep 2008 14:11:36 -0700 (PDT)
Message-ID: <200809222111.OAA29982_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.cfm?release=2008-177

NASA's Phoenix Lander Might Peek Under a Rock
Jet Propulsion Laboratory
September 22, 2008

TUCSON, Ariz. -- If the robotic arm on NASA's Phoenix Mars Lander can
nudge a rock aside today, scientists on the Phoenix team would like to
see what's underneath.

Engineers who develop commands for the robotic arm have prepared a plan
to try displacing a rock on the north side of the lander. This rock,
roughly the size and shape of a VHS videotape, is informally named
"Headless."

"We don't know whether we can do this until we try," said Ashitey Trebi
Ollennu, a robotics engineer at NASA's Jet Propulsion Laboratory,
Pasadena, Calif. "The idea is to move the rock with minimum disturbance
to the surface beneath it. You have to get under it enough to lift it as
you push it and it doesn't just slip off the scoop."

The lander receives commands for the whole day in the morning, so
there's no way to adjust in mid-move if the rock starts slipping.
Phoenix took stereo-pair images of Headless to provide a detailed
three-dimensional map of it for planning the arm's motions. On Saturday,
Sept. 20, the arm enlarged a trench close to Headless. Commands sent to
Phoenix Sunday evening, Sept. 21, included a sequence of arm motions for
today, intended to slide the rock into the trench.

Moving rocks is not among the many tasks Phoenix's robotic arm was
designed to do. If the technique works, the move would expose enough
area for digging into the soil that had been beneath Headless.

"The appeal of studying what's underneath is so strong we have to give
this a try," said Michael Mellon, a Phoenix science team member at the
University of Colorado, Boulder.

The scientific motive is related to a hard, icy layer found beneath the
surface in trenches that the robotic arm has dug near the lander.
Excavating down to that hard layer underneath a rock might provide clues
about processes affecting the ice.

"The rocks are darker than the material around them, and they hold
heat," Mellon said. "In theory, the ice table should deflect downward
under each rock. If we checked and saw this deflection, that would be
evidence the ice is probably in equilibrium with the water vapor in the
atmosphere."

An alternative possibility, if the icy layer were found closer to the
surface under a rock, could by the rock collecting moisture from the
atmosphere, with the moisture becoming part of the icy layer.

The Phoenix mission is led by Smith at the University of Arizona with
project management at NASA's Jet Propulsion Laboratory in Pasadena,
Calif., and development partnership at Lockheed Martin in Denver.
International contributions come from the Canadian Space Agency; the
University of Neuchatel, Switzerland; the universities of Copenhagen and
Aarhus in Denmark; the Max Planck Institute in Germany; and the Finnish
Meteorological Institute.

For more about Phoenix, visit: http://www.nasa.gov/phoenix or
http://phoenix.lpl.arizona.edu

------------------------------------------------------------------------

Media contacts: Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster at jpl.nasa.gov

Dwayne Brown 202-358-1726
NASA Headquarters, Washington
dwayne.c.brown at nasa.gov

Sara Hammond 520-626-1974
University of Arizona, Tucson
shammond at lpl.arizona.edu

2008-177
Received on Mon 22 Sep 2008 05:11:36 PM PDT