Andrew Yee[_1_]
June 4th 08, 11:31 PM
News Service
University of Michigan
Ann Arbor, Michigan
Contact: Nicole Casal Moore
Phone: (734) 647-1838
June 2, 2008
U-M simulations predicted Mars lander would hit subsurface
ANN ARBOR, Mich. -- University of Michigan simulations correctly predicted
that the pulsed jets of the Mars Phoenix lander would strip the soil to the
subsurface ice or rock as the craft touched down.
Photos of the area beneath the craft on Friday revealed a hard surface that
scientists say may be ice. It could also be rock, and researchers won't know
until the Phoenix can dig into the dirt. But it's clear the craft cleared
away soil as it landed.
"This is exactly what was predicted by our group," said Nilton Renno, an
associate professor in the Department of Atmospheric, Oceanic and Space
Sciences. "We've seen the most amazing photos of the hard surface under the
thrusters. The brightness and smoothness suggests it is ice."
This would mark the first time a spacecraft has touched ice on another
planet, Renno said.
Renno and Manish Mehta, a doctoral student in the same department, performed
a series of tests for NASA over the past year in part to determine how the
lander would affect the place it touches down. Phoenix's pulsed jet steering
and braking system is unique.
Mehta performed the most recent simulations in April at NASA Ames Research
Center using properly-sized crushed walnut shells and other fine dust
particles to simulate the Martian soil. Mehta showed that the pulsed jets
could cause a different, more explosive erosion than the continuous jets of
the Viking spacecraft, which landed on Mars in 1976. The Phoenix landing
process involved thrusters firing in bursts to slow the craft and guide it.
"In our simulations, the pulsed jets excavated to the hard, icy surface
within less than a second. The pulses fluidized the bed under the thrusters,
so that the soil behaves like water," Mehta said.
These results were presented at the Phoenix Science Team Meeting at Tucson,
Ariz. on May 19 and a site-alteration report was submitted to JPL and
Lockheed Martin.
Mehta suggested to the Phoenix science team that they check under its deck
on Mars to find exposed ice.
Phoenix landed on Mars on May 25 and will spend the next three months
analyzing soil and ice to uncover the history of water on the planet. Its
mission is to determine whether the arctic plains there could support
microbial life.
Renno is a co-investigator on the mission and lead of the Atmospheric
Science Theme Group. He is studying the chemical composition of the soil and
clouds in effort to determine how much water Mars has today and had in the
past. Mehta is currently working on the reconstruction of the mission
landing with NASA engineers at JPL.
Related Links:
* Mars Phoenix Project
http://phoenix.lpl.arizona.edu/news.php
* U-M scientists simulate the effects of blowing Mars dust on NASA's Phoenix
lander
http://www.ns.umich.edu/htdocs/releases/story.php?id=5903
* U-M scientist says Mars winds could pose challenges -- but manageable ones
-- for NASA's Phoenix lander team
http://www.ns.umich.edu/htdocs/releases/story.php?id=5968
* Nilton Renno
http://www.ns.umich.edu/htdocs/public/experts/ExpDisplay.php?ExpID=1107
University of Michigan
Ann Arbor, Michigan
Contact: Nicole Casal Moore
Phone: (734) 647-1838
June 2, 2008
U-M simulations predicted Mars lander would hit subsurface
ANN ARBOR, Mich. -- University of Michigan simulations correctly predicted
that the pulsed jets of the Mars Phoenix lander would strip the soil to the
subsurface ice or rock as the craft touched down.
Photos of the area beneath the craft on Friday revealed a hard surface that
scientists say may be ice. It could also be rock, and researchers won't know
until the Phoenix can dig into the dirt. But it's clear the craft cleared
away soil as it landed.
"This is exactly what was predicted by our group," said Nilton Renno, an
associate professor in the Department of Atmospheric, Oceanic and Space
Sciences. "We've seen the most amazing photos of the hard surface under the
thrusters. The brightness and smoothness suggests it is ice."
This would mark the first time a spacecraft has touched ice on another
planet, Renno said.
Renno and Manish Mehta, a doctoral student in the same department, performed
a series of tests for NASA over the past year in part to determine how the
lander would affect the place it touches down. Phoenix's pulsed jet steering
and braking system is unique.
Mehta performed the most recent simulations in April at NASA Ames Research
Center using properly-sized crushed walnut shells and other fine dust
particles to simulate the Martian soil. Mehta showed that the pulsed jets
could cause a different, more explosive erosion than the continuous jets of
the Viking spacecraft, which landed on Mars in 1976. The Phoenix landing
process involved thrusters firing in bursts to slow the craft and guide it.
"In our simulations, the pulsed jets excavated to the hard, icy surface
within less than a second. The pulses fluidized the bed under the thrusters,
so that the soil behaves like water," Mehta said.
These results were presented at the Phoenix Science Team Meeting at Tucson,
Ariz. on May 19 and a site-alteration report was submitted to JPL and
Lockheed Martin.
Mehta suggested to the Phoenix science team that they check under its deck
on Mars to find exposed ice.
Phoenix landed on Mars on May 25 and will spend the next three months
analyzing soil and ice to uncover the history of water on the planet. Its
mission is to determine whether the arctic plains there could support
microbial life.
Renno is a co-investigator on the mission and lead of the Atmospheric
Science Theme Group. He is studying the chemical composition of the soil and
clouds in effort to determine how much water Mars has today and had in the
past. Mehta is currently working on the reconstruction of the mission
landing with NASA engineers at JPL.
Related Links:
* Mars Phoenix Project
http://phoenix.lpl.arizona.edu/news.php
* U-M scientists simulate the effects of blowing Mars dust on NASA's Phoenix
lander
http://www.ns.umich.edu/htdocs/releases/story.php?id=5903
* U-M scientist says Mars winds could pose challenges -- but manageable ones
-- for NASA's Phoenix lander team
http://www.ns.umich.edu/htdocs/releases/story.php?id=5968
* Nilton Renno
http://www.ns.umich.edu/htdocs/public/experts/ExpDisplay.php?ExpID=1107