NASA's Phoenix Mars Lander is one
step closer to analyzing a sample of the rock-hard layer of ice underneath the
Martian dirt where the spacecraft touched down two months ago.
Overnight Tuesday to Wednesday, Phoenix
used its robotic arm to scrape the top of the icy layer in the trench
informally known as Snow White.
Mission controllers prepared commands to
send to the spacecraft Wednesday, telling it to take color images just a few
minutes after each of five more rounds of scraping it will do the following
day, Sol 58, or the 58th Martian day the spacecraft will have been
on red planet.
"We are monitoring changes
between the scrapes," said Doug Ming of NASA
Johnson Space
Center, Houston, the team's science lead for Sol 58
plans. "It appears that there is fairly rapid sublimation of some of the
ice after scraping exposes fresh material, leaving a thin layer of soil
particles that had been mixed with the ice. There's a color change from darker
to bluer to redder. We want to characterize that on Sol 58 to know what to
expect when we scrape just before collecting the next sample."
Within a few days, the team plans to
collect a sample from the icy layer and deliver it to Phoenix's Thermal and Evolved-Gas Analyzer
(TEGA). TEGA heats up the samples in its tiny ovens and then analyzes the
vapors given off to determine the soil's composition.
The aim of the $420 million mission,
which landed on May 25, is to characterize the dirt and icy layer that lies
below it in the north polar regions of Mars to look for signs that the planet
might have been habitable at some point in the past. Mission
scientists have applied to NASA to extend
the mission past its originally-slated 90 days.
Images from Phoenix have confirmed that the doors to the
oven into which the icy sample will be placed have opened
completely. Mission planners will now test
to make sure they can operate TEGA properly in the early Mars morning.
"For the next sample, we will
be operating the instrument earlier in the morning than we have before,"
said William Boynton of the University
of Arizona, lead scientist
for TEGA. "It will be almost the coldest part of the day, because we want
to collect the sample cold and deliver it cold."
Phoenix will also check for dirt devils
during Sol 58. NASA's Mars Rover Spirit has also imaged dirt devils south of
Mars' equator.
