Plans to
deliver a sample of Martian soil to the Phoenix Mars Lander's instruments were
delayed again after a communication glitch, mission controllers said on Thursday.
However, scientists
were able to examine images of some of the Martian dust and sand taken in
previous days by the lander's optical
microscope.
The glitch
occurred when NASA's Mars Odyssey Orbiter, through which mission controllers
have been communicating with Phoenix, went into safe mode Wednesday afternoon
after an energetic particle disrupted the orbiter's memory. Phoenix had been
primarily communicating with Odyssey after a different problem temporarily
disabled the Mars Reconnaissance Orbiter (MRO) last week.
Phoenix is now communicating with MRO again
while Odyssey is brought back to life, which mission controllers expect could
happen in the next few days. When Odyssey is fixed, the lander will have the
option of communications with both orbiters.
Because of
the glitch, instructions to scoop up a soil sample were sent to the Phoenix a day later than originally anticipated. Once scientists have confirmed the scoop
has enough soil, they will deliver the sample to the lander's Thermal and
Evolved-Gas Analyzer (TEGA) on Friday. Without its digging instructions, Phoenix instead ran one of its back-up sequences, which includes taking more images of the
landing site.
Phoenix also ran a back-up sequence on May 30, when
the mission team missed an earlier day of sending instructions due to the MRO
glitch.
On a more
positive note, mission scientists got data back from the lander's optical
microscope, which looked at particles that were kicked up into the atmosphere
by Phoenix's thrusters during its landing
on May 25.
The images
from the microscope show what the leader of the mission's geology team, Tom
Pike of University College London, described as "a very wide variety
of particles, both in coloration and size." They are the
highest-resolution microscopic images taken of the Martian soil to date — 10 times
higher than the images taken from the Mars Exploration Rovers, Spirit and Opportunity.
Among the
types of particles seen in the images are "a classic Martian, reddish
brown particle," that likely gives the surface its ruddy hue, Pike said.
The images also show "black, almost glassy particles that have been kicked
up by the retrorockets," he added.
Because the
particles weren't delivered by the robotic arm scoop but rather settled onto
the spacecraft after landing, "we don't have a guarantee that these are Martian
particles," said Michael Hecht, the lead scientist for the Microscopy,
Electrochemistry and Conductivity Analyzer (MECA) instrument. But mission
scientists are fairly certain they are from Mars, as the microscope was checked
out before liftoff and during its cruise to Mars and no particles were
apparent.
Extremely
fine particles can be seen in the background of the images, and are likely the
particles that are most easily blown up into the Martian atmosphere, giving the
planet's sky its pinkish color.
Scientists
also saw pale, whitish particles in the microscope images that could possibly
be the same whitish
material they have observed in the soil samples scooped up from the
surface. They won't be able to confirm this though until soil samples are
delivered to the microscope by the scoop.
Scientists
have proposed that the white chunks seen in the scoop could either be ice from
just below the surface or some kind of salt mineral. But the tiny pale
particles in the microscope are definitely minerals, as "any ice that we
collect would be slowly subliming," Pike explained.
It is
possible that on future digs, the soil could be transferred to the microscope
quickly enough to be imaged, Pike said. But that isn't the primary goal of the
microscopic experiments, Hecht said, which are geared at determining the
history of the particles, for example what environment they might have formed
in, by looking at properties such as their transparency and size.
Mission scientists aren't worried about
missing a second day of the mission, they said, because they budgeted for missing
one third of the scheduled 90-day mission while still being able to complete
all of their research goals.
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