Comm Glitch Delays Mars Digging

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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