NASA's Phoenix Mars Lander Ready to Gather Samples
TUCSON, Ariz. -- Two practice rounds of digging and dumping the clumpy soil
at the Martian arctic site this week gave scientists and engineers gathered at
the University of Arizona confidence to begin using Phoenix's Robotic Arm to
deliver soil samples to instruments on the lander deck.
Those samples will not be collected before Thursday. Following Wednesday's
briefing on the mission, the Phoenix team learned that NASA's Odyssey orbiter,
which relays Phoenix data to and from Earth, had entered a "safe mode,"
preventing Wednesday's (or sol 10) instructions from reaching the lander.
Instead, Phoenix will complete a sequence of commands that are already stored
on board. That sequence includes instructions for the lander to continue
taking images required to assemble a full-color 360-degree high-resolution panorama.
Odyssey mission managers are doing a check out of the orbiter to determine what
triggered the safe mode. During safe mode, the spacecraft turns off non-essential
operations and waits for instructions from Earth. In the meantime, the Phoenix team
has been directed to issue commands to the lander and receive data through Mars
Reconnaissance Orbiter (MRO). While Phoenix has been primarily utilizing Odyssey
for relay services since MRO's UHF radio unexpectedly powered off during a relay
pass on Sol 2, the radio has been exercised repeatedly over the past week and
appears to be operating well.
The two practice digs have already enticed scientists about some bright material
in the soil just beneath the surface.
"Two scoops into the soil we see there's a white layer becoming visible in the
wall of the trench," said Carol Stoker of NASA Ames Research Center, Moffett
Field, Calif., a member of the Phoenix science team.
Phoenix Principal Investigator Peter Smith said, "We've had an impassioned
discussion of whether that may be salts or ice or some other material even more exotic."
Concentrations of salts can be indicators of formerly wet conditions. One goal
for the Phoenix mission is to determine whether the ice beneath the surface of
far-northern Mars ever thaws during long-term climate cycles.
The location chosen for the sample is adjacent to the hole dug by the two
practice scoops. The team plans to command the arm to deliver the sample to
the lander's Thermal and Evolved-Gas Analyzer (TEGA), after it first receives
images to confirm that the scoop holds collected soil ready for delivery.
"The arm has been performing flawlessly," said Ashitey Trebi-Ollennu of NASA's
Jet Propulsion Laboratory, senior robotics engineer on the Phoenix Robotic Arm
team. The arm made daring, Tai Chi or Yoga-like moves to position the Robotic
Arm Camera to take pictures underneath the lander, and did its two test digs
"magnificently," he said.
Phoenix is the first mission to dig into Mars with a robotic arm since the
Viking landers in the 1970s.
"We have only dug to a depth of an inch or two, so we know there are challenges
ahead," Trebi-Ollennu added. "But we are confident that we'll get a good amount
of material to deliver to TEGA."
In addition to the bright material seen where the arm collected test samples, a
layer of hard, light-toned substrate has been seen in images taken underneath
the lander by the Robotic Arm Camera.
"We think the lander is sitting on a layer of this white material that possibly
extends beyond, out into our work area," said Uwe Keller, Robotic Arm Camera lead
scientist from the Max Planck Institute for Solar System Research, Katlenburg-Lindau,
Germany. Phoenix's telltale, which is part of the Canadian Space Agency's meteorological
package and the highest part of the lander, has proved to be very sensitive to
Martian winds, said Haraldur Gunnlaugsson of the University of Aarhus, Denmark,
which provided the device.
"A storm on Mars is a gentle hand movement on Earth," Gunnlaugsson said. Surface
Stereo Imager images of the telltale show a diurnal pattern to Martian winds. Winds
come from the south in the morning, blow in from the north by mid-day, from the west
in the afternoon, and again from the south by the end of the day.
Knowledge of wind direction and speed is important to prevent possible contamination
of samples during digging.
The Phoenix mission is led by Smith at the University of Arizona with project management
at JPL and development partnership at Lockheed Martin, Denver. International contributions
come from the Canadian Space Agency; the University of Neuchatel, Switzerland; the
universities of Copenhagen and Aarhus, Denmark; Max Planck Institute, Germany; and
the Finnish Meteorological Institute. For more about Phoenix, visit:
Media contacts: Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
Dwayne Brown 202-358-1726
NASA Headquarters, Washington
Sara Hammond 520-626-1974
University of Arizona, Tucson