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Phoenix Mars Lander Checking Soil Properties
Pasadena CA (JPL) Jun 08, 2008 The arm of NASA's Phoenix Mars Lander released a handful of clumpy Martian soil onto a screened opening of a laboratory instrument on the spacecraft Friday, but the instrument did not confirm that any of the sample passed through the screen. Engineers and scientists on the Phoenix team assembled at the University of Arizona are determining the best approach to get some of that material into the instrument. Meanwhile, the team has developed commands for the spacecraft to use cameras and the Robotic Arm on Saturday to study how strongly the soil from the top layer of the surface clings together into clumps. Images taken Friday show soil resting on the screen over an open sample-delivery door of Phoenix's Thermal and Evolved-Gas Analyzer, or TEGA, an instrument for identifying some key ingredients. The screen is designed to let through particles up to one-millimeter (0.04 inch) across while keeping out larger particles, in order to prevent clogging a funnel pathway to a tiny oven inside. An infrared beam crossing the pathway checks whether particles are entering the instrument and breaking the beam. The researchers have not yet determined why none of the sample appears to have gotten past the screen, but they have begun proposing possibilities. "I think it's the cloddiness of the soil and not having enough fine granular material," said Ray Arvidson of Washington University in St. Louis, the Phoenix team's science lead for Saturday and digging czar for the mission. "In the future, we may prepare the soil by pushing down on the surface with the arm before scooping up the material to break it up, then sprinkle a smaller amount over the door," he said. Another strategy under consideration is to use mechanical shakers inside the TEGA instrument differently than the five minutes of shaking that was part of the sample-receiving process on Friday. No activities for the instrument are planned for Saturday, while the team refines plans for diagnostic tests. Phoenix's planned activities for Saturday include horizontally extending a trench where the lander dug two practice scoops earlier this week, and taking additional images of a small pile of soil that was scooped up and dropped onto the surface during the second of those practice digs. "We are hoping to learn more about the soil's physical properties at this site," Arvidson said. "It may be more cohesive than what we have seen at earlier Mars landing sites." The Phoenix mission is led by Peter 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.
earlier related report The instrument will bake and sniff the soil to assess its volatile ingredients, such as water. Commands were received by Phoenix Friday, June 6, for the spacecraft's Robotic Arm to dump the sample into an opened door on the instrument called the Thermal and Evolved-Gas Analyzer, or TEGA. "It's looks like a good sample for us," said Peter Smith, Phoenix principal investigator at the University of Arizona, Tucson. "Over the next few days, and it may be as much as a week, the TEGA instrument will be analyzing this sample." Phoenix's Robotic Arm collected the sample of clumpy, reddish material from the top 2 to 4 centimeters (0.8 to 1.6 inches) of surface material at a site informally named "Baby Bear" on the north side of the lander. In the past week, engineers had used the arm to collect two practice scoops adjacent to Baby Bear and dump those scoopfuls back onto the surface. They have prepared for years with simulations and versions of the arm on Earth. "It's like being on a football team and having a pre-season that lasted five years, and now we're finally playing first game," said Matt Robinson, of NASA's Jet Propulsion Laboratory, Pasadena, Calif. He is the robotic arm flight software lead for the Phoenix team. The move was calculated to get enough material to be sure to get some delivered into the instrument without inundating the instrument with unnecessary extra soil. "We're ecstatic that we got a quarter to a third of a scoopful," Robinson said. The TEGA instrument will begin analyzing the sample for water and mineral content after it has analyzed a sample of the Martian atmosphere. Water can be bound to minerals, such as clays or carbonates, and it takes more heat to drive the water off some minerals than others. This is how the instrument can identify some minerals in the soil. "We are particularly interested in minerals that are formed or altered by the action of liquid water in the soil," Smith said. Related Links Watch the Science Briefings Phoenix at LPL Phoenix at JPL Phoenix at NASA Mars News and Information at MarsDaily.com Lunar Dreams and more
Mars lander Phoenix struggles with soil sample
Washington (AFP) June 8, 2008A soil sample from the Martian arctic dug up by the Phoenix probe appears to be too firmly clumped to deliver any particles into the spacecraft's main test instrument, mission experts said. |
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