 |
 |
||
 |
|
||
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
||||||||
 |
Planetary News: Phoenix (2008)Phoenix Zeros in on Possible IceBy A.J.S. Rayl
TUCSON -- Using its robotic arm camera, Phoenix took a picture of a “blind spot” underneath the lander, near a footpad, and discovered what may be ice exposed when soil was blown away as the spacecraft landed, mission scientists announced at a press conference in Tucson earlier today. Phoenix touched down last Sunday, May 25, and is currently perched in a region of permafrost on Mars's northern plains, analogous to northern Canada, dubbed Green Valley. "We could very well be seeing exposed ice or we could be seeing rock,” said Ray Arvidson of Washington University, St. Louis, who also served as chair of the Phoenix landing site working group and is co-investigator for the robotic arm. The image shows “three tabular surfaces,” as he described them. Over the next few sols, the Phoenix team will go back with the robotic arm camera, get closer, and take some color images with the robotic arm camera to see what that might reveal. "We think that if the hard features are ice, they will become brighter, because atmospheric water vapor will collect as new frost on the ice,” Arvidson said. Full confirmation of what those three tabular surfaces are, he said, “will come when we excavate and analyze layers in the nearby workspace,” he continued. “This is scientific method, exploration, and discovery. We have two hypotheses. We have rock. We have ice. We’re pushing for ice. The real way to [investigate] this is to continue to look at this feature, then get out to the work volume and expose whatever ice is underneath and see if we see a similar tabular shallow structure that we can sample and bring back into the spacecraft to really nail and test the hypothesis of ice versus rock.” “We still very much like our landing site,” Arvidson added. “We’ve brought you to a place that was safe, that was relatively flat, and scientifically interesting. As you know, we’ve touched down on a location that’s just intensely dissected by patterned ground. In fact, we’re at a location where we think we can sample a polygon and a trough and we’re still evaluating that within the work volume."
Testing last night of the Thermal and Evolved Gas Analyzer (TEGA), which is to bake and sniff the ice and rock samples to identify ingredients, however, revealed electrical behavior consistent with an intermittent short circuit in the spectrometer portion of the instrument. That prompted commands for diagnostic steps to be developed and sent to the lander in the next few days. "We found an anomaly that looks like we have a short circuit in the ion source, a part of the evolved gas analyzer that actually generates the ions that we analyze,” said William Boynton, of the University of Arizona, Tucson, lead scientist for the instrument. “We are working on some diagnostic packages we’ll send up in the next few days," Boynton said. "We have developed a strategy to gain a better understanding of this behavior, and we have identified workarounds for some of the possibilities. We’re actually quite optimistic that we have a workaround that will allow us to operate the instrument with nearly the full capabilities that we had when it left the ground." The latest data from the Canadian Space Agency's weather station, meanwhile, showed another sunny day at the Phoenix landing site with temperatures holding at -22 degrees Fahrenheit as the sol's high, and a low of -112 degrees Fahrenheit. The lidar instrument was activated for a 15-minute period just before noon local Mars time, and showed increasing dust in the atmosphere. "This is the first time lidar technology has been used on the surface of another planet," said the meteorological station's chief engineer, Mike Daly, from MDA in Brampton, Canada. "The team is elated that we are getting such interesting data about the dust dynamics in the atmosphere."
The mission passed a "safe to proceed" review on Thursday evening, meeting criteria to proceed with evaluating and using the science instruments. "We have evaluated the performance of the spacecraft on the surface and found we're ready to move forward,” said David Spencer of NASA's Jet Propulsion Laboratory (JPL), deputy project manager for Phoenix. “While we are still investigating instrument performance such as the anomaly on TEGA, the spacecraft's infrastructure has passed its tests and gets a clean bill of health." Although the anomaly on the TEGA instrument -- which was to have been the first instrument used to analyze samples -- may take a few days or sols to resolve, it won’t hold up the analyses or the mission, according to Leslie Tamppari, of JPL, the Phoenix project scientist. If TEGA is not available to analyze the first samples, then the samples will likely go to the Microscopy, Electrochemistry and Conductivity Analyzer (MECA) instrument, specifically to the optical microscope for initial analysis, she said. “The process is designed to be very flexible, to respond to discoveries and issues that come up every day,” Tamppari. We're in the process of taking images and getting color information that will help us understand soil properties. This will help us understand where best to first touch the soil and then where and how best to dig." 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. For more information, log back on as coverage of Phoenix flight continues, and be sure to check out Emily Lakdawalla's Planetary Society Planetary Weblog.
|
||||||||
 |
 |
||||||||
[ what is this? ]