Minor Glitch Detected In Thermal and Evolved Gas Analyzer

Scientists have discovered what may be ice that was exposed when soil was blown away as NASA's Phoenix spacecraft landed on Mars last Sunday. The possible ice appears in an image the robotic arm camera took underneath the lander, near a footpad.

"We could very well be seeing rock, or we could be seeing exposed ice in the retrorocket blast zone," said Ray Arvidson of Washington University, St. Louis, MO co-investigator for the robotic arm. "We'll test the two ideas by getting more data, including color data, from the robotic arm camera. 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.

"Full confirmation of what we're seeing will come when we excavate and analyze layers in the nearby workspace," Arvidson said.

Testing Thursday night of a Phoenix instrument that bakes and sniffs samples to identify ingredients identified a possible short circuit. This prompted commands for diagnostic steps to be developed and sent to the lander in the next few days. The instrument is the Thermal and Evolved Gas Analyzer. It includes a calorimeter that tracks how much heat is needed to melt or vaporize substances in a sample, plus a mass spectrometer to examine vapors driven off by the heat. The Thursday, May 29, tests recorded electrical behavior consistent with an intermittent short circuit in the spectrometer portion.

"We have developed a strategy to gain a better understanding of this behavior, and we have identified workarounds for some of the possibilities," said William Boynton of the University of Arizona, Tucson, lead scientist for the instrument.

The latest data from the Canadian Space Agency's weather station shows another sunny day at the Phoenix landing site with temperatures holding at minus 30 degrees Celsius (minus 22 degrees Fahrenheit) as the sol's high, and a low of minus 80 degrees Celsius (minus 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.

FMI: www.nasa.gov/phoenix, http://phoenix.lpl.arizona.edu