NASA's Phoenix Mars Lander has scooped up another sample of Martian dirt into one of its onboard laboratory ovens. The sample will complete a profile of all depths of the surface layer of Phoenix's arctic landing site.
The lander's robotic arm collected the sample, dubbed Burning Coals, from a trench informally named Burn Alive 3. The sample comes from an intermediate depth between the surface regolith and the rock-hard subsurface icy layer, which Phoenix confirmed was water ice on July 31.
Early on Thursday, mission controllers received information from Phoenix that confirmed that some of the Burning Coals sample had been delivered through the doors of cell number 7 of the lander's Thermal and Evolved-Gas Analyzer (TEGA), almost completely filling the cell. TEGA heats up samples and then analyzes the vapors given off to determine the composition of the surface material.
TEGA won't begin heating a sample on its own unless it senses the oven is completely full, so the Phoenix science team will command the oven door to close and the cell will begin heating the sample. TEGA scientists have sent commands to manually close oven doors before.
One particular signal the Phoenix team will be looking for is that of perchlorate, a highly oxidizing substance that is also soluble and was detected in samples delivered to the lander's wet chemistry lab. Seeing signs of perchlorate in TEGA would help confirm that wet lab finding.
"We are expecting the sample to look similar to previous samples," said William Boynton of the University of Arizona, lead scientist for TEGA. "One of the things we'll be looking for now is an oxygen release indicative of perchlorate."
"We want to know the structure and composition of the soil at the surface, at the ice and in-between, to help answer questions about the movement of water -- either as vapor or liquid -- between the icy layer and the surface," said Ray Arvidson of Washington University in St. Louis, a leader of Phoenix science team activities.
