Phoenix Robot Digs into Martian Soil for First Time
This color image, acquired by NASA's Phoenix Mars Lander's Surface Stereo Imager on Sol 7, the seventh day of the mission (June 1, 2008), shows the so-called "Knave of Hearts"first-dig test area to the north of the lander. The Robotic Arm's scraping blade left a small horizontal depression above where the sample was taken.
Credit: NASA/JPL-Caltech/UA/Texas A&M

NASA's Phoenix Mars Lander has successfully stretched out its robotic arm to scratch at the Martian soil for the first time, mission scientists said Monday.

Phoenix performed the test dig Sunday in a spot just above a dent left by the scoop of its robotic arm when it first touched the soil on May 31. Researchers dubbed the dent "Yeti" because of its strong resemblance to a footprint.

Touching the soil and performing this so-called "dig and dump" are the first practice steps toward digging up soil samples and delivering them to the instruments on the lander. The instruments aboard the $420-million spacecraft are designed to analyze the soil and underlying layers of water ice to see if the ice was at some point liquid and whether it could have created a habitable zone for microbial life.

Phoenix not only scooped up and dumped material on the Martian surface, it also snapped a photo of the stuff in its back hoe-like maw.

"The soil is crumbly and there's also some light-toned bits," said Ray Arvidson, the robotic arm co-investigator of Washington University in St. Louis.

These "light-toned bits" were also seen in the trench left by the scoop. "We got very excited because we see this nice streak of white material," said Phoenix senior engineer Pat Woida.

What exactly the white material is is uncertain, though Arvidson proposed one of two possibilities.

First, the white material could be salts that formed while liquid water was present. Second, and more tantalizing, the stuff could also be part of the underlying ice layer similar to the smooth bright regions spotted under the lander in photographs, which mission scientists also think could be ice exposed by the thrusters as the craft landed. Researchers christened the odd regions ?Snow Queen? and ?Holy Cow.?

"We were so excited about it we called it Holy Cow," Arvidson said.

The success of Sunday?s practice dig and dump means that the team can focus on the next stage of Phoenix's mission: sampling and analyzing the soil.

"That was all very, very successful, so I don't think we need to do any more testing," Arvidson said.

The team is currently scouting for new dig sites, which will likely be three side-by-side areas (one for each of the lander's three analysis instruments), which the team plans to name "Baby Bear," "Mama Bear" and "Papa Bear." The dig targets will likely be just to the right of the test dig, where Phoenix?s 7.7-foot (2.3-meter) robotic arm can easily reach.

The team has gone back to their original plan of delivering the first sample to the lander's Thermal and Evolved-Gas Analyzer (TEGA), which heats up samples and analyzes the vapors they give off, after a glitch over the weekend has been worked out. A filament in part of the analyzer shorted out, but mission engineers have found that they can use a second, back-up filament to do the analysis with the same amount of sensitivity.

Mission controllers will look at the data from Phoenix's downlink on Monday night and if the TEGA covers have fully retracted, "then TEGA will be good to go," Arvidson said.

NASA?s Phoenix Mars Lander touched down in the Martian arctic on May 25 to begin a planned three-month mission studying the surrounding terrain, weather and searching for water ice.