Making an impression

Dispatch from Mars, Sol 7

The Mars Phoenix Lander has made contact. Scientists reported Monday that they had successfully manipulated the Lander’s robotic arm to dig a test trench.

FIRST TRENCH This image, taken by the Phoenix Lander’s Stereo Surface Imager, shows the trench dug by the lander’s robotic arm during its first test dig on Sunday June 1. The area is just north of the lander and is informally called the Knave of Hearts. NASA, JPL-Caltech, Univ. of Arizona, Texas A&M University

YETI The Lander reached out and touched the Martian soil for the first time on Saturday, May 31, its first step in a series of actions expected to bring soil and ice to the lander’s instruments. By coincidence, the scoop appeared like a footprint. NASA, JPL-Caltech, University of Arizona

FIRST PILE This image, taken by the camera on Phoenix’s robotic arm, shows material that the arm collected on Sunday during its test dig. The white speckles in the right part of the image could be salts or ice. Red, green and blue LEDs were used to illuminate the scoop and take this color picture. NASA, JPL-Caltech, Univ. of Arizona, Max Planck Ins

Earlier, the scoop on the arm made its first interaction with the Martian surface. “Over the weekend, we had the robotic arm touch the surface and make a dent. That area was called Yeti because it kind of looks like a footprint,” said Phoenix scientist Ray Arvidson of WashingtonUniversity in St. Louis, during a press briefing. The tests validate that the scientists can guide the robotic arm to dig at particular places on the Red Planet’s surface.

Scientists did their first dig on what they call Sol 7, or the seventh day since Phoenix landed.

From the lander’s digging and dumping of soil, the scientists learned that the Martian surface in this area is crumbly and that there are some light-toned bits in the dump pile and the trench. The researchers think the white material is made of the same material as the white spots seen in photos taken under the Lander. The scientists are now ready to begin doing experiments to analyze the soil.

Peter Smith, principal investigator for the Phoenix mission, reported that scientists also solved an earlier problem with the Thermal Evolved Gas Analyzer, or TEGA — one of the instruments that will analyze the content of what the lander digs up.

The tool has an “electronic nose” called a mass spectrometer that had a nonresponsive heating filament last week. “Last night we had our first return with an attempt to switch filaments. We have two filaments and we used the backup filament as the primary and it turns out that was very successful,” he said.

Scientists also successfully opened TEGA’s covers, Smith said.

Because of concerns with the instrument’s operation status, the researchers considered taking the first dig sample and dumping it into one of their other instruments. TEGA, however, will still get the first dig sample because the instrument has a larger entry point and the scientists have practiced this move many times.

“We’re thinking Sol 9 is the first delivery day,” Smith said. In Earth days, this means the first dig could be as early as Tuesday.

Testing the soil will confirm whether the whitish areas, which the scientists think resemble ice, are indeed patches of frozen water. The light areas could be ice or they could be salts similar to those found by the Viking landers in the 1970s and also by the rover Spirit, which is still collecting data, Arvidson said.

The scientists are pretty sure it is ice, but soil testing will tell them about the composition for certain. Results from TEGA experiments need four days to run, and they do not run consecutively, Smith said. Conclusive evidence will therefore not be in for another few days.

The eight ovens of TEGA will bake the soil and measure at what temperature the minerals and salts in the samples change from solid to liquid to gas phase. The temperature at which the samples make these transitions will help in determining the character of the different materials in the soil. When the temperature reaches 1,000 degrees Celsius, most of the sample vaporizes into a stream of gases. TEGA’s “nose,” the mass spectrometer, will then sniff out the specific molecules and atoms in the sample.

Choosing the location for the first experimental dig is the scientists’ main priority. The researchers are thinking about moving just to the right of the first test dig site and doing a set of three sample collections.

As for the names of the spots, “It would be kind of nice to name the three areas Baby Bear, Mama Bear, and Papa Bear,” Arvidson said.

photo of Ashley Yeager

Ashley Yeager is the associate news editor at Science News. She has worked at The Scientist, the Simons Foundation, Duke University and the W.M. Keck Observatory, and was the web producer for Science News from 2013 to 2015. She has a bachelor’s degree in journalism from the University of Tennessee, Knoxville, and a master’s degree in science writing from MIT.

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