Images of the dust beamed 171 million miles away to Earth showed particles of varying size and colors ranging from semi-translucent white to glassy black.

“We are able to see the variety there is in what appears to be just reddish-brown soil,” Tom Pike, a mission geologist from Imperial College London, told reporters during a teleconference on Thursday.

“We are looking to use these particles as a way to read the history of the site,” added Michael Hecht, a scientist at NASA’s Jet Propulsion Laboratory.

Phoenix is now sitting on a plateau in Mars’ northern polar region. The lander will eventually test the soil — and a layer of ice believed to exist just inches below the surface — in dozens of ways. The seven-foot tall, 772-pound lander carries two types of microscopes, a “wet chemistry” set to test soil properties, and tiny ovens to vaporize and analyze the samples.

The researchers hope to learn whether Mars might have been habitable in past ages when conditions were more favorable to life. At the moment, they are not. Temperatures in Phoenix’s neighborhood are currently ranging from -13 to -116 degrees Fahrenheit.

The mission is especially interested in Mars’ water, virtually all ice now, and carbon-containing compounds that may be in the soil. Over the next several days, the researchers plan to analyze the Martian atmosphere using the “thermal and evolved gas analyzer” (TEGA), part of the robotic laboratory mounted on the lander’s deck. It contains a device called a mass spectrometer that measures the atomic weight of molecules and helps determine their concentration.

The task after that will be to deliver a sample of dirt to one of eight miniature ovens in the TEGA apparatus, where it will be heated to 1,800 degrees Fahrenheit over several days. This will cause constituents of the soil, including water, to evaporate at specific temperatures. As each “fraction” comes off as a gas, it will be directed into the mass spectrometer for analysis. The researchers are especially interested in carbon-based compounds. Ones made by living organisms on Earth generally vaporize below about 750 degrees Fahrenheit. Ones carried in by comets and meteors tend to be heavier. They vaporize at 1,400 degrees F.