The Surface Stereo Imager on NASA's Phoenix Mars Lander acquired the individual images that are combined into this one view, provided by NASA, on Thursday. ((NASA/Associated Press))

NASA's Phoenix Mars lander returned more detailed images from the Red Planet and was using some of its  instruments, including a robotic arm and a Canadian laser, for scientific tasks.

An image captured by the robotic-arm camera from underneath the lander may be of ice that was exposed when soil was blown away during the spacecraft's landing last Sunday, NASA scientists said in a release Friday.  

"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 in St. Louis, Mo., who is the robotic arm's co-investigator. "We'll test the two ideas by getting more data, including colour data, from the robotic-arm camera."

If the hard features are indeed ice, they will become brighter because atmospheric water vapour will collect as new frost on the ice, he said.

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

After testing the arm at warmer and colder temperatures on Thursday, the lander's titanium and aluminum arm began using its camera Friday to look under the lander to assess its underside as well as the terrain, NASA said.

The robotic arm will dig into the icy layers of the planet and deliver samples to instruments that will analyze what this part of the planet's northern arctic region is made of and whether it could have supported primitive life, the space agency said.

Another lander milestone included the activation and use of Canada's laser instrument — the light detection and ranging instrument, or lidar — a critical component of Phoenix's weather station provided by the Canadian Space Agency.

Data from the Canadian Space Agency's weather station showed another sunny day at the Phoenix landing site, with temperatures hovering around -30 Celsius. The lidar instrument was activated for a 15-minute period just before noon local Mars time, and showed increasing dust in the atmosphere, NASA said.

"This is the first time lidar technology has been used on the surface of another planet," said Mike Daly, the meteorological station's chief engineer in Brampton, Ont. "The team is elated that we are getting such interesting data about the dust dynamics in the atmosphere."

The instrument is designed to detect dust, clouds and fog by emitting rapid pulses of green laser-like light into the atmosphere, NASA said. The light bounces off particles and is reflected back to a telescope.

"One of the main challenges we faced was to deliver the lidar from the test lab in Ottawa, Canada, to Mars while maintaining its alignment within one 100th of a degree," Whiteway said. "That's like aiming a laser pointer at a baseball at a distance from home plate to the centre field wall, holding that aim steady after launch for a year in space, then landing."

Phoenix has delighted scientists with the first-ever peek of the planet's northern arctic region since its landing Sunday onto relatively flat terrain containing few rocks. Twin rovers have been operating near the Martian equator since 2004.

Texas A&M University's Mark Lemmon, who is in charge of the lander's camera, said scientists are still investigating geometric patterns in the surface likely caused by the expansion and contraction of underground ice. Some areas immediately surrounding the lander would be designated a no-digging "natural preserve," Lemmon said.

A few features on nearby terrain have been given such nicknames as Humpty Dumpty and Sleepy Hollow, he said.

The $420-million US mission is led by University of Arizona, Tucson, and managed by NASA's Jet Propulsion Laboratory in California.

With files from the Associated Press