Tucson (AZ) – NASA on Thursday said that its Phoenix Mars Lander has identified water, a requirement for life as we know it, in a soil sample. Heating of samples and resulting vapor led scientists to conclude that it has touched Martian water for the first time.
A group led by William Boynton of the University of Arizona said that the soil sample came from a trench. At a depth of about 2”, Phoenix’ robotic arm hit a hard layer of frozen soil. Initial attempts to retrieve samples of the icy soil failed as they got stuck in the arm’s scoop. Over a period of two days, some of the water in the sample apparently vaporized and enables Phoenix to analyze it.
The soil sample came from a trench approximately 2 inches deep. When the robotic arm first reached that depth, it hit a hard layer of frozen soil. Two attempts to deliver samples of icy soil on days when fresh material was exposed were foiled when the samples became stuck inside the scoop. Most of the material in Wednesday's sample had been exposed to the air for two days, letting some of the water in the sample vaporize away and making the soil easier to handle.
"We've seen evidence for this water ice before in observations by the Mars Odyssey orbiter and in disappearing chunks observed by Phoenix last month, but this is the first time Martian water has been touched and tasted," said Boynton, who is in charge for the lander’s thermal and evolved-gas analyzer (TEGA).
"The details and patterns we see in the ground show an ice-dominated terrain as far as the eye can see," said Mark Lemmon of Texas A&M University, lead scientist for Phoenix' surface stereo imager camera. "They help us plan measurements we're making within reach of the robotic arm and interpret those measurements on a wider scale."
Since its landing on May 25, Phoenix has been studying soil with a chemistry lab, TEGA, a microscope, a conductivity probe and cameras. Besides confirming the 2002 finding from orbit of water ice near the surface and deciphering the newly observed stickiness, the science team is trying to determine whether the water ice ever thaws enough to be available for biology and if carbon-containing chemicals and other raw materials for life are present.
"Mars is giving us some surprises," said Phoenix principal investigator Peter Smith of the University of Arizona. "We're excited because surprises are where discoveries come from. One surprise is how the soil is behaving. The ice-rich layers stick to the scoop when poised in the sun above the deck, different from what we expected from all the Mars simulation testing we've done. That has presented challenges for delivering samples, but we're finding ways to work with it and we're gathering lots of information to help us understand this soil."
The new results prompted NASA to extend funding for the Phoenix mission through Sept. 30. The original prime mission of three months ends in late August.
"Phoenix is healthy and the projections for solar power look good, so we want to take full advantage of having this resource in one of the most interesting locations on Mars," said Michael Meyer, chief scientist for the Mars Exploration Program at NASA Headquarters in Washington.