June 17, 2008
There has been some white stuff found in the Martian soil. Is it ice or salt?
In the three weeks since the Phoenix lander began digging into Mars’ north pole region to study whether the arctic could be habitable, that is what scientists have been asking. Phoenix merged two previously dug trenches over the weekend into a single pit measuring a little over a foot long and 3 inches deep at the edge of a polygon-shaped pattern in the ground that may have been formed by the seasonal melting of underground ice
New photos showed the exposed bright substance present only in the top part of the trench. According to scientists, this suggests it’s not uniform throughout the site. Phoenix will take images of the trench dubbed “Dodo-Goldilocks” over the next few days to record any changes. Scientists expect the substance which may be ice to sublimate (from solid to gas, bypassing the liquid stage) when exposed to the sun because of the planet’s frigid temperatures and low atmospheric pressure
If it turns out to be salt, the discovery would also be significant because salt is formed when water evaporates in the soil. Preliminary results from a bake-and-sniff experiment (the collected sample is aggitated and cooked at low temperatures) failed to turn up any trace of water or ice in the scoopful of soil that was delivered to the lander’s test oven last week. Scientists planned to try the same thing again this week but with the temperature increased to 1,800 degrees.
On May 25, the Phoenix landed on Mars for a three-month, $420 million mission to study whether the polar environment could be favorable for primitive life to emerge. The lander’s main job is to dig into an ice layer believed to exist a few inches from the surface.