Phoenix Finds Water, Trouble on Mars
(From the September/October 2008 issue of StarDate magazine)
Although a short-circuit may slash the number of samples it can analyze, the Phoenix Mars lander fulfilled one of its primary mission objectives within weeks of its May 25 touchdown: It confirmed that frozen water lurks just beneath the dust-covered surface in the planet’s northern plains.
Phoenix made the discovery not with its high-tech chemical laboratories, but with a series of pictures. A few small, round pellets congregated in the corner of a trench excavated by Phoenix’s robotic arm. But two days later, they had vanished. Scientists deduced that the pellets were made of water ice, which vaporized in the thin Martian atmosphere.
Phoenix’s robotic arm prepares to dig into the Martian surface. (NASA/JPL/Univ. Arizona/Texas A&M)
The surface was harder than scientists had expected, limiting the depth at which Phoenix could scoop out samples of possibly ice-rich soil. The soil also clumped together more than expected, so the first sample failed to enter a small chemical laboratory on the lander’s deck. Engineers jiggled the sample container to break particles free of the clumps. But the motion may have triggered a short-circuit that prevented the lids atop several other cells from opening. Engineers also were concerned that additional motion could short out the entire bank of eight laboratory cells. The cells are designed to vaporize the samples and analyze the gas for water vapor and organic compounds — the chemical building blocks of life.
While scientists and engineers resolved the problem, Phoenix’s weather station recorded temperatures that plunged to –100 degrees Fahrenheit or colder. The lander also stuck a fork-shaped instrument into the soil to measure its water content and used a microscope to study grains of soil.
Phoenix was expected to continue operating until early fall, when sunlight begins to fade and it loses power. DB
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