080703 Next Phoenix bake could be last

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Next Phoenix bake could be last
BY DR EMILY BALDWIN
ASTRONOMY NOW

Posted: July 3, 2008

After a busy weekend of scraping up piles of icy soil, Phoenix is preparing its ovens to sniff out the ingredients of this precious material, but a short circuit problem could make this the last trip to the Phoenix bakery.

The well-studied Snow White Trench, Phoenix’s current active digging area, is now about 33 centimetres long, 24 centimetres wide and 5 centimetres deep. The cross-cutting grid of grooves are about 2 millimetres deep and were made by the scraping tool. Image: NASA/JPL-Caltech/University of Arizona/Max Planck Institute.

On the 33rd Martian day, or sol, of the mission, Phoenix’s robotic blade made 50 scrapes in the ice layer buried under the surface soil in the Snow White trench, and heaped the scrapings into desert spoon sized piles. Mission scientists agreed that they had "almost perfect samples of the interface of ice and soil," and commanded the robotic arm to pick up the scrapings, which will soon be heated up in one of the Thermal and Evolved Gas Analyser (TEGA) ovens to sniff out volatile ingredients and determine the melting point of the ice.

However, engineers and scientists have discovered a short circuit in the instrument, likely caused by the lengthy vibration techniques employed to break up clumpy soil earlier in the mission to allow that particular sample to enter into one of the ovens. Delivery to any oven causes a vibration action and it is feared that the next attempt could trigger a further short circuit.
"Since there is no way to assess the probability of another short circuit occurring, we are taking the most conservative approach and treating the next sample to TEGA as possibly our last," says Peter Smith, Phoenix's principal investigator.

This picture documents the delivery of soil to one of four Wet Chemistry Laboratory (WCL) cells on the 30th Martian sol. WCL is part of the Microscopy, Electrochemistry and Conductivity Analyser (MECA) instrument suite onboard Phoenix. Image: NASA/JPL-Caltech/University of Arizona/Max Planck Institute.

A sample which remains in the robotic arm has now likely dried out, so this will be analysed by the optical microscope and Wet Chemistry Laboratory (WCL) instead. The new ice sample must be transferred quickly to TEGA after being exposed at the surface, to ensure that the materials do not change from a solid to a vapour during the delivery process.

And while mission teams mark Independence Day with a few days holiday, Phoenix will operate from pre-programmed science commands, such as taking atmospheric readings and panoramic images, under the watchful eye of a skeleton team. As well as establishing climatic conditions in the north polar region of Mars, Phoenix's ultimate goal is to determine the history of water in the arctic regions and to discover if this frigid soil could ever support life.