The mission of the Phoenix Mars Lander seems to have hit a snag last week after soil samples delivered by the robotic arm of the spacecraft failed to pass through the screen of the test oven of the Thermal and Evolved Gas Analyzer instrument. The TEGA instrument is equipped with seven other such ovens, which could possibly have identical screens. If this is indeed the case and an alternative solution is not found, then the Phoenix mission is pretty much dead.

During the three months on the planet, the Phoenix Mars Lander is supposed to make investigations on the soil of the north polar regions of Mars and determine whether or not water ice is present there and if the clime on the Red Planet could have been hospitable for life. Without the TEGA instrument, Phoenix can't conduct either of these experiments. Soil placed on top of the screen of the instrument is shaken until it passes through. The particles that make it into the instrument are then heated up until they start emitting gases, which are studied by the analyzer.

So far, no particles appear to have passed through the screen. "This soil is very cohesive and it's very hard for it to get through the screen", said William Boynton of the University of Arizona, mission controller for the Phoenix mission in charge with the TEGA instrument.

If additional shaking doesn't work, then mission controllers will have no other choice than to either sprinkle soil on the screen or grind it into even smaller bits using the robotic arm.

"To be honest, we never thought it would be working so well that we'd have to worry about a riches of just too much. Now that we see the nature of that soil we really are much better off with very small amounts of soil", said Boyton.

All of the eight ovens are one-use only and along with other instruments on board Phoenix are capable of detecting organic molecules associated with life, although the spacecraft is not capable of making direct detection of life. Until mission controllers sort out the new problem with the TEGA analyzer, Phoenix is scheduled to make further investigations with its optical microscope.