Thermo Fisher Scientific Inc., the world leader in serving science, recently announced that the Thermo Scientific Orion 229918 sensor assembly is part of the Wet Chemistry Laboratory (WCL) in NASA’s Phoenix Mars Mission launched from Cape Canaveral on August 4, 2007. Under contract with NASA’s Jet Propulsion Laboratory in Pasadena, California, the water specialists at Thermo Fisher Scientific developed the Orion 229918 sensor assembly for the WCL specifically for this mission to Mars.

The Orion 229918 sensor assembly consists of four identical “beakers” produced from cast epoxy chambers, the walls of which are embedded with electrochemical sensors. Each beaker is housed in an aluminum shell with circuitry for conveying sensor signals and is heated to ensure the chambers stay above the freezing point in the frigid Martian environment. The beakers are designed to receive soil samples extracted from different depths in a trench dug by a robotic arm on the Phoenix lander that is equipped with a scoop for digging.

While on Mars, the beakers will provide a platform for geological experiments. The following is a step-by-step representation of what the Orion 229918 sensor assembly will do:

-An actuator assembly, attached to the top of the beaker, will puncture a tank that will admit 25 mL (about an ounce) of solution into the sensing chamber. This solution, developed and formulated in Beverly, Mass., will serve as an initial calibrant for the sensors.

-Next, a reagent pellet drops into the solution to provide a second calibration point. The solution is then stirred from above using a Thermo Scientific Orion Model 960 stirrer impeller.

-After calibration, a sample drawer opens to the Martian atmosphere.

-The robotic arm on the Phoenix lander will drop approximately 1 cc of soil into the drawer. When the -drawer retracts, the soil will fall into the solution.

-26 sensors will monitor the leaching of ions from the soil, including monitors for pH, conductivity, sodium, potassium, calcium, magnesium, barium, chloride and others.

-Next, barium chloride pellets will be added to determine the sulfate ion concentration by the technique of titration.

Planetary scientists will analyze the ionic profile of the soil to determine its history, looking primarily for whether or not it was exposed to liquid water at some point in the past. The information provided by the Orion 229918 sensor assembly, when pieced together with information from other instruments and other missions, will create a clearer understanding of Martian geology, possibly even its biology. The Phoenix mission is the first to land in the gelid North polar region of Mars.

Currently, the Phoenix lander is traveling at 74,200 mph (relative to the sun) toward a rendezvous with Mars that is scheduled for late May 2008. For more information on the Phoenix Mission and other NASA missions, visit: www.nasa.gov/mission_pages/Phoenix/main/. For more information on Thermo Scientific water analysis products, visit: www.thermo.com/water.

Thermo Scientific is part of Thermo Fisher Scientific, the world leader in serving science.