The robotic arm placed its Martian dirt on top of two 4-inch-wide filter screens that are above the Thermal and Evolved-Gas Analyzer (TEGA). This is a photo of an engineering model of the TEGA which contains an oven that is designed to heat the samples so that its mass spectrometer can identify the gases released. The Phoenix Lander contains eight TEGA devices.
To shake the filter (not pictured in this photo), the three-bladed "whirlygig" spins and causes the top screw to bump the filter above. The samples are then expected to fall through the filter into the small black hole and the oven below.
Photo by University of Arizona
