Components of a mass spectrometer as designed by Alfred Otto Carl Nier (1911-1994). Mass spectrometers are analytical instruments used to measure the mass-to-charge ratio of one or more molecules in a sample. The components of the mass spectrometer pictured here include the ion source where a sample is ionized, a flight tube in which the ion beam is separated into its components, and three power supplies. Mass spectrometers also require a detector for analyzing the ion beams as they are received and a vacuum source. Alfred Otto Carl Nier (1911-1994) was an American Physicist who specialized in Mass Spectroscopy and the study of Uranium. He was involved in the Manhattan Project, mainly in designing the spectrographs used by the scientists creating the Atomic Bomb. After the war, Nier focused his research on space science and the noble gasses, designing the miniature Mass Spectrometers used on the Viking Lander Spacecrafts to sample and measure the atmosphere of Mars. Instruments similar to the spectrometer here were part of the atmospheric analysis instrumentation sent to Mars on the Viking 1 and Viking 2 spacecrafts.