Macalester's Gamma-Ray Spectrometer measures the spectrum of gamma rays emitted by unstable isotopes undergoing gamma decay. The detector in the Gamma-Ray Spectrometer does not contain any free electrons before the gamma emission of the radioactive unknown. The computer program Gamma Analysis then counts the number of photons emitted by the evelope and plots them with respect to the energy of the photons. At Mac students can identify unknown elements and isotopes via this process. This type of technology bears grand and exciting real-world applications. NASA, for example, also employs Gamma-Ray Spectrometers. Recently they were used on the Mars Odyessy Missions to search for evidence of previous volcanic activity and water on Mars.