 :apxs is also an abbreviation for apache extension tool, an extension for apache web servers. thumb|right|200px|alpha particle x-ray spectrometer  thumb|200px|msl curiosity's alpha particle x-ray spectrometer, with a ruler an alpha particle x-ray spectrometer (apxs) is a device that analyses the chemical element composition of a sample from the scattered alpha particles, and fluorescent x-rays after the sample is irradiated with alpha particles and x-rays from radioactive sources.  this method of analysing the elemental composition of a sample is most often used on space missions, which require low weight, small size, and minimal power consumption. other methods (e.g. mass spectrometry) are faster, and do not require the use of radioactive materials, but require larger equipment with less modest power requirements. a variation is the alpha proton x-ray spectrometer, such as on the pathfinder mission, which also detects protons. over the years several modified versions of this type of instrument such as aps (without x-ray spectrometer) or apxs have been flown: surveyor 5-7, mars pathfinder,  mars 96,  mars exploration rover, {{cite journal | title =the new athena alpha particle x-ray spectrometer for the mars exploratio
Canadian_inventions Mars_Exploration_Rover_mission Mars_Pathfinder Mars_Science_Laboratory_instruments Science_and_technology_in_Canada Space_program_of_Canada Space_science_experiments Spacecraft_instruments Spectroscopy University_of_Guelph