The Mars Observer spacecraft carries seven scientific instruments: * The Gamma Ray Spectrometer to determine the chemical elements present on and near the surface of Mars; * The Mars Observer Camera to provide daily global maps of the planet's surface over the four seasons of the Martian year; * The Thermal Emission Spectrometer to measure infrared thermal radiation emitted from the Martian atmosphere and surface and to investigate the waxing and waning of the Martian polar caps; * The Pressure Modulator Infrared Radiometer to record the structure and dynamics of the tenuous Martian atmosphere and provide high vertical-resolution profiles; * The Mars Observer Laser Altimeter to study the topography of Mars; * The. Radio Science investigation, using the spacecraft's own telecommunications antenna, to determine the structure, pressure and temperature of the atmosphere; * The Magnetometer and Electron Reflectometer to measure the planet's magnetic field; * An eighth instrument, the receiver/transmitter, was supplied by the French National Center for Space Sciences (CNES) to support a Russian balloon relay mission in 1996.