There are three main instruments on Pathfinder. The Imager for MESUR Pathfinder primarily provides stereoscopic images via CCD camera. The surface elemental chemistry is the focus of the Alpha Proton X-ray Spectrometer. Finally, the Atmospheric Structure Instrument/Meteorology Package has been given the task of taking data such as temperature and pressure for scientific analysis.
Imager for MESUR Pathfinder (IMP)
This stereo imaging system, with color capability, consists of three main sections: camera head, extendable mast with electronic cabling, and two plug-in electronics cards.
The camera is located at the top of a deployable mast, which when deployed, can provide an elevation of one meter.
This instrument will also investigate magnetic properties. Magnets of varying field strengths are mounted to a plate that is attached to the lander. Magnetic particles from the Martian "air" will be attracted to the plates, which will be imaged for mineral composition.
Also included in this investigation is the study of wind direction on Mars. Three small wind socks are mounted above a reference grid with a target for reference and calibration on the lander.
Alpha Proton X-ray Spectrometer (APXS)
This instrument will determine the elemental chemistry of materials found on the surface for all major elements except hydrogen. The APXS is mounted inside the rover where the temperature can be controlled. Its sensor head is mounted on a deployment mechanism. The spectrometer consists of an alpha particle source and detector for back-scattered alpha particles, protons and x-rays. Material will be exposed to a radioactive source that produces alpha particles of a certain energy, and by looking at the energy spectrum of the alpha particles, protons and x-rays emitted, the elemental composition can be determined.
Atmospheric Structure Instrument / Meterology Package (ASI/MET)
This instrument collected data during descent and landing in order to provide information on atmospheric density, temperature and pressure at about 100 km down to the surface.
Temperature and pressure sensors are mounted on the lander at various locations. Depending on the vertical descending rate of the lander, the sampling rate from the sensors can be increased or decreased. Since landing, the ASI/MET continues to sample the temperature and pressure to record the daily changes during the mission.