The experiments aboard Pathfinder promise to tell us all something new about Mars. In particular, these instruments will provide information about the element abundance, iron-bearing minerals, and atmospheric properties during descent and on the surface. These instruments and the science objectives they represent will provide us with a new, fresh view of the Red Planet from its surface.
Each of the IMP's two cameras (two in order to get stereo images) has 12 filters between wavelengths of 0.4 and 1.0 microns. These filters were carefully selected to allow determination of certain atmosphere and surface properties. For example, a band at 0.425 microns can look up at the sun through the atmosphere, and thereby provide an estimate of how much dust or cloud material is suspended in above the landing site. A band at about 1.0 microns will allow determination of the presence of pyroxene, a key mineral expected to be present in the rocks.
Besides studying the surface and atmosphere, IMP will assist in navigation for the Microrover, monitor wind conditions, and examine the magnetic constituents of the soil. A series of magnetic surfaces will be placed on the lander. Current plans (April 1994) call for having two targets, one near the surface level and one at a height of 0.5 meters. The magnetic targets, provided by a team under the direction of Dr. Jens Martin Knudsen of the University of Copenhagen, Denmark, will collect magnetic dust settled out of the atmosphere. Images of these magnetic materials will help determine the mineral composition and the magnetic strength of these minerals.
The IMP wind sock experiment promises to be very exciting. Like the IMP itself, the wind sock experiment has a unique Arizona connection. It is being developed by Dr. Ronald Greeley and Dr. Robert Sullivan of Arizona State University in Tempe. Small flags will be placed on one or two masts up to a height of about 0.5 meters. As the wind blows, the flags will point in the direction the wind is going.
Because the APXS is mounted on a rover for the very first time, scientists will be able to move around an area and sample the composition of a number of rocks and surfaces that would otherwise be inaccessible on a fixed lander. When collecting data, the APXS is placed on the surface to be examined. It must sit on that surface for 10 hours to collect data in the Alpha Proton mode, and 1 hour for the X-ray mode. The surfaces to be examined by the APXS will also be imaged by the microrover's two small cameras. The surface being examined is exposed to a radioactive source (Cm - 244) which provides the alpha particles. The detectors determine the energy of alpha particles, protons, and x-rays emitted off the surface being bombarded with alpha particles. Most important chemical elements (e.g., C, O, Mg, Al, Si, Ca, K, Fe, Ni) can be identified using this instrument. This will allow for investigation of rock and soil compositions.
The ASI/MET package is critical to meeting the engineering objectives of this mission. The ASI/MET will obtain data about the atmosphere as the spacecraft is descending toward the surface for landing. Data acquired during the entry and descent of Pathfinder will allow the reconstruction of profiles of atmospheric density, temperature, and pressure from an altitude of over 100 km down to the surface.
The hardware basically consists of an accelerometer and a number of temperature and pressure sensors mounted at several locations on the lander. Once the spacecraft has landed, these instruments will provide information about the day-to-day variations of weather on the martian surface.