THE IMAGER FOR MARS PATHFINDER EXPERIMENT

The imager for Mars Pathfinder (IMP), a stereoscopic, multispectral ca mera, is described in terms of its capabilities for studying the Marti an environment. The camera's two eyes, separated by 15.0 cm, provide t he camera with range-finding ability. Each eye illuminates half of a s ingle CCD detector with a field of view of 14.4 x 14.0 degrees and has 12 selectable filters. The f/18 optics have a large depth of field, a nd no focussing mechanism is required; a mechanical shutter is avoided by using the frame transfer capability of the 512 x 512 CCD. The reso lving power of the camera, 0.98 mrad/pixel, is approximately the same as the Viking Lander cameras; however, the signal-to-noise ratio for I MP greatly exceeds Viking, approaching 350. This feature along with th e stable calibration of the filters between 440 and 1000 nm distinguis hes IMP from Viking. Specially designed targets are positioned on the Lander; they provide information on the magnetic properties of wind-bl own dust, measure the wind vectors, and provide radiometric standard r eflectors for calibration. Also, eight low-transmission filters are in cluded for imaging the Sun directly at multiple wavelengths, giving IM P the ability to measure dust opacity and potentially the water vapor content. Several experiments beyond the requisite color panorama are d escribed in detail: contour mapping of the local terrain, multispectra l imaging of the surrounding rock and soil to study local mineralogy, viewing of three wind socks, measuring atmospheric opacity and water v apor content, and estimating the magnetic properties of wind-blown dus t. This paper is intended to serve as a guide to understanding the sci entific integrity of the IMP data that will be returned from Mars star ting on July 4, 1997.