The Netlander Panoramic Camera

Kurzfassung

The panoramic camera (PanCam) imaging experiment is designed to obtain high-resolution multispectral stereoscopic panoramic images from each of the four Mars NetLander 2005 sites. The main scientific objectives to be addressed by the PanCam experiment are (1) to locate the landing sites and support the NetLander network sciences, (2) to geologically investigate and map the landing sites, and (3) to study the properties of the atmosphere and of variable phenomena. To place in situ measurements at a landing site into a proper regional context, it is necessary to determine the lander orientation on ground and to exactly locate the position of the landing site with respect to the available cartographic database. This is not possible by tracking alone due to the lack of on-ground orientation and the so-called map-tie problem. Images as provided by the PanCam allow to determine accurate tilt and north directions for each lander and to identify the lander locations based on landmarks, which can also be recognized in appropriate orbiter imagery. With this information, it will be further possible to improve the Mars-wide geodetic control point network and the resulting geometric precision of global map products. The major geoscientific objectives of the PanCam lander images are the recognition of surface features like ripples, ridges and troughs, and the identification and characterization of different rock and surface units based on their morphology, distribution, spectral characteristics, and physical properties. The analysis of the PanCam imagery will finally result in the generation of precise map products for each of the landing sites. So far comparative geologic studies of the Martian surface are restricted to the timely separated Mars Pathfinder and the two Viking Lander Missions. Further lander missions are in preparation (Beagle-2, Mars Surveyor 03). NetLander provides the unique opportunity to nearly double the number of accessible landing site data by providing simultaneous and long-term observations at four different surface locations which becomes especially important for studies of variable surface features as well as properties and phenomena of the atmosphere. Major changes on the surface that can be detected by PanCam are caused by eolian activities and condensation processes, which directly reflect variations in the prevailing near-surface wind regime and the diurnal and seasonal volatile and dust cycles. Atmospheric studies will concentrate on the detection of clouds, measurements of the aerosol contents and the water vapor absorption at 936 nm. In order to meet these objectives, the proposed PanCam instrument is a highly miniaturized, dedicated stereo and multispectral imaging device. The camera consists of two identical camera cubes, which are arranged in a common housing at a fixed stereo base length of 11 cm. Each camera cube is equipped with a CCD frame transfer detector with 1024×1024 active pixels and optics with a focal length of 13 mm yielding a field-of-view of 53°×53° and an instantaneous filed of view of 1.1 mrad. A filter swivel with six positions provides different color band passes in the wavelength range of 400–950 nm. The camera head is mounted on top of a deployable scissors boom and can be rotated by 360° to obtain a full panorama, which is already covered by eight images. The boom raises the camera head to a final altitude of 90 cm above the surface. Most camera activities will take place within the first week and the first month of the mission. During the remainder of the mission, the camera will operate with a reduced data rate to monitor time-dependent variations on a daily basis. PanCam is a joint German/French project with contributions from DLR, Institute of Space Sensor Technology and Planetary Exploration, Berlin, Institut d'Astrophysique Spatiale, CNRS, Orsay, and Service d'Aéronomie, CNRS, Verrières-le-Buisson.