Engineering topics
Publications and source records attributed to Stoker, C..
Mars pathfinder successfully landed at Ares Vallis on July 4, 1997 and returned 2.3 Gbits of information during 3 months of surface operations of a lander, rover, three science instruments, engineering sensors and technology experiments.
Layered deposits and residual polar caps on Mars may record the deposition of ice and sediment modulated by periodic climate change. Topographic information relating to layer thicknesses, erosional processes, and formation of dark spirals within these deposits has been sparce or unreliable until the arrival of MOLA in orbit in September 1997. To assist in evaluating these terrains prior to launch and to assess formation and erosion processes in the polar deposits, we have assembled Viking stereo mosaics of the region and have produced the first reliable DEM models of the south polar deposits using automated stereogrammetry tools. Here we report our preliminary topographic results, pending final image pointing updates. The maximum total thickness of the layered deposits in the south polar region is 2.5 km. The thick layered deposits consist of a series of megaterraces. Each terrace is several tens of kilometers wide and is flat or slopes very gently toward the pole. These terraces step downward from a central plateau near the south pole. Terraces are bounded by relatively steep scarps 100-500 meters high that face toward the equator. These scarps correspond to the pattern of dark spirals observed within the residual cap in southern summer, and are interpreted as ice or frost-free surfaces warmed by solar insolation. Several tongue-shaped troughs, with rounded cirquelike heads, are observed near the margins of the deposit. These troughs are 300-600 meters in deep and may be similar to troughs observed in the northern polar deposit.
Mobility is a generic capability needed for Mars exploration. Requirements for mobility range from those needed to get observations of individual rocks all the way to those for getting high-resolution observations of regional areas. The Pathfinder mission and field experiments simulating rover missions provide guidance as to rover capabilities that can reasonably be expected in the next decade. Success of rover missions in achieving science goals depends on having adequate support imaging to enable traverses to targets of high science interest. Rover field experiments to date have used aerial photographs to provide support imaging. Pathfinder Sojourner operated in the field of view of the IMP camera. Plans for the future involve the use of descent imagers. However, the descent imager planned for the 2001 mission achieves resolution adequate to plan rover traverses only in the near vicinity of the lander (within a few hundred meters). Aircraft could provide aerial support imaging with a resolution of 10 cm over the entire area accessible to a rover. Aircraft could also provide the mobility needed to explore regional scale areas
Possible roles are explored for moist convection in the production of bright plume features in the Jupiter atmosphere. The features have been observed at least since 1881. A one-dimensional model is developed for a Jovian cloud and the conditions necessary for convection to occur on Jupiter are defined. The model is used to predict the vertical velocity and maximum altitude of moist clouds that are convected over a vertical extent of 100, 10 and 1 km. Convection within the ammonia layer would not produce sufficient buoyancy to sublime from the rising air parcel. Water rising from the 5 bar to 1 bar level could carry enough ammonia to the cooler region to form plume anvils in the stable layer above 700 mbar. If unpolluted during the convection, the water could be the source of high altitude haze above the entire equatorial zone.