Abstract. The WAVES investigation on the WIND spacecraft will provide comprehensive measurements of the radio and plasma wave phenomena which occur in Geospace. Analyses of these measurements, in coordination with the other onboard plasma, energetic particles, and field measurements will help us understand the kinetic processes that are important in the solar wind and in key boundary regions of the Geospace. These processes are then to be interpreted in conjunction with results from the other ISTP spacecraft in order to discern the measurements and parameters for mass, momentum, and energy flow throughout geospace. This investigation will also contribute to observations of radio waves emitted in regions where the solar wind is accelerated. The WAVES investigation comprises several innovations in this kind of instrumentation: among which the first use, to our knowledge, of neural networks in real-time on board a scientific spacecraft to analyze data and command observation modes, and the first use of a wavelet transform-like analysis in real time to perform a spectral analysis of a broad band signal.

No abstract

Chemical analyses returned by Mars Pathfinder indicate that some rocks may be high in silica, implying differentiated parent materials. Rounded pebbles and cobbles and a possible conglomerate suggest fluvial processes that imply liquid water in equilibrium with the atmosphere and thus a warmer and wetter past. The moment of inertia indicates a central metallic core of 1300 to 2000 kilometers in radius. Composite airborne dust particles appear magnetized by freeze-dried maghemite stain or cement that may have been leached from crustal materials by an active hydrologic cycle. Remote-sensing data at a scale of generally greater than ϳ1 kilometer and an Earth analog correctly predicted a rocky plain safe for landing and roving with a variety of rocks deposited by catastrophic floods that are relatively dust-free.Mars Pathfinder (named the Sagan Memorial Station) landed on the surface of Mars on 4 July 1997 (Figs. 1 and 2), deployed a small rover (named Sojourner) (Fig. 3), and collected data from three scientific instruments [named Imager for Mars Pathfinder (IMP), ␣-proton x-ray spectrometer (APXS), and atmospheric structure investigation/meteorology package (ASI/MET)] and technology experiments (1). In the first month of surface operations the mission returned about 1.2 gigabits of data, which include 9669 lander and 384 rover images and about 4 million temperature, pressure, and wind measurements. The rover traversed a total of about 52 m in 114 commanded movements, performed 10 chemical analyses of rocks and soil, carried out soil mechanics and technology experiments, and explored over 100 m 2 of the martian surface.Pathfinder used a rover, carrying a chemical analysis instrument, to characterize the rocks and soils in a landing area over hundreds of square meters on Mars, which provides a calibration point or "ground truth" for orbital remote-sensing observations (1, 2). The combination of spectral imaging of the landing area by the IMP, chemical analyses by the APXS aboard the rover, and close-up imaging of colors, textures, and morphologies with the rover cameras offers the potential for identifying rocks (petrology and mineralogy). Before the Pathfinder mission, knowledge of the kinds of rocks present on Mars was based mostly on the martian meteorites (all mafic igneous rocks) and inferences from Viking data (3, 4). In addition, small valley networks in heavily cratered terrain on Mars have been used to argue that the early martian environment may have been warmer and wetter (with a thicker atmosphere), at which time liquid water may have been stable (5).The Ares Vallis landing site (Fig. 4) was selected because it appeared acceptably safe and offered the prospect of analyzing a variety of rock types expected to be deposited by catastrophic floods, which enable addressing first-order scientific questions such as differentiation of the crust, the development of weathering products, and the nature of the early martian environment and its subsequent evolution (2). In the selection of the Pathfinder landing site...

No abstract