ALBERT

Description: A nonlinear filtering method is introduced for the study of the solar wind -- magnetosphere coupling and related to earlier linear techniques. The filters are derived from the magnetospheric state, a representation of the magnetospheric conditions in terms of a few global variables, here the auroral electrojet indices. The filters also couple to the input, a representation of the solar wind variables, here the rectified electric field. Filter-based iterative prediction of the indices has been obtained for up to 20 hours. The prediction is stable with respect to perturbations in the initial magnetospheric state; these decrease exponentially at the rate of 30/min. The performance of the method is examined for a wide range of parameters and is superior to that of other linear and nonlinear techniques. In the magnetospheric state representation the coupling is modeled as a small number of nonlinear equations under a time-dependent input.

Description: The ability of living organisms to survive on the smaller bodies in our solar system is examined. The three most significant sterilizing effects include ionizing radiation, prolonged extreme vacuum, and relentless thermal inactivation. Each could be effectively lethal, and even more so in combination, if organisms at some time resided in the surfaces of airless small bodies located near or in the inner solar system. Deep within volatile-rich bodies, certain environments theoretically might provide protection of dormant organisms against these sterilizing factors. Sterility of surface materials to tens or hundreds of centimeters of depth appears inevitable, and to greater depths for bodies which have resided for long periods sunward of about 2 A.U.

Description: The first Astronaut-Rover Interaction field experiment (hereafter designated as the ASRO project) took place Feb. 22-27, 1999, in Silver Lake, Mojave Desert, CA. The ASRO project is the result of a joint project between NASA Ames Research Center and Johnson Space Center. In the perspective of the Human Exploration and Development of Space (HEDS) of the Solar System, this interaction - the astronaut and the rover as a complementary and interactive team - in the field is critical to assess but had never been tested before the Silver Lake experiment. Additional information is contained in the original extended abstract.

Description: The tail currents predicted by empirical magnetic field models and global MHD simulations are compared. It is shown that the near-Earth currents obtained from the MHD simulations are much weaker than the currents predicted by the Tsyganenko models, primarily because the ring current is not properly represented in the simulations. On the other hand, in the mid-tail and distant tail the lobe field strength predicted by the simulations is comparable to what is observed at about 50 R(sub E) distance, significantly larger than the very low lobe field values predicted by the Tsyganenko models at that distance. Ways to improve these complementary approaches to model the actual magnetospheric configuration are discussed.

Description: Continuous ground-based observations of ionospheric and magnetospheric regions are critical to the Geospace Environmental Modeling (GEM) program. It is therefore important to establish clear intercalibrations between different ground-based instruments and satellites in order to clearly place the ground-based observations in context with the corresponding in situ satellite measurements. HF-radars operating at high latitudes are capable of observing very large spatial regions of the ionosphere on a nearly continuous basis. In this paper we report on an intercalibration study made using the Polar Anglo-American Conjugate Radar Experiment radars located at Goose Bay, Labrador, and Halley Station, Antarctica, and the Defense Meteorological Satellite Program (DMSP) satellites. The DMSP satellite data are used to provide clear identifications of the ionospheric cusp and the low-latitude boundary layer (LLBL). The radar data for eight cusp events and eight LLBL events have been examined in order to determine a radar signature of these ionospheric regions. This intercalibraion indicates that the cusp is always characterized by wide, complex Doppler power spectra, whereas the LLBL is usually found to have spectra dominated by a single component. The distribution of spectral widths in the cusp is of a generally Gaussian form with a peak at about 220 m/s. The distribution of spectral widths in the LLBL is more like an exponential distribution, with the peak of the distribution occurring at about 50 m/s. There are a few cases in the LLBL where the Doppler power spectra are strikingly similar to those observed in the cusp.

Description: Over the past 30 years, Gerald Schubert has made significant contributions to the understanding of Venus atmospheric dynamics. His research of Venus' atmosphere spans spatial scales both large and small, including: Venus westward atmospheric superrotation, Planetary scale waves and the global "Y" ultraviolet feature, Wind streaks and the global circulation of the lower atmosphere, Mesoscale convection in the clouds of Venus, Vertical propagation of small-scale internal gravity waves, and Interaction between small-scale dynamics and the large-scale mean flow. Furthermore, his role as Principal Investigator of the Pioneer Venus Working Group on Structure and Circulation in the late 1970's and early 1980's was instrumental in the advancement of our understanding of Venus' atmosphere. The Pioneer Venus work serves as the cornerstone of our view of Venus atmospheric dynamics today. This paper will review Jerry's extensive research on Venus' atmosphere. In addition, recent results on convectively generated internal gravity waves will be presented that combine his lifelong, interest in both large-scale and small-scale dynamics. It will be shown that small-scale internal gravity waves generated by convection within the clouds of Venus decelerate the westward superrotation below the clouds. Thus, mechanisms that support the Venus westward superrotation must overcome the influence of small-scale dynamics in the lower atmosphere.