"Some Research Problems on Hydrogen in Planetary Upper Atmospheres and the Interplanetary/Interstellar Medium" Superficially the common thread to the various problems described in this proposal is "hydrogen at low density", but actually these problems are the outgrowth of ones that have occupied the P.I. in one form or another throughout his research career of over 40 years. We expect to be absorbed with the first two problems in the first year of the grant; we will turn our attention to the 3rd and 4th problems in the second and third years, as progress with the first two and the subsequent availability of time permit. All the problems deal with matter at very low densities: the upper atmospheres of planets, exospheres and magnetospheres, and interplanetary/interstellar space. The problems are all theoretical in nature; to the extent that computational data analysis is required, we have an IBM PS/2 (an 80386 machine with a 387 math coprocessor) for our exclusive use when required. In addition, should more powerful computers be needed, we have ready access to Sun workstations, an Apollo DN10000, and a DEC Microvax II, all within the Department of Space Physics and Astronomy. Also the Rice University computing center has a mainframe IBM 3090. MAJOR RESEARCH DISCIPLINES: Atomic structure and spectra; celestial mechanics; radiative transfer; hydrodynamics; plasma physics PROGRAM OFFICE: Atmospheric Sciences, Aeronomy
