Dr. Tom Slanger and colleagues at SRI International will perform observations of the visible and near-infrared nightglow emissions from the atmospheres of Mars and Venus, using the Hubble space Telescope and the ARC 3.5-m telescope at the Apache Point Observatory, respectively. The Mars nightglow spectrum has never been recorded previously, either by planetary probes or by near-Earth telescope observations. Dr. Slanger predicts that Meinel band emissions from the OH radical will be prominent features in the Mars nightglow and that these emissions will provide essential information about the abundances of hydrogen atoms and ozone molecules in the Mars middle atmosphere, and indirectly provide information about the fate of atmospheric water. Observations of molecular and atomic oxygen emissions will also be performed, providing important constraints on models of oxygen atom profiles, about which we have little direct information. This group's pioneering telescope observations of the visible nightglow spectrum of Venus are having a significant impact. The discovery of oxygen green-line emission has challenged current interpretations of oxygen energy-transfer kinetics. That its intensity is highly variable (absent in 1975, present in 1999, and absent again in 2001) motivates an on-going program of observations to elucidate the origins of variability and the implications for understanding dayside-to-nightside, horizontal, and vertical transport.
The project will be conducted in close collaboration with the Astronomy Department at New Mexico State University. The extensive work carried out in recent years using astronomical sky spectra will be substantially enhanced by the direct collaboration and communication that will be required on this project. Over the last decade, the SRI Molecular Physics Laboratory has acted as host to almost 100 undergraduates in the NSF Research Experiences for Undergraduates (REU) program. This interaction will continue. ***
