Cover Page/Proposal Summary

ROSS-99    NRA 99-OSS-01

Date Due: 5/3/99

NASA PROCEDURE FOR HANDLING PROPOSALS

This proposal shall be used and disclosed for evaluation purposes only, and a copy of this Government notice shall be applied to any reproduction or abstract thereof. Any authorized restrictive notices that the submitter places on this proposal shall also be strictly complied with. Disclosure of this proposal for any reason outside the Government evaluation purposes shall be made only to the extent authorized by the Government.

Confirmation # 00-006   Date Received: Apr 07, 1999

Proposal Type: New Proposal

Proposal Category: Laboratory

Major Equipment Proposal? No

Do you intend to submit an Education/Public Outreach (E/PO) proposal? No

Proposal Title:
UV Emission Processes in Planetary Atmospheres by Electron Impact

Abbreviated Proposal Title:
UV Emission Processes by Electron Impact

Principal Investigator:
Dr. Joseph M. Ajello
UV Emission Processes Team Space Sciences Division MS 183-601
JPL
4800 Oak Grove Drive
Pasadena, CA 91109-8099
Phone: 818-354-2457   Fax: 818-393-4605   E-mail: jajello@jpluvs.jpl.nasa.gov

SignatureDate
_________________________________________________

Co-Investigators and Collaborators:
Type    Name    Affiliation    E-mail
Sci Co-I   Dr. Geoffrey K. James   JPL   gkjames@pop.jpl.na sa.gov
Sci Co-I   Prof. Donald E. Shemansky   USC   dons@hippolyta .usc.edu
Sci Co-I   Dr. Xianming Liu   USC   xliu@jpluvs.jpl.nasa .gov
Sci Collab   Dr. John T. Clarke   Univ. Michigan   clarke@sunshine.sprl.umich.edu
Sci Collab   Dr. Herve Abgrall   Meudon Observatory   abgrall@mesioq.obspm.fr
Sci Collab   Dr. Alex Dalgarno   Harvard   dalgarno@cf a.harvard.edu


Proposal Summary:

Analysis of observations of planetary atmospheres by Hubble Space Telescope, Galileo, Cassini and FUSE require laboratory measurements of collision cross sections. A dominant mechanisim for energy transfer in the upper atmosphere occurs through electron collision processes with neutral species. In response to the need for accurate collision cross sections JPL established UV instrumentation to routinely measure emission cross sections of gases. In this program we concentrate on the species H2, N2, O, O2 and H the most important species of the upper atmospheres of the Jovian Planetary Systems. The objectives are :1) to measure electron impact cross sections (0-2keV) and fluorescence spectra (50-400 nm)and 2) to develop analytic collision strengths for electron energy loss codes. Cross sections are needed to model spectroscopic observations of jovian and terrestrial planets in preflight instrument calibration, data analysis and mission planning phases. UV emission cross sections can not be established by theory due to the high density of perturbing states. JPL has established three unique UV instruments, including a high resolution spectrometer with resolving power of 60000, to study electron impact fluorescence. The rotationally resolved UV spectrum of H2 Rydberg bands (B,B',B",C,D,D')will be compared to theory. The H2 atlas will be updated with new rotational lines and Rydberg states. A pulsed gun technique allows separation of cascade (slow) and direct (fast) electron excitation processes. UV Lyman band observations are used to determine global energy input to the atmosphere. The H2 EF->B->X (cascade) and B->X (direct) excitation cross sections, which comprise the Lyman Band system can be separately measured. Atomic O and H radical source high density beams established for cross section studies of resonance lines: OI(130.4nm), H(102.5nm) and cascade (visble). N2 states (b,b',c,c',o) will be studied to determine rovibronic predissociation yields.