Jovian System Data Analysis Program
Analysis ProgramCover Page/Proposal Summary
ROSS-99 NRA 99-OSS-01
Date Due: 5/5/99
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. |
Proposal Type: New Proposal |
Proposal Category: Satellites and Rings |
Major Equipment Proposal? No |
Do you intend to submit an Education/Public Outreach (E/PO) proposal? No |
Proposal Title: |
Io Aurora Processes from Analysis of Galileo SSI and UVS Observations |
Abbreviated Proposal Title: |
Io Aurora Processes |
Principal Investigator: |
Dr. Joseph 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 |
Signature | Date |
_____________________________________ | ____________ |
Co-Investigators and Collaborators: | |||
Type | Name | Affiliation | |
Sci Co-I | Dr. Paul E. Geissler | Univ. Arizona | geissler@lpl.arizona.edu |
Sci Co-I | Dr. Amanda Hendrix | Univ. Colorado | hendrix@lasp.colorado.edu |
Sci Collab | Dr. Geoffrey K. James | JPL | gkjames@pop.jpl.na sa.gov |
Sci Collab | Dr. Louis Frank | Univ. Iowa | frank@iowasp.physics.uiowa.edu |
Proposal Summary:
The Galileo Orbiter Prime and GEM missions have obtained middle ultraviolet (MUV) and visible observations of the Io aurora with the Solid State Imager (SSI) and the Ultraviolet Spectrometer (UVS)over a combined wavelength range from 280-900 nm.
The spectral data and imaging observations provide important information about the atmospheric structure and energy output of the aurora. Galileo's SSI
imaging system has shown colorful blue, green and red aurorae in
visible
wavelength pictures of Io on GEM orbit E15. Similarly the UVS
successfully
observed an N-channel (280-430 nm) aurora on G8. These
emissions are most
likely caused by the impact of electrons on SO2
vented from volcanoes. The
electron impact emission spectroscopy of
SO2 is not well understood. We propose
to analyze medium resolution
(0.05-0.1 nm FWHM)emission spectra of SO2 from
3-100 eV electron
impact energies with a laboratory spectrometer and 1024-pixel
CCD
detector (200-900 nm). The electron energy range for the laboratory
study
spans the range of the Te~5 eV core and Te~100 eV suprathermal
distributions.
The spectral studies will define the excited states of
SO2 and its
dissociation/ionization products contributing to the
aurora. Candidate excited
states are SO2(a,A,B), SO2+(C) and SO(B).
The second goal of the program is to
use the cross sections and plasma
science(PLS) electron distributions to model
the SO2 column abundance
and amend the Io aurora SSI brightnesses for emissions
from MUV
wavelengths below 380 nm, where the brightest MUV/visible emissions
are
found. Color Coordinated simultaneous UVS and SSI observations of
Io with higher
S/N on orbits C22-G29 are planned. Red, green and blue
SSI filter intensity
ratios over volcanoes will be compared to
laboratory spectra to help define the
electron currents at Io.