PDS: The Planetary Atmospheres Node
Cover Page/Proposal Summary
ROSS-99 NRA 99-OSS-01
Date Due: 5/3/99
|
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: Tenuous Atmospheres |
| Major Equipment Proposal? No |
| Do you intend to submit an Education/Public Outreach (E/PO) proposal? No |
| Proposal Title: |
| Modeling the extended neutral atmosphere and plasma environment near Saturn |
| Abbreviated Proposal Title: |
| Modeling Saturn's Neutral and Plasma Environment |
| Principal Investigator: |
| Dr.
John D. Richardson Center for Space Research Room 37-655 Massachusetts Inst. Tech. 70 Vassar St. Cambridge, MA 02139-4307 Phone: 617-253-6112 Fax: 617-253-0861 E-mail: jdr@space.mit.edu |
| Signature | Date |
| _____________________________________ | ____________ |
| Co-Investigators and Collaborators: | |||
| Type | Name | Affiliation | |
| Sci Collab | Dr. Robert E. Johnson | University of Virginia | rej@virginia.edu |
| Sci Collab | Mr. Slobodan Jurac | University of Virginia | sj4u@virginia.edu |
Proposal Summary:
This proposal is for continuation of a study of the plasma and neutral environment surrounding Saturn. In the first phase of the project, we developed the first model for Saturn's inner magnetosphere and ring region which determines plasma and neutral densities and composition. The model reproduces the Voyager plasma and H and the Hubble OH observations fairly well. We have extended the plasma model to include the energy equation and will soon have a complete model of the energy balance as well. The weakness of the model used previously is that the treatment of plasma and neutrals is not self-consistent. The neutral source strength and distribution is a model parameter, not derived from sputtering results. The goal of the proposed work is to fully reconcile the Hubble Space Telescope detection of the neutrals and the Voyager plasma measurements by integrating a sophisticated neutral cloud model with a plasma transport model. In this way we expect to pin down the principal aspects of the Saturnian neutral and plasma tori in preparation for CASSINI's exploration of Saturn's system. We will combine the University of Virginia code which calculates sputtering rates and follows neutrals through the magnetosphere using a Monte Carlo calculation with the MIT plasma code already developed. The plasma and neutral interaction is of many forms. Sputtering of the icy surfaces by plasma provides some of the neutral source. Ionization of the neutrals creates the plasma. Ion-neutral collisions can heat the neutrals, expanding the size of the neutral cloud, and cool the plasma. Thus we expect the final neutral and plasma configuration result from a complex feedback loop, which we will simulate with our models. The output from the models will be the distribution of neutrals and plasma and radial distance and latitude, the composition of the neutrals, the composition of the plasma, the ion and electron temperatures, the neutral source rate, and the plasma diffusion coefficient.
