PDS_VERSION_ID                  = PDS3
RECORD_TYPE                     = STREAM

DATA_SET_ID                     = "HST-S-WFPC2-3-RPX-V1.0"

OBJECT                          = TEXT
  PUBLICATION_DATE              = 1998-07-17
  NOTE                          = "Abstract to HST proposal #5508, as
downloaded from http://presto.stsci.edu/public/propinfo.html in July
1997."
END_OBJECT                      = TEXT
END

 TRACKING FEATURES IN TITAN'S LOWER ATMOSPHERE AND ON ITS SURFACE: CYCLE4
                            HST Proposal 5508

Title:                 TRACKING FEATURES IN TITAN'S LOWER ATMOSPHERE AND
                       ON ITS SURFACE: CYCLE4
PI:                    PETER SMITH (LUNAR AND PLANETARY LABORATORY)
Category:              SOLAR SYSTEM SATELLITES
Cycle:                 4
Continuation ID:
Status:                completed
                                 Abstract
We propose here to take a major step forward in the study of Titan's
atmosphere and surface by doing a partial survey of the detectable
features at red and NIR wavelengths, probing from 100km to the surface. In
cycle 2 of the HST, 8 images of Titan were obtained with the Planetary
Camera; in the F850LP, several small- scale features, that could be either
on the surface or in the lower atmosphere, or both, were clearly seen
(Smith et al., 1992). The 1992 images proved the ex- istence of trackable
features; however, the photometry is inaccurate because of the image
reconstruction difficulties with WFPC1. A partial orbital revolution of
Titan will now be observed, with several filter sets, at several
intervals. We will identify, track, and characterize all surface and
near-surface features using five filters chosen to sound the altitude
range. Methane band filters are particularly useful in providing high
contrast and accurate altimetry. Features tidally locked with Saturn are
likely to be on the surface. Features not synch- ronous with Saturn are
probably atmospheric. Wind vectors can be derived from them. A
three-dimensional map of observed features, and their velocity vectors,
will be produced, using time history and limb-darkening information. The
final product will include a new global circulation model for Titan, a
revised atmos- pheric scattering model and a surface map.