A variety of HST times will be available to augment observations provided by ground based astronomers. A group of planetary scientists, Peter Smith and Robert Reid of the Lunar & Planetary Laboratory, and Matthew Golombek and Ken Herkenhoff of the Jet Propulsion Laboratory, have been granted some HST observing time through Cycle 6 (12 months beginning July, 1996) to determine climatic conditions, dust opacity, and dust storm activity at the Mars Pathfinder primary and secondary landing sites during cruise. Since the Pathfinder spacecraft does not go into orbit around Mars prior to landing, careful monitoring of all landing sites must be made well in advance in order to make necessary course corrections. This is especially true if the primary landing site is experiencing local dust storm activity and Pathfinder must be redirected to a secondary landing site. HST observations have been scheduled for all landing sites prior to trajectory course maneuvers (TCMs).

Dave Crisp of the Jet Propulsion Laboratory, as a member of the Wide Field/Planetary Camera 2 (WFPC2) Science Team, also has some observing time from HST as part of the Guaranteed Time Observing (GTO) program.

In addition, a team of planetary astronomers lead by Phil James of the University of Toledo will continue its long-term program of HST Mars observations during the 1996-97 apparition. These observations, begun in 1990 in HST Cycle 0, are designed to monitor the evolution of clouds, hazes, surface ices, and atmospheric ozone during the Martian seasonal cycle. As well, they will be used to search for long-term variations in Mars surface albedo features, to map the distribution of various minerals on the Martian surface, and to provide cruise-phase support information for the Mars Pathfinder and Mars Global Surveyor spacecraft missions.

The 1996-97 observations during HST Cycle 6 will occur at 8 points in the Mars seasonal cycle between September 1996 and June 1997. Planned observation windows are indicated in Table 1 below. Because of scheduling limitations, it is not possible to know the precise time that the observations will occur until only a few weeks before the observation window. The observations will be made with the Faint Object Spectrograph (FOS) and the WFPC2 instruments. WFPC2 images will be obtained using up to 10 filters, designed to optimize the detection and discrimination of clouds, ozone, ices, and surface minerals, during each orbit.

HST Cycle 6 ends at the end of June 1997. We are planning to propose to continue these and other observations during the beginning of HST Cycle 7 starting in July 1997, so as to provide synoptic HST Mars imaging coverage for the duration of the Mars Pathfinder Lander primary mission and for the remainder of the Mars Global Surveyor Orbiter cruise phase.

Other team members include James Bell (Cornell University), Todd Clancy (Space Sciences Institute), Steve Lee (University of Colorado), Leonard Martin (Lowell Observatory), and Mike Wolff (Space Sciences Institute).

Table 1: HST Mars observations during 1996-1997

Date	Observations
16-20 September 1996	Imaging at CML=165; FOS Scans
06-10 October 1996	Global Imaging at CML=045,165,285 (1st Pathfinder observation)
18-22 November 1996	Imaging at CML=165
02-06 January 1997	Global Imaging at CML=045,165,285; FOS Scans
25-31 March 1997	Global Imaging at CML=015,105,195,285
14-18 April 1997	Imaging at CML=045 (Pathfinder monitoring intensifies)
17-21 May 1997	Global Imaging at CML=045,165,285
26-30 June 1997	Global Imaging at CML=030,075,345 (Daily weather)

CML=Central Meridian Longitude

FOS=Faint Object Spectrograph

All Imaging will be performed with WFPC2 using up to 10 filters between 218 and 1042 nm