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MGS Schedules Imaging Opportunities For Viking, Pathfinder, Cydonia Region On Mars

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

Contact: Diane Ainsworth

FOR IMMEDIATE RELEASE           March 31, 1998

GLOBAL SURVEYOR SCHEDULES IMAGING OPPORTUNITIES FOR VIKING, 
PATHFINDER, CYDONIA REGIONS OF MARS

     The Mars Global Surveyor project has resumed scientific 
observations of the surface of Mars and has scheduled 
opportunities to image four selected sites: the Viking 1 and 2 
landing sites, the Mars Pathfinder landing site and the Cydonia 
region.

     Three opportunities to image each of the four sites using 
the spacecraft's high-resolution camera will take place over the 
next month, beginning on April 3 at 1:58 a.m. Pacific time, when 
Global Surveyor passes over the Viking 1 landing site.  The 
spacecraft will next pass over the Viking 2 landing site at 1:37 
p.m. Pacific time on April 3.  On April 4, Global Surveyor will 
try to image the now-silent Mars Pathfinder spacecraft at 1:16 
a.m. Pacific time.  It will then capture a portion of  the 
Cydonia region of Mars, location of the so-called "Face on Mars," 
on April 5 at 12:33 a.m. Pacific time. 

     Attempts to rephotograph the sites will occur during two 
additional opportunities falling about nine days apart.  A 
detailed schedule of the imaging attempts is listed below. 
Uncertainties in both the spacecraft's pointing and the knowledge 
of the spacecraft's ground track from its navigation data will 
provide only a 30- to- 50-percent chance of capturing the images 
of each site.  

     All of the selected targets are located south of Global 
Surveyor's periapsis, or point of closest approach to the Martian 
surface. Shortly before the spacecraft reaches this point, the 
Global Surveyor spacecraft will rotate slightly so that when it 
nears the selected target, the camera's field-of-view will sweep 
across the target as the spacecraft flies south and rises away. 

     The spacecraft will begin transmitting to Earth data stored 
on its onboard solid-state recorders about seven hours after the 
images are acquired, concluding about three hours later. 
Currently it takes radio signals from Mars Global Surveyor about 
20 minutes to travel from the spacecraft to Earth.

     Data will be received at one of NASA's Deep Space Network 
tracking stations at Goldstone, CA, near Madrid, Spain or near 
Canberra, Australia, and then sent by satellite to NASA's Jet 
Propulsion Laboratory, Pasadena, CA. There the images, along with 
all of the rest of Global Surveyor's science and engineering 
data, are placed in the project database for access by flight 
controllers.  This process takes only seconds for each bit of 
data.  Consequently, the image data will not be available be on 
the ground until about 10.5 hours after they are acquired.  Data 
received overnight will not be retrieved until 9 a.m. Pacific 
time on the following workday.

     When image data are retrieved by camera operators, the 
information is assembled into "raw" images.  Raw images may 
contain data errors or drop-outs introduced by noise in the 
telecommunications channel between the spacecraft and the ground, 
as well as very slight picture element variations inherent in the 
camera. This data processing takes about 30 minutes.

     Raw images will posted on three web sites:  JPL's Mars news 
site at http://www.jpl.nasa.gov/marsnews , the Mars Global 
Surveyor project home page at http://mars.jpl.nasa.gov ,  and 
NASA's Planetary Photojournal site at 
http://photojournal.jpl.nasa.gov .  Information identifying the 
acquisition time, predicted center latitude and longitude of the 
target location, and the local solar time will accompany these 
images. Contrast enhancement will be performed by JPL's 
Multimission Image Processing Laboratory and posted on World Wide 
Web a few hours later.  The Global Surveyor project home page 
also contains spacecraft orbital velocity and distance to the 
planet in real time. 

     Images of the Viking and Mars Pathfinder landing sites will 
not be posted until image enhancement and identification of the 
vehicles have been completed, because the small spacecraft will 
be at the limits of the camera's resolution. This process will 
take about 24 hours. 

     Mars Global Surveyor is part of a sustained program of Mars 
exploration known as the Mars Surveyor Program. The mission is 
managed by the Jet Propulsion Laboratory for NASA's Office of 
Space Science, Washington, DC.  JPL's industrial partner is 
Lockheed Martin Astronautics, Denver, CO, which developed and 
operates the spacecraft. JPL is a division of the California 
Institute of Technology, Pasadena, CA.

           

               Mars Global Surveyor Imaging Schedule 


First opportunity 
                                                    Approximate
                             Orbit                  Internet
Date    Time (UTC/Pacific)   Number  Target         Posting   

4-3-98  09:58/1:58 a.m.      216  Viking Lander 1   April 6
4-3-98  21:37/1:37 p.m.      217  Viking Lander 2   April 7
4-4-98  09:16/1:16 a.m.      218  Mars Pathfinder   April 7
4-5-98  08:33/12:33 a.m.     220  Cydonia           April 6 (mid-a.m.)       

Second opportunity
                                                    Approximate
                             Orbit                  Internet
Date    Time (UTC/Pacific)   Number  Target         Posting   

4-12-98 15:23/ 8:23 a.m.     235  Viking Lander 1   April 14
4-13-98 03:01/ 8:01 p.m.     236  Viking Lander 2   April 15
4-13-98 14:40/ 7:40 a.m.     237  Mars Pathfinder   April 15
4-14-98 13:57/ 6:57 a.m.     239  Cydonia          April 14 (mid-p.m.)                     

Third opportunity
                                                    Approximate
                             Orbit                  Internet
Date    Time (UTC/Pacific)   Number  Target         Posting   

4-21-98 20:45/1:45 p.m.      254  Viking Lander 1   April 23
4-22-98 08:23/1:23 a.m.      255  Viking Lander 2   April 24
4-22-98 20:02/1:02 p.m.      256  Mars Pathfinder   April 24
4-23-98 19:18/12:18 p.m.     258  Cydonia          April 24 (mid-a.m.)

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