The third image of the Cydonia Region taken by the Mars Global Surveyor spacecraft is now available on the MGS website:

http://mars.jpl.nasa.gov/mgs/target/CYD3/index.html

This is the raw image. Processed images will be available later today at the same site.

Also available is an MGS image of the Viking 1 landing site:

http://mars.jpl.nasa.gov/mgs/msss/camera/images/4_23_98_vl1_stereo_release/index.html

Captions to both images are appended below.

Ron Baalke

RAW IMAGE POSTED - April 24, 1998 10:00 AM Pacific Daylight Savings Time CYDONIA OBSERVATION #3 PHOTO CAPTION

Orbit:  258
Range:  409.53 km
Resolution:  3.46 m/pixel
Image dimensions:  1024 X 9600 pixels,  3.5 km x  33.2 km
Line time:  0.50 msec
Emission angle:  29.90 degrees
Incidence angle:  69.59 degrees
Phase angle:  60.62 degrees
Scan rate:  ~0.15 degree/sec
Start time:  periapsis + 410 sec
Sequence submitted to JPL:  Wed 04/22/98 21:45:00 PDT
Image acquired by MOC:  Thu 04/23/98 12:23:02 PDT
Data retrieved from JPL:  Fri 04/24/98 09:00 PDT



              MOC Acquires High Resolution Stereoscopic Images
                         of Viking One Landing Site

Mars Global Surveyor Mars Orbiter Camera Release:          MOC2-44A, -44B
Mars Global Surveyor Mars Orbiter Camera Image ID:         577659262.25403
                                                           P254-03 (partial)
                                                           576862349.23503
                                                           P235-03 (partial)

See also: Viking One Landing site

(A) Viking Orbiter 1 027A63, showing outline of area including Viking Lander 1 location covered by stereoscopic images

(B) Stereoscopic portions of MOC images 25403 (red) and 23503 (blue,green) reproduced at a scale of 7.5 meters/pixel (JPG = 676 KBytes)

CAPTION

Two MOC images of the vicinity of the Viking Lander 1 (MOC 23503 and 25403), acquired separately on 12 April 1998 at 08:32 PDT and 21 April 1998 at 13:54 PDT (respectively), are combined here in a stereoscopic anaglyph. The more recent, slightly better quality image is in the red channel, while the earlier image is shown in the blue and green channels. Only the overlap portion of the images is included in the composite.

Image 23503 was taken at a viewing angle of 31.6 from vertical; 25403 was taken at an angle of 22.4, for a difference of 9.4. Although this is not as large a difference as is typically used in stereo mapping, it is sufficient to provide some indication of relief, at least in locations of high relief.

The image shows the raised rims and deep interiors of the larger impact craters in the area (the largest crater is about 650 m/2100 feet across). It shows that the relief on the ridges is very subtle, and that, in general, the Viking landing site is very flat. This result is, of course, expected: the VL-1 site was chosen specifically because it was likely to have low to very low slopes that represented potential hazards to the spacecraft.

Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.


From the Mars Global Surveyor home page:

Announcement of Third Cydonia Observation

20-APR-98 11:00 AM PDT

The Mars Surveyor Operations Project is proceeding with the implementation of its third and final cluster of targeted imaging at Mars. This cluster will again target the two Viking Lander sites, a refined Mars Pathfinder landing site, and a new area in Cydonia.

On Tuesday, April 21st, at 1:43 PM PDT and on Wednesday morning, April 22, at 1:22 AM PDT, MGS will again attempt to image the sites of the Viking Landers on two consecutive orbits. Recall that on the first attempt, Viking 1 was slightly outside the camera's field of view. However, on the second attempt the site was in the image, but it was not possible to see the lander. The Viking 2 site has been covered with clouds on both previous attempts.

Then on Wednesday afternoon, April 22 at 1:00 PM PDT, MGS will again attempt to image the site of the Mars Pathfinder landing. This site was missed on the two previous attempts.

On Thursday afternoon at 12:17 PM PDT, MGS will again image a portion of the Cydonia region. Global Surveyor will again target to capture an image of the features known as "The City". This area contains features identified as "mounds", "city square", "pyramid" and the "fortress". The image will be targeted to capture portions of the "pyramid" and the "fortress", as well as "mounds".

As with the two previous images of the Cydonia region, the camera will be set to produce an image 1024 pixels wide so that the length of the image can be maximized to include as many features as possible. With a range from Cydonia to the spacecraft of 392 kilometers (244 miles), this will enable a resolution of 3.46 m/pixel (11.4 feet/pixel) and an image 3.5 km (2.2 miles) in width by 33 km (20.5 miles) in length.

The same probabilities of success of 30% to 50% will apply to each of these attempts based on navigation uncertainties and spacecraft attitude control performance. Experience with the first and second clusters of targeted images has shown that winter weather in the northern hemisphere of Mars at this time causes haze, dust storms, surface frost and heavy cloud cover to be significant factors in the success of seeing the targets clearly. The weather effects are not included in the probability of success estimates.

Results of the Cydonia imaging will be posted on the Internet, in the same manner as following the first and second observation attempts, at approximately mid-morning Pacific Time on Friday, April 24th. (When the playback of data from the spacecraft occurs overnight, as it does in this case, the image will be released shortly after the opening of business the following day.) If the landers are within the resulting images and can be identified, the image(s) containing it (them) will be released.


Previous news on imaging the "Mars Face" and "The City".


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