Predictions for April 5 Cydonia Imaging Opportunity

by Peter Nerbun and Mark Carlotto


According to JPL, the first opportunity to image Cydonia will be on April 5, 1998. Using the Redshift 3 orbital simulation program, Peter Nerbun has predicted the following image acquisition parameters:

Local solar time

10:11 AM

Sun elevation angle

25 degrees, 30 minutes

MGS distance to Cydonia

350 km

MGS elevation angle (as seen from Cydonia) 

69 degrees

MGS azimuth angle (as seen from Cydonia)

267 degrees


Unlike the earlier Viking images taken in the afternoon, this opportunity will hopefully capture the Face in morning light. Because it is winter in the northern hemisphere, the sun will be low in the sky and to the south. The Face will thus be lit from below with the sun about 25 degrees above the horizon.

At the time of image acquisition, MGS will be 350 km from Cydonia. The field of view will thus be 0.0076 radians x 350 km = 2.68 km, and the pixel resolution 2.68/2048 = 1.3 meters. Since MGS will not be directly above the Face, the image will be somewhat oblique (like some of the computer generated perspective views that have been produced of the Face).

The spacecraft will be to the west, looking east, and thus viewing the left or western side of the Face. The following is a low resolution image of what MGS can be expected to see given the above acquisition parameters. The image is a shaded rendition based on a Lambertian reflectance model and produced from an elevation map derived from Viking frame 70A13 with a pixel resolution of just under 50 meters/pixel. Of course, the MGS image will be about 50 times higher in resolution and will show considerable more detail.

Face rendered under predicted April 5 lighting conditions (left). For comparison, how the bust of J.S. Bach would look under the same conditions (right). Note that while the 3-D model of the bust of Bach has surface details on its right side (as seen from above in normal orientation), the Face does not and so appears incomplete on this side - a situation that will hopefully be remedied by new MGS images.

Same images as above but rotated so that faces are in normal orientation

Low resolution rendition of how the Face might look assuming that the structure on the right side matches that on the left.

Because of the illumination, some of the details seen in the Face such as the "teeth" and the crossed lines above the eyes may in shadow, and possibly not visible. The lighting geometry should however be ideal to verify the "pupil" structure in the left "eyeball" first detected by Vincent DiPietro. It should also reveal what is on the right side of the Face, the side which was shadowed in Viking frames 35A72 and 70A13.

(Page last updated April 4, 1998)

© 2020 Mark J. Carlotto