Spaceflight Now: Breaking News

Mars Pathfinder is filling in new NASA 'donut picture'
Posted: September 7, 2000

By combining three image mosaics, scientists have generated a donut-shaped picture with an overhead view of NASA's highly successfully and hugely popular Mars Pathfinder lander and Sojourner rover on the surface of the Red Planet.

Mars Pathfinder on the Red Planet's surface in 1997. Photo: NASA/JPL
This image is a product of three data sets: a color mosaic image of the "Gallery Panorama", an image which indicates the distance to the nearest object at each pixel location, referred to as a range image and a digital image of a full-scale museum model of the MPF Lander.

The Gallery Pan image and the range image were projected onto a continuous cylindrical/perspective coordinate system spanning 360 degrees of azimuth. The range image was then treated as a displacement map with respect to a sphere's surface, and the color image mosaic was draped onto the inside of the sphere so that lines of constant azimuth radiate from the center and lines of constant elevation are concentric circles. The position of the camera is fixed at the sphere's center, while its viewing direction is in this case looking at the south pole of the sphere. This projection preserves the resolution of the original panorama.

The distortion visible near the edges of this image is due to the large field of view, as well as the limitation introduced by using cylindrically-projected images on the sphere - the effects of which are less apparent when smaller fields of view are used.

The center of the image consists of the museum model image, which has been geometrically warped to spatially register with the projected Gallery Pan data. The position of the camera was fixed above the model so that the IMP Mast was roughly at Nadir.

The image has been rotated so that the main points of interest, which are the "Rock Garden", the rover Sojourner and the rock "Yogi", are visible arching across the upper hemisphere. In fixed Mars Surface coordinates, the top of the image looks out towards a point a few degrees north of West. Color has been enhanced to improve contrast in features, and is derived from IMP spectral filters 5, 9 and 0.