New Sharper Views of Apollo Landing Sites

Resolution comparison between nominal orbit images of the Apollo 17 landing site (a, b) and the new low orbit image (c; 27 cm x 56 cm pixel size). What is visible in an image is not simply a matter of the size of a pixel projected onto the surface. Sun angle and direction are also important factors, as is the exposure level. When the Sun is high above the horizon differences in surface brightness are enhanced, and when the Sun is low surface roughness is more obvious. Linear features are enhanced when they lie perpendicular to the direction to the Sun, and tend to disappear when parallel. When an image is underexposed or overexposed contrast and detail suffer. The top two images (a,b) have larger pixel scales (49 cm, 54 cm) and incidence angles (55 deg and 21 deg from vertical) that bracket the new higher resolution image (c; 45 deg).

Credit: NASA/Goddard/ASU.

NEXT PHOTO >