PIA00397: Boulder 'Big Joe' And Surface Changes On Mars

Boulder ‘Big Joe’ And Surface Changes On Mars


This pair of pictures from Viking Lander 1 at Mars' Chryse Planitia shows the only unequivocal change in the Martian surface seen by either lander. Both images show the one-meter (3-foot) high boulder nicknamed 'Big Joe.' Just to the lower right of the rock (right photo) is a small-scale slump feature. The picture at left shows a smooth, dust-covered slope; in the picture at right the top surface layer can be seen to have slipped downslope. The event occurred sometime between Oct. 4, 1976, and Jan 24, 1977. (Pictures taken before Oct. 4 do not show the slump; the first picture in which it appears was taken Jan. 24.) The surface layer, between one-half and one centimeter (one-fifth to one-third inch) thick, is apparently less cohesive than the underlying material. The layer that slipped formed a 30-centimeter-long (11.8-inch) 'tongue' of soil and a patch of exposed underlying material. The triggering mechanism for the event is unknown, but could have been temperature variations, wind gusts, a seismic event, or perhaps the lander's touchdown on July 20, 1976.

Cataloging Keywords:

Name Value Additional Values
Target Mars
System Mars
Target Type Planet
Mission Viking
Instrument Host Viking 1 Lander
Host Type Lander
Instrument Camera 1
Extra Keywords Dust, Grayscale
Acquisition Date
Release Date 1996-12-12
Date in Caption 1976-07-20 1976-10-04, 1977-01-24
Image Credit NASA/JPL
Source photojournal.jpl.nasa.gov/catalog/PIA00397
Identifier PIA00397