Sojourner: lost and found

Orbital images provide new clues to the demise of Mars Pathfinder and the Sojourner rover.
By | Published: January 12, 2007 | Last updated on May 18, 2023
Pathfinder close-up
A high-resolution camera aboard the Mars Reconnaissance Orbiter snapped this image of the landing site of 1997’s Pathfinder mission. The Pathfinder lander is visible in the center of the image as a light-colored blob.
NASA/JPL/Univ. of Arizona/USGS
January 12, 2007
In a planetary-science version of “Where’s Waldo?”, scientists with NASA’s Jet Propulsion Laboratory may have located the diminutive Sojourner rover that hitchhiked to the Red Planet aboard the Mars Pathfinder mission in 1997. The image, snapped by the Mars Reconnaissance Orbiter (MRO), includes the lander itself as well as its airbags, parachute, and fragments of its heat shield.
Pathfinder orbital
The Pathfinder landing site, recently imaged in detail by the Mars Reconnaissance Orbiter, lies north of Big Crater and east of Twin Peaks.
NASA/JPL/Univ. of Arizona/USGS
After landing, the Pathfinder lander transmitted data for about 3 months and then shut down. This left the semi-autonomous rover Sojourner still functional but unable to communicate with Earth via the lander.

Sojourner’s last known position lay about 43 feet (13 meters) from the lander. MRO used its super-sharp High Resolution Imaging Science Experiment (HiRISE) camera to image the region around Pathfinder’s landing site December 21, 2006.

Pathfinder close-up right
In this magnified image captured by the Mars Reconnaissance Orbiter, the Pathfinder lander is clearly visible in silhouette, including its airbags and the ramp that the Sojourner rover rolled down to reach the surface. Various named rocks and landscape features are indicated, as well as the possible site of the Sojourner rover, about 20 feet (6 meters) due south of the lander.
NASA/JPL/Univ. of Arizona/USGS
However, sometime in February, McEwen’s team will acquire color images of the Pathfinder site that may clear up the uncertainty.

If the blob turns out to be Sojourner, it would indicate that the robot roved around on its own after the lander died, perhaps in an attempt to reestablish contact with home.

Previously, MRO images have spied both of the Mars Exploration Rovers (Spirit and Opportunity) and both Viking landers.

MRO scientists identified an indistinct blob about 20 feet (6 m) from the lander that does not appear to match anything in the landscape photographed at ground level by Pathfinder.

It may be Sojourner, or maybe not, says Alfred McEwen of the University of Arizona in Tucson, lead scientist for the HiRISE instrument. “It’s not a certain identification by any means,” McEwen cautions.