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At 10 o'clock in the morning, U.S. Pacific Daylight Time, on July 4, 1997, the Mars Pathfinder spacecraft bounced to a stop on Mars, the first visit by a U.S. spacecraft to the surface of Mars since the Viking missions of 1976. Mars Pathfinder landed at a site known as Ares Vallis (Mars Valley) in a region called Chryse Planitia (Plains of Gold).
The spacecraft's entry, descent, and landing sequence demonstrated many engineering techniques that can now be used on subsequent planetary missions. Mars Pathfinder used a combination of a heatshield, parachute, and rockets, to slow its descent through the thin atmosphere. The lander, encased in airbags similar to those found in automobiles but much larger and designed for the Martian environment, bounced at least 16 times and for at least a minute and a half before coming to rest rightside up. Local Mars time at Ares Vallis was about 3:00 a.m., so these events occurred in the dark.
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Once at rest, the lander unfolded its petals and retracted the deflated airbags. Right on schedule, it sent a beacon signal indicating its progress to the antennas of NASA's Deep Space Network. When the Sun rose, about three hours after the landing, Mars Pathfinder turned on its transmitter and began to send detailed engineering data about its health and its descent through the atmosphere via the lowdata-rate antenna.
Later that day, the lander's high-data-rate antenna was pointed at Earth, and the first pictures from the surface of Mars in almost two decades began to flow in to controllers at the Jet Propulsion Laboratory (JPL) in Pasadena, California. The Imager for Mars Pathfinder, or "IMP" camera, returned many small frames that were mosaiced into this panoramic view. The IMP camera imaged the entire surrounding area from its position on top of the lander.
This view is to the west. A great flood of water washed over this region long ago, passing from left to right across this portion of the landscape. The Twin Peaks on the horizon are just about 1 kilometer (0.6 miles) away.
Named after Sojourner Truth, an African-American abolitionist and champion of women's rights during the Civil War era, the rover is still crouched on one of the lander petals. Airbag material billows out from beneath the petal. Rolled into tight cylinders at either end of Sojourner are the undeployed rover ramps. Early images were used to help rover engineers determine which direction was better suited for a safe rolloff. The images revealed that the airbags would interfere with proper deployment; a portion of the airbag is lying on top of one end of the ramp at Sojourner's right. The slight offset in the appearance of the ramp is caused by the way that separate images were patched together.
Late on July 4, JPL flight controllers sent commands to the lander to raise the rover petal, with Sojourner still firmly attached, reel in more of the airbags, and lower the petal back down level with the ground. This maneuver was successfully carried out, and the next day Sojourner rolled onto the surface of Mars to begin her mission of exploration.
This image and additional information about the Mars Pathfinder mission can be found on the Internet at: http://mpfwww.jpl.nasa.gov
The Mars Pathfinder mission is part of a long-term program of Mars exploration being conducted by NASA's Office of Space Science. JPL, an operating division of the California Institute of Technology, manages the Mars Exploration Program for NASA.
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