Mars Pathfinder was NASA mission to Mars, which launched on December 4th, 1996 and landed on the surface of Mars on July 4, 1997. Unlike the missions that went before it, the Pathfinder lander was also equipped with a tiny rover called Sojourner, which could venture away from the lander, crawl around the surface of Mars and study rocks up close. It was a relatively inexpensive mission that tested out many of the technologies build into later missions, like the Mars Exploration rovers Spirit and Opportunity.
The purpose of Pathfinder was to prove that the concept of “faster, better and cheaper” missions would work. Pathfinder only cost $150 million and was developed in under 3 years. It was also sent to study the surface of Mars, including the geochemistry of the rocks, the magnetic properties of the surface and the structure of the planet’s atmosphere.
When the Pathfinder mission arrived at Mars, it entered the atmosphere and deployed a parachute. Instead of using retrorockets to land gently on the surface, however, Pathfinder used an airbag system. This allowed it to save fuel; instead of landing gently, it was dropped from an altitude of about 100 meters onto the Martian surface. It bounced several times and came to a rest before opening up like the petals of a flower. Once everything checked out, the tiny Sojourner Rover was deployed onto the surface of Mars.
The area around the Pathfinder site had many rocks, large and small, and the NASA scientists gave them unique names like “Barnacle Bill” and “Yogi”. Sojourner was able to crawl around and study these rocks up close. It was able to study the chemical makeup of the rocks, and confirmed that they formed from past volcanic activity. Over the course of the entire mission, Pathfinder and Sojourner returned 16,500 images and made millions of measurements of the Martian atmosphere.
Pathfinder stopped communicating with Earth after 83 days on the surface of Mars. Its battery was only designed to be recharged 40 times, and once its battery stopped working, the spacecraft was unable to keep its electronics heated in the cold Martian night. After it stopped communicating, NASA decided to name the lander after Carl Sagan. It became The Carl Sagan Memorial Station.
Here’s a link to the original mission homepage for the Mars Pathfinder.
We’ve recorded several episodes of Astronomy Cast about missions to Mars. Start here, Episode 92: Missions to Mars, Part 1.