Today in History – July 6, 1997 – the Sojourner Rover (above), carried by the Pathfinder spacecraft, rolled onto the Mars’ surface. Click on the image above right to see a video of its initial positioning. Sojourner was designed as a six-wheeler that used a rocker-bogie suspension system; each wheel having its own drive motor, and the corner wheels also have independent steering motors.

Launched on December 4, 1996, Pathfinder impacted the surface of Mars earlier on July 4, 1997 at a velocity of  18 m/s (40 mph) and then bounced into the air 15 times at a maximum height of  15 meters (50 feet), before rolling and coming to rest  1 km from the initial impact site. The lander and landing site was named the Carl Sagan Memorial Station.  Pathfinder was designed, built and operated by the Jet Propulsion Laboratory (JPL) for NASA.

The project ended on March 10, 1998 when the lander failed to respond to communicate with controllers at JPL. The mission operated three times longer than its original 30-day planned lifetime.

The images from Pathfinder-Sojourner are spectacular, ranging from videos of Martian sunsets (click on image above left to see movie), data on the composition of the Martian rocks and the role of water on Mars. Quoting from a NASA press release of June 29, 1998:

The current assessment of data from this instrument suggests that all of the rocks studied by the rover resemble a type of volcanic rock with a high silicon content known on Earth as andesite, covered with a fine layer of dust. All of the rocks appear to be chemically far different from meteorites discovered. on Earth that are believed to have come from Mars.

The Jet Propulsion Laboratory’s  currently active Mars rovers – twin rovers called Spirit and Opportunity – landed on January 4, 2004 and January 25, 2004, respectively. They were originally scheduled to operate for three months, but are now in their sixth year of hard work.  The rovers have set the longevity record for broadcasting to Earth from a distant planet.   Although  Spirit got stuck in sand, Opportunity has been traveling towards the Endeavour crater on Mars since August 2008.

The next Mars rover Curiosity is planned to launch in 2011 and will be a six-wheeler much like  Spirit, Opportunity and Sojourner. Unlike these earlier Mars rovers, however, Curiosity will also use its mobility system as a landing gear when rocket-powered down to the Martian surface on a tether in August 2012.

I was honored to have served on the Advisory Board for the Engineering Division at JPL and was impressed with their “faster, better, cheaper” approach to space exploration.

For more information, see the Engineering Pathway‘s resources on the Pathfinder mission, Mars rovers and space exploration. For related educational resources, visit the Aerospace Engineering Education, Engineering Mechanics Engineering Education, Computer Engineering Education or the Mechatronics Engineering Education Community sites.

Also on this date in 1885, Pasteur first tests rabies vaccination. See our related resources on viruses and vaccines. or visit our Biomedical Engineering Education community site.