The Rover Revolution: Mars Pathfinder Quiz

Mars Pathfinder landed on July 4, 1997. It was a major milestone because it was the first successful landing on Mars since the Viking missions 21 years earlier, and it introduced a brand new way to land using airbags.

True. While the Viking missions were stationary landers, Sojourner was the first mobile vehicle. This allowed scientists to move the robot to different rocks, proving that rovers were the best way to explore a planet's diverse geology.

Once it landed, the Pathfinder lander was renamed the Carl Sagan Memorial Station. It acted as the "parent" station, providing a communication link between the tiny Sojourner rover and the scientists back on Earth.

Because Mars has a thin atmosphere, Pathfinder used a combination of parachutes, rockets, and a "cocoon" of 24 large airbags. The spacecraft hit the ground and bounced several stories high at least 15 times before finally coming to a stop.

Compared to modern rovers like Perseverance, Sojourner was tiny! It was only 11 inches tall and about 2 feet long. Its small scale was perfect for a "technology demonstration" mission to see if wheels could actually work on Mars' rocky soil.

Sojourner was solar-powered. It had a flat top covered in solar cells that collected energy from the Sun. Because of this, the rover could only move during the Martian day and had to "sleep" during the cold nights to save power.

False. Sojourner was never more than about 40 feet (12 meters) away from the Pathfinder lander. It needed to stay close to communicate and send its data back to the station, which then beamed the information to Earth.

The Alpha Proton X-ray Spectrometer (APXS) allowed Sojourner to touch a rock and identify the elements it was made of. This helped scientists understand if the rocks were volcanic or if they had been shaped by ancient water.

Pathfinder was a "Discovery" mission meant to be low-cost. It successfully tested the airbag landing system and the rover technology. However, it was not designed to bring samples back to Earth; that goal was saved for much later missions.

The rocker-bogie suspension system allows the rover to keep all six wheels on the ground while driving over uneven terrain. This design was so successful that NASA has used versions of it on every Mars rover since Sojourner.

True. Pathfinder landed in Ares Vallis, an ancient flood plain. By looking at the rounded pebbles and the way rocks were stacked, scientists concluded that massive amounts of liquid water must have flowed through the area billions of years ago.

Pathfinder was the first mission of the "Internet Age." NASA's website received millions of hits as people around the world logged on to see the newest color photos of the Red Planet almost as soon as they were sent back.

NASA chose the name after a year-long essay contest for students. Sojourner Truth was an activist who traveled "up and down the land," much like the rover was designed to travel across the Martian landscape.

The mission was a "pathfinder" because it blazed a trail for future exploration. It proved that landing was possible without expensive, heavy fuel-based rockets and that rovers could survive the harsh, dusty environment of Mars.

The mission was a huge success! The lander operated for 83 days and the rover for 91 days. The mission finally ended in September 1997, likely because the lander's battery failed due to the extreme cold of Martian nights.

False. Because radio signals take minutes to travel between Earth and Mars, real-time driving is impossible. Scientists sent a list of commands once a day, and the rover used its own "hazard avoidance" sensors to move safely on its own.

Scientists gave the rocks fun nicknames like "Barnacle Bill," "Yogi," and "Scooby-Doo" based on their shapes. This made it easier for the team to identify which rocks the rover should visit and analyze next.

Like the Viking missions before it, Pathfinder’s cameras showed that the Martian atmosphere is filled with fine, rusty dust that scatters sunlight, making the sky look like a salmon or butterscotch color instead of blue.

The lander was the "mother ship." It had a much larger antenna to send data to Earth. Also, the lander’s camera was much higher up, allowing it to take pictures of Sojourner as it moved, which helped scientists plan the rover's path.

Sojourner was a "proof of concept." Its success led directly to the much larger Spirit and Opportunity rovers, then Curiosity, and finally Perseverance. It showed that we could build small, smart robots to do the work of scientists on other worlds.