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78 Modern Robotics

It is hard to imagine how elated Donna Shirley and her colleagues were
when they saw this photo. The lander has arrived, and the cushioning
airbags have deflated. Sojourner is poised to begin an epic exploration of
Mars. (NASA photo)

contest to name the Mars rover. The winning student’s essay offered
the name Sojourner, in honor of Sojourner Truth, the American
woman who had played an important role in rescuing African
Americans from slavery in the mid-19th century. “Sojourner” also
means someone who undertakes a long journey, and that would cer-
tainly apply to the little Mars rover.
After a journey lasting seven months, Pathfinder and its Sojourner
landed on Mars on July 4, 1997. Or rather, it crashed, bouncing off
its air bags 15 times until it finally came to rest almost precisely on
the planned target. The elation brought by the first pictures from the
lander was matched only by the photos a little later that showed that
the rover had been driven down the ramp to plant its wheels firmly
on the Martian soil.
As Shirley recounted to interviewer Sally Richards:

My proudest moment was having my daughter, my second moment
was when the Pathfinder and Sojourner actually worked. When you
consider that it was going 17,000 miles an hour and it wasn’t sup-
posed to make just another hole in the ground—well, that was a great
achievement.