Chapter 1 of 8

Two jobs. One journey.

Preparing Mars Pathfinder and launching on 4 December 1996

Told in Pathfinder & Sojourner’s imagined voice · the events are real · source

Sojourner Rover Near The
Pathfinder & SojournerWe travelled together, but we were built for different jobs.
NASA/JPL
01Mars Pathfinder would become a stationary lander. Sojourner would explore nearby terrain. The mission tested a lower-cost way to land science equipment on Mars and operate a small rover. Both machines also carried tools for scientific observations.
A twelve-year-old helped give the rover its name.
02NASA named Sojourner after Sojourner Truth, inspired by the winning essay of twelve-year-old Valerie Ambrose. A real naming contest connected a young person on Earth with a machine preparing to explore another planet.
NASA's Sojourner rover and undeployed ramps onboard the Mars Pathfinder spacecraft can be seen in this image, by the Imager for Mars Pathfinder (IMP) on July 4 (Sol 1).
Pathfinder & SojournerOn December 4, 1996, a Delta rocket carried us away from Florida.
NASA/JPL
03The mission launched from Cape Canaveral's Launch Complex 17B. Course corrections refined the trajectory during the journey to Mars. We were not yet a station and a moving explorer—both were still travelling inside one spacecraft system.
The plan called for a month for the lander and a week for the rover.
04Those were design mission goals, not dates when the machines were guaranteed to stop. First came a harder requirement: reaching the ground with the instruments and the rover intact.

The big idea

One mission can divide its work between different machines. Landing, local exploration and communications require different capabilities.

Think about it

Why send a rover and a stationary lander instead of making one machine do every job?

In this chapter: Pathfinder lander, Sojourner rover, science instruments and Delta II launch vehicle

Sources: Main record · Mars Pathfinder · NSSDCA Master Catalog

Machine illustration: AI-made. Photos: NASA Image and Video Library, credited on each picture.

Chapter 1 of 8

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