Skip Navigation

Flight Projects

While much of the work done in robotics at JPL is research, the ultimate value of the technology is in its ability to enable and enhance our exploration of the solar system. Four flight projects are of special significance in the level of robotic technologies captured by them, and these contributions are described at the links below.

Current Flight Projects
Retired Flight Projects

Mars Pathfinder Rover: Sojourner (1996)

Fig. 1: The Sojourner rover at the end of its assembly and before integration to the main Pathfinder spacecraft.

Fig. 1: The Sojourner rover at the end of its assembly and before integration to the main Pathfinder spacecraft.

Mars Pathfinder Rover: Sojourner

In late 1996, the Mars Pathfinder spacecraft was launched from Earth. Attached to one of the lander petals and folded inside the tetrahedral landing configuration, the Sojourner Rover was a flight-experiment addition to the primary lander mission. On 4 July 1997, the Pathfinder spacecraft bounced to a stop on Mars. The spacecraft’s innovative Entry, Descent, and Landing system using heatshield, parachute, rockets, and airbags enabled a safe landing at Ares Vallis on the Mars surface.

The Sojourner rover drove off a ramp from the lander and onto the surface of the red planet the next day (sol), beginning a new era of Mars exploration by making in situ observations from an instrumented vehicle. The lander provided two critical functions for the rover's operations: It acted as a communications link from the rover to operators on Earth, and it imaged Sojourner and the surrounding terrain for the operators.

The mission ended when the lander's power system failed, eliminating it as a communication relay and stopping all interactions with the rover.

The Sojourner rover was developed around technologies developed in the years prior to the mission. A ‘rocker-bogie’ suspension system supported the main chassis distributing vehicle mass load across the six wheels. The chassis, containing the printed circuit board electronics and batteries, was thermally insulated with ultra-light aerogel. The rover carried the Alpha Proton X-Ray Spectrometer (APXS) science instrument, attached to an extendable deployment mechanism. A Material Adherence Experiment from NASA’s Glenn Research Center was also carried aboard the rover. Eleven brushed motors controlled the wheels (6), corner wheel steering (4), and instrument deployment. The rover was interconnected with the first ‘flex cable’ wiring harnesses to save mass and reduce thermal leakage from the chassis.

Sojourner was primarily solar powered, but had primary batteries which operated over the first three weeks of the mission and augmented the solar power. The rover communicated through a UHF link to the lander and had a range of 100 meters. The rover was 65 centimeters long, 48 centimeters wide, and was 30 centimeters tall, and had a mass of 10.5 Kilograms. Deployable ramps were developed for both sides of the petal allowing the selection of the best egress option for rove deployment to the surface.