Mars Pathfinder Rover

The Mars Pathfinder landed on Mars in July, 1997 and began a successful mission of exploration. Find out about the Landing Site, the Mission and the Sojourner Rover by clicking the links below.

LANDING SITE | MISSION | ROVER

Sojourner Rover

The Sojourner Rover is 65 centimeters (2 feet) long, 48 centimeters (1.5 feet) wide and 30 centimeters (1 foot) tall. On Earth it weighed 10.5 kilograms (23 pounds) but on Mars weighed only 4 kilograms (8.8 pounds) due to the difference in the size of the two planets. The robot carried a device called an Alpha Proton X-ray Spectrometer used to test soil and rock samples to determine what minerals were present.

In the descriptions below from NASA/JPL the Sol dates refer to Earth days to distinguish them from Mars days.

Sojourner rover tests the rock called Moe This color image (left) shows the Sojourner rover's Alpha Proton X-ray Spectrometer (APXS) deployed against the rock "Moe" on the morning of Sol 65. The rock behind the rover is "Half Dome", which was previously measured by the APXS.
(Image Description by NASA/JPL)

Half Dome Rock (right)
"This image of the rock "Half Dome" was taken by the Sojourner rover's left front camera on Sol 71 (September 14). Pits, linear textures, and pronounced topography on the rock are clearly visible."
(Image Description by NASA/JPL)

Half Dome rock is about the size of the rover. In the lower left corner a rover track is visible.

Sojourner rover on the rock called Wedge Wedge (left)
"This image taken on Sol 44 shows the Sojourner rover with its left front and middle wheels perched on the rock "Wedge". The rover's Alpha Proton X-ray Spectrometer (APXS) is the cylindrical object extending from the back of the rover."
(Image Description by NASA/JPL)

Using the Alpha Proton X-ray Spectrometer (APXS), it takes about 10 hours for a full study of a sample to determine its composition. The APXS bombards the sample with alpha particle radiation. Alpha particles are the nucleus of a Helium atom. The studies showed that Mars and Earth are made up of similar material, such as andesite from volcanic activity and basaltic igneous rock.

The image at right is the rover's view of the lander showing the deflated airbags, ramps and solar panels. The dark circle is the NASA logo on the side of the lander. Click image or here for a diagram of the lander and its instruments.

LANDING SITE | MISSION | TOP

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Click here for more information on
Mars Pathfinder
Sojourner Rover
Viking, Pathfinder and other Mars missions
NASA Planet Facts

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