Mars Exploration Rovers

MER Facts

What is a Robot Geologist? The mars Exploration Rovers were designed to operate on Mars. Our neighboring planet is very different than Earth and so the rovers needed to be built very carefully. Here are some quick facts about the rovers and their mission.

MER Main | Spirit | Opportunity | Rover Facts

Rover Detail. Click for larger view.

Quick Facts

The rovers weigh 174 kg (384 pounds) and are 1.5 meters (4.9 feet) high by 2.3 meters (7.5 feet) wide by 1.6 meters (5.2 feet) long. The rovers have 6 wheels that are about 10 inches in diameter and are designed to coil and uncoil like springs to absorb shocks as the rover moves over the martian surface. Using a low-gain antenna and a high-gain antenna they can communicate with Earth directly or relay through the Mars Global Surveyor or Mars Odyssey spacecraft orbiting the planet.

Each rover has several cameras to view the landing area so that scientists on Earth can direct the science investigation. Some cameras are for avoiding obstacles that may be in the path of a rover. The main mast will position the cameras about as high as a human geologist might see if one was surveying the site.

The rovers can travel up to 100 meters (110 yards) a day, however, most daily trips will be less so that the rover can study the soil, rocks, atmosphere, and so on. To keep the batteries and electronics warm there are 8 heaters. The temperatures may be as low as -105° C (-157° F) during the night. Solar panels will use the daytime sun to recharge the batteries and operate the vehicle. The rovers are designed to last about 90 days on Mars.

Science Instruments

For more information go to JPL's Rover Description page.

Panoramic Camera
Two high resolution color stereo cameras will be used to survey the surrounding area. Images will be studied by geologists to determine which rocks and soils to examine in greater detail. Surface features, type and location of rocks, andother geological features will be discovered by using images from this instrument. It has an angular resolution more that three times that of the Mars Pathfinder cameras.

Miniature Thermal Emisson Spectrometer (MTES)
This instrument looks at the infrared (heat) radiation emitted by objects such as rocks and soil. It will allow scientists to determine the composition of the soil, rocks and surface features at the landing site. Carbonates, silicates, organic molecules and minerals formed in water can be found using this instrument. Also, the MTES will be pointed upward to study the martian asmosphere.

Alpha-Particle X-ray Spectrometer
By using alpha particles and x-rays this instrument can analyze minerals and other elements that make up the rocks and soils on Mars. Information about weathering, potential water activity and how the martian crust was formed will also be gathered.

Mossbauer Spectrometer
This kind of spectrometer is designed to determine with great accuracy the type of iron-bearing minerals at the landing area. It can also examine the magnetic properties of the martian soil.

Microscopic Imager
This combination microscope and camera can make extreme closeup views of rocks and soils. It will also be used to look at any sedimentary rocks that may have been formed in water.

Rock Abrasion Tool
Ready to grind Adirondack Geologists use a rock hammer to break open rocks to study what is inside them. This tool has a small wire brush to remove dust and a grinding wheel to expose an area about 4.5 centimeters (2 inches) in diameter. It can grind to about 5 millimeters (0.2 inch) deep so that other instruments can inspect the inside of the rock.

This image shows the Mars Exploration Rover Spirit's "hand," or the tip of the instrument deployment device, poised in front of the rock nicknamed Adirondack. In preparation for grinding into Adirondack, Spirit cleaned off a portion of the rock's surface with a stainless steel brush located on its rock abrasion tool, seen here at the top of its hand. The image was taken by the rover's panoramic camera. Caption/Image Credit: NASA/JPL/Cornell

Magnet Arrays
A lot of the dust on Mars is magnetic. Magnetic minerals attracted to the 3 magnet arrays can provide clues to the planet's geologic history.

Calibration Target / Sundial
Mars Dial To make sure the instruments are accurate various targets are used to calibrate each. The target for the Panoramic Camera is in the shape of a sundial. Colored blocks will be used to check the color of the images taken by the camera and shadows cast by the central post will help adjust the brightness of the images.

Two views of a sundial called the Mars Dial can be seen in this image taken on Mars by the Mars Exploration Rover Spirit's panoramic camera. These calibration instruments, positioned on the solar panels of both Spirit and the Mars Exploration Rover Opportunity, are tools for both scientists and educators. Scientists use the sundial to adjust the rovers' panoramic cameras, while students participating in NASA's Red Rover Goes to Mars program will monitor the dial to track time on Mars. Students worldwide will also have the opportunity to build their own Earth sundial and compare it to that on Mars.

The left image was captured near martian noon when the Sun was very high in the sky. The right image was acquired later in the afternoon when the Sun was lower in sky, casting longer shadows. The colored blocks in the corners of the sundial are used to fine-tune the panoramic camera's sense of color. Shadows cast on the sundial help scientists adjust the brightness of images.
The sundial is embellished with artwork from children, and displays the word Mars in 17 different languages. Caption/Image credit: NASA/JPL/Cornell University

Mission

The mission is to determine the history of the climate and water on Mars. The geologic record at the two landing sites will be studied and evaluated whether life could have formed on the planet.

Images and measurements sent back by each rover will help scientists determine which soils and rocks to examine and where to send the rover.

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