Science Instruments

Mars Global Surveyor carried a complement of six scientific investigations to perform atmospheric monitoring for sister orbiters during aerobraking, and it helped rovers and lander missions by identifying potential landing sites and relaying surface telemetry.

Camera
Altimeter
Spectrometer
Magnetometer
Radio Science
Mars Relay System
  • A long, metallic, barrel-shaped instrument, oriented horizontally, points toward the left side of the frame, on a slight diagonal toward the viewer, showing a pitch-black opening that looks like the hole of a deep well. Its sides are covered in what looks like thin, gold foil, it has a bundle of wires protruding from its base, and it's attached to a circular brown metal base at the right rear of the image.

    Mars Orbiter Camera

    At the time of its operations, most data volume from Surveyor was generated by a dual-mode camera called the Mars Orbiter Camera (MOC). This device worked like a television camera, but took still images instead of motion video. In narrow-angle mode, MOC's black and white, high-resolution telephoto lens spotted Martian rocks and other objects as small as 4.6 feet (1.4 meters) across from orbit. The pictures were sharp enough to help scientists conduct detailed geological studies without setting foot on the planet.

    In contrast to the detailed surface images, MOC's wide- angle, global monitoring mode used a "fish-eye" lens to generate spectacular color panoramic images spanning from horizon to horizon. These pictures resemble weather photos of Earth commonly shown on news broadcasts.

    Using hundreds of these panoramic photographs, scientists all over the world were able to play them like a slow-motion "flip-book" or a film. This helps show the life history of Martian weather phenomena such as dust storms, cloud formations, and the polar ice cap growth and contraction. In addition, these time-lapse animations allowed scientists to track surface features that get blown by the wind, such as dust streaks and sand dunes.

  • A black-and-white photo of a science instrument, consisting of a metal platform elevated atop three retangular feet. Above the platform rises a squat silver cylinder with an open top and mirrored outside. Sicking up from inside the cylinder is a black, mushroom-shaped element. The base of the cylinder is wrapped in silver foil, and a black box also rests on the platform, to the right.

    Mars Orbiter Laser Altimeter

    The laser altimeter, known as the Mars Orbiter Laser Altimeter (MOLA), gathered data used to calculate the height of surface features.

    This altitude determination process measures how long a pulse of light takes to leave the spacecraft, reflect off the ground, and return to MOLA's collecting mirror. By multiplying the reflection time by the speed of light, scientists were able to calculate Surveyor's altitude above the local terrain to within 98 feet (30 meters) or better.

    As the spacecraft flew above hills, valleys, craters, and other surface features, its altitude constantly changed. A combination of MOLA data with images from the camera allowed scientists to construct a detailed topographical atlas of the planet. Such maps have helped in the understanding of the geological forces that shaped Mars.

  • A boxy scientific instrument sits on an uncluttered surface. Its bottom half is dull black, metallic, and has a plaque with some writing affixed to its front. The upper half consists of two sections – on the right, a silver, metal box with crisp edges, about the same shape as a toilet tank. The left side is also metallic silver, with a curved top; the top has what looks like a semicircular door or indentation, resembling a swinging trash-can lid.

    Thermal Emission Spectrometer

    The Thermal Emission Spectrometer (TES) instrument systematically measured and monitored the Martian surface and atmosphere throughout all phases of the mission. The TES spectrometer collected over 206 million infrared spectra, and the TES bolometer was in continual full-time use throughout the entire mission.

    TES was both an instrument and a technique. TES first flew aboard the Mars Observer spacecraft. Following the loss of that spacecraft, TES was rebuilt and launched along with five of the original seven Mars Observer instruments aboard the Mars Global Surveyor spacecraft. The purpose of TES was to measure the thermal infrared energy (heat) emitted from Mars. This technique, called thermal emission spectroscopy, can tell us much about the geology and atmosphere of Mars. TES data provided the first detailed look at the composition of Mars.

Maps of Recurrent Slope Linea Markings on Mars: This pair of maps indicates locations of confirmed sites of recurrent slope linea on Mars, with respect to elevation (upper map) and surface brightness, or albedo (lower map). The albedo information comes from the Thermal Emission Spectrometer on NASA's Mars Odyssey orbiter. Surface topographical information for the map comes from the Mars Orbiter Laser Altimeter on NASA's Mars Global Surveyor orbiter.
NASA/JPL-Caltech/Arizona State Univ.

Magnetometer  (Electron Reflectometer)

The magnetometer studied the magnetic properties of Mars to gain insight into the interior of the planet. This instrument found small, localized magnetic fields and remnants of larger areas of ancient magnetic fields, providing clues to how Mars evolved.

A rust-colored sphere representing the planet Mars occpies most of the frame against a black background in this illustration. A gold and royal blue spacecraft is approaching the sphere from the left, an arrow tracing its looping trajectory past the planet, coming closest at its upper right side. On the surface below that, two small red spots have concentric semicircles emanating from each side of them, mixing together in the space betwen them, like ripples on a pond.
This is a simple schematic representing localized magnetic sources in the crust of Mars, buried beneath the surface, and revealed by observation of the magnetic field (blue) extending up to satellite altitude, about 75 miles (120 kilometers).
NASA/JPL/GSFC

  • Radio Science (Gravity Field Experiment)

    The radio science investigations had two distinct objectives: to map the planet's gravitational field and to measure the atmospheric pressure and temperature in the polar regions.The gravity field results, combined with topographic data from the MOLA experiment, allowed estimates to be made of the structure of the Martian interior, from which studies could be done of the thermal and chemical evolution of the planet and the history of surface features and the atmosphere. The atmospheric experiment aided in studies of atmospheric dynamics and meteorology, and in detailed studies of transport of water, dust, and carbon dioxide in the atmosphere.

Mars Relay System

Of the six main instruments that flew to Mars on Surveyor, the Mars Relay was the only one not designed to take scientific measurements. Instead, this cylindrical-shaped antenna collected data transmitted to Surveyor from landers on the Martian surface. After collecting the data, Surveyor transmitted it back to Earth. By using Surveyor as a relay satellite for Mars landers, the lander spacecraft did not need to carry large antennas to talk with Earth. Instead, this reduction in the weight of the landers allowed the spacecraft to carry more scientific instruments.

The relay operated at a UHF frequency of 437.1 megahertz and could listen to stations on the Martian surface up to 3,125 miles (5,000 kilometers) away from Surveyor. The French space agency CNES (Centre National d'Etudes Spatiales) provided the relay antenna to NASA as part of an international cooperation toward the study of Mars.

Mars Global Surveyor Nadir Deck, 1996. Note locations of Mars Orbiter Camera (MOC) and Mars Relay antenna.
NASA/JPL/LMA
A black and white photo shows a surface that appears shiny and hard looks
Mars Global Surveyor MOC image of Nili Patera sand dunes, 1999. This dramatic image shows a field of dark sand dunes in the Nili Patera region of Syrtis Major. The shapes of these dunes indicate that wind has been steadily transporting the dark sand from the right/upper right toward the lower left. This picture was taken on the first day of the MGS Mapping Phase during the second week of March 1999. It shows an area 1.3 miles (2.1 kilometers) wide at the full commanded resolution of 10 feet (3 meters) per pixel. Illumination is from the upper left.
NASA/JPL/MSSS
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