Mars Global Surveyor is a well-designed machine that successfully operated since launch on
November 7, 1996 to a battery failure in November, 2007.
To enable the spacecraft to last nearly a decade, the Mars Global Surveyor team worked creatively to conserve fuel and
invigorate the aging spacecraft.
Drawing of Mars Global Surveyor
Image credit: NASA/JPL
The spacecraft, fabricated at the Lockheed Martin Space Systems plant in Denver, Colorado,
looks like a rectangular-shaped box with wing-like projections extending from opposite sides.
The body (or bus) houses the computers, radio system, solid-state data recorders, fuel tanks,
and other equipment. Attached to the outside of the bus are several rocket thrusters, which
were fired to adjust the spacecraft's path during cruise to Mars and to modify the spacecraft
orbit around the planet.
When fully loaded with propellant at the time of launch, the vehicle weighed 1,060-kilograms
(2,342 pounds). The spacecraft is about 3 meters (10 feet) tall with its braking engine and
instruments. The bus or main body of the spacecraft measures 1.2 by 1.2 meters (4 by 4 feet)
and is 12 meters (40 feet) across from tip to tip when the solar panels are fully unfolded.
The high-gain antenna is deployed on a 2-meter-long (6-1/2-foot) boom.
To minimize costs, spare units left over from the Mars Observer
mission were used in portions of the spacecraft's electronics and for some of the science
instruments. The spacecraft design also incorporated new hardware - the radio transmitters,
solid-state recorders, propulsion system, and composite material bus structure-and retains
many backup and redundant features of the original Mars Observer design in case of failure
of critical elements such as the primary processors, recorders or transmitters.
The solar arrays, which always point toward the Sun (when the spacecraft isn't behind the planet),
provide 980 watts of electricity for operating the electronic equipment and for charging nickel
hydrogen batteries. The batteries provide electricity when the spacecraft is mapping the dark
side of Mars. To maintain appropriate operating temperatures, most of the outer exposed parts
of the spacecraft, including the science instruments, are wrapped in thermal blankets.
Spacecraft communications with Earth utilize X-band frequencies for radio tracking, return of
science and engineering telemetry, commanding, and the radio science experiments. Primary
communications to and from the spacecraft occur through the 1.5-meter-diameter (4.9-foot)
high-gain antenna. Mars Global Surveyor can receive instructions from Earth at a maximum
rate of 12.5 commands per second.