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Mars Observer |
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Spacecraft
Launch: September 25, 1992
Mass: 2,573 kilograms (5,672 pounds)
Science instruments: High-resolution Camera, Thermal Emission Spectrometer,
Laser Altimeter, Magnetometer/Electron Reflectometer, Pressure Modulator
Infrared Radiometer, Gamma Ray Spectrometer, Radio Science Experiment
Overview
After a 17-year gap since its last mission
to the red planet, the United States launched Mars Observer on September 25,
1992. The spacecraft was based on a commercial Earth-orbiting communications
satellite that had been converted into an orbiter for Mars. The payload of
science instruments was designed to study the geology, geophysics and climate
of Mars.
The mission ended with disappointment on
August 22, 1993, when contact was lost with the spacecraft shortly before it
was to enter orbit around Mars. Science instruments from Mars Observer are
being reflown on two other orbiters, Mars Global Surveyor and 2001 Mars
Odyssey.
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Mars Pathfinder |
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For more information, see the Mars Pathfinder home page. |
Spacecraft
Launch: December 4, 1996
Landing: July 4, 1997
Mass: 895 kilograms (1,973 pounds) at launch, fueled
Science instruments: Imager; Magnets for measuring magnetic properties
of soil; Wind socks; Atmospheric structure instrument/meteorology package
Rover
Mass: 10.6 kilograms (23 pounds)
Science instruments: Alpha Proton X-ray Spectrometer, three Cameras
(also technology experiments)
Overview
Mars Pathfinder was originally designed as a
technology demonstration of a way to deliver an instrumented lander and a
free-ranging robotic rover to the surface of the red planet. Pathfinder not
only accomplished this goal but also returned an unprecedented amount of data
and outlived its primary design life.
Mars Pathfinder used an innovative method of
directly entering the Martian atmosphere, assisted by a parachute to slow its
descent through the thin Martian atmosphere and a giant system of airbags to
cushion the impact. The landing site, an ancient flood plain in Mars’ northern
hemisphere known as Ares Vallis, is among the rockiest parts of Mars. It was
chosen because scientists believed it to be a relatively safe surface to land
on and one which contained a wide variety of rocks deposited during a
catastrophic flood.
The lander, formally named the Carl Sagan
Memorial Station following its successful touchdown, and the rover, named
Sojourner after American civil rights crusader Sojourner Truth, both outlived
their design lives — the lander by nearly three times, and the rover by 12
times.
From landing until the final data
transmission on September 27, 1997, Mars Pathfinder returned 2.3 billion bits
of information, including more than 16,500 images from the lander and 550
images from the rover, as well as more than 15 chemical analyses of rocks and
soil and extensive data on winds and other weather factors. Findings from the
investigations carried out by scientific instruments on both the lander and the
rover suggest that Mars was at one time in its past warm and wet, with water
existing in its liquid state and a thicker atmosphere.
For more information, see the Mars Pathfinder home page.
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Mars Climate Orbiter |
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Spacecraft
Launch: December 11, 1998
Mass: 629 kilograms (1,387 pounds), fueled
Science instruments: Pressure modulator infrared radiometer, color
imager
Overview
Mars Climate Orbiter was designed to
function as an interplanetary weather satellite and a communications relay for
Mars Polar Lander. The orbiter carried two science instruments: a copy of an
atmospheric sounder on the Mars Observer spacecraft lost in 1993, and a new,
lightweight color imager combining wide- and medium-angle cameras.
Mars Climate Orbiter was lost on arrival
September 23, 1999. Engineers concluded that the spacecraft entered the
planet's atmosphere too low and probably burned up.
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Mars Polar Lander/Deep Space 2 |
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Mars Polar Lander
Launch: January 3, 1999
Mass: 576 kilograms (1,270 pounds), fueled
Science instruments: Mars Volatiles and Climate Surveyor (integrated
package with surface imager, robotic arm with camera, meteorology package, and
thermal and evolved gas analyzer); Mars Descent Imager; Lidar (including Mars
microphone)
Deep Space 2
Mass: 3,572 grams (7.9 pounds)
Science instruments: Sample collection/water detection experiment, soil
thermal experiment, atmospheric descent accelerometer, impact accelerometer
Overview
Mars Polar Lander was an ambitious mission
to set a spacecraft down on the frigid terrain near the edge of Mars' south
polar cap and dig for water ice with a robotic arm. Piggybacking on the lander
were two small probes called Deep Space 2 designed to impact the Martian
surface to test new technologies.
Mars Polar Lander and Deep Space 2 were lost
at arrival December 3, 1999