Mars Global Surveyor
The Mars Global Surveyor became the
first successful mission to the red planet in two
decades when it launched November 7, 1996, and entered
orbit on September 12, 1997. After a year and a half
trimming its orbit from a looping ellipse to a circular
track around the planet, the spacecraft began its
prime mapping mission in March 1999. It has observed
the planet from a low-altitude, nearly polar orbit
over the course of one complete Martian year, the
equivalent of nearly two Earth years. 
Mars
Global Surveyor recently completed its primary mission
on January 31, 2001, and is now in an extended mission
phase.
COI provided the all-carbon
fiber composite camera body and shutter housing, which
can be seen in its gold foil sheathing protruding
from the bottom of the spacecraft.
The mission has studied
the entire Martian surface, atmosphere, and interior,
and has returned more data about the red planet than
all other Mars missions combined. Among key science
findings so far, Global Surveyor has taken pictures
of gullies and debris flow features that suggest there
may be current sources of liquid water, similar to
an aquifer, at or near the surface of the planet.
Magnetometer readings show that the planet's magnetic
field is not globally generated in the planet's core,
but is localized in particular areas of the crust.
New temperature data and closeup images of the Martian
moon Phobos show its surface is composed of powdery
material at least 1 meter (3 feet) thick, caused by
millions of years of meteoroid impacts. Data from
the spacecraft's laser altimeter have given scientists
their first 3-D views of Mars' north polar ice cap.
Mars Exploration Rover
In 2003, two powerful new Mars rovers
will be on their way to the red planet. With far greater
mobility than the 1997 Mars Pathfinder rover, these
robotic explorers will be able to trek up to 100 meters
(about 110 yards) across the surface in a Martian
day. Each rover will carry a sophisticated set of
instruments that will allow it to search for evidence
of liquid water that may have been present in the
planet's past. The rovers will be identical to each
other, but will land at different regions of Mars.
The landing for each
will resemble that of the Pathfinder mission. A parachute
will deploy to slow the spacecraft, rockets will fire
to slow it further just before impact, and airbags
will inflate to cushion the landing. Upon reaching
the surface, the spacecraft will bounce about a dozen
times, and could roll as far as one kilometer (0.6
miles). When it stops, the airbags will deflate and
retract and the petals will open up, bringing the
lander to an upright position and revealing the rover.
COI is building the heavy-duty
all-composite petals as well as the solar array substrates,
which will mount the solar cells providing power to
the indepentently functioning rover.
The
landed portion of the mission features a design dramatically
different from Mars Pathfinder mission. Where Pathfinder
had scientific instruments on both the lander and
the small Sojourner rover, these larger rovers will
carry all their instruments with them. Immediately
after landing, each rover will begin reconnaissance
of the landing site by taking a 360-degree visible
color and infrared image panorama. Then they will
each leave the petal structure behind, driving off
to begin exploration.
Using images and spectra
taken daily from the rovers, scientists will command
the vehicle to go to rock and soil targets of interest
and evaluate their composition and their texture at
microscopic scales. Initial targets may be close to
the landing sites, but later targets can be far afield.
These rovers will be able to travel almost as far
in one Martian day as the Sojourner rover did over
its entire lifetime.
Rocks and soils will
be analyzed with a set of five instruments on each
rover, and a special tool called the "RAT,"
or rock abrasion tool, will be used to expose fresh
rock surfaces for study. Each rover has a mass of
nearly 180 kilograms (about 400 pounds) and has a
range of up to 100 meters (about 110 yards) per sol,
or Martian day. Surface operations will last for at
least 90 sols, extending to late May 2004, but could
continue longer, depending on the health of the vehicles.
