will depend once again on key navigational aids produced
by Northrop Grumman Corporation when it launches
its Mars Exploration Rovers and spacecraft planned for later
this month. The mission will attempt to determine whether
water once existed on the planet.

The company’s Navigation Systems Division produces LN-200S
inertial measurement units (IMUs) that are used by both
spacecraft and Mars Exploration Rovers. These units sense
acceleration and angular motion and convert them to outputs
that are used by vehicle control systems for guidance.

“The Northrop Grumman LN-200S is a low-weight, space-tested,
fiber optic inertial measurement unit that has proven its
reliability in challenging environmental conditions during
more than 12 space missions,” said Richard Wujek, LN-200S
program manager at Northrop Grumman.

One IMU is mounted on the backshell, or heat shield, of
the spacecraft’s entry vehicle, while another is installed
in the rover. Both units maintain spacecraft attitude information
and measure deceleration during descent into the Martian
atmosphere to help determine when a parachute can be deployed
safely to slow the spacecraft during entry.

The rover IMU provides attitude and acceleration information
during surface operations, and positions the rover’s high-gain
antennae. The IMU will cycle through temperatures of -40
degrees C to + 40 degrees C on the surface of Mars and will
be turned off each night to conserve the battery power derived
from the solar cells of the rover.

The first rover is scheduled to reach Mars Jan. 4, 2004,
and the second Jan. 25, 2004. The Mars Exploratory Rovers
will be able to travel up to 40 meters (44 yards) across
the surface each Martian day, and will be able to travel
the distance of several football fields during the course
of their entire missions. Scientists will evaluate images
and measurements from the rovers and will command the vehicles
to move to rock samples and soil targets of interest and
evaluate their composition.

Each Mars 2003 rover carries sophisticated instruments to
search for evidence of liquid water that may have been present
in the planet’s past. The rovers will land at different
regions of Mars and each mission is expected to last at
least 92 days, but could continue longer depending on the
health of the vehicles.

Jet Propulsion Laboratories, a division of the California
Institute of Technology, Pasadena, manages the Mars Exploratory
Rover program for NASA’s Office of Space Science.

The value of the contracts funding this effort is approximately
$3 million and includes long-lead development, analysis,
support, primary units and spares. Each Northrop Grumman
LN-200S unit undergoes rigorous space certification testing.
The units are produced at the same high-rate production
facility that manufactures the LN-200 IMU. Thousands of
the LN-200 inertial navigation systems family have been

Based in Woodland Hills, Northrop Grumman’s Navigation Systems
Division provides situational awareness for the defense
and commercial markets. It offers integrated avionics, inertial
navigation and guidance systems, satellite electronics,
identification friend or foe systems, cockpit displays,
fiber-optic sensors and systems, and logistic support products
and services.

The Navigation Systems Division is part of the company’s
Baltimore, Md.-based Electronic Systems sector, a world
leader in the design, development and manufacture of defense
and commercial electronics and systems including airborne
radar systems, navigation systems, electronic warfare systems,
precision weapons, air traffic control systems, air defense
systems, communications systems, space systems, marine systems,
oceanic and naval systems, government systems and logistics

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