Mars Exploration Rover Spirit Mission Status - January 3, 2004

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

JPL Newsroom (818) 354-5011
Jet Propulsion Laboratory, Pasadena, Calif.

NEWS RELEASE: 2004-002 January 3, 2004

Mars Exploration Rover Spirit Mission Status

Navigators for NASA's Spirit Mars Exploration Rover put the spacecraft
so close to a bull's-eye with earlier maneuvers that mission managers
chose to skip the final two optional maneuvers for adjusting course
before arrival at Mars.

With less than four hours of flight time remaining, Spirit was on
course to land within a targeted ellipse 62 kilometers long by 3
kilometers wide (39 miles by 2 miles) within Mars' Gusev Crater. A
trajectory correction maneuver scheduled for four hours before landing
was cancelled.

"The navigation status is truly excellent," said Dr. Lou D'Amario, the
mission's navigation team chief at NASA's Jet Propulsion Laboratory,
Pasadena, Calif. A slight trajectory adjustment on Dec. 26 was the
fourth and final for the flight.

Preparations in the past two days for arrival at Mars have included an
adjustment that will open Spirit's parachute about two seconds earlier
than it would have been without the change, in order to compensate for
recent weather on Mars. "A dust storm seen on the other side of the
planet has caused global heating and thinning of the atmosphere at
high altitudes" said JPL's Dr. Mark Adler, Spirit mission manager.

Also, engineers sent commands today to alter the timing when several
pyro devices (explosive bolts) will be put into an enabled condition
prior to firing. Enabling will begin 40 minutes earlier than it would
have under previous commands. These pyro devices will be fired to
carry out necessary steps of descent and landing, such as deploying
the parachute and jettisoning the heat shield.

Mars is 170 million kilometers (106 million miles) away from Earth
today, a distance that takes nearly 10 minutes for radio signals to
cross at the speed of light. Counting that communication delay,
Spirit will hit the top of Mars' atmosphere at about 04:29 Jan. 4,
Universal Time (8:29 p.m. Jan. 3, Pacific Standard Time), and reach
the surface six minutes later.

manages the Mars Exploration Rover project for NASA's Office of Space
Science, Washington, D.C. Additional information about the project is
available at

http://marsrovers.jpl.nasa.gov
http://www.nasa.gov

and from Cornell University, Ithaca, N.Y., at

http://athena.cornell.edu/

-end-