[meteorite-list] Mars Exploration Rover Mission Status - November 19, 2003

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:27:51 2004
Message-ID: <200311192309.PAA05877_at_zagami.jpl.nasa.gov>

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

Guy Webster (818) 354-6278
Jet Propulsion Laboratory, Pasadena, Calif.

NEWS RELEASE: 2003-153 November 19, 2003

Mars Exploration Rover Mission Status

NASA's Spirit spacecraft made its third trajectory correction maneuver
on Friday, Nov. 14,
fine tuning its flight path toward Mars with an engine-firing
operation planned into the seven-month trip.

The trajectory adjustment was designed to alter Spirit's velocity by
0.6 meters per second (1.3 miles per hour), moving the arrival point
by 770 kilometers (478 miles) and arrival time by 16.5 minutes closer
to the planned target location and time, said Louis D'Amario, the
project's navigation team chief. To accomplish that adjustment, the
flight team commanded Spirit to fire its engines for 132 seconds in
the direction of the spacecraft's rotation axis and for short pulses
totaling 27 seconds in a direction roughly perpendicular to the
rotation axis.

Spirit has three more scheduled dates for additional trajectory
corrections before reaching Mars less than seven weeks from now. The
spacecraft is carrying the first of two Mars Exploration Rovers
equipped to examine the geology around their landing sites for
evidence about past environmental conditions.

Both Spirit and its twin, Opportunity, have rebooted their computers
in the past two weeks. Mission controllers at NASA's Jet Propulsion
Laboratory, Pasadena, Calif., sent commands for that procedure on each
spacecraft to correct possible corruption of computer memory registers
by radiation from powerful solar flares in late October and early
November. The flares were among the most intense ever recorded.

"We had no evidence of memory problems, but we considered it prudent
to reboot both spacecraft to assure memory integrity, using the
sleep-wake cycle that we plan to do each night after the rovers are on
the surface of Mars," said JPL's Peter Theisinger, project manager for
the Mars Exploration Rover Project.

High-energy protons ejected by the stormy Sun appeared on Oct. 28 as
bursts of bright spots in star-tracking instruments used by both
Spirit and Opportunity to sense the spacecrafts' orientation. The
instruments interpreted the proton hits as stars, so the bursts
overwhelmed their ability to recognize star patterns and determine
spacecraft attitude. Both spacecraft temporarily switched to a backup
method of attitude sensing, using the Sun. They resumed use of the
star trackers last week.

Spirit's target is arrival at Mars' Gusev Crater at 04:35 Jan. 4,
2004, Universal Time (8:35 p.m. Jan. 3, Pacific Standard Time and
11:35 p.m. Jan. 3, Eastern Standard Time). These are "Earth received
times," meaning they reflect the delay necessary for a speed-of-light
signal from Mars to reach Earth; on Mars, the landing will have
happened nearly 10 minutes earlier. Three weeks later, at 05:05 Jan.
25, Universal Time, Opportunity will arrive at a level plain called
Meridiani Planum on the opposite side of Mars from Gusev. Each rover
will examine its landing area for geological evidence about the
history of water there, key information for assessing whether the site
ever could have been hospitable to life.

As of 6 a.m. PST on Nov. 19, Spirit had traveled 396.5 million
kilometers (246.4 million miles) since its June 10 launch, with 91.5
million kilometers (56.2 million miles) to go before reaching Mars.
Opportunity, launched on July 7, had traveled 326 million kilometers
(202 million miles) and has 130 million kilometers (81 million miles)
yet to go.

JPL, a division of the California Institute of Technology, manages the
Mars Exploration Rover project for NASA's Office of Space Science,
Washington, D.C. Additional information about the project is
available from JPL at

http://mars.jpl.nasa.gov/mer

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

http://athena.cornell.edu/ .

-end-
Received on Wed 19 Nov 2003 06:09:07 PM PST


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