Mars Exploration Rover Mission Status
December 29, 2003
NASA's Spirit rover spacecraft fired its thrusters for 3.4 seconds on
Friday, Dec. 26, to make a slight and possibly final correction in its
flight path about one week before landing on Mars.
Radio tracking of the spacecraft during the 24 hours after the maneuver
showed it to be right on course for its landing inside Mars' Gusev Crater
at 04:35 Jan. 4, 2004, Universal Time (8:35 p.m. Jan. 3, Pacific Standard
Time.) Spirit's twin, Opportunity, will reach Mars three weeks later.
"The maneuver went flawlessly," said Dr. Mark Adler, Spirit mission manager
at NASA's Jet Propulsion Laboratory, Pasadena, Calif.
This was Spirit's fourth trajectory correction maneuver since launch on
June 10. Two more are on the schedule for the flight's final three days, if
needed. Adler said, "It seems unlikely we'll have to do a fifth trajectory
correction maneuver, but we'll make the final call Thursday morning after
we have a few more days of tracking data. Right now, it looks as though we
hit the bull's-eye."
The adjustment was a quick nudge approximately perpendicular to the
spacecraft's spin axis, said JPL's Chris Potts, deputy navigation team
chief for the NASA Mars Exploration Rover project. "It moved the arrival
time later by 2 seconds and moved the landing point on the surface
northeast by about 54 kilometers" (33 miles), Potts said. The engine
firing changed the velocity of the spacecraft by only 25 millimeters per
second (about one-twentieth of one mile per hour).
For both NASA rovers approaching Mars, the most daunting challenges will be
descending through Mars' atmosphere, landing on the surface, and opening up
properly from the enclosed and folded configuration in which the rovers
arrive. Most previous Mars landing attempts, by various nations, have
failed.
Each rover, if it arrives successfully, will then spend more than a week in
a careful sequence of steps before rolling off its lander platform. The
rovers' mission is to examine their landing areas for geological evidence
about past environmental conditions. In particular, they will seek
evidence about the local history of liquid water, which is key information
for assessing whether the sites ever could have been hospitable to
life. Opportunity will land halfway around Mars from Spirit.
As of 13:00 Universal Time (6 a.m. PST) on New Year's Day, Spirit will have
traveled 481.9 million kilometers (299.4 million miles) since launch and
have will have 5.1 million kilometers (3.2 million miles) left to
go. Opportunity will have traveled 411 million kilometers (255 million
miles) since its July 7 launch and will have 45 million kilometers (27.9
million miles) to go, with three remaining scheduled opportunities for
trajectory correction maneuvers.
JPL, a division of the California Institute of Technology, manages the Mars
Exploration Rover project for NASA's Office of Space Science, Washington.
Additional
information about the project is available from JPL at http://marsrovers.jpl.nasa.gov and
from Cornell University, Ithaca, N.Y., at http://athena.cornell.edu .
