PUBLIC INFORMATION 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

Mars Pathfinder Mission Status
June 26, 1997
Mars Pathfinder, now eight days away from landing on the surface of Mars, performed the last of its scheduled trajectory correction maneuvers at 10 a.m. Pacific Daylight Time on Wednesday, June 25.

The correction maneuver was performed in two phases occurring 45 minutes apart. The first burn, lasting just 1.6 seconds, involved firing four thruster engines on one side of the vehicle. The second burn lasted 2.2 seconds and involved firing two thrusters closest to the heat shield. The combined effect of both burns changed Pathfinder's velocity by 0.018 meters per second (0.04 miles per hour), which places the spacecraft on target for a July 4 landing in an ancient flood basin called Ares Vallis. Pathfinder is scheduled to land at 10:07 a.m. PDT (in Earth-received time). The one-way light time from Mars to Earth is 10 minutes, 35 seconds, so in actuality, Pathfinder lands at 9:57 a.m. PDT.

If necessary, a fifth trajectory correction maneuver may be performed just before Pathfinder hits the upper atmosphere of Mars. The maneuver would be carried out either 12 hours or six hours before Pathfinder reaches the atmosphere at 10 a.m. PDT in Earth-received time. The flight team will make a decision to proceed with the final correction maneuver the evening before landing.

A final health check of the spacecraft and rover was performed on June 20. All spacecraft systems, including science instruments and the critical radar altimeter, remain in excellent health from the last check about six months ago. The rover received a "wake up" call, woke up on command from the lander, then accepted a software upgrade. Flight controllers next loaded the 370 command sequences that will be required by Pathfinder to carry out its surface operations mission.

The spacecraft is now ready to begin its entry, descent and landing phase. It will be commanded into that mode at 1:42 p.m. PDT on June 30 by an onboard sequence.

Mars Pathfinder is currently about 180 million kilometers (111 million miles) from Earth and about 3.5 million kilometers (2.2 million miles) from Mars. After 202 days in flight, the spacecraft is traveling at about 18,000 kilometers per hour (12,000 miles per hour) with respect to Mars.

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