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Flight Status Report

Friday, 12 September 1997

The Mars Global Surveyor spacecraft continues to perform flawlessly 24 hours after entering orbit around the red planet. As of 11:59 p.m. PDT, the spacecraft has completed half of its first revolution around Mars by reaching the high point of the orbit. This point lies at an altitude of 33,570 miles (54,026 km) above the planet. The spacecraft is now falling back toward Mars, and will reach the low point and start its second orbit at 3:28 p.m. PDT on Saturday.

Today, the navigation team released a preliminary solution of the spacecraft's orbit following yesterday's successful Mars orbit insertion burn. "We targeted for a 45-hour orbit period and achieved an orbit of 44 hours, 59 minutes, and 34 seconds," said chief navigator Dr. Pat Esposito. "That's what I call a precision maneuver," he added.

Data transmitted to Earth from Surveyor corroborates Esposito's assessment of a precision maneuver. This data was collected by the spacecraft's accelerometers and shows that that the orbit insertion burn slowed the spacecraft by 2,176.61 m.p.h. (973.03 meters per second). This value differs from the expected value of 2,176.58 m.p.h. by less than one-thousandth of one percent.

Lead propulsion engineer Sam Dominick reports that the burn consumed 621.15 pounds (281.75 kg) of Surveyor's propellant supply. As expected, this value amounts to most of the spacecraft's total capacity. Currently, the hydrazine fuel tanks are only 31% full, and the nitrogen tetroxide oxidizer tank contains just over 9% of its original supply.

Saturday evening, the flight team will activate Surveyor's science instruments two hours after the start of the second orbit. This activation will allow the Magnetometer and Thermal Emission Spectrometer science instruments to collect data on a continuous basis. However, the Mars Orbiter Camera and Mars Orbiter Laser Altimeter instruments need to be pointed directly at Mars to collect data. The first opportunity for these two instruments will occur during a 15-minute time period centered on the start of third orbit on Monday at 12:28 p.m. PDT. Additional science data will be acquired during the forthcoming aerobraking phase of the mission. The actual start of mapping operations will not begin until March 1998.

After a mission elapsed time of 309 days from launch, Surveyor is 158.18 million miles (254.56 million kilometers) from the Earth and in an orbit around Mars with a period of 45 hours. The spacecraft is currently executing the T1 command sequence, and all systems continue to be in excellent condition.

Status report prepared by:

Office of the Flight Operations Manager
Mars Surveyor Operations Project
NASA Jet Propulsion Laboratory
California Institute of Technology
Pasadena, CA 91109