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Flight Status Report

Thursday, 11 September 1997

After conducting a "go/no-go" poll of Surveyor's flight controllers at 5:45 p.m PDT today, lead controller Kyle Martin reported to flight operations manager Joe Beerer that "all systems are go for the Mars orbit insertion burn." Beerer's concurrence with the status check enabled project manager Glenn Cunningham to give the official "go ahead" for the engine firing to put Surveyor in orbit around Mars.

Almost 46 minutes later, at 6:31 p.m. PDT, the onboard computer command Surveyor's tiny attitude-control thrusters to fire for 20 seconds. These tiny thruster rockets are normally used to stabilize the spacecraft during main-engine firings. The initial, 20-second thruster firing settled the liquid in the spacecraft's tanks to ensure a smooth flow of propellant to the more powerful main rocket engine that was used for the orbit insertion maneuver.

Immediately after the small, settling burn, the computer commanded Surveyor's main engine to fire. Ignition occurred at an altitude of about 930 miles (1,500 km) with the spacecraft moving at a velocity of 11,390 m.p.h. (5,090 meters per second). Twelve minutes into the burn, Surveyor passed behind Mars. Although contact was lost when the spacecraft passed behind Mars, the computer continued to carry out the orbit insertion burn without incident.

When Surveyor reemerged from behind Mars at 6:57 p.m PDT, the burn had already completed. Over the course of the 22-minute burn, the engine expelled over 617 pounds (280 kilograms) of nitrogen tetroxide and hydrazine propellant to slow Surveyor by a total of 2,176 m.p.h. (973 meters per second).

Chief navigator Dr. Pat Esposito has announced that tracking data gathered by stations in California and Australia confirm that the burn was executed successfully and flawlessly. Although the navigation team is currently performing a detailed analysis to determine the exact nature of Surveyor's orbit around Mars, preliminary indications show that the orbit's low point is about 155 miles (250 km) above the Martian surface, and the high point is at an altitude of just over 31,000 (50,000 km). In this orbit, Surveyor will take roughly 45 hours to circle the red planet.

The flight team at the Jet Propulsion Laboratory in Pasadena and the Lockheed Martin Astronautics facility in Denver is currently busy monitoring the health and status of the spacecraft. However, initial data shows that all systems are functioning normally. One of the next tasks will the preparation of command sequence T2 for transmission to Surveyor. This sequence will be sent Saturday morning, just prior to the start of the second orbit around Mars. The primary purpose of T2 will be to configure the spacecraft and science instruments for orbital and aerobraking operations.

After a mission elapsed time of 308 days from launch, Surveyor is 158.06 million miles (254.38 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