NASA's Mars probe may miss orbit Faulty clock could doom mission

August 24, 1993|By John Noble Wilford | John Noble Wilford,New York Times News Service

After an 11-month, 450-million-mile voyage, the Mars Observer spacecraft should arrive at its destination today, primed to swing into orbit around Mars.

But there has been nothing but silence from the craft since Saturday night, and puzzled flight controllers were becoming more fearful yesterday that the $1 billion mission might be doomed.

Mission officials said there was one "ray of hope." Engineering studies on the ground suggested that a faulty clock aboard the spacecraft could be responsible for the recent loss of communications. New commands were being radioed to try to switch to a backup clock, which could restore normal operation.

In that case, officials said, flight controllers would have to race against time to check out the spacecraft's performance and transmit a new set of instructions needed by the onboard computer to direct the rocket firings to slow the craft and send it into orbit around Mars.

Those maneuvers must begin today at 4:42 p.m. EDT. Any delay would mean the spacecraft would speed past Mars. Its expected harvest of mapping and geological data, on which future expeditions to Mars, including landings by humans, were to have been based, would be lost.

"We all believe there's time to do this," Glenn E. Cunningham, the project manager, said yesterday at a news briefing at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

If the last ditch efforts are unsuccessful, he said, "we will not go into orbit around Mars and will not be

able to accomplish the mission objective. This would be a great blow to the planetary science community."

As the nation's first mission to Mars in 17 years, the craft was to have mapped the planet's surface and examined its geology and meteorology for a full Martian year, or about two Earth years. In addition, the spacecraft was to act as a radio relay for French scientific balloons that are to be released into the Martian atmosphere by a Russian landing mission in 1996.

Because of the mission's importance to plans for future exploration, Dr. Arden Albee of the California Institute of Technology, the chief project scientist, said, "If it should fail, we would have to redo Mars Observer sometime in the future."

The cost of the mission for NASA is estimated to be close to $1 billion, including $400 million each for the spacecraft and the space shuttle launching expenses.

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