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Mars Observer Falls Silent at Crucial Point


NASA engineers struggled furiously Sunday to regain communication with the Mars Observer after the $980-million space probe fell ominously silent when it was supposed to start pressurizing some fuel tanks in anticipation of arriving at the Red Planet.

The space agency's Jet Propulsion Laboratory in Pasadena lost contact Saturday evening, 11 months after launch and less than 68 hours before the craft was scheduled to perform the mission's most critical maneuver, insertion into Mars orbit.

JPL spokeswoman Diane Ainsworth said ground controllers on Friday afternoon had routinely transmitted to the spacecraft's computer memory instructions for entering Mars orbit. She said the satellite is capable of performing the maneuver on its own.

However, even if placed in orbit, the craft would be useless to scientists if NASA engineers are unable to re-establish radio contact and receive data from the research instruments on board.

When the problem arose, engineers tried to coax the satellite to turn on its transmitter and point its antenna toward Earth by sending up commands every 20 minutes for 18 hours. That approach was fruitless.

Early Sunday afternoon, engineers tried to wring some sign of life from the craft by issuing a number of commands in series. They were unsure early Sunday evening whether this new approach had succeeded.

JPL workers were described as "tense but not gloomy" as they tried to sleuth out potential causes of the problem, which threatens a mission that many people in the National Aeronautics and Space Administration were counting on to restore luster to the agency's tarnished image.

NASA engineers have overcome similar problems with the Mars Observer and other craft in the past, Ainsworth said. For example, communications interruptions with the Magellan probe to Venus a few years ago were corrected with new computer software.

Ground controllers also lost touch with the Mars Observer for more than an hour shortly after it was launched from Cape Canaveral, Fla., on a Titan III rocket in September. However, that problem was blamed not on the spacecraft but on faulty equipment aboard the booster rocket that pushed the 5,600-pound satellite out of Earth orbit toward Mars.

Although it is the most sophisticated planetary satellite ever lofted, Mars Observer also had been considered one of NASA's most reliable craft because it was built out of components that had been extensively tested and flight-proven on other missions.

Beyond the damage that it could inflict on NASA, failure of the Mars Observer would be a profound disappointment to scientists around the world. An international team of researchers has been counting on the satellite to supply unprecedented amounts of information about the makeup of the Martian surface and the nature of its core. And it was designed to be the first alien-based weather channel, providing a full Martian year--687 Earth days--of daily weather reports from the Red Planet.

Dozens of less-sophisticated American and Russian probes dating back to the 1960s had established that Mars is cold, dry and--almost assuredly--dead. Mars Observer was designed to help scientists figure out if it had always been that way.

Weathering and erosion patterns on the planet's boulder-strewn, volcano-pocked surface have teased geologists with the possibility that Mars once had enough water to form mighty rivers. This, in turn, suggests that it must have had an atmosphere far different from the wisps of carbon dioxide that now surround the planet.

Mars, in other words, once may have resembled ancient Earth. Scientists are eager to learn how closely the planets resembled one another and why they are so different today.

After a roundabout 450-million-mile route from Earth, Mars Observer was supposed to start easing into a 234-mile-high polar orbit Tuesday, then spend three months readying its battery of sophisticated instruments to answer some of those questions.

Researchers are particularly interested in learning more about how Mars works as an ecosystem--how weather and water have shaped its surface, how hurricane-force dust storms influence weather, whether Mars is geophysically active, and how volcanoes have affected the planet's evolution.

And, perhaps most of all, they want to learn what happened to all the water that apparently carved deep channels into its spectacularly rugged landscape.

"We want to understand the early conditions on Mars and how it evolved and changed," said Mars Observer project scientist Arden L. Albee. "Earth, Mars and Venus are all about the same size and (roughly) the same distance from the sun. How in the heck did they all wind up so different? We think there are lessons to be learned."

The computer-packed space probe, about the size of a golf cart but as heavy as two Jeep Cherokees, is designed to help scientists answer such questions by sending more scientific data than all American planetary probes prior to the recent Magellan mission to Venus.

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