Magellan Calls Its Own Orbital Shot : Space: Engineers finally regain radio contact with balky craft. They remain at a loss to understand its behavior while it zips around Venus.

Like the cantankerous explorer whose name it bears, the Magellan spacecraft charted its own course Wednesday, refusing to communicate with engineers until they finally regained radio contact with their balky craft late in the afternoon.

Magellan dropped out of contact with the Jet Propulsion Laboratory Tuesday night for the second time in less than a week, then transmitted a short “bleat” shortly after noon Wednesday, suggesting that it was listening to a few commands from the weary engineers at the Pasadena lab. Later, its signal locked on with ground receivers briefly, and it responded to one key command at 4:37 p.m., leaving experts encouraged but unsure of exactly what is going on with the space probe.

The bleat told relieved ground controllers that at least the spacecraft is alive. But nobody is certain what gremlin is causing Magellan to break off communications as it zips around Venus, 149 million miles from home.

Engineers will spend the next few days trying to understand the problem before they order Magellan to begin its two-year task of mapping the surface of Venus.

The latest problems came hours after scientists had released the first radar images of Venus. Tired workers had just gone home for dinner Tuesday night when the National Aeronautics and Space Administration’s tracking station in Australia lost its radio “lock” on Magellan at 7:03 p.m. Three minutes later the signal was picked up again, but it was weaker, and seconds later it disappeared entirely.

That sent engineers scurrying back to the lab and they worked through the night to re-establish communications.

There was nothing to cheer about until around noon Wednesday when Magellan’s signal was picked up again. But seconds later, the spacecraft passed behind Venus, blocking out the transmission.

That told controllers that the craft was responding to at least some of the commands, and most important, it meant that Magellan’s solar panels were pointed toward the sun, keeping its batteries charged. Had the craft failed to maneuver the panels into the right solar orientation, it would have lost all electrical power and eliminated any chance of regaining control--the ultimate nightmare for space engineers.

Controllers did not expect to hear anything when Magellan emerged from behind Venus about 28 minutes later, because it should have rotated in response to commands designed to put it in a “safe mode” while engineers work on the problem. But instead, they heard the bleat.

That meant the craft almost seems to have a mind of its own and is not entirely going along with the game plan.

Nearly five centuries ago, Ferdinand Magellan set out from Spain for the Spice Islands east of Asia, which he thought he could reach by sailing south. He was right, but his ships had to sail around the entire world to get there.

Magellan had a difficult, brutal cruise, but in the end it was deemed a success because he accomplished what no other explorer had done before.

Engineers at JPL would settle for a similar performance by Magellan’s namesake.

They held out hopes of eventually taking full command of the spacecraft.

“We expect to get it back,” JPL engineer David Okerson said in an interview broadcast to all NASA centers Wednesday morning. By noon, he had his bleat, telling him the craft was still kicking.

At 2:04 p.m. he got the best news of the day when Magellan’s transmitter locked on with NASA receivers. The lock was only temporary, but it told engineers something they desperately wanted to hear: the craft was “coning,” which is sort of a graceful wobble. That maneuver had been commanded by controllers because as the craft wobbles, its antennas sweep across the sky so they will periodically point toward Earth, making it possible to re-establish communications.

At 3:51 p.m. ground controllers commanded the craft to stop wobbling and keep its antenna pointed toward Earth. Magellan radioed at 4:43 p.m. that it had performed as commanded.

So by the end of the day Wednesday, JPL engineers were increasingly confident they would be able to take control of the mission.