Fickle Magellan’s Venus Map Mission on Hold : Spacecraft: Engineers trying to determine why erratic probe keeps losing radio contact with Earth.

Magellan’s mission to map the rugged surface of Venus is being delayed again so a team of 40 engineers can figure out why the spacecraft keeps losing contact with Earth, a NASA official said today.

“We’re targeting for the last week in September to start mapping,” said Tony Spear, Magellan project manager at the space agency’s Jet Propulsion Laboratory in Pasadena.

Spear had said Friday that engineers hoped to fix the problem in time to have Magellan working properly by mid-September. Before Magellan started malfunctioning, the National Aeronautics and Space Administration planned for it to make pictures and maps of Venus on a regular basis starting Saturday.

The spaceship remained in a protective “safing mode” today, Spear said during an interview.

Engineers still haven’t figured out why Magellan’s radio link to Earth failed for 14 hours starting Aug. 16 and again for 17 1/2 hours beginning Aug. 21, he added.

So Spear said he organized a “tiger team” of 40 engineers from the laboratory and from Martin Marietta Corp., which built Magellan in Denver, to determine what is wrong with the spaceship and repair it.

Magellan’s $744-million mission is to use radar to peer through Venus’ thick clouds and make the best pictures and maps yet of the planet’s surface. It was launched from space shuttle Atlantis on May 4, 1989.

Pictures made during an Aug. 16 radar test showed extensive “Venusquake” faults, vast flows of solidified lava, cinder cones, a lava-filled meteorite impact crater and countless valleys and mountain ridges on the surface of Earth’s nearest planetary neighbor.

Spear said one major theory is that something went wrong when Magellan entered orbit around Venus on Aug. 10. It functioned almost flawlessly during the 15 months it traveled a looping path of 948 million miles from Earth.

Spear ruled out the possibility, raised Friday, that Magellan’s braking rocket may have failed to separate from the spacecraft after it went into Venus orbit.

Mapping is being delayed not only because time is needed to fix Magellan, but also because the spacecraft’s troubles have left engineers “mentally and physically exhausted,” Spear said. “We’ve decided to give the team three days off around Labor Day.”

Engineers want to make sure Magellan doesn’t break down again when mapping is in progress because “it’s not good for people’s hearts,” he added.

Spear, fully aware of NASA’s problems stemming from temporary grounding of the shuttle fleet and a severe defect on the Hubble Space Telescope, appealed to the public to “have patience” with Magellan.

“We’re going to make it work,” he pledged. “Have confidence in us.”