PASADENA, CALIF., AUG. 18 -- Magellan sent information to Earth today to help engineers learn why they temporarily lost contact with the spacecraft after its first pictures displayed quake faults, volcanic cinder cones and plains made of lava flows on Venus.

"After steady contact with the spacecraft was reestablished Friday night, engineers commanded the spacecraft to transmit all of the information in its computer memories back to Earth. This will continue throughout the weekend," said Mary Beth Murrill, spokeswoman for NASA's Jet Propulsion Laboratory (JPL).

She said it might take days to figure out why Magellan lost contact with Earth on Thursday night after it sent back its first test pictures of Venus -- images that had scientists marveling.

"The radar works far better than we ever dreamed it would," said Steve Saunders, Magellan's chief scientist. "The kind of faulting we see would certainly mean there are 'Venusquakes.' "

The pictures will be released Tuesday, the National Aeronautics and Space Administration said.

Before the problem developed, Magellan was scheduled to start its formal mapping mission Aug. 29, using its radar to peer through Venus's thick clouds. Murrill said a delay is likely.

Engineers today continued the process of returning Magellan to normal operation. It lost touch with Earth for almost 15 hours starting Thursday night, then had erratic radio contact over the next eight hours.

A computer command sent to Magellan on Friday night restored steady radio contact.

Magellan was deployed May 4, 1989, from the shuttle Atlantis on its $744 million mission to make the best maps and pictures yet of Venus. The spaceship went into orbit around Venus on Aug. 10 after a looping 948-million-mile voyage.