The National Aeronautics and Space Administration has slated another attempt at blastoff for Wednesday July 2. The space agency had to call off one attempt Saturday night due to high winds at Cape Canaveral.

"The launch is further postponed to Wednesday, July 2, by problems with the cork insulation on the Delta launch vehicle," NASA spokesman George Diller, spokesman said.

A fresh attempt will be made at 11:17 pm Wednesday (0317 GMT Thursday), with a second potential launch window shortly afterwards at 11:50 pm.

Opportunity is waiting to follow its twin probe, the Mars Expedition Rover "Spirit," which was launched June 10 and is scheduled to land in early January 2004 in the Gusev Crater, 15 degrees south of the equator of Mars.

The seven-month journey will take the Opportunity 491 million kilometers (305 million miles) to the Meridiani Planum, a zone containing a concentration of ferrous oxide situated two degrees south of Mars' equator.

The Opportunity rover -- also known as Mars Exploration Rover-B -- will look for evidence that water once flowed on the Red Planet's surface.

Researchers are seeking answers to one of space exploration's most persistent questions -- whether conditions present on the Red planet were favorable enough for life to evolve.

"We know Mars ... had water in the past," said Ed Weiler, NASA's associate administrator.

"It may have it in the present. What we don't know is how long this water persisted in any given place ... If it stayed there for tens of millions of years, then there is a good chance life might have evolved."

Although both probes will set down relatively close to the Martian equator, they will be on virtually opposite sides of the planet, some 6,000 miles (9,600 kilometers) apart.

NASA is investing some 800 million dollars on the two six-wheeled vehicles, which for three months are to probe sites thought to be geologically important, roaming in search of clues to whether Mars has or could support life.

"These missions are not designed to find life on Mars," NASA associate administrator Ed Weiler told a press conference Friday. "They are not designed to find water on Mars. They are designed to answer a critical question in the search for life.

"We know Mars has water, we know it had it in the past and may have it in the present," he said. "What we don't know is how long the water persisted in any given place.

"If it stayed there for tens of millions of years, then there is a good chance that life might have evolved. Because on Earth, wherever we find water and energy and organic compounds, we find life, no matter what the conditions are."

Spirit is scheduled to arrive at Mars on January 3, while Opportunity will arrive three weeks later on January 24.

SPACE.WIRE