A computer design downloaded from the internet of the Mars Global Surveyor, is shown in this Jan. 29, 1999 file photo. NASA's best effort to find the missing probe failed Monday night, as scientists at the space agency began to lose hope for the 10-year-old planet-mapping workhorse, which has been silent for more than two weeks. [AP]

After more than two weeks of silence from the Mars Global Surveyor, NASA will make other tries to locate it, but scientists were pessimistic.

"We may have lost a dear old friend and teacher," Michael Meyer, the lead scientist for NASA's Mars Exploration Program said in a news conference.

The $154 million surveyor, which was supposed to last only two years but continued sending data for almost a decade, is the oldest of six different active space probes on or circling the red planet.

Among its accomplishments are more than 240,000 pictures of Mars, offering the best big-picture view of the planet. Meyer credited the probe with proving that Mars once had water.

"Every good thing comes to an end at some point," said Arizona State University scientist Phil Christensen. "It certainly in my mind greatly exceeded our wildest expectations of what to hope for. It revolutionized what we were thinking about Mars."

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