NASA scientists said on Thursday they had lost contact with the Mars Spirit rover for more than 24 hours, describing the problem as "a very serious anomaly."

Spirit project manager Pete Theisinger told a news briefing that a scientist team had met through the night and this morning looking for answers at the NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.

Theisinger said the Spirit rover has stopped sending intelligible data back to Earth for more than 24 hours, and the team was unsure what had caused the problem. NASA last heard from Spirit early Wednesday, its 18th day on Mars.

The rover had been scheduled on Thursday to grind away a tiny area of the weathered face of a sharply angled rock called Adirondack. Examination of the rock beneath could offer clues to Mars' geologic past.

The six-wheeled robot landed on Mars on Jan. 3 on a planned three-month mission to explore the geologic history of the planet. It is one half of an 820-million-dollar mission. Its twin, Opportunity, is scheduled to land on Mars early Sunday.

(Xinhua News Agency January 23, 2004)