Opportunity lands successfully on Mars

PASADENA, Calif. - NASA's Opportunity rover successfully landed on Mars late Saturday, arriving at the Red Planet exactly three weeks after its identical twin set down, prompting whoops and cheers of delight from mission scientists who gathered to monitor the touchdown.

"We're on Mars everybody," Rob Manning, manager of the entry, descent and landing portion of the Mars mission, shouted as fellow scientists at NASA's Jet Propulsion Laboratory burst into wild applause.

The unmanned, six-wheeled rover landed at 9:05 p.m. PST in Meridiani Planum, NASA said. The smooth, flat plain lies 6,600 miles and halfway around the planet from where its twin, Spirit, set down on Jan. 3.

Together, the twin rovers make up a single $820 million mission to determine if Mars ever was a wetter world capable of sustaining life. NASA launched Spirit on June 10. Opportunity followed on July 7.

Since arriving, Spirit has developed serious problems, cutting off what had been a steady flow of pictures and other scientific data.

Shortly before entering the martian atmosphere, Opportunity jettisoned its cruise stage, shedding the disc-shaped structure that had provided power, propulsion and communications capabilities during its seven-month trip through space.

In the minutes before cruise separation, mission scientists at NASA's Jet Propulsion Laboratory broke open containers of "good luck peanuts" they had brought for the occasion, and Gov. Arnold Schwarzenegger, and his wife, Maria Shriver, arrived to watch the drama unfold. Also on hand was former Vice President Al Gore.

Scientists laughed and joked nervously in the final minutes heading up to landing.

As they prepared for Opportunity's landing, scientists said earlier Saturday they were closing in on the root of the problem that led the Spirit rover to begin spewing gibberish and beeps instead of science and engineering data earlier this week.

They brought stability to the six-wheeled vehicle by disabling its flash memory, which is similar to the memory digital cameras use to store pictures, said Orlando Figueroa, director of NASA's Mars exploration program.

Opportunity, like Spirit, had to execute a choreographed sequence of events to ensure its safe arrival on Mars. The only difference: Opportunity was to open its parachute 4,500 feet higher above Mars than Spirit did to compensate for the higher elevation of its landing site.