Fate of NASA’s Mars Mission Rests on Curiosity’s Landing

By KENNETH CHANG

PASADENA, Calif. — The future of NASA’s exploration of Mars now comes down to a struggle between gravity and a half-million lines of computer code.

Currently snug in an interplanetary spacecraft, the plutonium-powered rover called Curiosity will end its eight-and-a-half-month journey from Earth on Sunday, plowing into the Martian atmosphere at 13,000 miles per hour in a burst of fire.

When that happens, control over the $2.5 billion mission will transfer to the onboard computer, which must slow the car-sized Curiosity and execute a series of intricate maneuvers to lower it to the ground.

Because of a 14-minute communications gap between the two planets, scientists on Earth will be mere spectators. Landing was scheduled to occur at 10:31 p.m. Sunday here in Pasadena, though officials warned that confirmation of a successful touchdown could take several hours or even days.

Failure could set back American-led Mars explorations for years.

Because of tightening budgets, NASA has already pulled out of collaborations with the European Space Agency planned for 2016 and 2018. The space agency is now contemplating what alternative missions it can fly on its own to Mars in 2018 — but nothing nearly as ambitious or expensive as Curiosity.

If Curiosity fails, NASA would have to start over.

Doug McCuistion, the Mars exploration program director, said NASA would persist as it had following earlier Mars failures. After the loss of two Mars spacecraft in 1999, NASA then built and landed two highly successful rovers, Spirit and Opportunity, in 2004.

“We’ll pick ourselves up, dust ourselves off,” Mr. McCuistion said at a news conference on Saturday. “This will not be the end.”

At landing time, two NASA craft, the Mars Reconnaissance Orbiter and Mars Odyssey, will be passing close overhead, with Odyssey relaying transmissions to Earth.

But the landing could pass without word from Curiosity.

“It doesn’t necessarily mean something bad has happened,” said Richard Cook, the deputy project manager.

If the landing succeeds, the first black-and-white photographs could be beamed back on Monday.

Over the first week, Curiosity is to deploy its main antenna, raise a mast containing cameras, a rock-vaporizing laser and other instruments, and take its first 360-degree panorama shot of its surroundings.

NASA will spend the first month checking out Curiosity. Mr. Cook said the first drive could occur early next month. The rover would not scoop its first sample of Martian soil until mid-September at the earliest, and the first drilling into rock would occur in October or November, he said.

Michael Schwirtz contributed reporting from New York.

A version of this article appeared in print on August 5, 2012, on page A17 of the New York edition with the headline: Mars Mission’s Fate Rests on Landing.

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