MOSCOW - Russia's space-agency chief said yesterday that a spacecraft may be dispatched to knock a large asteroid off course and reduce the chances of Earth impact - though U.S. scientists say such a scenario is unlikely.

Anatoly Perminov told Golos Rossii radio that his space agency would meet soon to assess a mission to Apophis. He said his agency might eventually invite NASA, the European Space Agency, the Chinese space agency, and others to join the project.

When the 885-foot asteroid was discovered in 2004, astronomers estimated its chances of smashing into Earth in its first flyby, in 2029, at 1 in 37. Further studies have ruled out the possibility of an impact in 2029, when the asteroid is expected to come no closer than 18,300 miles from Earth, but they indicated a small possibility of a hit on subsequent encounters.

NASA had put the chances that Apophis could hit Earth in 2036 as 1 in 45,000. In October, after researchers recalculated the asteroid's path, the agency changed its estimate to 1 in 250,000. NASA said another close encounter in 2068 would bring a 1-in-330,000 chance of impact.

Don Yeomans, who heads NASA's Near-Earth Object Program, said better calculations of Apophis' path in several years "will almost certainly remove any possibility of an Earth collision" in 2036.

He said in an e-mail yesterday, "While Apophis is almost certainly not a problem, I am encouraged that the Russian science community is willing to study the various deflection options that would be available in the event of a future Earth threatening encounter by an asteroid."

Without mentioning NASA's conclusions, Perminov said he heard from a scientist that Apophis was getting closer and might hit the planet.

"People's lives are at stake," he said. "We should pay several hundred million dollars and build a system that would allow us to prevent a collision, rather than sit and wait for it to happen and kill hundreds of thousands of people."

Scientists have long theorized about asteroid-deflection strategies. Some have proposed sending a probe to circle around a dangerous asteroid to gradually change its trajectory. Others suggested sending a spacecraft to collide with the asteroid and alter its momentum.