A team from the U.S. won the top prize in an international competition to solve a dilemma more commonly associated with Hollywood blockbusters like Armageddon and Deep Impact: How do you track an asteroid headed for Earth?

The winning team, led by SpaceWorks Engineering Inc. of Atlanta working in conjunction with SpaceDev Inc. of Poway, Calif., won the Apophis Mission Design Competition's $25,000 US first-place prize on Tuesday, according to The Planetary Society, the space exploration advocacy group that held the contest.

The competition takes its name from the asteroid 99942 Apophis, which scientists once calculated had a one in 42 chance of striking Earth in 2036. Further study has since scaled those odds back considerably, to about one in 45,000.

The society's aim with the competition was to seek out new, more accurate methods of tracking an asteroid to give governments better information about whether or not a mission to deflect it off our path was necessary.

Large asteroids can have a potentially disastrous impact if they strike the Earth. Scientists have theorized that a collision of an asteroid off the coast of the Yucatan Peninsula in Mexico 65 million years ago wiped out the dinosaurs by causing an upheaval in the planet's climate.

The actual contest required teams to come up with a plan to track Apophis as it nears Earth.

Plenty of 'Foresight'

The winning team's plan, called Foresight, calls for a spacecraft to be equipped with a radio beacon and two tracking instruments and would launch aboard an Orbital Sciences Corp. Minotaur IV rocket sometime between 2012 and 2014.

It would rendezvous with the asteroid some five to 10 months later, orbit it for a month to collect data, and then fly alongside it, using radio tracking from Earth to determine the exact orbit.

The winning team said the total cost of the operation would be $137.2 million US.

A team from the Georgia Institute of Technology, also of Atlanta, won the $5,000 US first-place prize awarded to students.

The competition received 37 mission proposals from 20 countries, according to the Planetary Society, the international group founded in 1980 by Carl Sagan and other astronomers.

NASA's Near-Earth Object (NEO) program office already tracks the paths of both near-Earth asteroids and comets. As of Jan. 20, 2008, the NEO office said it has discovered 5,086 near-Earth asteroids.

In September 2007 NASA's Dawn spacecraft lifted off from Cape Canaveral on an eight year, 6.4 billion-kilometre mission to monitor the asteroids Vesta and Ceres.

But both of these asteroids lie in the asteroid belt between Jupiter and Mars, and neither is seen as a danger to Earth.