Picture: Nasa probe collides with comet

PASADENA, California - A Nasa spacecraft collided with a comet half the size of Manhattan tonight, creating a brilliant cosmic smashup that capped a risky voyage to uncover the building blocks of life on Earth.

"We hit it just exactly where we wanted to," said Don Yeomans, a scientist at Nasa's Jet Propulsion Laboratory.

The spectacular collision, 134 million km away from Earth, unleashed a spray of below-surface material formed billions of years ago during the creation of the solar system.

"As of now, I think we have a completely different understanding of our solar system," said laboratory director Charles Elachi. "Its success exceeded our expectations." The washing machine-sized probe, which performed three final targeting manoeuvres in the mission's last two hours, crashed into comet Tempel 1 right on schedule, snapping images of its rocky terrain up until 3.7 seconds before impact.

An image of the 5.52pm (NZ time) crash taken by Deep Impact, the mission's mother ship, showed a brilliant burst of material coming from the bottom of the avocado-shaped comet.