NASA on Wednesday launched the "Deep Impact" spacecraft on a mission to smash a hole in a comet from which scientists hope to find frozen remains from the early years of the formation of the solar system.
The craft was launched at 1:47 p.m. EST (1847 GMT) from the Cape Canaveral Air Force Station, Florida.
The spacecraft will release a 372-kg projectile one day before the projectile will run into Comet Tempel 1 at the speed of 37,000 kmph on July 4, about 132 million km away from the Earth.
The National Aeronautics and Space Administration (NASA) scientists hope the 330 million-US dollar comet probe mission could help them know better about the conditions in the early years of the formation of the solar system. Comets are believed to contain frozen remains from that period.
Scientists have estimated the force of the strike will be equivalent to 4.5 tons of TNT.
The collision is expected to create a hole into the surface of Tempel 1, about the size of a football field and 2-14 story building deep.
Scientists stressed the strike will not break the comet, nor distract Tempel 1 from its original orbit around the sun into a course to collide with the Earth.
Deep Impact is carrying the most powerful telescope ever sent into deep space. It will remain with the mother ship and will fly by the comet and observe the collision.
Scientists are organizing a world-wide observation of the event in order to gather as much information as possible.
NASA space telescopes including Hubble and Spitzer will also watch the strike, the first ever attempt of its kind.