A NASA spacecraft will blast off next week on an audacious mission to blow a chunk out of a comet that may provide clues to the origin of the solar system.

The Deep Impact probe is scheduled to be launched from Cape Canaveral in Florida on January 12, beginning a six-month journey that will end with a celestial firework display on American Independence Day on July 4.

When the £140 million craft reaches the comet Tempel 1, it will fire an 800lb “impactor” module that will crash into its target at a speed of 22,800mph.

Although the impactor will be obliterated by the 3.7 mile-wide comet, it will blast a hole seven storeys deep and as wide as a football pitch in its core, releasing clouds of debris into space. The mother ship loaded with scientific instruments will film the collision and analyse contents of the dust.

Comets are thought to be ancient relics that date back to the birth of the solar system an estimated 4.6 billion years ago, so the experiment promises to offer important insights into how the planets formed.

“We know so little about the structure of cometary nuclei that we need exceptional equipment to ensure that we capture the event,” said Michael A’Hearn, Professor of Astronomy at the University of Maryland and Deep Impact’s chief scientist. “We will be capturing the whole thing on the most powerful camera to fly in deep space.”

Deep Impact’s eyes will not be the only ones trained on the collision. The Hubble, Chandra and Spitzer space telescopes will all be observing as the material is blown away, and hundreds of professional and amateur astronomers will also be watching the event.

The six-month journey is relatively short in cosmic terms. “From Central Florida to the surface of a comet in six months is almost instant gratification from a deep space mission viewpoint,” said Rick Grammier, Deep Impact project manager at Nasa’s Jet Propulsion Laboratory (JPL) in Pasadena, California. “It is going to be an exciting mission and we can all witness its culmination together as Deep Impact provides the planet with its first man-made celestial fireworks on our nation’s birthday.”

When the impactor collides with the comet it will essentially be “run over” by the speeding lump of rock and ice, which is as large as a mountain.There is no danger that it will divert the comet’s path in any significant way, let alone that it might nudge it into an orbit that could threaten a collision with Earth. The data that scientists gather from the mission, however, could be useful in planning future missions to divert comets that do present a threat. Deep Impact was the name of 1998 disaster movie about comets on collision course with Earth.

Don Yeomans, a Deep Impact mission scientist at JPL, said: “In the world of science, this is the astronomical equivalent of a mosquito running into a 767 airliner. It simply will not appreciably modify the comet’s orbital path. Comet Tempel 1 poses no threat to the Earth now or in the foreseeable future.”

Tempel 1 was discovered in 1867 and orbits the Sun every five and a half years. It often passes through the inner solar system, making it a good target for scientific study.

Researchers are also eager to learn whether gas and ice from comets is spewed into space as an “exhaust”, or is sealed inside the nucleus. Another aim is to find out whether the interior of the nucleus is very different from its surface.

TO BOLDLY GO...

The British-built £35m Beagle 2 spacecraft was intended to land on Mars on Christmas Day 2003. But contact was lost and it is assumed to have crashed

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