Deep Impact spacecraft to boldly go on 1.6 billion-mile journey

A SPACECRAFT that made history in 2005 by firing a torpedo probe into a comet is setting off on a 1.6 billion mile journey across the solar system.

On July 4, 2005, Deep Impact blew a hole in Tempel 1 to reveal what lay beneath its frozen surface.

Today, it will start its new mission, heading for a flyby rendezvous with another comet, Hartley 2 — only this time there will be no explosions.

En route, the spacecraft will turn the largest of its two telescopes to the stars, to search for new planets.

The Extrasolar Planet Observations and Characterisation mission will target five nearby stars already known to have “hot Jupiter” planets — giant gas worlds that orbit close to their parent star. Deep Impact will study the physical properties of these planets and conduct a search for other undiscovered worlds as small as three earth masses.

By analysing their light, it should be possible to learn what kind of atmospheres, if any, they possess.

Deep Impact passes by Earth on December 31 to get itself slung by gravity towards an encounter with comet Hartley 2.

The planet search will take place during the first six months of the probe’s two-and-a-half-year journey.

Before intercepting the comet, the spacecraft will have to take three trips around the sun. In total, it will cover a distance of about 1.6 billion miles, or 18 times the distance between the Earth and sun. When it reaches Hartley 2, the comet will be about 12.4 million miles from Earth.

At the nearest point of its flyby, Deep Impact will be about 550 miles from the comet.

There is no second probe to fire into the comet. Instead, the spacecraft’s two telescopes will provide close up views of the comet’s surface features. At the same time, its infrared spectrometer will check the composition of any outbursts of gas from the surface.

Deep Impact leader and astronomer Dr Michael A’Hearn, from the University of Maryland in the US, said: “It’s exciting that we can send the Deep Impact spacecraft on a new mission that combines two totally independent science investigations, both of which can help us better understand how solar systems form and evolve.”

Comets are dirty snowballs left over from the birth of the solar system.

Despite three comet missions, the original Deep Impact mission, Deep Space 1 and Stardust, scientists are still puzzled about the nature of comets. Tempel 1, in particular, yielded unexpected data.

“One of the great surprises of comet explorations has been the wide diversity among the different cometary surfaces imaged to date,” said Dr A’Hearn. “We want a close look at Hartley 2 to see if the surprises of Tempel 1 are more common than we thought, or if Tempel 1 really is unusual.”

A brief history of world space discovery:

* October 4, 1957: The USSR launch the first artificial satellite, Sputnik 1.

* November 3, 1957: The USSR launch Sputnik 2, with a dog on board. Laika, dies from overheating and panic a few hours into the mission.

* December 6 1957: The US makes its first attempt to launch a satellite. It ends in humiliation when the rocket, dubbed “kaputnik”, explodes on the launch pad.

* January 31, 1958: Explorer 1, a US satellite, discovers the Van Allen radiation belts above Earth.

* May 28, 1959: The US sends two monkeys, Able and Baker, into space. They become the first living creatures to successfully return from a trip to space.

* April 12, 1961: The USSR sends the first man into space. Yuri Gagarin makes a single orbit of earth in 108 minutes.

* May 25, 1961: JFK calls for millions of dollars to fund a space programme to get the first man on the moon by 1970.

* February 20, 1962: John Glenn becomes the first American to orbit earth.

* March 18, 1965: Cosmonaut Alexei Leonov carries out the first spacewalk

* July 20, 1969: The first human landing on the Moon by Apollo 11’s Neil Armstrong and Edwin “Buzz” Aldrin.

* April 13, 1970: Apollo 13 is crippled by an explosion leading to the famed expression: “Houston, we’ve had a problem here.” They manage to return safely.

* December 15, 1970: The Soviet Venera 7 makes the first landing on Venus, returning a temperature reading of 470C.

* May 14, 1973: Nasa launches the Skylab space station.

* July 20, 1976: The first of two Viking probes lands on the surface of Mars.

* April 12, 1981: US shuttle Columbia, the first ever re-usable manned spacecraft, takes its maiden voyage.

* January 28, 1986: All seven astronauts on Nasa’s Challenger die when it explodes due to a faulty booster seal.

* September 2, 1993: The basis for an International Space Station is agreed by Russia and the US.

* October 15, 2003: China is third country to launch human into space.

* December 25, 2003: British-built Beagle 2 is lost after scientists fail to receive a signit had landed on Mars.

* January 4, 2004: Spirit, Nasa’s robotic rover, lands on Mars and is joined afterwards by its “twin”, the Opportunity.

* January 14, 2004: President George W Bush announces his Vision for Space Exploration and says he wants Americans back on the Moon by 2020.