http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2005/01/10/nspace10.xml

Spacecraft counts down to blast-off and a close encounter with a comet
(Filed: 10/01/2005)

Explosion will cause a fireworks display visible from Earth and give clues to
origin of life, reports Nic Fleming

A spacecraft is to be launched this week on a spectacular mission to blow a
chunk the size of Rome's Coliseum out of a comet.

The Deep Impact probe's 80 million-mile journey will end in a 23,000mph
collision creating a celestial firework display visible from Earth with
binoculars on July 4, American Independence Day.

Its dramatic encounter with the Tempel 1 comet, creating an explosion
equivalent to igniting 4.5 tons of TNT, will release a shower of debris that
astronomers hope will provide clues to the origins of the solar system and
possibly to life on Earth.

The spacecraft and impactor probe will lift off from Cape Canaveral in Florida
on Wednesday.

Comets are essentially enormous, dirty snowballs from the outer solar system
made up of a nucleus of ice and embedded dust and a surrounding "coma" of gas
and debris.

Some scientists believe comets could have brought material to Earth that
provided the raw chemical materials that kick-started life.

Dr Simon Green, a senior lecturer at the Open University's Planetary and Space
Science Research Institute, said: "If we can study the inside of a comet where
the ices are untouched by the Sun you can learn about the conditions that
prevailed in the outer solar system at the time the solar system and Earth were
formed 4.5 billion years ago.

"We also want to understand the structure of comets, how dense and how porous
they are.

"Comets may be the original source of material that provided the raw materials
for life on Earth. It's a controversial theory that used to be seen as wacky
but is now being taken increasingly seriously."

The 3ft by 3ft copper-fortified probe will be released from the Deep Impact
craft 24 hours before its rendezvous with Tempel 1. It is expected to blast a
hole in the comet the equivalent of seven storeys deep.

The spacecraft is named after the 1998 Hollywood film Deep Impact, about a
comet on collision course with Earth.

One of the project's aims is to find out more about the structure of comets so
that scientists would know how to deflect one found to be heading towards
Earth.

However, Nasa stresses that there is no risk of the comet being diverted on to
a collision course with Earth as its orbit brings it no closer than 50 million
miles away and the impact will not change this by more than 330ft.

Don Yeomans, a Deep Impact mission scientist at Nasa's jet propulsion
laboratory in Pasadena, California, said: "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."

Images of the July 4 event will be beamed back to Earth by the Deep Impact
mother ship. The Hubble, Chandra and Spitzer space telescopes will also be
watching and thousands of professional and amateur astronomers are hoping to
observe it.

The project will also gather data that will inform similar future missions such
as the European Space Agency's Rosetta programme, which hopes to land a craft
on a comet in 2012 and transmit information back to Earth about material it
finds there.

http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2005/01/10/nspace10.xml

Spacecraft counts down to blast-off and a close encounter with a comet
(Filed: 10/01/2005)

Explosion will cause a fireworks display visible from Earth and give clues to
origin of life, reports Nic Fleming

A spacecraft is to be launched this week on a spectacular mission to blow a
chunk the size of Rome's Coliseum out of a comet.

The Deep Impact probe's 80 million-mile journey will end in a 23,000mph
collision creating a celestial firework display visible from Earth with
binoculars on July 4, American Independence Day.

Its dramatic encounter with the Tempel 1 comet, creating an explosion
equivalent to igniting 4.5 tons of TNT, will release a shower of debris that
astronomers hope will provide clues to the origins of the solar system and
possibly to life on Earth.

The spacecraft and impactor probe will lift off from Cape Canaveral in Florida
on Wednesday.

Comets are essentially enormous, dirty snowballs from the outer solar system
made up of a nucleus of ice and embedded dust and a surrounding "coma" of gas
and debris.

Some scientists believe comets could have brought material to Earth that
provided the raw chemical materials that kick-started life.

Dr Simon Green, a senior lecturer at the Open University's Planetary and Space
Science Research Institute, said: "If we can study the inside of a comet where
the ices are untouched by the Sun you can learn about the conditions that
prevailed in the outer solar system at the time the solar system and Earth were
formed 4.5 billion years ago.

"We also want to understand the structure of comets, how dense and how porous
they are.

"Comets may be the original source of material that provided the raw materials
for life on Earth. It's a controversial theory that used to be seen as wacky
but is now being taken increasingly seriously."

The 3ft by 3ft copper-fortified probe will be released from the Deep Impact
craft 24 hours before its rendezvous with Tempel 1. It is expected to blast a
hole in the comet the equivalent of seven storeys deep.

The spacecraft is named after the 1998 Hollywood film Deep Impact, about a
comet on collision course with Earth.

One of the project's aims is to find out more about the structure of comets so
that scientists would know how to deflect one found to be heading towards
Earth.

However, Nasa stresses that there is no risk of the comet being diverted on to
a collision course with Earth as its orbit brings it no closer than 50 million
miles away and the impact will not change this by more than 330ft.

Don Yeomans, a Deep Impact mission scientist at Nasa's jet propulsion
laboratory in Pasadena, California, said: "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."

Images of the July 4 event will be beamed back to Earth by the Deep Impact
mother ship. The Hubble, Chandra and Spitzer space telescopes will also be
watching and thousands of professional and amateur astronomers are hoping to
observe it.

The project will also gather data that will inform similar future missions such
as the European Space Agency's Rosetta programme, which hopes to land a craft
on a comet in 2012 and transmit information back to Earth about material it
finds there.