7/3/05 Probe heads for comet collision
Probe heads for comet collision
By Paul Rincon
BBC News science reporter
The US Deep Impact spacecraft has launched a projectile into the path of a comet millions of kilometres from Earth to find out what is inside.
The washing machine-sized 372kg (820lbs) "impactor" should smash into Comet Tempel at 0552 GMT on Monday.
By studying the comet's interior, scientists hope to learn more about the formation of the Solar System and the chemical building blocks of life.
Its mission will be short-lived but is certain to be spectacular.
Spacecraft instruments and ground-based telescopes will record the event, as a hole the size of a football stadium is blasted in the comet.
Like any good geologist would, we want to hit it with a hammer and see what's inside
Jessica Sunshine, mission scientist
The cosmic fireworks are scheduled for 4 July - American Independence Day.
Deep Impact, the spacecraft which carries and ejects the impactor will take pictures and gather data from the collision and its aftermath, 133 million kilometres (83 million miles) from Earth.
Comets are porous balls of ice and rock hailing from the frigid outer boundaries of our Solar System. Periodically, some journey inwards, looping around the Sun.
Like other comets, Tempel 1 contains "pristine" material unchanged since the Solar System formed. This is hidden beneath an outer crust.
"These materials have not seen the light of day for 4.6 billion years," mission scientist Jessica Sunshine told reporters at a news conference in Pasadena, California. But scientists still know very little about the composition of this material.
"Like any good geologist would, we want to hit it (Tempel 1) with a hammer and see what's inside," Dr Sunshine added.
The impactor itself will shatter as the comet crashes into it at a relative velocity of 37,000 km/h (23,000 mph), but an onboard camera will record the approach in the last minutes before collision.
Cometary impacts early in Earth history are thought to have first brought water to our planet.
They might also have seeded it with the chemical building blocks required for life. "We want to find out what those materials were," explained Rick Grammier, Deep Impact project manager.
World watches
Mr Grammier likened the mission to "a bullet trying to hit another bullet with a third bullet in the right place at the right time" to watch it. Despite the complexities, team members are confident they will not miss.
Mission manager Dave Spencer said: "We've got good navigation, a good idea of the comet's trajectory and we've been correcting for that all along.
"We're well prepared to position ourselves for this train that's going to run over us." The impact is expected to excavate a crater more than 25m (80ft) deep and 100m (330ft) across, ejecting ice, dust and gas and exposing pristine material.
The Hubble, Chandra, Spitzer and XMM Newton space observatories will be trained on Tempel 1 for the collision, as will ground-based telescopes worldwide.
Deflecting danger
The mission could inform strategies for deflecting a comet, should one threaten to strike Earth in the future.
"If you are worried about defending Earth from possible impactors, it's a whole lot easier to change the course of something if you know what it is you're changing the course of," said Dr Mike A'Hearn, Deep Impact principal investigator.
This week, astronomers got a preview of the pyrotechnics to come when Tempel 1's nucleus released a short-lived blizzard of particles and gas.
These outbursts seem to occur as comets heat up when approaching the Sun.
By Paul Rincon
BBC News science reporter
The US Deep Impact spacecraft has launched a projectile into the path of a comet millions of kilometres from Earth to find out what is inside.
The washing machine-sized 372kg (820lbs) "impactor" should smash into Comet Tempel at 0552 GMT on Monday.
By studying the comet's interior, scientists hope to learn more about the formation of the Solar System and the chemical building blocks of life.
Its mission will be short-lived but is certain to be spectacular.
Spacecraft instruments and ground-based telescopes will record the event, as a hole the size of a football stadium is blasted in the comet.
Like any good geologist would, we want to hit it with a hammer and see what's inside
Jessica Sunshine, mission scientist
The cosmic fireworks are scheduled for 4 July - American Independence Day.
Deep Impact, the spacecraft which carries and ejects the impactor will take pictures and gather data from the collision and its aftermath, 133 million kilometres (83 million miles) from Earth.
Comets are porous balls of ice and rock hailing from the frigid outer boundaries of our Solar System. Periodically, some journey inwards, looping around the Sun.
Like other comets, Tempel 1 contains "pristine" material unchanged since the Solar System formed. This is hidden beneath an outer crust.
"These materials have not seen the light of day for 4.6 billion years," mission scientist Jessica Sunshine told reporters at a news conference in Pasadena, California. But scientists still know very little about the composition of this material.
"Like any good geologist would, we want to hit it (Tempel 1) with a hammer and see what's inside," Dr Sunshine added.
The impactor itself will shatter as the comet crashes into it at a relative velocity of 37,000 km/h (23,000 mph), but an onboard camera will record the approach in the last minutes before collision.
Cometary impacts early in Earth history are thought to have first brought water to our planet.
They might also have seeded it with the chemical building blocks required for life. "We want to find out what those materials were," explained Rick Grammier, Deep Impact project manager.
World watches
Mr Grammier likened the mission to "a bullet trying to hit another bullet with a third bullet in the right place at the right time" to watch it. Despite the complexities, team members are confident they will not miss.
Mission manager Dave Spencer said: "We've got good navigation, a good idea of the comet's trajectory and we've been correcting for that all along.
"We're well prepared to position ourselves for this train that's going to run over us." The impact is expected to excavate a crater more than 25m (80ft) deep and 100m (330ft) across, ejecting ice, dust and gas and exposing pristine material.
The Hubble, Chandra, Spitzer and XMM Newton space observatories will be trained on Tempel 1 for the collision, as will ground-based telescopes worldwide.
Deflecting danger
The mission could inform strategies for deflecting a comet, should one threaten to strike Earth in the future.
"If you are worried about defending Earth from possible impactors, it's a whole lot easier to change the course of something if you know what it is you're changing the course of," said Dr Mike A'Hearn, Deep Impact principal investigator.
This week, astronomers got a preview of the pyrotechnics to come when Tempel 1's nucleus released a short-lived blizzard of particles and gas.
These outbursts seem to occur as comets heat up when approaching the Sun.
posted by Aestrea Raven at Sunday, July 03, 2005
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