US spacecraft to blow up comet for solar system study

A spacecraft of the US National Aeronautics and Space Administration (NASA) steered from the Pasadena-based Jet Propulsion Laboratory (JPL) will attempt to blow up a comet next month to find out more about the origins of the solar system.

The spacecraft, named Deep Impact, will have traveled 173 days and 268 million miles (about 470 million km) when it has close encounter with comet Tempel 1 on July 3.
Deep Impact will release a copper-fortified probe whose job is to make a crater in the orbiting iceberg that could range in size from a large house up to a football stadium from two to 14 storiesdeep.
The idea is to reveal the interior of the comet, which is thought to contain material that has not changed since the solar system was formed.
The potentially spectacular collision will be observed by the Deep Impact spacecraft and ground and space-based observatories.
Rick Grammier, Deep Impact project manager at the Jet Propulsion Laboratory, said the mission is like "a bullet trying to hit a second bullet with a third bullet."
"We are really threading the needle with this one," he said. "In our quest of a great scientific payoff, we are attempting something never done before at speeds and distances that are trulyout of this world."
Tempel 1 is hurtling through space at about 11 km per second --fast enough to travel from New York to Los Angeles in less than 6.5 minutes.
Hours before hitting the comet, Deep Impact will send the 99-cmcubic shaped impactor into the path of the comet, which is about one-half the size of Manhattan Island.
Over the next 22 hours, Deep Impact navigators and mission members, more than 132.8 million km away at the JPL, will steer the impactor and the probe toward the comet.
The impactor will steer into the comet and the flyby craft willpass about 310 miles (about 540 km) below.
Ice and dust debris is expected to be ejected from the crater, revealing the material beneath. The flyby spacecraft has about 13 minutes to take images and scientific measurements of the collision before it encounters a potential blizzard of particles from the nucleus of the comet.
"The last 24 hours of the impactor's life should provide the most spectacular data in the history of cometary science," said Deep Impact's principal investigator, Michael A'Hearn of the University of Maryland.
"With the information we receive after the impact, it will be awhole new ball game," he said. "We know so little about the structure of cometary nuclei that almost every moment we expect tolearn something new."
The Deep Impact spacecraft has four data collectors to observe the effects of the collision.
Also, "the impact simply will not appreciably modify the comet's orbital path," Don Yeomans, a Deep Impact mission scientist at the JPL, said, "Comet Tempel 1 poses no threat to Earth now or in the foreseeable future.''
Mission scientists expect the project will answer basic questions about the formation of the solar system by offering a better look at the nature and composition of the frozen celestial travelers called comets