NASA set for spacecraft’s up-close study of comet
The Deep Impact spacecraft will pass within 700km of comet Hartley 2 at a speed of 43,000km per hour on Thursday.
According to NASA, the comet will be travelling at a rate of 7.8 miles per second when the spacecraft makes its closest approach.
Its mission, dubbed Epoxi, is to take high resolution images of the comet’s nucleus using two telescopes with digital and an infrared spectrometer.
Scientists have captured close images of four other comets, but never one with such a small nucleus, and hope Hartley 2 will provide new details about the composition of comets and the formation of the solar system.
Australian Malcolm Hartley, who discovered the comet in 1986, will watch the fly-by at NASA’s Jet Propulsion Laboratory in California. Hartley 2 was the second of 10 comets Mr Hartley, of the Australian Astronomical Observatory near Coonabarabran, discovered by scrutinising photos of the night sky.
“Once you find one, you want to find more. It is kind of compulsive,” he said before leaving for the US.
Deep Impact is being reassigned after delivering a probe to crash into the comet Tempel 1 in 2005, in the first such look at the inner material of a comet. The mother ship, however, remained in good condition, and NASA decided to reuse the spacecraft for a look at another comet.
Hartley 2 is much smaller – with a nucleus that is about a kilometre wide – and more visible from Earth than Tempel 1, providing scientists with a chance to compare the celestial objects. They also hope to learn about jets of material emitted by comets.
The orbiting bodies of ice, dust and gas are considered key to learning about the formation of the solar system, because they are believed to be leftover building blocks of the early solar system that may have brought water and other organic compounds to Earth.
The craft will send back 64,000 pictures with its camera, which is fine tuned enough to “distinguish between a car and a pickup truck” from 640 kilometres away, said Amy Walsh, lead engineer of the mission.
“There are billions of comets in the solar system, but this will be only the fifth time a spacecraft has flown close enough to one to snap pictures of its nucleus,” mission science team member Lori Feaga, of the University of Maryland, said. “This one should put on quite a show.”
Meanwhile, NASA has cleared space shuttle Discovery for its final flight.
Mission managers gathered at Kennedy Space Centre in Florida yesterday morning for the traditional flight review. They voted unanimously to press toward a liftoff tomorrow.
This will be Discovery’s grand finale. NASA is close to wrapping up its shuttle programme. Only one other mission remains on the official lineup, by the shuttle, Endeavour.
Discovery and its crew of six will head to the International Space Station with equipment, including a humanoid robot.
