Deep Space 1鈥檚 fly-by of comet Borrelly on Saturday gave researchers a detailed glimpse of the rocky comet鈥檚 core, and yielded a surprising discovery: the comet is lopsided.
Comets consist of an ice and rock centre called the nucleus surrounded by a cloud of dust and gas. But researchers analysing the cloud of energetic ions surrounding the comet found that the nucleus is off-centre.
鈥淚t is in the wrong place and we have to figure out why,鈥� said Donald Yeomans, manager of NASA鈥檚 Near Earth Objects program at the Jet Propulsion Laboratory in Pasadena, California.
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Although Deep Space 1 was designed for testing a new ion engine, not comet-hunting, NASA decided to try to get squeeze some extra value out of the ageing spacecraft. The four-year old spacecraft flew within 2,000 kilometres of comet Borrelly.
Bowling pin
Deep Space 1鈥檚 snapshots of comet Borrelly, released on Tuesday, show a nucleus that looks like a giant bowling pin, eight kilometres long, with a mottled surface. The white areas indicate narrow jets of gas and dust that are spewing from holes in the surface.
快猫短视频s believe that when the Sun heats the comet, internal gases expand and shoot out a hot beam of gas and dust. It may be these jets that are causing the ion cloud to skew to one side.
In the coming weeks, the researchers will learn more about the nucleus鈥檚 composition from data gathered by an infra-red spectrometer.
Space oasis
This is only the second close examination of a comet: the first was of Halley鈥檚 comet in 1986. The two comets also belong to different classes. Halley鈥檚 comet is thought to have originated at the far outer edge of the solar system, while comet Borrelly comes from the closer-in Kuiper Belt.
Studying the composition of these comets can tell scientists more about how the solar system formed, and may help determine if precursors of life such as organic molecules hitchhiked to Earth on a comet.
But there is another reason to study comets, says Yeomans. Comets contain about 50 per cent water, a potential oasis in space. 鈥淐omets could be the watering holes and fuelling stations for interplanetary colonisation,鈥� he says.