- NASA astronomers conducting a monthly sweep of the night sky to identify
previously unknown asteroids and comets will be able to double their coverage
and the number of discoveries they make, thanks to new, state-of-the-art
computer and data analysis hardware.
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- The new equipment was purchased with
funds from NASA, which recently doubled its resources for near-Earth object
research.
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- The new real-time analysis system, which
serves a fully automated charged-couple device (CCD) camera and telescope
atop Mt. Haleakala, Maui, HI, is part of the Near-Earth Asteroid Tracking
(NEAT) project, based at NASA's Jet Propulsion Laboratory, Pasadena, CA.
The new system features four 300- megahertz processors that will be devoted
solely to the enormous amount of data coming back from the NEAT telescope
on a nightly basis.
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- "This new system will speed up the
processing of data and allow us to analyze up to 40 gigabytes of data each
night, or the equivalent of nearly 70 CD-ROMs," said Dr. Steven Pravdo,
NEAT project manager at JPL. "We will be able to double the amount
of sky we search each night, which is currently 500 square degrees, as
well as the number of new asteroids and comets we find during each monthly
observation cycle." Installed in 1995, the NEAT camera uses a very
large, very sensitive 4,096- by 4,096-pixel CCD chip. The camera is located
on a 1-meter-diameter (39-inch) telescope operated by the U.S. Air Force
and located at an elevation of 3,000 meters (nearly 2 miles) above the
Pacific Ocean. With stable climate, clear, dry air and little light pollution,
the NEAT tracking system has been highly successful and continues to operate
six days out of each month. With additional support, the project hopes
to increase this six-day observational run to 18 nights of observations
each month.
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- Asteroids are considered relics of the
formation of the early solar system. Most of them are rocky materials,
with some composed of nickel and iron. Most range in size from boulders
up to the largest main belt asteroid, Ceres, which is approximately 965
kilometers (600 miles) in diameter. Comets, on the other hand, are bodies
of ice with embedded rock and organic materials which heat up and become
active, spewing gases and dust as they approach the Sun.
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- The NEAT telescope detects these small
bodies by observing the same part of the sky three times during an interval
of about one hour and comparing the three images to determine the location
of objects moving across the sky. Since its inception, this fully automated
system has detected more than 25,000 objects, including 30 near-Earth asteroids,
two long-period comets and the unique 1996 PW, which has the most eccentric
orbit of all objects discovered to date. More information about NEAT discoveries,
along with black-and-white images of the objects, is available at <a
href=http://huey.jpl.nasa.gov/~spravdo/neat.htmlhttp://huey.jplnasa.gov/~sprav
d o/neat.html</a.
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- Most recently, the NEAT team has discovered
two new Earth- crossing asteroids. One, designated 1998 HT31, is a relatively
small Apollo-type asteroid 270 meters (800 feet) in diameter; the other,
1998HD14, is the 30th Aten to be discovered since JPL astronomer Eleanor
Helin first identified this class of asteroid 22 years ago, and the fifth
discovered with the NEAT tracking system. Both are classified as potentially
hazardous asteroids because their orbits come within 5 million kilometers
(3 million miles) of Earth, or about 20 times the distance of the Moon.
However, neither currently poses a threat to Earth. "Atens are a
rare class of asteroid because of their small orbits, which are smaller
than that of Earth's, and which never allow them to wander far from our
planet," said Helin, who is the principal investigator of the NEAT
program. "1998 HD14 passed within 5 million kilometers (3 million
miles of Earth) just a week after we discovered it on April 29. This is
relatively close but poses no threat in the foreseeable future. Atens
are of particular interest to us because they stay so close to Earth's
orbit."
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- Along with near-Earth asteroids, astronomers
are also interested in tracking long-period comets, which travel vast distances
from the Oort Cloud, a region far beyond Pluto's orbit, which is believed
to house trillions of incipient comets. These objects travel in very long
paths through the solar system, and can appear unannounced, with no calling
cards.
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- "We are particularly interested
in these comets because they give us little time before appearing in Earth's
vicinity," Helin said.
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- Astronomers dedicated to discovering
and tracking near-Earth objects are eager to find all of the potentially
dangerous asteroids and comets long before they are likely to approach
Earth. For instance, the NEAT team at JPL is developing two new CCD cameras
and hopes to install them at Mt. Haleakala or other facilities.
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- "With additional telescopes, longer
observational runs and our new operating system, we will be able to detect
90 percent of the Earth-crossing asteroids that are larger than 1 kilometer
(6/10ths of a mile) in diameter in the next 10 years," Pravdo said.
"As our knowledge about these objects grows, we will be able to provide
better information which can be used in studies of ways to divert Earth-crossers
on threatening orbits toward Earth."
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- NEAT was built and is being managed by
the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington,
DC. JPL is a division of the California Institute of Technology in Pasadena,
CA.
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