PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov
Contact: Diane Ainsworth
FOR IMMEDIATE RELEASE
April 24, 1996
LATEST SENSORS BRING NEW ASTEROIDS AND A COMET INTO FOCUS
Operating a newly installed electronic camera pointed at
the night sky from atop Maui's Haleakala volcano, NASA
astronomers have discovered four new Earth-crossing asteroids and
a fast-moving comet just months after initiating a new near-Earth
asteroid and comet discovery program.
The camera -- called NEAT for Near-Earth Asteroid Tracking
system -- enabled astronomers at NASA's Jet Propulsion Laboratory
to make their first discovery of a new long-period comet on March
15, the first night of the monthly observing program. The comet
was officially designated 1996 E1, after confirmation was
received from observers in Maui, Australia, Japan, the Czech
Republic and Camarillo, Calif.
"The relatively bright, magnitude 16 comet was discovered in
the constellation of Cancer," said Dr. Eleanor Helin, principal
investigator of the NEAT camera team at JPL. "It was diffuse,
with strong central condensation, sporting a 15-arcsecond tail.
Its closest approach to Earth, at about 30 million miles,
occurred at the end of March."
The comet, which has a parabolic orbit highly inclined to
the ecliptic plane, is on a long journey through the Solar
System. Named NEAT 1, the long-period comet was discovered
automatically by NEAT's software and was sighted, coincidentally,
on the Ides of March, "a most auspicious beginning for a
discovery program," Helin added.
Four unusual Earth-crossing asteroids were also discovered
using NEAT, which is the world's first autonomous imaging system.
These near-Earth asteroids have been designated 1996 EN, 1996 EO,
1996 FR3 and 1996 FQ3.
"All are noteworthy for different reasons," Helin said.
"1996 EN is a large, 3-kilometer-diameter (2-mile-diameter)
asteroid which moves in a very elliptical orbit and displays a
high inclination of 39 degrees relative to the ecliptic plane.
As a result of its brightness at magnitude 15.5, and its
placement with respect to Earth, it will be accessible for
observations through the end of the year."
Of the other Earth-crossers, 1996 EO has a diameter of about
1 kilometer (0.62 mile). It is not on a collision course with
Earth, but asteroids of this size and larger have been identified
by the scientific community as sufficient to cause severe damage
over a large area of Earth should one impact the planet, Helin
noted.
1996 FR3 is significant because it moves in a long
elliptical orbit extending well inside the orbit of Venus, making
it one of only a handful of asteroids that passes so close to the
Sun. Astronomers speculate that this object may be an extinct
comet, having passed close to the Sun enough times to have lost
its gaseous atmosphere.
1996 FQ3 is a small near-Earth asteroid about 100 meters
(328 feet) in diameter with an absolute magnitude of 21. Although
small, Helin believes this asteroid may prove to be a possible
candidate for a future spacecraft fly-by mission, given its very
low inclination of 1 degree relative to the ecliptic plane.
Discovery of the four new Earth-crossing asteroids
represented half of all the Earth-crossing asteroids discovered
worldwide during the month of March. Two of the discoveries --
1996 EN and 1996 FR3 -- are classified as "potentially hazardous
asteroids," being capable of coming exceedingly close to the
Earth.
"These discoveries certainly suggest that we could face a
surprise encounter with a large, unseen object," Helin said. "If
these newly discovered Earth-crossing asteroids have not been
seen before, then there is strong evidence that many others are
near the vicinity of Earth and the inner planets, which NEAT and
other programs are designed to discover."
March was the first "good weather" month for NEAT
astronomers since the new electronic camera came on-line in
December 1995, said Dr. Steven Pravdo, manager of the project at
JPL. The March observing run alone produced more than 1,000
asteroid sightings, including high-inclination inner-belt
asteroids and a number of potential Mars-crossers. Total
detections since NEAT went on-line in December 1995 have climbed
to more than 2,400 objects, of which about 45 percent are known
objects and more than 200 to date are new discoveries receiving
new designations.
When the camera is upgraded later this month to use a very
large 4,096 by 4,096-pixel charge-coupled device (CCD),
astronomers expect to detect four times the number of comets and
asteroids currently being observed.
Developed at the Jet Propulsion Laboratory, the NEAT system
and its operation mark the beginning of a new observing program
that will be focused on discovering and tracking asteroids and
comets -- fleeting chunks of rock and ice -- as they enter the
inner solar system from deep space. The autonomous imaging system
contains a sophisticated computer controller and a highly
sensitive CCD camera sensor.
"NEAT is next-generation technology that will significantly
improve our capabilities to detect near-Earth objects," Pravdo
said.
The NEAT camera is installed on a 1-meter (39-inch)
telescope operated at the summit of Mt. Haleakala by the U.S. Air
Force, Pravdo said. With its short exposure time and fast
electronics, NEAT is able to achieve wide-sky coverage and detect
objects much fainter than was possible using the photographic
Schmidt telescope at Palomar Observatory in Southern California.
Systematic searches for asteroids and comets destined to
cross Earth's orbit have been the topic of renewed interest in
recent years, especially in the aftermath of Comet Shoemaker
Levy-9 and the recent arrival of Comet Hyakutake. Today charge-
coupled devices -- light detectors made of silicon -- are
emerging as a favored approach to asteroid detection because CCD
sensors can record light 100 times more efficiently than the most
sensitive photographic film.
NEAT was built and will be managed jointly by the Jet
Propulsion Laboratory and the U.S. Air Force. JPL will manage its
portion of the program for NASA's Office of
Space Science, Washington, D.C.
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