Johns Hopkins Gazette: February 12, 1996

APL Awaits Launch Spacecraft To Fly Near Asteroid

Steve Libowitz

     It is said that a voyage of a thousand miles begins with one
step. Such is the case for the Near Earth Asteroid Rendezvous
spacecraft, the Applied Physics Laboratory-designed and -built
orbiter, which is scheduled on Friday to begin its 1.3 billion
mile journey to asteroid 433 Eros. It is expected to reach its
destination in early 1999.

     The NEAR spacecraft--the first asteroid orbiter of the space
age--will be the initial launch in NASA's Discovery program for
"faster, better, cheaper" planetary exploration. 

     NEAR is also the first spacecraft to orbit an asteroid,
chunky pieces of rock--sometimes hundreds of miles wide--that
litter space generally along a belt between Mars and Jupiter.
They are interesting enough to study as remnants from the
creation of the solar system. But they also are quite
unpredictable, often leaving their orbit and crashing into

     In some cases, these cosmic collisions demolish the planet
hit or create havoc upon them. Smaller asteroid assaults created
craters on Earth. It is theorized that such a collision was
responsible for setting into motion the environmental crisis that
led to the extinction of the dinosaurs 65 million years ago.
Today, some asteroids pass dangerously close to Earth. NEAR's
target is one of them.

     The 25-mile-long Eros asteroid--the smallest solar system
body to be orbited by a spacecraft--is one of a type that exists
relatively near Earth. Asteroids such as Eros are thought to be
dead comets or fragments from Main Belt asteroids, which orbit
the sun. Approximately 250 near-Earth asteroids are known, and
scientists estimate that there are at least 1,000 with diameters
of 0.6 mile or more. Some scientists predict that Eros may one
day cross Earth's path. So astronomers and physicists want to get
a better look at it in hopes of being able to better predict its
future course as well as to better understand the origins and
makeup of the universe.

     The mission's scientific goal is to determine Eros' size,
shape, mass and magnetic field and to measure--for the first
time--an asteroid's detailed composition and surface structure.
NEAR may provide scientific clues to long-standing scientific
mysteries, such as the origin of meteorites and the relationship
between asteroids, meteorites and comets.

     As a bonus during its 35-month journey to Eros, NEAR could
pass within 750 miles of the large Main Belt asteroid 253
Mathilde. The flyby of Mathilde is tentatively scheduled for June
27, 1997. In addition, the spacecraft returns to Earth's vicinity
for a slingshot gravity assist on Jan. 22, 1998, a maneuver that
bends the NEAR trajectory 11 degrees out of the ecliptic  to
match Eros' orbital plane.

     The spacecraft makes its initial closest approach to the
asteroid before it glides into orbit at approximately 310 miles
on Feb. 6, 1999. During the yearlong rendezvous, NEAR will probe
the asteroid at altitudes as low as 9 miles.

         APL is the first space center outside NASA to conduct a
planetary mission. Although the NEAR mission will be managed by
NASA from its headquarters in Washington, APL will direct mission
and science operations from its Rockville campus. 

        The project marks a new way NASA will be doing business
in an era of tightened purses. The Jupiter-bound Galileo mission
cost the federal government $1.6 billion when it was launched six
years ago. The Discovery mission guidelines called for a
development ceiling of $150 million in fiscal year '92. APL built
the NEAR spacecraft for less than $112 million (in fiscal year
'92 dollars) and completed it in less than the three years
allowed by NASA.

     "This is a revolution," NASA associate administrator for
space science Wesley T. Huntress Jr. told The New York Times.
"It's a whole new way of doing business."

     "We took a planetary mission and did it better, faster and
cheaper," APL's Stamatios M. Krimigis told the Times.

     NEAR's instrument package includes an X-ray/gamma ray
spectrometer, near-infrared spectrograph, laser rangefinder,
magnetometer, radio science experiment and a multispectral imager
fitted with a CCD imaging detector capable of photographing
details on Eros' surface as small as 3 feet. Several of the
instruments are derived from designs developed by JHU/ APL for
Department of Defense spacecraft, an example of dual-use
technology transferred to the civilian sector.

NEAR on the Net

     You can follow the progress of the NEAR mission by turning
to the following homepages on the World Wide Web:


JHU/APL Space Department,



NASA Headquarters Discovery Program,

NSSDC Asteroid,

NSSDC Asteroid factsheet,

NASA/Ames Asteroid and Comet Impact Hazard,

     The Near Earth Asteroid Rendezvous launch is scheduled for
Friday, Feb. 16, at 3:53 p.m. EST. For up-to-date information
about the launch, call (407)867-2314.

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