- The NEAR (Near Earth Asteroid Rendezvous)
spacecraft is about to make interplanetary history. On Jan. 10, 1999, after
traveling more than a billion and a half miles, it will reach asteroid
433 Eros and embark on the first close-up and comprehensive study of an
asteroid. The NEAR mission, the first launch in NASA's Discovery program,
is being managed by The Johns Hopkins University Applied Physics Laboratory
(APL), in Laurel, Md., which also built the spacecraft.
-
- "What we now know about asteroids
is very limited," says NEAR Mission Manager Dr. Robert W. Farquhar
of APL. "It's come from ground-based observations and quick flybys.
But now, for the first time, we're going to go into orbit around an asteroid
and study it intensely for a year. We expect to get astounding information."
-
- During its year-long mission to unlock
the secrets of asteroid Eros, NEAR will confront the challenge of orbiting
a tumbling, irregularly shaped body from extremely close distances. Never
before has any small body been orbited by a spacecraft, but the additional
task of maneuvering a spacecraft within 9 miles (15 kilometers) of the
asteroid's surface makes the engineering challenge even more complex.
-
- A cluster of six instruments will take
millions of measurements and images over the entire surface of Eros from
various altitudes. From these data, scientists will determine the asteroid's
physical and geological properties and its elemental and mineralogical
composition.
-
- NEAR's rendezvous with Eros requires
that the spacecraft be sped up with a series of engine burns so that it
can catch up with the faster-moving asteroid. At 5 p.m. (EST) on Dec. 20,
1998, when NEAR is nearly 150,000 miles (242,000 kilometers) from Eros,
a bi-propellant rocket engine firing (or "burn") will increase
the spacecraft's speed by 1,500 mph (650 meters per second).
-
- On Dec. 28, a second burn will increase
NEAR's speed by 680 mph (294 meters per second) while at a distance of
13,000 miles (21,000 kilometers) from Eros, reducing the spacecraft's speed
relative to Eros to less than 70 mph (30 meters per second). On Jan. 3,
1999, a third burn will reduce the relative speed a further 50 mph (22
meters per second) at a distance of 3,000 miles (5,000 kilometers). At
10 a.m., on Jan. 10, 1999, NEAR is scheduled to lock into orbit around
Eros with a final burn reducing relative speed to 19 mph (8 meters per
second) at a distance of about 630 miles (1,000 kilometers).
-
- For the next year NASA's Deep Space Network
will transmit data from the spacecraft to NEAR's Science Data Center, at
the Applied Physics Laboratory, and commands from the Laboratory's Mission
Operations Center back to the spacecraft. Regular tweaking of the spacecraft's
orbit will be needed to ensure that spacecraft instruments are used to
their full advantage.
-
- Dr. Joseph Veverka of Cornell University,
Science Team Leader for the mission, says the challenges that face the
NEAR mission are significant. "This will be the first characterization
in detail, not only of the surface of an asteroid, but of the interior
of the asteroid, and the history that this asteroid has gone through based
on its surface characteristics and materials composition."
-
- The NEAR spacecraft was launched Feb.
17, 1996. Its flyby of asteroid Mathilde on June 27, 1997, provided the
program's first science return. By mission's end, Feb. 6, 2000, scientists
expect to know much more about Eros and thus near-Earth asteroids in general.
From this, they hope to gain insight into the Earth's origin and the formation
of the solar system.
-
- To follow the NEAR mission as it unfolds,
visit the mission's Web site: <http://near.jhuapl.eduhttp://near.jhuapl.edu
-
- Updates of mission activities and science
returns will be posted on the Web site and provided to media through press
conferences and briefings. The following conferences and briefings are
currently scheduled:
-
- * Dec. 16, 1998, 1 p.m. EST, NASA headquarters,
Washington, D.C., live over NASA TV.
-
- * Jan. 10, 1999, noon EST, JHU/APL, Laurel,
Md., live over NASA TV.
-
- * Jan. 14, 1999, 1 p.m. EST, JHU/APL,
Laurel, Md., live over NASA TV.
-
- For directions to the APL campus and
information on hotel accommodations, visit Web site: <http://near.jhuapl.edu/public/visit/locat.htmhttp://near.jhuapl.edu/public/vis
it/locat.htm
-
- APL is located on Johns Hopkins Road,
0.5 mile west of the intersection of Johns Hopkins Road and U.S. Route
29, just south of Columbia, Md.
"The point here is, people, space flight is still a 'raw' technology
- fraught with danger. And for those that
are really involved with the
- wonders in space, it is not for the
meek of heart, or the reckless and it
- is not subject to mumbo jumbo stuff.
Perhps then, on all the myriad of
- 'space' related web sites out there,
a little praise of NASA is in order."
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