[meteorite-list] NEAR Shoemaker Primed for Final Weeks in Orbit
From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 09:41:58 2004
10 January 2001
NEAR Shoemaker Primed for Final Weeks in Orbit
Low Flyovers Lead to Feb. 12 Controlled Descent
The NEAR Shoemaker spacecraft - the first to orbit an asteroid - embarks on
a series of low-altitude passes over 433 Eros this month in a prelude to its
daring February descent to the surface of the rotating, 21-mile-long space
The orbit segment of NASA's Near Earth Asteroid Rendezvous (NEAR) mission
wraps up Feb. 12 with NEAR Shoemaker's controlled descent to Eros, a tricky
maneuver that will allow the craft's digital camera to snap close-ups of the
asteroid's cratered, boulder-strewn landscape. But the weeks before the
historic event won't be much easier, as NEAR mission operators and
navigators take the spacecraft on several low passes over the ends of the
potato-shaped Eros from Jan. 24-28.
"NEAR Shoemaker is nearly out of fuel, and by the end of January it will
have completed its scientific objectives at Eros," says Dr. Robert W.
Farquhar, NEAR Mission Director at The Johns Hopkins University Applied
Physics Laboratory in Laurel, Md. "The maneuvers are kind of risky, but we
want to end the mission getting a lot of bonus science - with images better
than we've ever taken."
On Jan. 24, NEAR Shoemaker will dip from its current 22-mile (35-kilometer)
circular orbit to begin a four-day series of flyovers. The spacecraft will
complete five to six passes, each within about 3 to 4 miles (5 to 6
kilometers) of the surface. In the early hours of Jan. 28 the spacecraft
will zip between 1 to 2 miles (2 to 3 kilometers) over the surface - closer
than it has ever come before.
"The flyovers will give us a detailed look at the surface, much like we saw
when the spacecraft came within 3 miles of Eros during the first low flyover
in October," says NEAR Project Scientist Dr. Andrew F. Cheng, of the Applied
Physics Laboratory. "This time we're going over different areas, so we can
find out if the small-scale geological features we saw in the earlier images
are typical of the surface."
The spacecraft will swing out from that low pass back to a 22-mile orbit,
where it will stay until the controlled descent. Mission designers are
working out the final details of the descent, but they plan to slow the
craft's fall with several intermittent engine burns.
NEAR Shoemaker's telescopic camera will gather high-resolution images during
the last 3 miles of the maneuver, until about 1,650 feet (500 meters) above
the asteroid. Before touching down near Eros' distinctive "saddle"
depression, NEAR Shoemaker could deliver images showing features as small as
4 inches (10 centimeters) across.
"NEAR Shoemaker was never designed to land, so that's not the main goal of
the controlled descent," Farquhar says. "The definition of success here is
getting the close-up images. We're not optimizing this maneuver to ensure
the spacecraft survives this event."
The first launch in NASA's Discovery Program of low-cost planetary missions,
NEAR Shoemaker has been in orbit around Eros since Feb. 14, 2000, conducting
the first in-depth study of an asteroid. The Applied Physics Laboratory
designed and built the spacecraft and manages the NEAR mission for NASA. The
NEAR team also includes NASA's Jet Propulsion Laboratory; Cornell
University; Massachusetts Institute of Technology; University of Maryland;
University of Arizona; NASA's Goddard Space Flight Center; Southwest
Research Institute; Northwestern University; Space Environment Center; Solar
Data Analysis Center; Malin Space Science Systems, Inc.; University of
California, Los Angeles; Catholic University; Max Planck Institute for
Chemistry; and Computer Sciences Corp.
For the latest news and images visit the NEAR Web site at (near.jhuapl.edu).
JHU Applied Physics Laboratory:
Michael Buckley Helen Worth
Laurel, MD 20723 Laurel, MD 20723
Phone: 240-228-7536 Phone: 240-228-5113
Received on Wed 10 Jan 2001 10:08:09 PM PST