[meteorite-list] Spacecraft Makes Improbable Landing On Asteroid

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 09:41:09 2004
Message-ID: <200102122318.PAA25986_at_zagami.jpl.nasa.gov>

http://www.cnn.com/2001/TECH/space/02/12/near.landing.02/index.html

Spacecraft makes improbable landing on asteroid
By Richard Stenger
CNN.com
February 12, 2001

(CNN) -- A NASA robot ship ended a deep space odyssey by touching down on an
asteroid on Monday, despite having no landing gear.

Shortly after the first landing on an asteroid, excited mission managers
were considering an almost unthinkable encore: coaxing the craft from its
resting spot for another flight.

NEAR engineers should decide within hours after landing whether to command
the resilient robot to fire up its thrusters for a return to space, mission
director Robert Farquhar said.

"I am happy to report that the NEAR has touched down. We are still getting
signals. It is still transmitting from the surface," said Farquhar as NEAR
engineers cheered and clapped their hands.

NEAR's landing was confirmed when mission control received a beacon signal
from the craft resting on the surface of Eros, some 196 million miles from
Earth.

Before colliding with the space rock, the NEAR-Shoemaker spacecraft beamed
back pictures with unprecedented clarity of the asteroid. NASA scientists
hope to see features as small as a human hand when they process the images
in the coming hours and days.

Mission astronomers didn't expect the $225 million orbiter to survive the
impact. It was designed to study, not land, on Eros, an oddly shaped rock
whose appearance has been likened to everything from a potato to a kidney
bean. But somehow against all odds it survived the landing and sent a radio
message back home.

Mission engineers think NEAR-Shoemaker landed on its side on a sunlit
landing site between the South Pole and a distinctive saddle-shaped
depression.

NEAR-Shoemaker began descending toward the asteroid in the morning, drifting
toward its rocky companion and using its thrusters to brake several times
after closing to within 3 miles (5 km) of Eros.

The spacecraft snapped dozens of pictures in its final hour, the closest
only several hundred yards away, NEAR scientists said. It likely smacked
into the surface at about 5 mph (8 km/h), according to NEAR scientists, a
speed similar to that of a parachutist hitting the ground.

Its yearlong mission over, its budget exhausted, its fuel spent,
NEAR-Shoemaker was sent on the deadly dive to gain "bonus science," said
Farquhar.

NEAR scientists have puzzled over strange surface features first spotted in
images in October. They hope the close-ups taken by the spacecraft will help
to answer their questions about the geology of the asteroid more than 196
million miles from Earth.

'Another door has opened'

Some unexplained erosion processes seem to have taken place on Eros,
according to team scientist Joseph Veverka.

"Suddenly we started seeing things we didn't expect and hadn't seen on other
surfaces in the solar system," the Cornell University astronomer said. "It's
like another door has opened."

Already the spacecraft has sent home a bonanza of data about the
composition, gravity and appearance of Eros, which it zapped with 11 million
laser pulses and photographed almost 200,000 times.

The pictures reveal a haunting panorama with fields of craters, mysterious
bright spots and boulders the size of soccer fields. Some have been turned
into dramatic movies of NEAR's close-up view as it swooped near the surface
of the revolving rock.

The data has given scientists clues about the history of the solar system.
Eros is considered a geologic relic from the infancy of the solar system,
which formed about 4.5 billion years ago.

It could also prevent a future catastrophe. The 21-mile-long (34-km) Eros
belongs to a group of large asteroids with orbits relatively close to Earth,
like the one that scientists speculate slammed into Earth and killed off the
dinosaurs 67 million years ago.

Scientists warn that there is a remote risk another such killer asteroid
will someday hit Earth. Learning about Eros could offer them clues to
prevent such a catastrophic collision.

Named after famed astronomer Eugene Shoemaker, a pioneer in lunar and
asteroid studies, NEAR-Shoemaker traveled about 2 billion miles (3.2 billion
km) during a trek that lasted five years.

It was supposed to reach Eros in 1998 but a software glitch sparked a costly
engine misfire that pushed back its arrival time until February 14, 2000.
Eros became only the fifth celestial body touched by a human spacecraft,
following the Moon, Mars, Venus and Jupiter.
Received on Mon 12 Feb 2001 06:18:49 PM PST