NEAR Space Probe Lands on Asteroid Eros
Monday February 12 3:49 PM ET
LAUREL, Md. (Reuters) - Space probe NEAR Shoemaker set down
on asteroid Eros on Monday, the first time in history that
any craft has landed on this kind of space rock.
Against tremendous odds, the craft kept sending signals even
after it touched down on the cosmic object, 196 million miles
from Earth.
``I'm happy to report that the NEAR spacecraft has touched down on the surface of
Eros,'' a jubilant mission director, Robert Farquhar, announced from the control room
in Laurel, outside Washington.
``We are still getting some signals, so evidently it's still transmitting from the surface
itself,'' Farquhar said. ``The pictures are still coming in. This is the first time that any
spacecraft has landed on a small body.''
Farquhar and other scientists had given the craft less than a 1 percent chance of
being able to send signals back to Earth, after it reached the asteroid's
boulder-strewn surface.
The landing -- some NASA (news - web sites) officials dubbed it a controlled crash --
took place almost exactly on schedule shortly after 3 p.m. EST But it will take years for
astronomers to analyze all the data provided by this bus-sized $223 million robotic
craft.
NEAR was never meant to land -- it orbited the 21-mile-long asteroid for a year, taking
some 160,000 images and beaming them back to Earth -- but it was at the end of its
expected life and had satisfied all its objectives, so Farquhar and others decided a
landing attempt could provide some ``bonus science.''
To get the solar-powered ship out of its 21-mile-high orbit, thrusters were fired
around 10:31 a.m. EST to send it toward the asteroid. Four subsequent braking
burns aimed to slow the craft to a soft landing.
The braking burns were to bring NEAR to a speed ranging from 2 to 7 mph -- or as
slow as about 1 yard per second. The asteroid rotates faster than that, and because
there are boulders, hills and valleys on the Erosian surface, it was possible that the
asteroid could slam into the spacecraft before it had completely descended.
Because it takes 17.5 minutes for light to travel from the craft to Earth, scientists had
little information at the time of touchdown, except that the craft was still functioning.
Ed Weiler, the head of space science at NASA, hesitated to even call the event a
landing; without landing gear on the craft, he maintained, NEAR could only end in a
controlled crash.
``We cannot measure NEAR's success by whether we hear it or not after it lands,
because we do not expect to hear it,'' Weiler said in a conversation with reporters. The
most scientists should hope for is a faint signal that the craft is still ``alive,'' Weiler
said, and even this was highly unlikely.
The spacecraft's camera was to go out of focus at about 100 to 500 yards, Weiler
said, but even so, its last pictures were expected to have a resolution of about 4
inches.
Weiler was basking in the success of the mission, which he said would give space
voyagers practice for future landings on asteroids and even on comets. Asteroids and
comets are primordial bodies that could give clues to the very beginning of the solar
system.
NEAR Shoemaker -- short for Near Earth Asteroid Rendezvous
and in honor of the late astronomer Gene Shoemaker -- could
have been flattened on impact if maneuvers went awry. But
even if that had occurred, the mission had accomplished its
objectives of getting a close look at Eros.
It took NEAR about four years to travel a 2 billion-mile, looping
route to Eros, named for the Greek god of love. At a cost of
$223 million, the mission is considered a model for the cheaper,
faster space flights envisioned by NASA.
The National Aeronautics and Space Administration rated the mission
a success for the data it collected about Eros, a so-called
near-Earth asteroid that has the potential to collide with
the planet in 1.5 million years or so.
If Eros ever did hit Earth, the results would be catastrophic;
indeed, a much smaller space rock is thought to have been
responsible for wiping out the dinosaurs 65 million years ago.
Astronomers are also interested in the composition of this
rock because it is probably a remnant from the formation of
the rocky inner planets of our solar system some 4.5 billion
years ago.
It looks like those 5 MPH bumpers held up well!
o~~~ O |
