PLEASE NOTE:


*

CCNet 25/2001 - 13 February 2001: NEAR-SHOEMAKER SPECIAL III
------------------------------------------------------------


"I am happy to report that the NEAR has touched down. We are still
getting signals. It is still transmitting from the surface."
--Robert Farquhar, NEAR Mission Director, 12 February 2001


"Engineers at APL are looking at the prospects for relaunching the
NEAR Shoemaker spacecraft from the surface of asteroid Eros. A command is
already built into the probe as it rests upon the space rock's
surface. The liftoff from the asteroid is on tap for this Wednesday,
roughly 2:00 p.m. Eastern time, according to David Dunham, NEAR's mission
designer at APL. The launch from Eros would be after nine rotations of the
asteroid following today's NEAR Shoemaker landing, Dunham said."
--Leonard David, Space.com, 12 February 2001



(1) MISSION TEAM CONSIDER RELAUNCHING NEAR SHOEMAKER FROM EROS
    Space.com, 12 February 2001

(2) NEAR SHOEMAKER MAKES HISTORIC TOUCHDOWN ON ASTEROID EROS
    Ron Baalke <baalke@jpl.nasa.gov>

(3) AMERICAN CRAFT LANDS ON ASTEROID
    Spaceprogramme News, 13 February 2001

(4) NEAR SHOEMAKER SURVIVES ASTEROID LANDING
    Spaceflight Now <newsalert@spaceflightnow.com]

(5) SPACECRAFT MAKES IMPROBABLE LANDING ON ASTEROID
    CNN, 12 February 2001

(6) METEORITES HARDER TO TRACE THAN FAMILY TREES
    Ron Baalke <baalke@jpl.nasa.gov>

(7) CATASTOPHE/APOCALYPSE COURSE AT BARD COLLEGE
    Benny J Peiser <b.j.peiser@livjm.ac.uk>

(8) NEO DEFLECTION BY NEO COLLISION/FLY-BY
    Christian Gritzner <christian.gritzner@mailbox.tu-dresden.de>

=============
(1) MISSION TEAM CONSIDER RELAUNCHING NEAR SHOEMAKER FROM EROS

From Space.com, 12 February 2001
http://www.space.com/missionlaunches/missions/nearlanding_preview_010212.html

By Leonard David
Senior Space Writer

LAUREL, MARYLAND - What goes down, may come back up again.

Engineers at APL are looking at the prospects for relaunching the NEAR
Shoemaker spacecraft from the surface of asteroid Eros. A command is already
built into the probe as it rests upon the space rock's surface.

The liftoff from the asteroid is on tap for this Wednesday, roughly 2:00
p.m. Eastern time, according to David Dunham, NEAR's mission designer at
APL.

The launch from Eros would be after nine rotations of the asteroid following
today's NEAR Shoemaker landing, Dunham said.

"Since we've got a lock on the signal, it's got to be pretty much in the
right position" for the liftoff, said Dunham.

Dunham said the probe may rise upwards well over 1,300 feet (400 meters)
above Eros. "It could sit in the dirt and wiggle a little bit before
liftoff. These are weaker thrusters on the spacecraft," he said.

Some thought has been given to sequencing a double boost of thrust from the
asteroid, hurtling it perhaps as high as a kilometer above the asteroid.

Dunham said that if the camera has not been damaged in the first landing,
more images above the asteroid could be taken. However, pictures of the
first landing spot on Eros are not likely to come into view, he said.

The spacecraft would then settle down to a new landing spot.

"The whole thing is just more icing on the cake," Dunham said.

The NASA probe had already happily surprised scientists earlier today, when
it made space history with a successful landing atop an asteroid more than
196 million miles (316 million kilometers) from Earth.

"I'm happy to report the near spacecraft has touched down on the surface of
Eros. We're still getting some signals, so evidently it's still transmitting
from the surface itself. This is the first time that any spacecraft has
landed on a small body," said Robert Farquhar, NEAR mission director at The
Johns Hopkins University Applied Physics (APL) Laboratory in Laurel,
Maryland.

NASA Administrator Dan Goldin was among the first to congratulate the team.

"I'm just overwhelmed with the courage and talent it took to get to this
point," Goldin said shortly after the landing.

The car-sized NEAR Shoemaker probe has been orbiting Eros since February 14,
2000. Since it began looping the tumbling space rock almost a year ago -- at
a range of high and low-altitudes over Eros -- the craft has amassed an
asteroid photo gallery made up of 150,000 snapshots.

Touchdown took place shortly after 3:05 p.m. Eastern time. The spacecraft
fell onto the dust-laden, cratered, and rock-piled surface of Eros. While
the vehicle is a fully equipped science spacecraft, NEAR Shoemaker is
without landing legs or airbag.

"We're right on the money," cried out mission controllers as the craft
drifted closer and closer to Eros. Images relayed on the way down to the
surface showed what appears to be ancient craters buried below the thick,
dusty face of Eros.

"We're seeing things really well," said Joseph Veverka, NEAR's imaging team
leader from Cornell University in Ithaca, New York. "The pictures are
absolutely fantastic. This is a great experience to just sit here and
accompany a spacecraft down to the surface."

In one image, a giant boulder could be clearly seen fractured in at least
six pieces. As one image after another reached Earth, the spacecraft
appeared to be headed toward a smooth landing surface.

For over four-and-a-half hours, as engineers and scientists here at The
Johns Hopkins University Applied Physics Laboratory (APL) cheered close-up
images the probe sent back during its descent, the probe drifted down toward
the rock of ages.

APL built and managed the NEAR mission for NASA, one of the Discovery-class
of probes that signals a cheaper, better, faster approach to space
exploration.

Price tag for this long-term survey of an asteroid by the econo-class
spacecraft: $223 million.

NEAR's mission control at The Johns Hopkins University's Applied Physics
Laboratory reported the craft blasted its hydrazine-fueled motors for 20
second starting at 10:31 a.m. Eastern time.

The burst of rocket thrust moved the NASA probe out of its current orbit
22-miles (35-kilometers) above Eros.

The spacecraft immediately began dropping toward Eros. In the next
four-and-a-half hours, a series of braking maneuvers led to the spacecraft
making contact with Eros.

Small body, big hopes

The craft has relayed a bounty of scientific data about the asteroid,
including some 160,000 images that covered all of the 21-mile-long
(34-kilometers) asteroid's surface.

Eros is moving in a clockwise direction as it spins on its axis.

NEAR Shoemaker drifted onto the surface of Eros, softly touching down in an
area bordering Himeros - a distinctive saddle-shaped depression. On the way
down to the landing zone, the highest-resolution images ever taken of Eros'
boulder-strewn, cratered terrain were transmitted to Earth.

NEAR Shoemaker was not designed specifically for the touchdown, with the
daring dive called for as the mission drew to a successful close on February
14.

"It's a very nice way to end this mission," Louise Prockter, a member of the
NEAR imaging team at the Applied Physics Laboratory (APL) told SPACE.com.

"At least we'll know exactly where the spacecraft is and what happened to
it. So if there's a future mission out that way, we'll be able to look for
it," Prockter said.

Remaining fuel a question

When the spacecraft was launched February 17, 1996, its fuel tanks were
filled with 715 pounds (325 kilograms) of fuel. After five years, exactly
how much propellant remains is unknown. Precious bursts of fuel were needed
to prod NEAR Shoemaker lower and lower to the surface of Eros and mission
director Robert Farquhar was not sure the probe would have enough gas to the
end.

"The primary thing is to get high-resolution images. The closer we get the
more success we have," Farquhar said.

After plopping down on Eros, the spacecraft was healthy enough to transmit
science data. Over the next two days, ground stations on Earth will keep an
active ear to transmissions from NEAR Shoemaker.

Roundtrip communications time between NEAR and Earth is 35 minutes. At
Goldstone, California, a Jet Propulsion Laboratory (JPL) Deep Space Network
antenna is to keep a lock on NEAR, with another big dish in Madrid, Spain
also at the ready.

Landing on an asteroid is no cakewalk, Farquhar said, particularly when the
spacecraft is not built for such a task.

Any number of things could have gone wrong. Engines could misfire; the
camera could be pointed the wrong way; or the landing site terrain could
have proved impossible for NEAR to navigate successfully.

From a distance

Scientists are delighted that the spacecraft relayed high-quality, close-up
images of Eros.

The telescopic camera, built for remote distance viewing, stayed in focus
down to an altitude of about 0.3 mile (0.5 kilometer) above the surface.

"The camera should reveal things on the surface, down to as small as a tea
cup," said Clark Chapman, member of the NEAR Shoemaker science team from
Southwest Research Institute in Boulder, Colorado.

"The close-up images are what we're after," said Lucy McFadden, NEAR science
team member from the University of Maryland in College Park. "We're going to
microscopic views relative to where we started. It's just tremendous."

Prockter said the spacecraft's last in-focus snapshots may help quell
considerable debate between scientists working on the project. The nature of
the regolith -- broken up bits of rock and dirt that cover the asteroid --
as well as how deep and how much is there, and the origin of that material,
are all questions being argued.

"Looking close up might help us answer some of those questions," Prockter
said.

Chapman said a head-scratcher for him is understanding why so many giant
boulders populate Eros.

"We've been arguing between ourselves about what it means geologically,"
Chapman said. "Why is it so different than the Moon? I've just got to
believe that the higher resolution images are going to give us a whole bunch
of additional clues as to what's really going on. There's lots of
speculation."

Survivor for science?

Now that the craft has touched down on the surface of Eros, hopes run high
that NEAR's onboard magnetometer can relay measurements directly from the
asteroid.

To date, the magnetometer has not seen anything that can be attributed to
Eros. Why that's the case is a little puzzling, said Andrew Cheng, NEAR
project scientist, because most of the meteorites that are thought to be
related to Eros are magnetized.

But whether or not the magnetometer ever picks up data from Eros,
researchers are still constrained by finances. Money for mission operations
runs out on February 14, 2001.

Prior to the landing, McFadden was wistful.

"It's really sad the whole thing is going to end Monday," she said.
 
Copyright 2001, Space.com

=========
(2) NEAR SHOEMAKER MAKES HISTORIC TOUCHDOWN ON ASTEROID EROS

From Ron Baalke <baalke@jpl.nasa.gov>

http://near.jhuapl.edu/news/flash/01feb12_8.html


For Immediate Release
 
Feb. 12, 2001

Media Contact:
Helen Worth
(240) 228-5113
helen.worth@jhuapl.edu

Mike Buckley
(240) 228-7536
michael.buckley@jhuapl.edu

NEAR Shoemaker Makes Historic Touchdown on Asteroid Eros

Today, at 3:02:10 EST, NASA's NEAR Shoemaker spacecraft traveled its last
mile, cruising to the surface of asteroid Eros at a gentle 4 mph (1.9 meters
per second)-finally coming to rest after its 2-million-mile journey.

Cheers and congratulations filled the Mission Operations Center at the Johns
Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., which
built the spacecraft and manages the mission for NASA, when NEAR Mission
Director Robert Farquhar announced, "I'm happy to say the spacecraft is
safely on the surface of Eros."

The last image snapped by NEAR Shoemaker was a mere 394 feet (120 meters)
from the asteroid's surface and covered a 20-foot (6-meter) area. As NEAR
Shoemaker touched down it began sending a beacon, assuring the team that the
small spacecraft had landed gently. The signal was identified by radar
science data, and about an hour later was locked onto by NASA's Deep Space
Network antennas, which will monitor the spacecraft until Feb. 14.

NEAR Shoemaker's final descent started with an engine burn at 10:31 a.m.
(EST) that nudged the spacecraft toward Eros from about 16 miles (26
kilometers) away. Then four breaking maneuvers brought the spacecraft to
rest on the asteroid's surface in an area just outside a saddle-shaped
depression, Himeros. When it touched down, NEAR Shoemaker became the first
spacecraft ever to land, or even attempt to land on an asteroid. The success
was sweetened by the fact that NEAR Shoemaker was not designed as a lander.

The spacecraft spent the last year in a close-orbit study of asteroid 433
Eros, a near-Earth asteroid that is currently 196 million miles (316 million
kilometers) from Earth. During that time it collected 10 times more data
than originally planned and completed all its science goals before
attempting its descent to the asteroid.

Details of NEAR Shoemaker's landing will be discussed at a post-landing
press conference that will be held at APL's Kossiakoff Center at 1 p.m.,
Wednesday, Feb. 14. Panelists will be:

               Jay Bergstralh, Acting Director, Solar System
               Exploration, NASA Hq., Washington, D.C.

               Robert Farquhar, NEAR Mission Director, APL

               Bobby Williams, Navigation, NASA's Jet
               Propulsion Laboratory, Pasadena, Calif.

               Joseph Veverka, Imaging Team Leader, Cornell
               University, Ithaca, N.Y.

               Thomas Coughlin, NEAR Project Manager, APL

The press conference will be telecast live on a Ku band satellite at:
Telstar K5 97 degrees West Longitude Transponder 12 Downlink Frequency 11936
MHz Horizontal Polarity Audio 6.2 & 6.8

Media wishing to follow the press conference on the Internet can contact
NASA Hq. (202-358-1727) or APL Public Affairs (240-228-5113) for access
instructions and passwords. To register for the press conference visit the
NEAR Web site at http://near.jhuapl.edu and go to News Center - Upcoming
Events. Images are also available on the Web site.

=============
(3) AMERICAN CRAFT LANDS ON ASTEROID

From Spaceprogramme News, 13 February 2001
http://www.spaceprogramme.com/?action=display&article=5731206&template=space/index.txt&index=recent

COLUMBIA, Md. (AP) - NEAR, the spacecraft that became the first manmade
object to land on an asteroid, may continue sending its signal for months,
but after Wednesday nobody will be listening.

The spacecraft, which was designed for orbiting and not landing, astounded
even the experts on Monday by touching down so gently on the asteroid Eros
that its radio beacon continued to send a strong signal to Earth.

Mission director Robert Farquhar said that if the craft's solar panels
continue to generate electricity, the signal could last at least three
months.

But on Wednesday, Valentine's Day, the five-year mission officially ends,
said Farquhar, and NASA's Deep Space Network will no longer relay signals
from Eros, some 196 million miles away.

"We could still speak to it, but we won't be able to,'' he said. And, in
any case, NEAR will eventually be silenced when the craft's landing point on
Eros moves out of sunlight and the solar panels can no longer make
electricity. The craft's signal then would slowly fade as its batteries
died.

NEAR's signal carries almost no information, so there is little likelihood
of getting new scientific data from the spacecraft, which had been orbiting
Eros for the past year and relaying photos and other information to Earth,
officials said. The signal is little more than a hum that lets mission
control known that NEAR is still alive - not of a quality high enough to
send data or photos.

The featherlight landing of the 1,100-pound NEAR - for Near Earth Asteroid
Rendezvous - surprised even the most optimistic of mission officials.

"I just figured something had to go wrong, but it didn't,'' said Farquhar,
the official who had first proposed the landing. He had estimated that the
odds of NEAR being able to send a signal after landing was less than 1
percent.

Some NASA officials even warned that it would be "a controlled crash'' and
not a landing on Eros, a potato-shaped object about 21 miles long.

Instead, NEAR precisely fired its rockets to drop from a 15-mile orbit over
the asteroid and then drifted down, slowed by four more rocket firings. It
hit the asteroid, with rockets still firing, and bounced back up, before
alighting firmly on the surface.

Some engineers said the bounce may have carried NEAR more than 300 feet up
in the low gravity of Eros, where an object dropped from six feet could take
seconds to fall.

"This was a landing, not an impact,'' said Farquhar. He said the landing
speed, relative to the surface of Eros, was about 3.5 miles an hour, a fast
walk.

The mission was controlled by the Johns Hopkins University Applied Physics
Laboratory and funded by the National Aeronautics and Space Administration.

"They made a spacecraft that was only designed to orbit and then they put
it down on an asteroid and it's still working,'' said Ed Weiler, NASA's
chief scientist. "That is amazing.''

NASA administrator Dan Goldin said Monday he first doubted NEAR's chances
for a successful landing.

"I was dubious that we would ever get a signal back,'' he said. "They
pushed the boundaries. Wonderful, bold, courageous, brilliant - those are
the words to come to mind.''

Goldin said he called the Mission Control Center in Houston, which is
commanding the flight of space shuttle Atlantis to the International Space
Station.

"I told them to tell the astronauts that we have just landed on an
asteroid,'' said Goldin.

After the news was relayed to the Atlantis crew, spacewalking astronaut
Thomas Jones radioed back: "I hope we'll have some astronauts following to
the asteroids in just a few years.''

The United States does plan to send more robot missions to asteroids and to
eventually land a craft on a comet and bring back samples. But no manned
missions to an asteroid are planned.

Putting a spacecraft on the asteroid was a major first for the United
States. Never before had an American craft made the initial landing on an
outer space body, NASA officials said. The first robot landings on the moon,
Mars and Venus were all Soviet craft.

Weiler said the NEAR landing taught valuable lessons that will help in
future exploration of asteroids and comets. Such missions, he said, could be
important if an asteroid such as Eros ever threatens the Earth. A similar
space mountain is thought to have killed the dinosaurs 65 million years ago.


"This landing gives us a lot of practice,'' said Weiler. "We'll eventually
want to land on comets.''

NEAR achieved orbit of Eros, an asteroid named for the Greek god of love, on
Valentine's Day last year. The landing completes a five-year, 2-billion-mile
mission for NEAR and boosts the cheaper-faster-better philosophy pushed by
NASA for exploring outer space.

Developed by scientists at Johns Hopkins, NEAR was designed, built and
launched in just 26 months, far shorter than most NASA missions. Its cost,
$223 million, was less than expected. Johns Hopkins returned about $3
million to NASA, Weiler said.

NEAR was launched Feb. 17, 1996, into an independent solar orbit. NEAR swung
by the Earth once to pick up speed and then streaked outward toward Eros,
which is in an elongated orbit that nears Mars and approaches Earth's orbit.


On the Net:
Mission site: http://near.jhuapl.edu

Copyright 2001 Associated Press.

=============
(4) NEAR SHOEMAKER SURVIVES ASTEROID LANDING

From Spaceflight Now <newsalert@spaceflightnow.com]

The NEAR Shoemaker probe is apparently alive and well after touching down on
the surface of asteroid Eros today. The spacecraft returned remarkable close
up views of the asteroid's surface as it swooped down to its historic
landing. Check our home page for the latest news
and pictures.

http://spaceflightnow.com/

============
(5) SPACECRAFT MAKES IMPROBABLE LANDING ON ASTEROID
 
From CNN, 12 February 2001
http://www.cnn.com/2001/TECH/space/02/12/near.landing.02/index.html

Web posted at: 7:57 p.m. EST (0057 GMT)

By Richard Stenger
CNN.com Writer

(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.

Copyright 2001, CNN

=============
(6) METEORITES HARDER TO TRACE THAN FAMILY TREES

From Ron Baalke <baalke@jpl.nasa.gov>

From San Francisco Chronicle, 12 February 2001
http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2001/02/12/MN192684.DTL

Meteorites Harder to Trace Than Family Trees
Chemicals, radiation help determine celestial parentage of former asteroids

Keay Davidson
San Francisco Chronicle
February 12, 2001

In a modern-day version of the legendary quest for the source of the Nile,
space scientists seek the source of the heavens' gift to Earth: meteorites.

These fragments of rock and metal are chips off multibillion-year-old flying
mountains -- asteroids -- that hurtle through the night sky and occasionally
crash to Earth.

Like birds and bugs, meteorites and asteroids aren't homogeneous: rather,
they come in different varieties. For decades, space scientists have debated
which types of meteorites come from which types of asteroids.

"This, of course, is the Holy Grail of asteroid science -- to establish
parent body asteroid types for each of the major classes of meteorites,"
says Donald K. Yeomans, a noted space scientist at NASA's Jet Propulsion
Laboratory in Pasadena.

Resolving this debate is a key goal of NASA's Near Earth Asteroid Rendezvous
mission to the asteroid Eros. Today, if all goes as planned, the one-ton,
9-foot-long robotic spaceship will end its five-year, highly successful
journey by crashing into the asteroid surface.

One of NEAR's prime goals has been to use X-ray and gamma-ray spectrometers
to analyze the surface of Eros. The scientists hope to determine how well
Eros' chemical composition matches that of the commonest type of meteorites,
technically dubbed "ordinary chondrites."

Full story here:

http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2001/02/12/MN192684.DTL

==============
(7) CATASTOPHE/APOCALYPSE COURSE AT BARD COLLEGE

From Benny J Peiser <b.j.peiser@livjm.ac.uk>

"Catastrophe/Apocalypse" is a course being given every fall at Bard College
by Prof. William Mullen. Bill and his students have set up a website
featuring this innovative course about "cenocatastrophism" and would
appreciate feedback and suggestions by CCNet readers on how the course might
be improved. They would also like to hear from others involved in similar
courses elsewhere. Please feel free to send your comments and suggestions to
ceno@bard.edu.

For further details about the course, see:
http://inside.bard.edu/specialproj/clas214

============================
* LETTERS TO THE MODERATOR *
============================

(8) NEO DEFLECTION BY NEO COLLISION/FLY-BY

From Christian Gritzner <christian.gritzner@mailbox.tu-dresden.de>

Dear Benny, dear Mr. Frisbee,

in CCNet 12 Febr. 2001, Joseph H. Frisbee presented his ideas on NEO
deflection. I just want to add that the NEO deflection concept of inter-NEO
collisions was already proposed at the "Near-Earth Object Interception
Workshop" in Los Alamos in 1992 (LA-12476-C conference, issued Feb. 1993,
LANL, NM 87545). In chapter 6 "Assessment of current and future
technologies" (pp. 227-236) the two following concepts were presented:

a) "Billiards Shot" - The orbit of a small NEO will be changed in this
concept in order to achieve a collision with the (larger) NEO being on
collision course with Earth. This method would be capable to deflect even 10
km-class NEOs. But this requires very accurate astrodynamical capability and
the impacting NEO has to be available for this manoeuvre, i.e. we need a
deflection system that provides enough delta-v for this.

b) "Brilliant Mountains" - This concept was proposed by T. Zuppero which
requires large amounts (1,000 to 10,000 tons) of (asteroidal/cometary/lunar)
material in Earth orbit. These mass packages shall be directed onto a
collision course with the incoming NEO which requires only a small delta-v.
It is assumed that the collision (close to the Earth) would fragment the NEO
and that these fragments would miss the Earth.

Such concepts cannot be realised in the near future because they require a
deflection system for the small impactor NEO which is not available today...
But it is worth to further analyse this concept! If we study all the
alternative mitigation concepts now, we will know what to do if the next NEO
on collision course with our planet is discovered. The lead time available
may decide whether the mitigation mission will be successful or not - this
calls for intensified NEO detection and tracking activities, and for
detailed studies on mitigation systems.

Best wishes,
Christian Gritzner
--
Technische Universitaet Dresden
Institut fuer Luft- und Raumfahrttechnik
Dr.-Ing. Christian Gritzner, Senior Engineer
01062 Dresden, Germany
Tel.: +49-351-463-8234 (Fax: -8126)
E-mail: christian.gritzner@mailbox.tu-dresden.de
Homepage: www.tu-dresden.de/mw/ilr/space/space.htm

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CCCMENU CCC for 2000

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The content and opinions expressed on this Web page do not necessarily reflect the views of nor are they endorsed by the University of Georgia or the University System of Georgia.