PLEASE NOTE:
*
CCNet 12/2003 - 5 February 2003
--------------------------------
"NASA should be assigned to lead a new research program to
better
determine the population and physical diversity of near-Earth
objects
that may collide with our planet, down to a size of 200 meters,
according to the final report of a workshop on the scientific
requirements
for the mitigation of hazardous comets and asteroids. "As
our discussions
proceeded, it became clear that the prime impediment to further
advances in
this field is the lack of assigned responsibility to any national
or
international governmental organization," said planetary
scientist
Michael Belton, organizer of the September 2002 workshop."
--National Optical Astronomy Observatory, 4 February 2003
"A group of astronauts, scientists, and technologists want
to engage
in celestial shoving match. The winner may well be the Earth. The
goal of
an assembly of experts is straightforward: To significantly alter
the
orbit of an asteroid "in a controlled manner" by the
year 2015. They have
dubbed their effort the B612 Project, brought into being by what
the
group feels is a current lack of action to protect the Earth from
the impact
of near Earth asteroids (NEAs)."
--Leonard David, Space.com, 5 February 2003
(1) "NASA SHOULD LEAD ASTEROID DEFENSE"
National Geographic News, 4 February 2003
(2) NASA SHOULD LEAD MORE FOCUSED PROGRAM TO REDUCE THREAT FROM
HAZARDOUS
ASTEROIDS
Ron Baalke <info@jpl.nasa.gov>
(3) FINAL REPORT: NASA WORKSHOP ON SCIENTIFIC REQUIREMENTS FOR
MITIGATION OF
HAZARDOUS COMETS AND ASTEROIDS
National Optical Astronomy Observatory
(4) IN DEFENSE OF EARTH: KEEPING ASTEROIDS AT A DISTANCE
Space.com, 5 February 2003
(5) MORE FROM INSURANCE DAY
Michael Paine <mpaine@tpg.com.au>
(6) A SALUTE TO GALILEO AND FRIENDS OF PLANETARY DEFENSE
Andy Smith <astrosafe22000@yahoo.com>
(7) METEOR STORM IN JUNE 1991?
Hossein Alizadeh <immgharib@hotmail.com>
(8) BRIAN CARNELL ON THE CHALLENGER O-RING FAILURE
Ed Grondine <epgrondine@hotmail.com>
==========
(1) "NASA SHOULD LEAD ASTEROID DEFENSE"
>From National Geographic News, 4 February 2003
http://news.nationalgeographic.com/news/2003/02/0204_030204_asteroids.html
Earth has a history of being struck by asteroids, sometimes with
devastating
effects such as tsunamis, firestorms, and even large-scale
extinction of
life. Yet no one knows for sure how many large asteroids are out
there and
if-or when-one might be headed for us. Now a group of experts has
recommended a strategy to prepare a planetary defense.
The biggest obstacle towards creating a plan to defend Earth
against
asteroid impacts is that no national or international
organization has been
tasked with the job, says an international group of scientists,
engineers,
and military experts who gathered to assess the danger. The group
recommends
that NASA should get the job.
The Workshop on Scientific Requirements for Mitigation of
Hazardous Comets
and Asteroids gathered 77 experts from the United States, Europe,
and Japan.
It released its final report this week.
"NASA should be assigned to lead a new research program to
better determine
the population and physical diversity of near-Earth objects that
may collide
with our planet, down to a size of 200 meters (200 yards),"
according to a
statement released by the workshop.
The workshop's report also recommended that the U.S. Department
of Defense
(DoD) work to more rapidly communicate surveillance data on
natural
airbursts of smaller rocky bodies, and it concludes that
governmental policy
makers must "formulate a chain of responsibility" to be
better prepared in
the event that a threat to Earth becomes known.
"As our discussions proceeded, it became clear that the
prime impediment to
further advances in this field is the lack of assigned
responsibility to any
national or international governmental organization," said
planetary
scientist Michael Belton, organizer of the September 2002
workshop. "Since
it is part of NASA's newly stated mission to 'understand and
protect our
home planet,' it seems obvious that this responsibility should
reside in
NASA."
Belton presented the findings of the workshop this week in
Washington, D.C.,
to officials at NASA, the National Science Foundation, and the
Office of
Management and Budget, and the report was delivered to the U.S.
Congress.
About 2,225 near-Earth objects (NEOs) have been detected,
primarily by
ground-based optical searches, in the size range between 10
meters (11
yards) and 30 kilometers (19 miles), out of a total of about one
million.
But some information about the physical size and composition of
these NEOs
is available for only about 300 objects.
The total number of objects a kilometer in diameter or larger, a
size that
could cause global catastrophe upon Earth impact, is now
estimated to range
between 900 and 1,230, according to the workshop. The NASA-led
Spaceguard
Survey has a congressional mandate to detect 90 percent of these
kilometer-sized (thousand-yard) objects by 2008, and it is making
"excellent
progress" on this goal, the report said.
However, a full survey of objects that could cause significant
damage on
Earth should reach down to NEOs at least as small as 200 meters
(220 yards),
the report said, which should be within the capability of
proposed
ground-based facilities such as the Large Synoptic Survey
Telescope and the
PanStarrs telescope system.
Ground-based radar systems will remain a "critical
contributor" to obtaining
the most accurate possible data on the orbits of many hazardous
objects, the
report said.
The workshop report discusses a preliminary "roadmap"
based on five themes:
more complete and accurate surveys of the orbits of potentially
hazardous
objects; improved public education about the risk; characterizing
the
physical properties of a range of asteroids and comets; more
extensive
laboratory research; and initial physical experiments toward a
realistic
plan to intercept and divert a future incoming object.
In order to keep maximum annual expenses on the order of a
typical
spacecraft mission (approximately U.S. $300 million), the report
estimates
that it would take about 25 years to accomplish this roadmap.
Copyright 2003, National Geographic News
=============
(2) NASA SHOULD LEAD MORE FOCUSED PROGRAM TO REDUCE THREAT FROM
HAZARDOUS
ASTEROIDS
>From Ron Baalke <info@jpl.nasa.gov>
http://www.noao.edu/outreach/press/pr03/pr0303.html
National Optical Astronomy Observatory
FOR IMMEDIATE RELEASE: February 4, 2003
RELEASE NO: NOAO 03-03
NASA Should Lead More Focused Program to Reduce Threat from
Hazardous
Asteroids
For More Information:
Douglas Isbell
Public Information Officer
National Optical Astronomy Observatory
Phone: 520/318-8214
E-mail: disbell@noao.edu
NASA should be assigned to lead a new research program to better
determine
the population and physical diversity of near-Earth objects that
may collide
with our planet, down to a size of 200 meters, according to the
final report
of a workshop on the scientific requirements for the mitigation
of hazardous
comets and asteroids.
The workshop's report also recommends that the U.S. Department of
Defense
(DoD) work to more rapidly communicate surveillance data on
natural
airbursts of smaller rocky bodies, and it concludes that
governmental policy
makers must "formulate a chain of responsibility" to be
better prepared in
the event that a threat to Earth becomes known.
"As our discussions proceeded, it became clear that the
prime impediment to
further advances in this field is the lack of assigned
responsibility to any
national or international governmental organization," said
planetary
scientist Michael Belton, organizer of the September 2002
workshop. "Since
it is part of NASA's newly stated mission to `understand and
protect our
home planet,' it seems obvious that this responsibility should
reside in
NASA."
Belton presented the findings of the workshop today in
Washington, DC, to
officials at NASA, the National Science Foundation, and the
Office of
Management and Budget, and the report was delivered to the U.S.
Congress.
About 2,225 near-Earth objects (NEOs) have been detected,
primarily by
ground-based optical searches, in the size range between 10
meters and 30
kilometers, out of a total estimated population of about one
million; some
information about the physical size and composition of these NEOs
is
available for only 300 objects.
The total number of objects a kilometer in diameter or larger, a
size that
could cause global catastrophe upon Earth impact, is now
estimated to range
between 900 and 1,230. The NASA-led Spaceguard Survey has a
congressional
mandate to detect 90% of these kilometer-sized objects by 2008,
and it is
making "excellent progress" on this goal, the report
says.
However, a full survey of objects that could cause significant
damage on
Earth should reach down to NEOs at least as small as 200 meters,
the report
says, which should be within the capability of proposed
ground-based
facilities such as the Large Synoptic Survey Telescope and the
PanStarrs
telescope system. Ground-based radar systems will remain a
"critical
contributor" to obtaining the most accurate possible data on
the orbits of
many hazardous objects, the report says.
The workshop report discusses a preliminary roadmap based on five
themes:
more complete and accurate surveys of the orbits of potentially
hazardous
objects; improved public education about the risk; characterizing
the
physical properties of a range of asteroids and comets; more
extensive
laboratory research; and initial physical experiments toward a
realistic
plan to intercept and divert a future incoming object.
In order to keep maximum annual expenses on the order of a
typical
spacecraft mission (approximately $300 million), the report
estimates that
it would take about 25 years to accomplish this roadmap.
The Final Report of the NASA Workshop on Scientific Requirements
for
Mitigation of Hazardous Comets and Asteroids, held in Arlington,
VA, from
September 3-6, 2002, is available on the Internet at:
http://www.noao.edu/meetings/mitigation/report.html
The workshop was attended by 77 scientists from the United
States, Europe
and Japan. It was co-sponsored by Ball Aerospace, Science
Applications
International Corp., Lockheed Martin Corp., the National Optical
Astronomy
Observatory and the University of Maryland.
==============
(3) FINAL REPORT: NASA WORKSHOP ON SCIENTIFIC REQUIREMENTS FOR
MITIGATION OF
HAZARDOUS COMETS AND ASTEROIDS
>From National Optical Astronomy Observatory
http://www.noao.edu/meetings/mitigation/workshop_report_final.html
Held in Arlington, VA, September 3-6, 2002
1. Executive Summary and Recommendations
Purpose of the workshop and primary conclusions:
The "Workshop on Scientific Requirements for Mitigation of
Hazardous Comets
and Asteroids," supported by the NASA's Office of Space
Science, was held on
September 3 - 6, 2002, at the Hyatt Hotel in Arlington, VA.
Seventy-seven
scientists, engineers and military experts from the United
States, Europe,
and Japan participated. Its purpose was to consider the
scientific
requirements for avoidance and mitigation of hazards to the Earth
due to
asteroids and comets, i.e., what should be done to ensure that an
adequate
base of scientific knowledge is created that will allow efficient
development of a reliable, but as yet undefined, collision
mitigation system
when needed in the future.
It became clear that the prime impediment to further advances in
this field
is the lack of any assigned responsibility to any national or
international
governmental organization to prepare for a disruptive collision
and the
absence of any authority to act in preparation for some future
collision
mitigation attempt.
Eighteen major conclusions (listed below) were formulated that
provided the
basis for five recommendations. In brief, these are:
That NASA be assigned the responsibility to advance this field,
That a new and adequately funded program be instituted at NASA to
create,
through space missions and allied research, the specialized
knowledge base
needed to respond to a future threat of a collision from an
asteroid or
comet nucleus,
That the Spaceguard survey be extended to cover the hazardous
part of the
population of possible impactors down to 200 m in size,
That the DoD more rapidly communicate surveillance data on
natural
airbursts,
That governmental policy makers formulate a chain of
responsibility for
action in the event a threat to the Earth becomes known.
A record of some of the workshop presentations can be found in a
volume of
extended abstracts on the web at: www.noao.edu/meetings/mitigation/eav.html
. Other invited papers will be published by Cambridge University
Press as a
book entitled "Mitigation of Hazardous Impacts due to
Asteroids and Comets,"
in the spring of 2003.
What was discussed:
All aspects of near-Earth objects were discussed. These included
the
completeness of our knowledge about the population of potential
impactors,
their physical and compositional characteristics, the properties
of surveys
that need to be done to find hazardous objects smaller than 1 km
in size,
our theoretical understanding of impact phenomena, new laboratory
results on
the impact process, the need for space missions of specific
types, education
of the public, public responsibility for dealing with the threat,
and the
possible roles of NASA, the military, and other agencies in
mitigating the
threat.
Brief assessment of status and needs:
About 2,225 near-Earth objects are now known in the 10m to 30km
size range
out of a total population of about a million. Physical
information exists
only for a small number (~300) of these. It is estimated that
there are
roughly 25,000 are larger than 150m in size (above which the
potential
exists for easy penetration of the Earth's protective atmosphere)
but it is
estimated that only ~250 of these are potentially hazardous. The
number of
objects larger than 1 km (i.e., objects capable of global scale
catastrophe)
is now estimated to lie between 900 and 1230 and about 55% of
these have
been found - none on Earth intersecting trajectories. Without
continuing
improvements to existing survey equipment it is expected that
~70% will have
been found by 2008. Extension of the Spaceguard survey may be
needed to
achieve its goal.
To find a significant fraction of potentially hazardous objects
between 100m
and 1km in a reasonable time will require advanced telescopic
capabilities
(LSST, PanStarrs). Extensive follow-up astrometric observations
including
radar data will also be needed to confidently identify hazardous
impactors
with enough lead-time (decades) to allow effective mitigation.
New space and telescopic observations together with modeling
indicate high
internal porosity for many near-Earth objects and have resulted
in changing
views as to the nature of the surface processes on asteroids.
Physical and
compositional knowledge of the surface layers and interiors of
near-Earth
objects, given their diversity, is judged inadequate for
mitigation
purposes. Extensive observational and experimental studies from
spacecraft,
and Earth based telescopic systems, are required. Similarly
laboratory and
theoretical work is needed to clarify how porosity at the surface
or in the
interior of an object affects the outcome of a rapid application
of large
amounts of energy. Modeling suggests that deep layers of porous
surface
materials may have a dramatic effect on mitigation using
high-energy
explosives so that with previous estimates of requirements may
have to be
possibly increased by factors of 100 or more.
Substantial investment and time will be required to accomplish an
adequate
level of physical and compositional knowledge.
A roadmap for future advances:
A strawman roadmap suggests that $5-6B over 25yr (to keep total
annual
expenditures to <$300M/yr) involving a number of government
agencies will be
required. This roadmap also includes resources for in-space
interaction
experiments so that the process of learning how to apply possible
mitigation
techniques, and the rapid identification of the most effective
techniques,
can begin.
Major conclusions:
On the hazardous population -
A future collision of an asteroid or cometary nucleus with the
Earth with
catastrophic effects is inevitable unless technology is developed
to modify
the orbit of such bodies.
The most likely objects to collide with the Earth with
catastrophic effects
are 100 m or more in size and have a significant probability
(20%) of
colliding with the Earth over times of human interest (~100yr).
Excellent progress has been made in satisfying the congressional
mandate
charged to NASA to find 90% of near-Earth objects with H<18
(size greater
than 1 km) by 2008. However, models indicate that completion by
2008 will
require that technical improvements to the current discovery
systems be
made.
On the organization needed to respond to a threat -
There exists no government agency or international organization
with the
assignment or acceptance of responsibility for averting the
threat of an
impending collision.
Once an object is verified to be on an Earth-threatening
trajectory, There
is no identified organization responsible for the timely
reporting of these
events to the public or other nations.
The NASA charter includes the goal of protecting our home planet,
which is
relevant to the mitigation problem.
The priorities of the technical and scientific objectives of
space missions
designed to acquire a relevant basis of knowledge for mitigation
purposes
may be distinct from those in other high priority space
exploration programs
which address the same class of targets (small planetary bodies)
and that
are already being pursued by NASA and other foreign space
agencies.
The costs incurred by the above program of space and associated
Earth-based
research will be substantial, but possibly could eventually be
offset by
profitable activities in the low-gravity, resource-rich
environment of
asteroids and cometary nuclei.
An estimate of the time necessary to acquire this basis of
knowledge is
measured in decades.
The threat of catastrophic collisions with the Earth is global
and any and
all nations may be affected.
There is strong international interest in understanding the
nature of this
threat.
On what is required to respond to a threat -
The development of a relevant and adequate knowledge basis for
future
attempts to reliably mitigate an impending collision of an object
greater
than 100 m in size will require scientific proof of the efficacy
of a wide
range of proposed techniques in the space environment, including
ways to
measure relevant physical and compositional properties.
A series of space missions is required in order to acquire a
relevant and
adequate basis of knowledge on which to base the future
development of a
reliable collision mitigation system.
A multifaceted program of Earth-based theoretical, experimental,
observational, and interpretive research is necessary to support,
complement, guide, and extend a program of space missions for
mitigation
purposes.
Relatively low-cost Earth-based surveys for NEOs are now
technically
feasible down to a size limit of about 200 m.
Committees of the National Research Council of the National
Academy of
Sciences have recommended the construction of a large-aperture
synoptic
survey telescope (LSST) that is capable of detecting 90% of
near-Earth
objects above the 200 m size limit within approximately a decade.
On concerns with current activities -
Department of Defense space surveillance programs regularly
observe upper
atmosphere airbursts with the release of 1 kT of energy and above
caused by
objects entering the Earth's atmosphere from space with typical
sizes near
10 m.
The public and other nations with nuclear capability outside the
U.S. may
not be aware of this continuing flux of extraterrestrial objects
and their
effects in the Earth's upper atmosphere.
Recommendations:
Based on the above conclusions, the members of the workshop's
scientific and
local organizing committees formulated the following
recommendations that,
when implemented, will lead to the acquisition of a relevant body
of
scientific knowledge on which a practical and reliable collision
mitigation
system could be developed at some time in the future.
Recommendation 1. That the National Aeronautics and Space
Administration be
assigned the responsibility to acquire relevant scientific
knowledge on the
compositional and physical properties of the diverse population
of hazardous
objects that may threaten the Earth and on which the future
development of a
reliable collision mitigation system could be based. In
undertaking this
responsibility, the interests and cooperative support of the
international
community should be welcomed.
Recommendation 2. That a new and appropriately funded program be
instituted
at the National Aeronautics and Space Administration, consistent
with its
mission to "Understand and protect our home planet," to
create an adequate
basis of scientific knowledge through space missions and
supporting
Earth-based research on which future attempts to reliably
mitigate impending
collisions of hazardous objects with the Earth can be founded.
Recommendation 3. That the congressionally mandated survey
presently being
pursued by the National Aeronautics and Space Administration to
catalog
near-Earth objects brighter than H~18 (~ 1 km in size), be
extended to
include 90% of hazardous near-Earth objects down to a size range
of 200 m
over the next decade.
Recommendation 4. That the Department of Defense increase the
speed with
which it makes information about natural airburst phenomena
available to the
public and other nations to prevent possible misinterpretations
of these
small, frequent events.
Recommendation 5. That government and international policy makers
act now to
formulate and publish an agreed uponto chain of responsibility
for action in
the event that an Earth-threatening object is discovered.
FULL REPORT at
http://www.noao.edu/meetings/mitigation/workshop_report_final.html
=============
(4) IN DEFENSE OF EARTH: KEEPING ASTEROIDS AT A DISTANCE
>From Space.com, 5 February 2003
http://www.space.com/businesstechnology/technology/asteroid_deflection_030205.html
By Leonard David
BOULDER, COLORADO -- A group of astronauts, scientists, and
technologists
want to engage in celestial shoving match. The winner may well be
the Earth.
The goal of an assembly of experts is straightforward: To
significantly
alter the orbit of an asteroid "in a controlled manner"
by the year 2015.
They have dubbed their effort the B612 Project, brought into
being by what
the group feels is a current lack of action to protect the Earth
from the
impact of near Earth asteroids (NEAs).
For the immediate future, they point out, the changes are slim
that our
planet will be at the end of the trail for a space rock - one
that would
cause a highly destructive impact.
Nevertheless, the upshot from a heavenly slam shot is extreme,
say B612
Project officials, so much so that mitigation efforts should
start now.
Those involved in the B612 Project believe that by physically
deflecting a
representative asteroid -- one not headed toward the Earth -- is
a
worthwhile a trial project. Thus, a longer term, more challenging
operational system can become a reality.
Let's get pushy
It's high time to get pushy with Earth menacing asteroids,
suggests Apollo 9
astronaut, Russell Schweickart, chairman of the B612 Foundation
and a
retired business and government executive. The capability and
technological
wherewithal to anticipate and prevent an asteroid impact is now
available,
he contends.
If B612 sounds familiar, there is a reason. That's the asteroidal
address
for The Little Prince, authored by the French writer Antoine de
Saint
Exupery in 1943.
The B612 Foundation is a non-profit private organization with
principal
offices in Houston, Texas. It was formed late last year to
champion the
development of a space system to protect the Earth from future
asteroid
impacts.
"Nothing like being part of the largest environmental
project of all time,"
Schweickart explains.
Schweickart recently advocated the need for a United Nations
"Asteroid
Deflection Treaty" - an international agreement to help
shape a "trustworthy
system" that nudges threatening space rocks out of harm's
way.
"Since new Earth approaching asteroids are discovered every
day, initiation
of this effort should begin as soon as possible,"
Schweickart noted during a
special Organization of Economic Cooperation and Development
(OECD) workshop
on "Near Earth Objects: Risks, Policies and Actions",
held January 20-22 in
Frascati, Italy.
"When specific knowledge of an impact exists, it will be
known by the world
public in real time. It seems highly likely that, when that time
comes,
there will be widespread public expectation that these matters
will already
have been resolved," Schweickart said.
Action item strategy
One of the action items on the foundation's to do list this year
is
developing the first version of a "design reference
mission" - laying out
the requirements for a demonstration mission to deflect an
asteroid by 2015.
"Our strategy calls for the use of a long duration, low
thrust system design
to rendezvous and directly dock with the asteroid,"
Schweickart told
SPACE.com from his office in the Netherlands. "We would then
utilize the
system to first de-rotate the asteroid and then push it tugboat
fashion. We
call it a NEA-Tug...changing its velocity...over many
months," he said.
The attachment of a NEA-Tug to a tumbling asteroid's surface --
along with
control issues during de-rotation and acceleration -- "raise
substantial
questions that must be answered," Schweickart added. Due to
the NEA-Tug's
low thrust level, he said, many of the issues related to an
asteroid's
structural integrity and surface characteristics are not likely
to be an
issue.
Assurance policy
Honing the hardware for asteroid deflection means putting dollars
into space
power and propulsion. Doing so would also yield a scientific
bonanza too.
"From an institutional perspective the biggest challenge I
see is making the
decision to spend money on the effort and to assigning
responsibility for
getting the job done," Schweickart said. "We are not
proposing an
operational system. We are proposing that a demonstration mission
be
performed to meet several goals," he said.
Among those goals is stimulating the development of the enabling
technologies. Chiefly, those involve nuclear/electric power
generation and
plasma or ion propulsion. Furthermore, there's need to clearly
assure the
public that should a pending asteroid impact be discovered in the
next
decade or so, the necessary technologies and techniques to
protect the Earth
are available.
"Since the basic technologies we propose to use for asteroid
deflection will
also enable cost effective missions beyond low Earth orbit for
both
scientific research and, potentially, resource exploitation, the
incremental
funding required for this purpose is small. Yet great public
benefit is
gained by utilizing this mission to demonstrate the new power and
propulsion
technologies," Schweickart noted.
Practice before proceeding
Joining Schweickart in B612 Foundation work is noted asteroid
expert, Clark
Chapman, a scientist here at the Southwest Research Institute's
Department
of Space Studies in Boulder. He serves on the foundation's board
of
directors.
At first blush, Chapman advises, it might seem easy to move a
small
asteroid. "An elementary physics equation -- force equals
mass times
acceleration -- would seem to guarantee that if you pushed on the
'space
rock,' it would move. But asteroids are much more complex than
that," he
told SPACE.com.
There's need for practice, Chapman said. Learning how to despin
an asteroid
before pushing is a likely priority. Coming up with ways to
anchor a
low-thrust device firmly to a small, nearly gravitationless body
is another
factor. No telling what kind of surface an asteroid might have,
be it sandy
or fluffy, maybe rocky or metallic.
"Solving such problems will involve both improved scientific
understanding
of asteroids as well as technology development," Chapman
said. "It is too
early in developing the concepts for Project B612 to know just
how much more
science is needed, and how it must be phased as the project
proceeds. But I
expect that the science and technology will proceed in
tandem," he said.
Surprises in store
Similar in view is Dan Durda, also a Southwest Research Institute
space
scientist. "The best way to learn how to work around and on
a small asteroid
is to actually try to do it," he said.
Durda said anticipating what might occur on an asteroid by
extrapolating
from past space experiences is somewhat limited. "Until you
actually press
onto the real thing you have no way to know what environmental
and
operational surprises may be in store," he said.
Chapman said that on-going ground-based, Earth-orbit based,
theoretical, and
up-close spacecraft studies of comets and asteroids will help
those involved
in the B612 work to better recognize challenges as they progress
toward
their central goal.
Such complexities as 'rubble pile' compound of Near Earth
Objects, asteroids
orbited by natural satellites, 'tumbling' rotations, and
questions about
presence or lack of top surface materials on small bodies - all
make the
task of moving such objects "a fascinating challenge,"
Chapman said.
Face the public
Also on the B612 Foundation board of directors is NASA astronaut,
Edward
Tsang Lu. He is assigned to the Expedition 7 crew that was to
occupy the
International Space Station in March.
Another board member is Geoffrey Baehr of the venture capital
firm, U.S.
Venture Partners in Menlo Park, California, as is Piet Hut,
Professor of
Interdisciplinary Studies at the Institute for Advanced Study in
Princeton,
New Jersey.
Astrophysicist Hut underscored his keen interest in asteroid
deflection work
in a letter to U.S. President Bush last December.
"Would you be willing to face the public if an asteroid
would be discovered
heading our way? You would have to tell them that NASA has been
discovering
and tracking asteroids, but that funding had not been sufficient
to
catalogue most of them, and that there had not been any funding
so far to
study the question of how to deflect an asteroid, once found,
even though
the technology has in principle been available. Not a nice speech
to give, I
bet," he advised the U.S. President.
White House legacy?
Hut said the technological ingredients to prod a 328-feet
(100-meter)
diameter asteroid so it will miss Earth are at hand. A test
mission, he
said, could demonstrate the ability to do so.
"That way, when we discover an asteroid with our name on it,
so to speak, we
will be prepared. We could be in a position to save millions of
lives, and
at the very least we could not be accused of knowing about a
danger and
ignoring it," Hut wrote.
"Even if we are lucky, and no life-threatening asteroid
crosses our path in
the foreseeable future, developing the technology to gently nudge
asteroids
is likely to help us to explore the solar system," Hut
counseled the
President.
"This could be a major legacy of your administration,"
Hut's letter to the
White House concluded, "to open the door to populating other
worlds while at
the same time making our own world a safer place."
Copyright 2003, Space.com
============================
* LETTERS TO THE MODERATOR *
============================
(5) MORE FROM INSURANCE DAY
>From Michael Paine <mpaine@tpg.com.au>
Dear Benny,
Following your posting on CCNet today I went searching the
Insurance Day
website for more on asteroids. Here is an intersting one.
regards
Michael Paine
-------------
Super-cat [catastrophe] that will threaten life on Earth: it is
only a
matter of when
Insurance Day 23 April 2002
BILL MCGUIRE, professor of geophysical hazards and director at
the Benfield
Greig Hazard Research Centre, University College London, warns of
some of
the catastrophic risks facing Earth
CATASTROPHE insurance is, or certainly should be, underpinned by
the
capability to make adequately accurate predictions about future
floods,
storms, and earthquakes, so as to ensure that portfolios are not
unreasonably exposed to large, unforeseen losses.
The over-riding lesson to be learnt from the events of September
11,
however, must be expect the unexpected.
As ever, changing circumstances continue to lead the insurance
industry by
the nose. Following the Northridge quake in 1994, better seismic
risk
assessment was the sought-after grail, while following Hurricane
Andrew's
concerted attempt to obliterate Miami, tropical cyclone
forecasting was all
the rage.
Inevitably, for the last six months, terrorism has taken centre
stage, with
industry researchers attempting to quantify future terrorist
threat using
game theory and other esoteric mathematical jiggery-pokery.
If insurers are not to be caught out again, it is clear that they
must
become proactive rather than reactive, adopting a 'clear horizon'
approach
that seeks to identify and quantify future threats before they
happen.
Inevitably, any such policy will find itself uncovering rare
events
characterised by low frequency but high impact. Squarely into
this category
fall those phenomena labelled by hazard scientists as global
geophysical
events and defined as natural catastrophes with the potential to
have a
detrimental physical effect on the entire planet or at least a
substantial
fraction of it.
The last few years have seen a growing awareness of such shadowy
phenomena
as asteroid and comet impacts, volcanic super-eruptions, and
giant tsunami,
which have now become, as it were, respectable passing from the
rather
airy-fairy realm of science fiction to the cold, hard world of
hazard
science.
If one could put a finger on just when this transition occurred,
it would be
July 16, 1994, when the first of 21 chunks of fragmented comet
ploughed into
the giant planet Jupiter, creating impact scars larger than our
own world.
Suddenly, the Earth seemed a more fragile and vulnerable place,
with the
human race clinging to life only with the consent of Mother
Nature. Within
months, scientific programmes were in place to find and map all
those
objects that threatened to collide with our planet, while
national
governments including those of the US and the UK established task
forces
better to assess the threat.
At the same time, popular perception was raised by two Hollywood
blockbuster
films, Armageddon and Deep Impact, which detailed, with varying
degrees of
scientific plausibility, what will happen when the Earth is next
struck by a
large object from space.
Note here that I use the word will rather than is. Gaining
acceptance that
global geophysical events such as asteroid or comet impacts are
certain
rather than just possible remains difficult, and getting the
message across
that such phenomena constitute normal if infrequent
behaviour, in geological terms, is still a struggle. While
experts agree on
the size-threshold of an impactor capable of causing global
mayhem something
on the order of 1 km to 1.5 km there is
still some discussion over the frequency of collisions with such
objects,
with estimates ranging from every 100,000 to 300,000 years.
There is also some debate about how many threatening bodies there
are out
there, and the number of large Earth-threatening asteroids may be
as low as
500 or as high as 1,200. So far we have spotted less than 400.
The effects
of an impact event on the Earth and our society depend upon the
energy of
the collision. This is largely size-dependent although comets can
travel at
double the speed of asteroids.
A 10 km did for the dinosaurs around 65m years ago and a similar
collision
would obliterate our race. An object in the critical 1 km to 1.5
km size
range would be sufficient to obliterate a small country or state
and would
kick up enough debris to block out the sun's rays and lead to a
world-wide
freeze, sometimes referred to as a Cosmic Winter. Resultant death
tolls of
the order of a billion have been estimated, largely due to
starvation
related to global crop failure and subsequent famine.
As if the threat from space was not sufficient, future
catastrophes are also
brewing beneath our feet. A couple of times every hundred
millennia, an
explosive volcanic blast several thousand times greater than that
which blew
Mount St. Helens apart in 1980, ejects sufficient gas and debris
into the
stratosphere to dramatically reduce the amount of sunlight
reaching the
surface.
The last time this happened, at Toba in Sumatra, a global freeze
this time a
volcanic rather than a cosmic winter followed, which some
anthropologists
believe reduced the human population to just a few thousand
individuals.
The Earth does not run like clockwork and natural catastrophes do
not
operate to a timetable, but the fact that some 74,000 years have
passed
since the Toba eruption should start us thinking.
Add to this the fact that we are currently only monitoring a few
hundred of
the world's 3,000 or so active volcanoes and the cogitation
rapidly turns to
concern. Yellowstone Park (Wyoming, US) is probably the
best-studied
super-eruption source, having produced three gigantic blasts
during the past
2m years.
The last, around 650,000 years ago, led to volcanic debris 20 cm
deep
accumulating more than 1,500 km away, and ash falling in what is
now El Paso
and Los Angeles.
A similar event today would bring the US economy to its knees,
notwithstanding its effects on the planet's climate as a whole.
Yellowstone
is closely monitored and likely to provide decades of warning of
a new
super-eruption.
What is happening today at unmonitored volcanoes in the southern
Andes or
the jungles of south-east Asia is on the other hand anyone's
guess.
Both super-eruptions and the aforementioned asteroid or comet
impacts depend
upon the atmosphere to spread their effects worldwide, in the
case of giant
tsunami regularly incorrectly referred to as 'tidal waves'.
However, the
oceans are the transmitting medium.
Unlike the run-of-the-mill, though deadly, tsunami generated by
submarine
earthquakes, giant tsunami which may exceed 100 m in height
result from the
collapse of volcanic ocean islands.
Evidence exists for such waves pounding the coastline of eastern
Australia
following massive landslides on the Hawaiian Islands around
100,000 years
ago. Much more recently, attention has focused on the Canary
Island of La
Palma, where a mass of rock the size of the UK's Isle of Man,
started to
slide seawards in 1949.
A recent model of the future collapse which could occur in
hundreds or
thousands of years' time predicts waves up to 50 m high crashing
into the
east coast of the US and Caribbean some eight to12 hours after
collapse,
with the UK, southern Europe, South America and North Africa also
affected.
The depressing lesson, then, is that natural catastrophes on a
planetary
scale are waiting in the wings ready to exact an enormous toll on
the global
economy, and by default on the insurance industry. But can
anything be done?
As is often the case, the answer is yes, but only if we have
sufficient
warning.
Although the physical damage arising during the aforementioned
scenarios
will inevitably be beyond experience and economic and insured
losses
unprecedented, complete collapse of the global economy and social
fabric can
be avoided by taking appropriate mitigatory measures, including
evacuation,
emergency powers and rationing.
Whether the insurance industry in its present form could survive
a global
natural catastrophe is questionable, and it is clearly too much
to expect
for companies to build contingency funds to cushion its effects.
There is no such thing as too much knowledge, however, and in the
aftermath
of September 11 it can do the industry no harm at all to begin to
familiarise itself with the far greater natural threats that it
faces going
forward.
Copyright 2002, Insurance Day
===========
(6) A SALUTE TO GALILEO AND FRIENDS OF PLANETARY DEFENSE
>From Andy Smith <astrosafe22000@yahoo.com>
Hello Benny and CCNet,
Galileo's birthday (15 Feb.) is an excellent time to salute the
great
pioneer and the many friends of planetary defense (PD) who live
and work in
Italy. All of us, in the global family of advocates, appreciate
what you
have done and continue to do, in the interest of the safety of
the human
race and planet Earth.
We share a common bond, which is our awareness of the great
danger we face.
We also share the great responsibility of being members of the
first
generation, in the history of life on this planet, with the
capability to
fully understand the dangers and to prepare a defense. We stand
on the
shoulders of more than 400,000 generations (a very tall pyramid)
and we
"have the ball".
Thanks to Galilei Galileo, Max Wolf, Gene and Carolyn Shoemaker,
Tom
Gehrels, Ted Bowell, Brian Marsden, Arthur Clarke, Karri
Muinonen, Anatoly
Zaitsev, Michael Paine, Andrea Carusi, Vadim Simonenko, Don
Yeomans, Steve
Ostro, Syuzo Isobe, Duncan Steel, Jay Tate, Andrea Milani, Jin
Zhu, Fred
Whipple, Chris Aikman, Richard Binzel, Mario Carpino, Pete
Worden, Eleanor
Helin and many, many others...from all over the Globe...we are
making
progress and moving toward the day when we can truly feel secure
about NEO
impact safety.
We, the people of this Planet, welcome this opportunity to thank
you all for
your many contributions. We expecially want to thank the NEODyS
team, the
SPACEGUARD team and everyone at the University of Pisa for the
support they
have given to PD. Since the founding of the U.P., in 1472, there
has been a
proud and growing tradition of excellence....and the leadership
you have
shown, in this vital effort, brings credit to your country and to
the human
race.
Finally, we want to salute the planners of MACE 2003, the
international
Meeting on Asteroids and Comets in Europe, which will be held
from 1-4 May,
in Mallorca. We wish you the best and we urge you, if possible,
to post the
full agenda, with abstracts and e-mail addresses, and the
presentations, if
possible, on the Web. Our 1995 Planetary Defense Workshop, the
Russian
SPACE SHIELD (PDE) international conferences and several others
have been so
posted and they have proven to be of great value to the world
community of specialists. We are
also hoping that the 2004 AIAA Planetary Defense Conference, in
California,
will do the same. The Web is such a wonderful tool for the
sharing of
information.
Cheers,
Andy Smith/International Planetary Protection Alliance
(IPPA)/ astrosafe22000@yahoo.com
===========
(7) METEOR STORM IN JUNE 1991?
>From Hossein Alizadeh <immgharib@hotmail.com>
Dear Benny,
I have a vast collection of meteor and meteorite lore which I
have
discovered in Persian astronomical and historical manuscripts,
including
several events over a period of 500 years which recall me of
Tunguska class
events if it could have happened in a more dry climate. I am
currently
working to arrange all of these in chronical order to be
published in a
scholarly journal.
But what I am going now to report is the accounts of a hitherto
unknown
meteor storm which my mother had observed in the dawn sky
of June 28th 1991
while she was along my late father in their pilgrimage to Mecca.
(Our elder
generation dreamed about making the once in a lifetime pilgrimage
to Mecca,
but our younger generations dream about admission to such
prestigious
academic centers like New Mexico Tech, Caltech, UCLA and MIT!)
I have asked my mother to write down her observation in the Vol.
5 of my
hefty notebooks, all devoted to recording similar events of
astronomical
interest. A verbatim translation from the original Persian is as
this:
"On our way from Mecca to Medina [exactly to direction of
the North] on the
highway I observed that a meteor shower began by the midnight,
each one [of
the meteors] being 3 cm in length and some of those which rained
where
smaller.
And our travel was began by Khordad 17th 1370 [June 7th 1991] and
it lasted
for 31 days. We have been in Mecca for 21 days and for the rest
of our
travel we have been in Medina. And from Medina we directly
returned to
Tehran. [Then the night of the shower was by the dawn of the
Friday June
28th 1991] I felt that the meteor shower was like a rain and
perhaps lasted
for one hour. And the meteors directly rained toward the earth
and no
oblique ones were observed. And I felt very sad and uneasy by
seeing this,
because it was like a rain of fire, and I did not knew what the
reason for
this rain was."
I have asked my mother about her seat in the bus and she says it
was in the
left side seats, then her window in a Northward road should have
provided a
view towards the West and since the bus ceiling blocked the
upward view, she
probably could have a view up to a height of 75 of the western
sky (25
degrees to the Zenith). By then the age of the Moon was 15 days
and it was
placed in Sagittarius, low over the SSE horizon ,so moonlight
might have
washed away the light of the fainter meteors.
About the Radiant of this meteor storm I just can make the rough
guess that
probably it was within an area of the sky bordered by the
constellations
Capricorn-Aquarius to the south and Cassiopeia-Cepheus to the
north, which
interestingly is an approximate antipode to the general vicinity
of the
constellation Taurus which homes the radiant of the now famous
Taurid
daylight shower.
Also I have asked her questions to see if she was sure they could
not have
been reflections of inside and outside lights, but she says she
clearly can
differentiate between these.
My mother says the meteors she observed were colored orange-red
;like fire.
If this observation be genuinely about a meteor storm, then as it
lasted for
about 1 hour, and during that period the Earth had been rotated
by about 15
to the East, then we may expect that since she could only had a
view towards
the West then the meteors might have been visible also in a slice
of the
Earth stretching from Western Iran to Israel and Lebanon. I have
tried to
locate any hint about a meteor storm by the dawn of June 27th
1991, without
any result up to know.
May anyone else have also observed this meteor storm?
Yours Sincerely
Hossein Alizadeh Gharib
immgharib@hotmail.com
==============
(8) BRIAN CARNELL ON THE CHALLENGER O-RING FAILURE
>From Ed Grondine <epgrondine@hotmail.com>
Hello Benny -
Contrary to what Brian Carnell wrote (CCNet, 4 Feb 2003), the
Challenger
failure mode is no myth.
Shuttle o-ring failures prior to Challenger are are well
documented with
fully illustrated cross sections in the Challenger accident
report (5
volumes, if I remember, supporting documentation in multiple
boxes, current
repository unknown) as is the un-tested use in Challenger of a
new asbestos
free sealant to replace the asbestos based one.
In other words, the o-rings had failed before, but the asbestos
sealant kept
the blow-bys from progressing. It is almost as though the
pre-Challenger
shuttles were held together by a garish toxic chewing gum -
(actually a kind
of furnace cement) - that's the kind of margin of safety the NASA
was
promoting then.
The extensive pre-flight testing of the new external tank
insulation appears
to be a lesson NASA learned from Challenger.
This was 17 years ago. I have one blow by failure illustration
somewhere in
my mounds of papers (say about two hours to dig it out), but
digging out the
sealant information again would take a tremendous amount of time.
yours in science,
Ed
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*
CCNet 11/2003 - 5 February 2003
--------------------------------
"NASA investigators remain unconvinced that the chunk of
foam
insulation that struck Columbia's heat-resistant tiles on takeoff
led to
its destruction, and also are now considering the possibility the
craft was struck by space debris while in orbit, the agency's
chief
flight director said Tuesday. "Did we take some hit?"
Milt Heflin, the
flight director, said in an interview Tuesday at Johnson Space
Center.
"That's a possibility. Something was breached."
--Los Angeles Times, 5 February 2003
"NASA should perform a thorough risk assessment to determine
the
likelihood that the space shuttle could be severely damaged by
meteoroids and orbital debris, says a new report* from a
committee of the
National Research Council. In addition, the spacecraft should be
re-
examined to identify components that may require additional
protection.
Although NASA is taking steps to protect the shuttle from orbital
debris such as spent rocket bodies, satellite fragments, and
paint
chips, there still is a real risk that a collision could cripple
the
shuttle or threaten the safety of the crew."
--The National Academies, 16 December 1997
(1) NASA: COLUMBIA MAY HAVE BEEN STRUCK BY METEORITE OR SPACE
DEBRIS
The Los Angeles Times, 5 February 2003
(2) ORBITAL DEBRIS MAY POSE SIGNIFICANT RISK TO THE SPACE SHUTTLE
National Academies, 16 December 1997
(3) PROTECTING THE SPACE SHUTTLE FROM METEOROIDS AND ORIBTAL
DEBRIS
Committee on Space Shuttle Meteoroid/Debris
Risk Management, National
Research Council
===========
(1) NASA: COLUMBIA MAY HAVE BEEN STRUCK BY METEORITE OR SPACE
DEBRIS
>From Los Angeles Times, 5 February 2003
http://www.latimes.com/news/nationworld/nation/la-na-nasa5feb05,0,3696741.story?coll=la%2Dhome%2Dheadlines
By Scott Gold and Ralph Vartabedian, Times Staff Writers
HOUSTON -- NASA investigators remain unconvinced that the chunk
of foam
insulation that struck Columbia's heat-resistant tiles on takeoff
led to its
destruction, and also are now considering the possibility the
craft was
struck by space debris while in orbit, the agency's chief flight
director
said Tuesday.
"Did we take some hit?" Milt Heflin, the flight
director, said in an
interview Tuesday at Johnson Space Center. "That's a
possibility. Something
was breached."
NASA investigators have developed what has become known inside
Johnson Space
Center as a "fault tree" - a list of potential mishaps
and flaws that might
have caused Columbia to break apart Saturday morning over East
and central
Texas.
The list, aimed at finding the cause of what NASA terms the
"thermal event"
that destroyed the shuttle, includes several theories. Although
the current
investigation focuses on several scenarios related to tile
damage, some
analysts also have questioned whether faulty wiring or corrosion
could have
played a role.
Nonetheless, the prime suspect remains the piece of foam
insulation that
fell off the external tank during the Jan. 16 liftoff, possibly
damaging the
protective tiles.
Tile vulnerability has been an object of warnings for years. One
study
prepared for NASA nearly a decade ago warned that insulation and
ice debris
could result in enough damage to doom the orbiter during reentry.
"We estimated that [the loss of a shuttle] was a
possibility," said Paul
Fischbeck of Carnegie Mellon University in Pittsburgh, one of the
authors.
Despite warnings that the shuttle could be endangered if debris
struck its
underbelly during liftoff, some engineers do not believe that any
scenario
would have been destructive enough to cause Columbia to crash.
NASA's computers have calculated the potential damage caused by
the foam
insulation. Under two worst-case scenarios, NASA investigators
say, the
insulation either would have destroyed a single heat-resistant
tile near the
landing gear door or caused damage to a 32-by-7-inch patch of
tiles along
the shuttle fuselage.
That means the spacecraft's tiles - 24,000 ceramic pieces that
have been
problematic from the beginning of the shuttle program - could
have been
damaged some other way, Heflin said, possibly by space junk or a
tiny
meteorite. NASA engineers say they are considering the
possibility that a
small piece of space debris could have grazed the shuttle,
damaging or
loosening tiles just enough to start a chain reaction once the
craft started
roaring through the atmosphere.
The ceramic tiles act as a protective armor around the body of
the space
shuttle, protecting it against the intense heat of reentry
through the
atmosphere. Although many tiles are damaged or knocked off during
missions,
missing tiles in a particularly vulnerable portion of the
spacecraft, such
as at the leading edge of its wings, could imperil its ability to
fly.
The skepticism of some engineers and attempts to broaden the list
of
suspects failed to shift attention from insulation debris Tuesday
as more
reports documenting past warnings emerged.
"The foam insulation falling off the external tank could
certainly damage
tiles," Fischbeck said in a telephone interview.
The 1994 report he co-authored with Elisabeth Pate-Cornell of
Stanford
University specifically cited concerns about Columbia, noting
that tiles
"were put in place under severe schedule constraints, which
may have
affected the quality of the work."
Columbia was the first orbiter built, and the report found
problems with
tile adhesion and trapped water. Fischbeck and Pate-Cornell
advised that the
tiles be waterproofed. The report did not indicate whether those
recommendations were followed, but Fischbeck said the agency took
the
recommendations seriously and made improvements.
NASA officials have said in news briefings that a 20-inch chunk
of foam,
weighing about 2.67 pounds, was videotaped falling off the
external tank and
striking the underside of Columbia's left wing about 80 seconds
after
liftoff. That represented the largest piece of debris ever known
to have
fallen off the tank. At 80 seconds into flight, the orbiter was
nearing a
speed of 2,000 mph, meaning the foam carried substantial energy
into the
impact and could have caused serious tile damage, according to
Fischbeck.
The 1994 report warned NASA of several scenarios that could cause
catastrophic safety problems, including the potential for a
"zipper effect"
where the loss of a single tile would, in turn, cause adjacent
tile losses
until opening a large unprotected gap. Such exposure could make
vital areas
of the shuttle - such as critical hydraulic lines, computers or
fuel tanks -
vulnerable to destructive heat, the report said.
After the report was issued, Fischbeck said NASA took steps to
sharply
reduce foam debris. The experts also urged NASA to find ways to
improve tile
safety, despite budget cuts.
"NASA must find ways of being cost-effective, because it
simply cannot
afford financially or politically to lose another orbiter,"
the report
cautioned.
Heflin said his engineers have no hard evidence Columbia was
struck by a
piece of space junk or a space pebble, known as a micrometeor.
What's more,
NASA takes great care during missions to avoid the man-made
objects, from
ejected payload shrouds to tools left behind by astronauts after
spacewalks,
that are in constant orbit. By some estimates, there are more
than a million
objects within 1,200 miles of the Earth's surface.
Heflin also pointed out that the space debris theory has not
supplanted the
foam insulation theory, but has been placed alongside it on the
"fault
tree."
Analysts inside and outside the space program are torn over the
possibility
that space debris is to blame. There are several problems with
the theory.
First, the Air Force and NASA together perform a comprehensive
analysis of a
shuttle's projected path before each mission to ensure that it is
not struck
by debris, said Howard Sands, a former NASA official who worked
as a
contracting officer for space shuttle logistics before he retired
in 1986.
The Air Force has the ability to pinpoint the location of space
debris that
is just centimeters in diameter, and would have warned NASA about
the
dangers of debris large enough to damage it.
Second, there are "clean" and "dirty" levels
of orbit above Earth. The space
shuttle typically coasts along at 15,000 mph in one of the
relatively clean
levels, close to the atmosphere. At that level, much of the
debris left
behind by earlier space flights or defunct satellites falls into
the
atmosphere and burns up before it can do damage.
"Up higher, things can stay around for hundreds, maybe
thousands of years,"
said a Boeing engineer who works on the international space
station, which
orbits in a higher and much "dirtier" path. The
engineer spoke on the
condition of anonymity. "Down where the shuttle is, things
are kind of
getting sucked into the Earth's orbit like there's a big vacuum
cleaner," he
said.
Finally, if something struck the shuttle with enough force to
ultimately
bring it down, many analysts say NASA, its crew and the craft's
computers
would have known instantly. NASA's test facility in White Sands,
N.M.,
recently conducted a study of the potential impact of space
debris. The
conclusion: A piece of plastic the size of a walnut could tear a
5-inch-wide
hole through aluminum as thick as the Los Angeles telephone book.
In other
words, one analyst said Tuesday, if the shuttle struck something,
"everybody
would know. It would be loud."
"That stuff moves so fast relative to the shuttle,"
said the analyst,
speaking on condition of anonymity.
On the other hand, "there is a lot of debris up there,"
said William Ailor,
president of Aerospace Corp., a nonprofit group in El Segundo
that provides
technical support to the Air Force and studies orbital matter.
After all,
Ailor said, "we've been in space for 40 years."
There are enough pieces of debris in space that some scientists
have
proposed a variety of remedies. Some hope to install robotic arms
on
spacecraft that can grab old satellites and pull them into orbits
where they
can't do any damage.
NASA has had to adjust the flight path of space shuttles at least
eight
times to avoid large pieces of debris, Ailor said. Most of the
debris is
found at extremely high levels of orbit, where satellites are
kept - more
than 250 miles higher than the space shuttle typically flies.
Studies show
that all but 9,000 of the pieces are smaller than a tennis ball,
including
thousands of tiny particles left behind by solid rocket motors.
In addition, there are countless micrometeorites, some of them
smaller than
the diameter of a strand of hair, Ailor said. Most of them are so
tiny that
they can do no damage to a spacecraft as large as a commercial
airplane. One
study showed that a craft that had been in space for more than
five years
was struck by these particles more than 30,000 times, with no ill
effect.
Still, NASA has discovered pockmarks on at least two shuttle
windshields
after the crafts returned safely, Sands said, possibly because of
collisions
with that matter in space. A speck of paint once chipped the
windshield of
the space shuttle Challenger during a mission completed before it
exploded
in 1986. Some have estimated that the speck was traveling 20
times faster
than a bullet travels on Earth.
That sort of matter could weigh just enough to damage a thermal
tile, Ailor
said. And, Sands added, it's possible that a piece of space
debris could
have broken off a satellite or a larger piece of space trash
during
Columbia's 16-day mission, and didn't show up on engineers' maps
until it
was too late. "It could happen," Sands said. "It
is a possibility."
Meanwhile, NASA expanded its search Tuesday for Columbia's
wreckage by
several states.
After scouring the ground for clues in Texas and Louisiana - and
discounting
reports that the shuttle may have begun breaking up farther west
- NASA sent
investigators to California and Arizona when credible reports
surfaced that
pieces of Columbia may have landed there. If the debris proves to
be from
the shuttle, it may offer an early glimpse of what was happening
before
Columbia broke up over Texas.
Michael Kostelnik, the high-ranking NASA official responsible for
the
shuttle and space station programs, said what may prove to be the
wreckage
of the shuttle's main engines has been located in Louisiana.
Heavy pieces,
like the engines, would travel farther after the spaceship broke
up.
Kostelnik said he did not know the location of the reported
debris in
California and Arizona.
"It's not clear what the material is," Kostelnik added.
"We have had some
e-mail correspondence that potentially looks like it could be
either [tiles]
or potentially wing material. If it is wing material, obviously
that would
be very important to the investigation.
"Certainly something that early in the event is most
important," Kostelnik
said.
NASA's main priority for now is to recover the remains of the
astronauts'
bodies, and thereafter to hunt for the most important pieces of
wreckage.
The crew compartment has not been recovered in any identifiable
form,
Kostelnik said, though pieces of it may be in official custody.
Times staff writers Ricardo Alonso-Zaldivar in Washington and
Eric Malnic in
Houston and Nona Yates in Los Angeles contributed to this report.
Copyright 2003, Los Angeles Times
=========
(2) ORBITAL DEBRIS MAY POSE SIGNIFICANT RISK TO THE SPACE SHUTTLE
>From the National Academies, 16 December 1997
http://www4.nationalacademies.org/news.nsf/isbn/0309059887?OpenDocument
Date: Dec. 16, 1997
Contacts: Molly Galvin, Media Relations Associate
Sean McLaughlin, Media Relations Assistant
(202) 334-2138; Internet <news@nas.edu>
Orbital Debris May Pose
Significant Risk to the Space Shuttle
WASHINGTON -- NASA should perform a thorough risk assessment to
determine
the likelihood that the space shuttle could be severely damaged
by
meteoroids and orbital debris, says a new report* from a
committee of the
National Research Council. In addition, the spacecraft should be
re-examined
to identify components that may require additional protection.
"Although NASA is taking steps to protect the shuttle from
orbital debris
such as spent rocket bodies, satellite fragments, and paint
chips, there
still is a real risk that a collision could cripple the shuttle
or threaten
the safety of the crew," said committee chair Frederick
Hauck, president and
chief executive officer, AXA Space, Bethesda, Md. "NASA
needs to obtain a
more precise picture of the potential dangers and assess
additional methods
for reducing these threats."
The most recent examination of overall risks posed to the
shuttle, conducted
in 1995, did not assess the hazards from orbital debris. For some
missions,
the committee said, adding the debris threat to estimates of
potential risks
-- such as the risks during launch or re-entry to the Earth's
atmosphere --
almost doubles the likelihood that the crew will be harmed or
that the
spacecraft will incur major damage. NASA should consider reducing
its
allowable level of risk from orbital debris.
Moreover, the space agency should expand efforts to model the
sources of
debris that could be in the shuttle's orbit. Predictions of risk
for
individual missions may be highly inaccurate -- especially for
estimates of
the number of very small objects, the committee said. Because
debris can
collide with the shuttle at speeds of six miles per second, even
tiny debris
like paint chips can cause considerable damage.
Providing Protection
A complete evaluation of the shuttle's components and subsystems
and their
vulnerability to damage should be performed, the committee said.
NASA should
explore further modifications to hardware that would protect
critical
systems. For example, the agency plans to add shielding to the
shuttle's
radiator system. In addition, NASA should examine whether new
operational
procedures could minimize damage caused by orbital debris.
In-flight
inspections and repairs of the shuttle's exterior should be
considered.
NASA's four operating space shuttles, designed in the 1970s, were
not built
to repel bombardment by orbital debris because such objects were
not
recognized as a substantial threat. New data indicates that the
craft often
is exposed to debris that could cause major damage. For example,
debris as
small as a quarter-inch in diameter could punch a hole through
the wall of
the crew's cabin and cause a loss of air pressure. An object that
punctures
the shuttle's wing could cause structural failure when the
shuttle re-enters
the atmosphere. Even relatively minor damage can require repairs
that add
significant expense and delays.
Avoiding Collisions
NASA routinely moves the shuttle out of the path of debris large
enough to
be tracked by ground-based sensors operated by the Department of
Defense
(DOD). However, estimates indicate that more than 95 percent of
debris that
could critically damage the shuttle is too small to be picked up
by current
sensors. NASA and DOD should work together to improve the
collision warning
system and identify ways to track smaller debris, the committee
said. It
also urged NASA to examine how the shuttle can be protected when
it is used
to support the international space station, scheduled for launch
in 1998.
The study was funded by NASA. The National Research Council is
the principal
operating arm of the National Academy of Sciences and the
National Academy
of Engineering. It is a private, non-profit institution that
provides
independent advice on science and technology issues under a
congressional
charter. A committee roster follows.
==========
(3) PROTECTING THE SPACE SHUTTLE FROM METEOROIDS AND ORIBTAL
DEBRIS
>From Committee on Space Shuttle Meteoroid/Debris Risk
Management, National
Research Council
http://www.nap.edu/catalog/5958.html
The space shuttle orbiter has already been struck many times by
small
meteoroids and orbital debris, but it has not been damaged
severely. There
is a real risk, however, that a meteoroid or debris impact could
one day
force the crew to abort a mission or might result in loss of life
or loss of
the shuttle itself. Protecting the Space Shuttle from Meteoroids
and Orbital
Debris assesses the magnitude of the problem and suggests changes
that the
National Aeronautics and Space Administration can make to reduce
the risk to
the shuttle and its crew.
FULL REPORT at http://www.nap.edu/catalog/5958.html
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