CCNet 117/2002 - 8 October 2002
"Those Representatives who were able to attend the [U.S.
Congressional] hearing were not pleased by some of the responses
they received; while the Representatives were still unclear as to the
depth of exactly what is going on, they showed clear signs that they
understood that NASA's very limited NEO search agenda is placing their
constituents at considerable risk. Even though the Representatives
are heading toward elections in November, as their awareness of the
ineptitude of certain government agencies grows, so does their anger
with them: the Representatives not only have the job ensuring the safety
of those who chose them to represent them, they feel responsible by duty for
their constituents' safety and well being."
--Ed Grondine, 8 October 2002
"Quaoar definitely hurts the case for Pluto being a planet. If Pluto
were discovered today, no one would even consider calling it a planet
because it's clearly a Kuiper Belt object."
--Mike Brown, California Institute of Technology, 7 October
(1) REPORT ON THE FIRST CONGRESSIONAL HEARING OF 2002 ON THE IMPACT HAZARD
E.P. Grondine <firstname.lastname@example.org <mailto:email@example.com>>
(2) NASA STUDY ON ASTEROID-SEARCHING TECHNOLOGY DUE NEXT JUNE
Aviation Now News, 4 October 2002
(3) BILL COULD HELP ASTEROID WATCH
UPI, 4 October 2002
(4) THREAT OF ASTEROIDS WORRIES LAWMAKERS: MEMBERS OF A HOUSE SCIENCE PANEL
UPSET THAT LITTLE IS SPENT ON PROTECTING EARTH.
Orlando Sentinel, 4 October 2002
(5) CONGRESS CONTEMPLATES ASTEROID THREAT
Florida Today, 4 October 2002
(6) ADD KILLER ASTEROIDS TO YOUR LIST OF ANXIETIES
Pittburgh Post-Gazette, 4 October 2002
(7) DISCOVERY THREATENS PLUTO'S STATUS
The Washington Post, 8 October 2002
(8) GOLD STAR CHART POINTS WAY TO GERMAN 'STONEHENGE'
The Sunday Telegraph, 6 October 2002
(9) OCEANIC IMPACT SIGNATURES AND PERMIAN EXTINCTIONS?
Adrian Jones <"firstname.lastname@example.org><mailto:email@example.com>
(10) COMPLIMENTS FOR THOUGHT-PROVOKING CCNET
Rich Kulawiecz <"firstname.lastname@example.org><mailto:email@example.com>
(1) REPORT ON THE FIRST CONGRESSIONAL HEARING OF 2002 ON THE IMPACT HAZARD
>From E.P. Grondine <firstname.lastname@example.org <mailto:email@example.com>>
Hello Benny -
I hope that I may be forgiven the short delay which occurred in sending off
to Conference participants this report on the first Congressional hearing of
2002 on the impact hazard; I returned home on Thursday evening to learn that
a close relative of mine had had a heart attack and died. Uncle "Pud" had
served and fought under Patton in WW2, gone on to a successful career in
business, and was a horseman who was always great fun at the races. As I
write, the preparations for his funeral are underway.
I had earlier hoped not to spend any more at all of my time writing on
events in Washington until the National Science Foundation's independent
impact hazard study was returned to the Congress in mid 2003; but then so
much has changed in the last month. As it is, I expect that that sense of
duty, the one which makes such large demands on so many of us here, will be
requiring yet even more of my time shortly - I suspect that there may
shortly be another hearing on the impact hazard, this for at least two
reasons, if not three.
First, this initial hearing was interrupted by the immediate necessity for
many of the Representatives to discuss the ways of dealing with Iraq's
Saddam Hussein, and as a result many of the Representatives who wished to
attend this hearing were unable to do so.
Second, those Representatives who were able to attend the hearing were not
pleased by some of the responses they received; while the Representatives
were still unclear as to the depth of exactly what is going on, they showed
clear signs that they understood that NASA's very limited NEO search agenda
is placing their constituents at considerable risk. Even though the
Representatives are heading toward elections in November, as their awareness
of the ineptitude of certain government agencies grows, so does their anger
with them: the Representatives not only have the job ensuring the safety of
those who chose them to represent them, they feel responsible by duty for
their constituents' safety and well being.
Third, as I have mentioned before, about 70% of the public wishes that NASA
would spend their money on research of great immediate interest to them,
specifically finding the next piece of stuff to come from space before it
hits the Earth and kills people, rather than spending their money on more
esoteric research of less immediate import. If the event in Russia's north
turns out to be yet another impact (as I write we have not yet heard from
the US Air Force on their reconnaissance satellite data) the US public is
likely to become even more concerned. As the November elections approach, it
will then become likely that several of the Representatives will want to be
seen by their constituents doing their job of trying to help ensure their
safety. Unfortunately, as Saddam's actions prevented many of the
Representatives from doing this at this first hearing, a second hearing on
the failure of NASA's response in dealing with the impact hazard may come
even before the elections in November.
WHAT'S WRONG AT NASA, PART 1: THE CONTINUING SAGA OF ED WEILER'S EFFORTS TO
SANDBAG THE IMPACT HAZARD
The big news from the hearing were the changes in Ed Weiler's efforts to
sandbag any requirement on NASA to deal with the hazard. One month ago there
was in place an independent NSF effort to estimate the hazard, whose report
was due to the Subcommittee in mid 2003, and which would form the basis for
Congressional action; then there appeared an independent parallel NASA
effort at the same, in which Alan Harris was involved, and on which I
reported on less than a week ago; and now there is a joint NRC-NASA report
on the hazard which again is due in June, 2003. This reminds me of the old
Bolshevik trick of setting up parallel structures, structures which then go
on to assume the function of the original structure, the one it is wished to
replace; in this case the structure which Weiler wishes to replace is the
independent NSF assessment of the impact hazard.
It was quite amusing to watch the change in Dr. Weiler's description of this
report which occurred during the course of the hearing. At first Weiler
described the June 2003 study as simply an effort to quantify the threat,
while by the end of the hearing, after close questioning by the
Representatives, Weiler was describing the report as being the basis for
correctly handling the problem once and for all instead of handling it on an
ad hoc piecemeal basis. Amazingly, Weiler made no mention of the fact that
NASA already has in hand a detailed engineering study of solutions for this
problem by Dr. Mazanek of NASA's Langley Research Center, a report which
clearly sets out the capabilities of both free space and Moon based
telescopes for the detection of potential impactors. As it is, there is no
need for any of us here to wait until June 2003 for Weiler's own
conclusions, as they were set out during the hearing itself, and will be
described more fully later on.
At the hearing's beginning, Weiler set forth his position that the entire
search for impactors could be conducted from the ground by the NSF, while
NASA remained focused on "exploration", for which read "manned flight to
Mars". This did not go over too well with the Representatives, and in the
press release following the hearing, Representative Gordon reminded NASA
that one of its "mission statements" was "protecting planet Earth". In any
case, how the hell anyone is supposed to reliably find 100 meter diameter
dark objects in deep space with ground based telescopes is beyond me.
WHAT'S WRONG AT NASA, PART 2: A GIANT FALLS: DR. MORRISON NEGLECTS THE
IMPACT HAZARD PRESENTED BY COMETS
It usually brings on a certain melancholy sadness to watch a pioneer in any
field of research either fall behind the field with age or go off on a bad
tangent of research - all of us realize that if we're lucky, we can be sure
that in the future one or the other of these fates will meet up with us one
day. However, when peoples' lives are put at risk by this rather natural
progression through life, one's feelings must be circumscribed.
Dr. Morrison has been warned many times about the impact hazard arising from
comets, yet he continues to ignore it. I think that this arises in part as a
consequence of the fact that Morrison's original work with Gene Shoemaker
focused on asteroids. For another part, it may derive from Morrison's
involvement with the "Nemesis" hypothesis out of the University of
California at Berkeley: specifically, that there is a massive companion near
our Solar System which amazingly remains both unobserved as well as
undetected, and thus remains entirely imaginary.
For Morrison it is as though Victor Clube and Bill Napier's pioneering work
on comets during the last 20 years never existed, little less all the work
on comets subsequent to it. In the hearing Morrison repeatedly claimed that
the task of locating all of the larger "dinosaur killer" asteroids was well
on its way to completion. Unfortunately, the dinosaurs were killed by a
comet, and we know this because the carbonaceous chondritic remains of at
least one comet if not two separate comets have already been recovered.
Morrison failed to mention that as Clube and Napier predicted in 1991, comet
impact has been implicated in nearly all of the extinction level events, and
that these extinctions may even occur with a chaotic regularity (on a 26
million year cycle), that is whenever the Earth and the rest of our Solar
System passes through the plane of our galaxy, the Milky Way.
As for the smaller impact events, the city killers and continent destroyers,
Morrison's efforts to put an end to Velikovsky's rubbish during the 1950's
has rather hopelessly blinded him to most evidence of the "smaller" impacts
events. For Morrison these impacts occur at a rate about 10% of the rate
which is actually observed.
While the initial Congressional request to NASA in 1994 specifically
included finding 1 kilometer and larger comets, both Morrison and Weiler
continue to ignore them. As Brian Marsden pointed out at the very end of the
hearing, they had failed entirely to discuss comets - and I add, they had
thus nearly completely misled the Representatives as to the degree of the
impact hazard, and instead had presented it as being about 1/3 to 1/10 as
large as it actually is.
The consequences of Morrison's failure to account for impacts by comets in
the June 2003 NRC-NASA study are likely to be severe as well. Since
Morrison's old studies had used extremely limited crater counts for the Moon
which had been completed during Project Apollo, and had then attributed all
of the craters solely to asteroid impact, and found agreement with estimated
populations of asteroids, if this work is used it will clearly corrupt the
report in its entirely.
Put simply, since Morrison feels that he has accounted for all the impact
craters solely by the impacts of asteroids, the impacts of comets do not
exist for him. Morrison continues to hold this position even though it is
now widely known that the impact of comets comprises the largest part of the
total impact hazard. Given the results of the first hearing, perhaps the
next Congressional hearing will focus specifically on the way that NASA has
responded to their request to locate potentially impacting comets of 1
kilometer diameter and larger.
WHAT'S WRONG AT THE NRC: WEILER TRIES TO FIND A NEW ALLY FOR HIS SANDBAGGING
EFFORT: JOSEPH BURNS OF THE NRC
Sadly, the independent view was supposedly represented at the hearing by
Joseph Burns of the National Research Council. Given Burn's repetition of
the NASA 50% completion claim for large asteroids in his opening testimony,
and his general failure to mention the impact hazard arising from comets,
there is little doubt that he is yet another astrophysicist with a very
limited understanding of the impact hazard in real terms.
Here the hearing represented a break for Weiler, as Wayne van Citters from
the NSF was not invited to testify at it. I'm quite sure that the
Representatives would have been most interested in hearing van Citters'
account of how Weiler simply informed him one Monday morning that the
Areceibo radar observations of asteroids were now the NSF's, and
specifically his, responsibility. Instead, Burns was allowed to attack the
NSF ("The solar system exploration community is concerned that the NSF is
often unwilling to to fund solar system research. This is particularly
unfortunate given that the NSF charter to support the best science and its
leadership role in other aspects of ground based astronomy.") without
allowing van Citters the opportunity to reply. Burn's statement here was
also particularly unfortunate in that it did not touch on two of the issues
which were immediately at hand, the first being the extraordinarily large
sums of money which NASA itself spends each year on other solar system
research, and the second being the rather complete lack of money NASA spends
on finding chunks of stuff in space before they hit the Earth and kill
Burns' opening testimony made but a passing mention of the use of space
based telescopes, pointing to an earlier claim that airborne and orbital
telescopes would only play a supplemental role in the search. The problem is
that we know that objects down to even 75 meters in size present a real
hazard in the real world, and that dark objects of this size simply can not
be found with ground based telescopes. Of course, space based telescopes
for impactor detection could be NASA's responsibility in their entirety, and
as we have seen before Weiler is doing all he can to avoid this
Burns spoke glowingly about the Large Scale Synthetic Aperture Telescope,
telling the Subcommittee that it would cost some $125-150 million total
including 5 years operating costs. This is strange, as the NSF cost
estimates for the LSST, which had previously been reported in the press, are
at least $170 million, not including some $20-30 million per year in
operating costs. Burns spoke glowingly about the astrophysical other uses to
which the LSST could be put besides that of impactor detection.
THE REPRESENTATIVES' QUESTIONS: SOMETHING'S NOT QUITE RIGHT HERE, BUT WHAT
I am constantly amazed at the analytical abilities of our representatives in
both the House and the Senate - they often deal with highly technical and
abstruse topics such as the impact hazard and can almost instantly determine
when someone is b***sh****** them. They can do this even when dealing with
highly skilled senior officials, who have developed their talents in
obfuscation with decades of practice, and even when distracted by other
pressing matters such as madmen intent on using weapons of mass destruction.
Oft times the Representatives from the southern part of the United States
will draw out the person being interrogated with introductory self
denigrating comments such as, "Well now, I hope you can excuse me, Doctor,
as I'm just a country boy who made good, but doesn't..." Having watched this
before, it was really a pleasure to watch Rep. Wenner of New York develop an
entirely new northern variant of this tactic with his, "Look, I may not be
the sharpest tool in the shed, but it seems to me..." Ahh, but no fools are
elected to the Congress, and if they are, they do not remain there long.
SURF'S UP: CHAIRMAN ROHRABACHER'S CONCERN ABOUT THE HAZARDS OF IMPACT
The line of questioning on mega-tsunami was started by Rep. Rohrabacher, who
as acting chairman jumped in when Morrison confidently stated in his opening
testimony that no survey of mega-tsunami caused by the oceanic impact of
200-400 meters objects had been done within the community. This is a
statement which I'm sure Dr. Bryant and the other geologists who have indeed
studied these mega-tsunami will find quite surprising. Morrison also made no
comment regarding mega-tsunami caused by comet impact, a phenomena which the
decimation of the Olmecs pretty well testifies to. As it was, Morrison
provided Rohrabacher with an opening to begin questions about the survey of
the smaller objects, and when general questioning came later, the other
Representatives poured through the breach which Rohrabacher opened.
Morrison replied to Rohrabacher that "a number" of these smaller objects
(read "asteroids") had already been found. Closer to the truth is Marsden's
short answer that about 1,800 of the 300 meter to 1 kilometer sized
asteroids have been found so far out of the total estimated population
40,000 to 50,000 of them, and about 400 of these asteroids are found each
year with the current facilities. This means that with the current ground
based facilities NASA will find all of the asteroids down to 300 meters
within the next 100 years, say right around the year 2,100 AD. It is certain
that most 100 meter (Tunguska class) asteroids would be missed by this, as
would the majority of the 200 meter asteroids; simply no one knows how much
warning time this would provide of any comet's approach.
Brian Marsden and Pete Worden both did their usual excellent jobs in their
opening testimony in setting forth their needs and concerns. Marsden made
his quite request for a few more staff so that he and his colleagues could
stop working 80 to 120 hour weeks, as they have been doing for a year now.
Worden reported that officials from NASA and the Department of Defense would
meet in the week following the hearing, and that dealing with the NEO hazard
would be on their agenda. While Worden has proposed using the Air Force
satellites which surveil geosynchronous orbit for NEO detection as well, in
the same manner in which the Air Force's GEODSS ground based telescopes are
used for the LINEAR NEO survey, I do not know whether or not this would
represent a sufficient and adequate solution for the problem of dealing with
the hazard presented by either 100 meter to 300 meter objects (Tunguska
class to Great Wall of Water class impactors) or long period comets. My
guess is that a large dedicated space telescope is going to be necessary at
a minimum; from Dr. Mazanek's studies, while a space based telescope might
be adequate, it is certain that man tended Moon based facilities would be
best, particularly in giving the earliest warning of the approach of
dinosaur killer class comets.
MORRISON GOES DOWN
Worden saw this system using military satellites as coming into existence
within 10 years, and all of this may have something to do with Morrison's
blunt refusal to answer a direct question by Representative Gordon on the
value of the use of space based platforms for NEO detection. First Morrison
begged off answering by claiming that he was a NASA employee. Gordon then
asked him as a scientist, and Morrison again refused to answer. Gordon asked
Morrison again. This time, in closing his refusal to answer, Morrison noted
that "other US agencies" (read "the Air Force") have capabilities in this
regard. At this, Gordon noted that Morrison was of no use to them, which was
taken by most as a joke and met with laughter. Sadly, the impact hazard is
no joke, and neither was Gordon's observation on Morrison's usefulness in
dealing with it.
THE NRC'S JOE BURNS BAILS OUT
At this point Joseph Burns from the NRC realized the way the winds were
blowing, and he bailed out, noting that the wording of the NASA founding
legislation would appear to specifically make dealing with the impact hazard
their responsibility, and that they should do whatever it took to deal with
whatever was coming in. I don't know what to make of this change of his from
his prepared testimony, other than to note that Burns is certainly a fellow
who is firm in his confusion.
WORDEN TO PARTICIPATE IN WEILER'S JUNE 2003 REPORT
In his reply to Representative Gordon, Pete Worden revealed that he would be
the Department of Defense's representative in the June 2003 report - but
amazingly Worden identified the National Science Foundation as a participant
in this report, instead of the NRC, as Burns claimed earlier.
WEILER REFUSES TO PROVIDE FINANCIAL SUPPORT FOR THE LSST
In his response to Representative Gordon, Weiler tried to equate finding the
next potential impactor with every other ground based telescope space
science task which he has ever dealt with. I don't see how this is possible,
as I am almost certain that none of these earlier science projects of his
represented matters of life and death.
Gordon then asked Weiler who he thought should be responsible for the ground
based NEO search, and Weiler replied that that was the National Science
Foundation. Given this reply, it is indeed unfortunate that the National
Science Foundation's Wayne van Citters was not also invited to testify at
this hearing. Of course, it is likely that he probably will be invited to
the next one.
A FALSE SHELTER OFFERED AND TAKEN: THE USES OF ASTEROIDS (AND COMETS)
In an attempt to defuse the tension following Gordon's questions,
Rohrabacher raised the topic of the opportunities which asteroids may
present. Conspicuously absent from Rohrabacher's list of the uses of comets
and asteroids was their possible use as impactors to free the volatiles held
in Mars' mantle. While this has happened before naturally, it seems likely
that it may be possible to make Mars much more suitable for human use though
the simple tactic of diverting either asteroids or comets into its surface.
The use of 1999 KY26 as a natural cycler vehicle for manned Mars flight may
also present itself as an opportunity, but all of this is depends on first
being able to divert these things away from the Earth.
Weiler took advantage of the temporary respite that Rohrabacher offered,
bringing up the $1,600,000,000 that NASA is spending on characterizing the
physical properties of asteroids and comets. Since this effort is about the
only part of the total hazard solution which NASA has handled correctly, I
suppose it would be churlish not to give Carl Pilcher, Wesley Huntress, and
Ed full credit for this. That said, I am not quite sure that knowing exactly
what it was that hit you is going to be of much comfort to those who survive
the next fatal impact event.
If you're going stop them from hitting, you're going to have to find them
first, and this includes both asteroids and comets. Rohrabacher immediately
returned Weiler to the topic of the underfunding of the Minor Planet Center.
>From this Rohrabacher proceeded to the simple fact that no organization for
regular continued work on mitigation studies exists.
CUTTING THROUH THE BS: REPRESENTATIVE WENNER OF NEW YORK: "I'M NOT CONCERNED
ABOUT THE ONES THAT ARE GOING TO MISS ME..."
Representative Wenner's district encompasses the mouth of the Hudson River,
the coastal barrier of Long Island, and island of Manhattan, all areas
particularly susceptible to impact mega-tsunami caused by the impact of 100
to 300 meter diameter objects which NASA is regularly failing to detect.
Wenner's questions on impact mega-tsunami occurred late in the meeting,
after he had finally been able to tear himself away for a few minutes from
the pressing business of what to do with Saddam.
Wenner's questions were right to the point, as were his suggestions. Wenner
wanted to know why NASA had not detected the 75 meter 2002-MT7 until after
it had passed between the Earth and the Moon. He was not satisfied by
responses that the system was working: Wenner rightly considers these very
close Near Earth Objects to be somewhat similar to potential terrorists, and
he would like NASA to know exactly where they are.
Rep. Wenner also very correctly suggested that an analysis of how the
failure to detect 2002-MT7 occurred would lead to the improvement of NASA's
system for detecting approaching Near Earth Objects. In ordinary
circumstances this suggestion would make great sense, but unfortunately
Wenner was not aware that NASA has absolutely no system in place for
reliably detecting small menacing objects. Indeed, NASA can only but barely
locate the largest asteroids, those which present little threat, and quite
likely never did, as it has usually been comets and smaller asteroid
fragments which have hit the Earth; further, the only reason NASA can even
"do" this is because they are able to claim credit for the Air Force's
LINEAR program, which to date have found about 90% of all of these
asteroids. (This last is the work of Grant Stokes.)
Why did Wenner not understand that no warning system exists at all? This is
quite understandable, as stupidity on such a scale by responsible government
officials is simply beyond imagining. Of course, so was flight training for
pilots who did not want to learn how to take off or land.
Wenner was relentless in his questions, and the best that Morrison could
finally offer him was that now they were finding some of them, while before
they missed all of them. I doubt if Wenner was particularly pleased by this
improvement in performance. I also wonder what Wenner's reaction is going to
be when someone actually tells him about NASA's non-existant program for
detecting approaching hazardous comets. I do know that I certainly want to
be around for the fish fry which will occur when that happens.
NO NEED TO WAIT UNTIL JUNE 2003: ED WEILER'S PLAN OF INACTION
In one of his replies to Wenner, Pete Worden also asserted that the Air
Force would build space telescopes capable of doing part of the job, a slip
which should be of great interest.
There would seem to be no need to wait until June 2003 for the NASA-NRC
report. Weiler plans to hand off the ground based part of the asteroid
survey to the NSF, who are supposed to take full responsibility for the
LSST, and he plans to hand off the space based part of the asteroid survey
to the Air Force, who will augment their surveillance satellites to perform
the space based part of the job. As Weiler considers that this will be
sufficient to deal with the impact hazard, you may be sure that any estimate
of the hazard which he produces will be adjusted to fit this remedy.
No one has bothered to ask Weiler yet how he plans to handle impacting
comets, which was mentioned before constitute nearly all of the extinction
level event ("dinosaur killer") hazard, and more than 50% of the small
impact hazard. Perhaps they'll be asking his successor. Though Weiler is
currently in charge of funding the physical study of both comets and
asteroids, he seems to be oblivious to the simple facts concerning the
relative roles of asteroids and comets as part of the total impact hazard.
Weiler stated that the current large asteroid search would provide better
estimates as to the size of the population of 100 meter to 1 kilometer sized
impactors, and also mentioned that his team for the June 2003 report
includes experts in this.
Unless Weiler is funding new crater counts for Mars for his report, which is
about the only data which will clarify the estimates of both the total
population of small asteroids as well as the total population of small
fragments of comets, his claims are nonsense and will continue to be
nonsense. Though I currently know of no usable work being done on crater
counts of the new Mars imagery, the appointment of Scott Hubbard as the
Director of NASA's Ames Research Center should be noted, as Hubbard is quite
fully aware of the impact problem in nearly all of its aspects.
REPRESENTATIVE BARTLETT: EXACTLY HOW BIG ARE THE WAVES OF THOSE
Representative Bartlett of Maryland joined with Rohrabacher in his concern
about the mega-tsunami waves which ocean impact will produce. Morrison
cautioned ahead of time about his estimate, and then relied on formula for
wave size and tried to hint that 500 foot (say 200 meter) diameter impactors
would produce 50 foot waves. This quickly defaulted to 1,000 foot waves, and
the committee determined that for an Atlantic impact the people living in
Pittsburgh, Pennsylvania would be safe, though the fate of those living in
Scranton, Pennsylvania would be uncertain. Of course, Maryland would be
Bartlett went on to ask about the travel time of the waves, and when given
the estimate of 2 and 1/2 hours warning, noted that it had taken him 5 hours
to leave Washington after the attack last September. Bartlett was quite
right here: with only but a few more hours warning, millions of peoples
lives could be saved by the simple act of evacuation.
THE NEXT HEARING ON THE IMPACT HAZARD
In closing down the hearing, Rohrabcher waxed poetic about the next panel on
the impact hazard, which he envisioned happening 5 years from now. I don't
think it is going to be that long: if Representatives Boehlert or Hall want
a crack at Weiler, five weeks might be more likely; on the other hand, both
the NSF and NASA-NRC reports are due shortly, and June 2003 is only some 8
months from now.
As Rohrabacher he tried to close the hearing, Marsden interrupted him to
point out that they had not talked about the impact threat arising from long
period comets at all, and that everything which they had discussed had
pertained only to asteroids. This started a new line of inquiry, and using
Hale-Bopp as an example, Marsden estimated that as it currently sits we
would have about 2 years to save ourselves. I suppose that's better than
what the Hurrians had, which was 28 days.
Weiler immediately added that his June 2003 report would include the hazard
presented by long period comets, and stated that this report would do it
right one time, instead of piecemeal. Well then, being the nice guy that I
am, I can save Weiler and everybody else some 8 months of work here: all
they need to do in that case is simply to order up copies of Dr. Mazanek's
study and present the options to the Congress: either pay for large free
space based telescopes, or pay for large Moon based telescopes. Nothing
That's the bottom line, as well as my last one here for today. In closing
this summary, it is important to note that Representative Rohrabacher is
working with Senator Nelson of Florida in moving the Pete Conrad Bill
through the Senate, and this in combination with the possible Russian impact
may lead to a Senate hearing on the impact hazard occurring soon.
Oh well. I suppose if they hold a hearing, I'll have to drive up the
interstate highway once again to cover it.
Your very tired correspondent,
(2) NASA STUDY ON ASTEROID-SEARCHING TECHNOLOGY DUE NEXT JUNE
>From Aviation Now News, 4 October 2002
By Marc Selinger/Aerospace Daily
NASA's Office of Space Science has assigned a group of scientists to
determine what technology is needed to expand the search for asteroids and
other objects that could collide with Earth.
Edward Weiler, associate administrator for space science at NASA, testified
before the House Science space subcommittee Oct. 3 that he expects to
receive a report from the group, or Science Definition Team (SDT), in June
NASA already has taken steps to find near-Earth asteroids (NEA) with
diameters of 1 kilometer (.62 miles) or more, so the SDT study will
determine whether the technology exists to search the skies for NEAs as
small as 300 meters. The possibility of looking for comets also is being
Although an asteroid with a diameter of about 5 to 10 kilometers wiped out
the dinosaurs and 99 percent of life on Earth 65 million years ago, NASA
already has determined that no asteroids of that size are a threat to the
In addition, NASA's Spaceguard Survey has found 619 of the estimated 1,000
or so NEAs that are 1 kilometer or larger and could collide with Earth. NEAs
of that size still "would likely threaten civilization," Weiler said. NASA
hopes to find 90 percent of those NEAs by the end of 2008.
But due to several factors, including technical limitations of existing
telescopes, NASA is not searching for NEAs smaller than 1 kilometer, even
though such asteroids have the potential to cause huge devastation. Joseph
Burns, a professor of astronomy and engineering at Cornell University,
testified that there is a 1 percent chance that a 300-meter object will
collide with the Earth in the next century. The human death toll from such a
collision would be about 100,000.
David Morrison, senior scientist at NASA Ames Research Center, Calif., said
there are an estimated 50,000 NEAs that have a diameter of 300 meters or
more. Most of those have not been found.
Large telescope urged
Burns, a member of the National Academies' Solar System Exploration Survey,
said the survey recommended that NASA and the National Science Foundation
build a ground-based Large-aperture Synoptic Survey Telescope (LSST) to find
90 percent of all near-Earth objects (NEOs) down to 300 meters in diameter.
Costs would include $83 million to build the telescope, $42 million to
provide data processing and distribution for five years, and $3 million a
year for routine operating costs.
But Weiler said it is premature for NASA to endorse such an approach. He
said the agency needs to address such issues as whether two smaller
telescopes would be better than one, and whether a space-based system would
be a better option. NASA also wants to explore whether a threshold besides
300 meters makes more sense.
Air Force Brig. Gen. Simon "Pete" Worden, deputy director for operations at
U.S. Strategic Command, who stressed he was testifying as a scientist and
not a representative of the Defense Department, said building a set of
three-meter diameter telescopes that could scan the entire sky every few
weeks would allow the U.S. to catalog NEOs as small as 100 meters or less.
U.S. and Canadian officials are discussing the possibility of jointly
developing a microsatellite that could, among other things, search for NEOs
near the sun, where they are hard to find, Worden said.
The Space Based Space Surveillance System (SBSS) system, a constellation of
larger satellites that the Air Force is developing to track satellites, also
could help search for NEOs.
Before trying to divert asteroids that threaten Earth, more information will
be needed about their internal structure, according to Worden. With the
emergence of microsatellites, missions costing $10 million each could be
carried out to "sample many types of NEOs in the next decade or so to gain a
full understanding of the type of objects we face," he said.
Copyright A9 2002 Aviation Week
(3) BILL COULD HELP ASTEROID WATCH
>From UPI, 4 October 2002
By Scott R. Burnell
UPI Science Correspondent
>From the Science & Technology Desk
WASHINGTON, Oct. 4 (UPI) -- Legislation that creates financial incentives
for amateur astronomers to locate and track large celestial debris capable
of striking Earth would be welcomed by professional astronomers, according
to testimony presented on Capitol Hill.
The federal government needs more effective efforts to locate and track
potentially dangerous near-Earth objects, said Rep. Dana Rohrabacher,
R-Calif., chairman of the House Science Subcommittee on Space and
Aeronautics. Within just the past year, he said, three asteroids showed some
possibility of striking Earth.
"We should not take comfort in the fact these asteroids missed us, because
in astronomical terms they missed by a hair," Rohrabacher said. "We need to
clearly understand the future goals of a national NEO policy in terms of
cost, technical know-how and technology to meet the challenge of finding,
monitoring and mitigating (these objects)."
One piece of Rohrabacher's agenda, H.R. 5303, the "Pete" Conrad Astronomy
Awards Act, passed the House on a voice vote earlier this week. The bill,
named for the third man to walk on the moon, would reward amateur
sky-watchers who either spot new large NEOs -- as the near-Earth objects are
called -- or help track previously identified ones, helping free up more
advanced equipment to spot smaller but still-dangerous solar system
Although amateurs occasionally spot comets and rarely spot asteroids,
encouraging their activities makes sense, said Brian Marsden, director of
the Smithsonian Institution's Minor Planet Center. NEO surveys need all the
assistance they can get -- the MPC's operations, while highly automated,
only have three staff members, Marsden told the subcommittee.
"The part of the Pete Conrad Award ... for follow-up observations should
actually be more (encouraging)," Marsden said. "It should also be noted
there are better prospects for amateur discoveries in the Southern
Hemisphere, because of the absence of professional surveys there."
Most NEO discussions cover objects larger than 100 meters (about 325 feet)
in diameter and their ability to cause continental or even global
catastrophes. The most immediate threat, however, comes from smaller objects
impacting the atmosphere and exploding with enough force to resemble nuclear
detonations, said Brig. Gen. Pete Worden, vice director of operations at the
U.S. Air Force's Space Command.
One such impact occurred over the Mediterranean Sea early this past June,
Worden said, when new nuclear powers India and Pakistan were exchanging
sporadic gunfire over the disputed Kashmir region. If the blast, one of the
largest military sensors have ever seen, had occurred over Southwest Asia,
it might have triggered a nuclear exchange before U.S. or other agencies
with sophisticated sensors could have announced the true cause, he said.
"There is considerable synergy related to man-made satellites and global
security requirements related to NEO impacts," Worden told the subcommittee.
"Adding a modest number of people, probably (fewer) than 10, to current
early-warning centers and supporting staff within (the complex in Colorado
at) Cheyenne Mountain could form the basis of an Natural Impact Warning
Although the National Aeronautics and Space Administration is nearing
completion of a congressionally mandated survey of all NEOs larger than a
kilometer in diameter, official efforts in this area need more support, said
subcommittee member Rep. Anthony Weiner, D-N.Y.
"For too long we've assumed that the worst asteroid risk would come from
Hollywood, in the form of a sequel to flops like "Deep Impact" or
"Armageddon," Weiner said. "If we can plow $100 million into a summer flick,
we can certainly give NASA the means to make us safer from real-life
Copyright A9 2002 United Press International
(4) THREAT OF ASTEROIDS WORRIES LAWMAKERS: MEMBERS OF A HOUSE SCIENCE PANEL
UPSET THAT LITTLE IS SPENT ON PROTECTING EARTH.
>From Orlando Sentinel, 4 October 2002
By Gwyneth K. Shaw | Sentinel Staff Writer
WASHINGTON -- Asteroids and other space flotsam -- some of it big enough to
cause chaos and destruction here on Earth -- are whizzing through and around
the Earth's orbit, but the government isn't spending much money to keep tabs
on the stuff and has no way to prevent a direct hit.
At a congressional hearing Thursday on the threat to the planet from large
objects flying close to home, a panel of experts and government officials
stressed that the chances of a major asteroid striking are small.
But the potential for eventual trouble is great, said Joseph Burns, an
engineering and astronomy professor at Cornell University who testified
before the House science subcommittee.
"This is a real threat with devastating consequences," he said "There's a
small threat of this occurring in our lifetimes, but it's an inevitable
U.S. Rep. Dana Rohrabacher, who called the hearing, and others on the panel
were not appeased by learning that scientists probably could warn of an
impending collision years, if not decades, in advance. They were upset that
there isn't a plan to defend the planet against such a collision.
Rohrabacher made a joking reference to the 1998 film Armageddon, in which
Bruce Willis blasts into space to destroy an asteroid hurtling toward Earth.
But the California Republican got serious quickly.
"I don't believe that Bruce Willis is going to be contacted and save us at
the last minute," Rohrabacher said. "I think it's up to us. . . . There's
not going to be any last-minute savior out there."
For more than three years, the National Aeronautics and Space Administration
has been working to complete a census of asteroids in near-Earth orbit that
are larger than six-tenths of a mile in diameter -- large enough to envelop
the planet in dust for months, potentially causing the collapse of society.
So far, more than 600 have been detected, and a group of scientists is
monitoring their positions.
Of equal concern, however, are smaller asteroids -- big enough to take out a
city or cause a devastating tidal wave, but not currently part of NASA's
"I think it's very important to go down to 200- or 300-meter objects,
however it is done," said Brian Marsden, an astronomer at the Smithsonian
Astrophysical Observatory and director of the Minor Planet Center.
Marsden and Burns support a larger ground-based telescope that would make
the smaller objects easier to catalog.
"We could do it with the existing structure, but it would take a century,"
But tracking smaller objects, developing a defense system and beefing up
detection of interplanetary interlopers will cost money -- and neither NASA
nor the military is clamoring to come up with the cash.
NASA is spending $1.6 billion on the large-object survey [uh-huh... let's
say less than $4 million, BJP], which is done with telescopes on the ground.
Whether it's NASA, the Air Force or the National Science Foundation that
finally takes the reins, Rep. Bart Gordon, D-Tenn., said, someone should
"Clearly, somewhere, we have to draw a line and determine what can be done
cost-effectively, versus the risk," Gordon said.
Gwyneth K. Shaw can be reached at firstname.lastname@example.org or 202-824-8229.
Copyright A9 2002, Orlando Sentinel
(5) CONGRESS CONTEMPLATES ASTEROID THREAT
>From Florida Today, 4 October 2002
By Larry Wheeler
Gannett News Service
WASHINGTON -- In the 1998 science-fiction film "Armageddon," a heroic Bruce
Willis saved Earth from a marauding asteroid by detonating a nuclear device
at the last possible second.
The explosion vaporized Willis' character and split the killer space rock
into twin boulders that harmlessly whizzed past the planet. Humanity lived
to see another sunrise.
In real life, a solution to the threat of civilization-ending death from
above must wait until Congress, NASA, and the Air Force figure out what they
are going to do next.
NASA, the nation's civilian space agency, has mapped all the really big
asteroids, roughly10 miles in diameter, zipping around the solar system and
concluded that none poses a collision risk. If one did hit, it would cause
extinction equivalent to the asteroid strike believed to have wiped out the
dinosaurs 65 million years ago.
Pesky smaller asteroids, more than half a mile in diameter, also concern
scientists because a head-on collision with one would distress the climate
enough to depress global temperatures, cause massive crop failure and
possibly break down civil society as we know it.
The good news: NASA has identified and calculated the orbits of 619 of these
rocks, known as Near Earth Objects, and none is on course to collide with
the home planet.
The bad news: 300 to 700 more undiscovered travelers could be lurking in the
The other bad news: Neither NASA nor the Air Force has plans or equipment to
divert an incoming asteroid or comet like they do in the movies.
"When I go to my leaders and talk about something that happens every 100
million years, they feel that is something we can defer from this year's
budget," said Brig. Gen. Simon Worden, deputy director for operations with
the U.S. Strategic Command.
Worden was one of several government officials who testified Thursday at a
House subcommittee hearing on the threat near Earth asteroids pose.
"It's just a matter of time before we're faced with an event unparalleled in
human history," said Rep. Dana Rohrabacher, R-Calif., who organized the
hearing and repeatedly expressed his fear that the sky might fall on his
Southern California congressional district.
The truly disturbing news from the hearing: Space rocks keep hurtling by
Earth only to be detected after they pass. This year alone, three previously
unknown asteroids sped past. The closest was one-third the distance to the
Moon, a hair's width in astronomical terms.
Worden also warned lawmakers of another near calamity.
On June 6, U.S. early warning satellites detected an energy release in the
atmosphere comparable to the Hiroshima atomic bomb. A small asteroid,
probably less than 6 miles in diameter, exploding over the Mediterranean
caused the event.
Had the asteroid exploded over India or Pakistan, two nuclear powers on the
brink of war at that time, the event could have ignited a nuclear horror
because neither country has the sensors to differentiate between a near
Earth object detonation and a nuclear weapon, Worden said.
While U.S. satellites can detect the difference, the Air Force now has no
way of sharing that information with other countries, he said.
Copyright A9 2002 FLORIDA TODAY.
(6) ADD KILLER ASTEROIDS TO YOUR LIST OF ANXIETIES
>From Pittburgh Post-Gazette, 4 October 2002
While most members of Congress were debating a possible war to disarm Iraqi
leader Saddam Hussein, a House of Representatives panel spent yesterday
morning worrying about even greater weapons of mass destruction -- killer
"Objects out in space could be heading toward Earth that would make Saddam
Hussein look like a minor factor in our lives," Rep. Dana Rohrabacher,
R-Calif., chairman of the House Subcommittee on Space and Aeronautics, said
of the danger posed by such huge rocks whizzing by our planet.
Experts from NASA, the Air Force and the National Academy of Sciences told
the subcommittee that the threat from asteroids, while remote, needs to be
Currently, the U.S. government is spending less than $4 million a year to
detect dangerous asteroids and figure out what to do about them. The
subcommittee's witnesses urged a substantial increase.
So far, 619 so-called "near Earth objects" more than a half-mile in diameter
have been spotted under the Spaceguard program that Congress ordered in
None of these objects is as big as the 10-mile-wide monster asteroid that
crashed into what is now Mexico's Yucatan Peninsula 65 million years ago,
wiping out 90 percent of existing species, including dinosaurs. But any one
of the 619 would cause enormous devastation.
Air Force Brig. Gen. Simon Worden, vice director of operations of the U.S.
Space Command at Peterson Air Force Base, Colo., pointed out another current
Worden noted that a very small asteroid, less than 10 yards across, exploded
in the atmosphere over the Mediterranean Sea on June 6, releasing as much
energy as the atomic bomb at Hiroshima. If the flash had occurred a few
hours earlier, over India or Pakistan, either of those two nuclear powers
could have suspected an attack and launched its atomic weapons.
"The resulting panic in the nuclear-armed and hair-triggered opposing forces
could have been the spark that ignited a nuclear horror we have avoided for
over a half century," Worden said.
Copyright 2002 PG Publishing Co.
(7) DISCOVERY THREATENS PLUTO'S STATUS
>From The Washington Post, 8 October 2002
By William Harwood
Astronomers have discovered a small, cold world in the hinterlands of the
solar system, orbiting even farther from the sun than distant Pluto.
Though too small to be considered a planet, the 800-mile-wide object,
tentatively dubbed Quaoar (KWAH-o-ar), is the largest body discovered in
Earth's solar system since Clyde Tombaugh spotted Pluto 72 years ago.
Located about 4 billion miles from the sun, and about 1 billion miles beyond
Pluto, the object is also the farthest body in the solar system ever to be
seen by a telescope.
This latest addition to the sun's known family of planets, moons, asteroids
and comets takes 288 years to complete one orbit.It's in the Kuiper Belt, a
vast swarm of icy, comet-like debris left over from the formation of the
solar system and extending 7 billion miles behind the orbit of Neptune.
The discovery of Quaoar is yet another blow to Pluto's status as a planet,
something that astronomers have increasingly questioned in recent years. It
is, many now believe, simply one member of the Kuiper belt.
"Quaoar definitely hurts the case for Pluto being a planet," Mike Brown, a
professor of planetary science at the California Institute of Technology,
said in a statement. "If Pluto were discovered today, no one would even
consider calling it a planet because it's clearly a Kuiper Belt object."
The debate about Pluto's planetary status has even been chronicled in the
song "Planet X" by Christine Lavin, a cult favorite among astronomers:
Saint Christopher is looking down on all this and he says, "Pluto, I can
relate. When I was demoted from sainthood, little buddy, it didn't feel too
And Scorpios look up in dismay because Pluto rules their sign. Is now
reading their daily horoscope just a futile waste of time?
Quaoar is about half the size of Pluto, but about as big as all the known
asteroids put together. It is believed to be made up mostly of ice, mixed
Quaoar is too new to have been officially named by the International
Astronomical Union, but its discoverers, Brown and postdoctoral student
Chadwick Trujillo, proposed naming it after a creation god of the Native
American Tongva tribe, the original inhabitants of the Los Angeles basin.
The discovery of Quaoar was announced yesterday at a meeting of the Division
of Planetary Sciences of the American Astronomical Society in Birmingham,
Brown and Trujillo found the distant object in a digital image taken June 4
by a 48-inch telescope atop Mount Palomar in California. They then examined
archived photographs and found the body in images taken as early as 1982.
Analyzing changes in the position of the object in the current and archived
photographs, they calculated the distance to Quaoar, and determined that its
orbit is remarkably circular and that it is tilted just 7.9 degrees from the
plane of all the other planets except Pluto.
It takes Pluto 248 years to complete one orbit. But Pluto's orbit is tilted
17 degrees to the plane of the other planets and it is highly elliptical,
the result of ancient gravitational interactions. For a small part of each
orbit, Pluto is actually closer to the sun than Neptune.
Quaoar, however, orbits in a near circle, never approaching the sun and
undergoing the slight heating that Pluto periodically experiences. Quaoar is
believed to be rotating and it reflects about 10 percent of the light that
falls on it.
While the object shows up as a point of light in the 48-inch telescope used
by Brown and Trujillo to discover it, NASA's Hubble Space Telescope has been
able to resolve Quaoar's disk, allowing astronomers to measure its diameter
at roughly 800 miles.
Prior to the discovery of Quaoar, the previous record holders for the
largest Kuiper Belt objects were Varuna and a bodycalled 2002 AW197, each
approximately 540 miles across (900 kilometers).
Brown said the discovery of Quaoar implies other bodies of similar size or
even larger are probably lurking in the Kuiper Belt.
For Lavin, the fate of Pluto is not just idle talk. The neck of her brand
new hand-made guitar features a technically accurate, inlaid solar system.
The builder told her he would add another planet, free of charge, if one is
discovered in his lifetime.
"He didn't say anything about [removing it] if Pluto was demoted," Lavin
A9 2002 The Washington Post Company
(8) GOLD STAR CHART POINTS WAY TO GERMAN 'STONEHENGE'
>From The Sunday Telegraph, 6 October 2002
By Tony Paterson in Berlin
Archaeologists in Germany believe that they have discovered the world's
earliest accurate depiction of the cosmos embossed in gold on a
3,600-year-old Bronze Age disc. They believe that it might also lead them to
the site of a German "Stonehenge".
The disc adds to a growing body of evidence about the Bronze Age in Europe
which is causing historians to revise radically their understanding of the
period. Until recently the era was considered to have been relatively
Scientists are beginning to discover, however, that Bronze Age man was a
highly adept astronomer whose religion was intrinsically linked to the
The disc bearing elaborate gold leaf images of the sun, 32 stars, and a
crescent moon, was found three years ago at the site of a Bronze Age camp
near the town of Nebra in east Germany, but the results of tests on its
authenticity were only published last week.
The disc, valued at A36.4 million, was uncovered by a group of people using
metal detectors who had kept their discovery secret. Seven members of the
group are under investigation in connection with the theft of ancient
objects from the state of Saxony-Anhalt, on whose land the disc was
The police set a trap for the group in February by luring its members to
meet what they believed to be a prospective buyer in the basement of the
Hilton hotel in Basle, Switzerland.
The disc was handed to scientists at the Institute for Archaeological
Research in Halle where it has been studied and subjected to carbon data
The archaeologists had kept the discovery a secret for most of this year to
prevent treasure hunters from searching the Nebra site.
Announcing the find last week Harald Meller, the institute's director, said
"It is without doubt the earliest genuine depiction of the cosmos ever to
have been discovered. It suggests that the site where it was found almost
certainly functioned around 1600bc as an astronomical observatory, like
Stonehenge in Britain."
The first henge on the site of what is now Stonehenge in Wiltshire was just
a large earthwork probably built around 3100bc and abandoned soon after. It
was not until 2150bc, archaeologists believe, that the second and most
impressive stage of Stonehenge began with the transportation of the stones
from the Prescelli mountains in south-west Wales.
Mr Meller said that although an earlier impression of the cosmos dating from
2400bc was found in Egypt, it was the invention of an artist and not an
accurate depiction of the night sky. The painting was found in the burial
chamber in the pyramid of the Egyptian pharoah Unas, which is decorated with
Earlier this year German archaeologists revealed that a series of golden
cones decorated with astrological symbols that had been found at sites
across Europe, were in fact ceremonial hats, worn by Bronze Age "wizards" or
Photographs of the disc were published in Germany last week. They show a
round shield-like bronze plate covered in verdigris as a result of being
buried underground for thousands of years. Yet the 12-inch diameter disc
clearly bears the images of what is either the sun or a full moon, a
crescent moon and the horizon embossed in gold.
The plate is also studded with 32 stars, but most significant according to
the archaeologists, is a group of objects thought to be the Pleiades star
cluster, which appear at the time of the autumn equinox.
"During the Bronze Age the Pleiades were considered a heavenly sign which
signalled the approach of autumn," said Wolfhard Schlosser, an astronomer at
Bochum University who is researching the disc.
"The arrival of the stars in the night sky showed that it was time to start
bringing in the harvest."
The disc suggests that the European Bronze Age was also influenced by
ancient Egyptian culture. A curved scythe-like object at its base is thought
to represent the "sun ship" that the pharoahs believed pulled the stars
through the heavens.
Mr Schlosser said that the disc was most probably one of a pair. "The other
disc may yet be found at the Nebra site and if our assumptions are correct,
it most likely depicts the heavens during the spring equinox. Both would
have been used for religious and agricultural purposes to see into the
future," he said.
The scientists believe that the disc was originally smeared with rotten
eggs. These would have caused a chemical reaction on its bronze surface,
which would have turned the disc's background a deep violet colour
simulating a night sky out of which the gold-embossed stars would have
Mr Meller and his team are currently excavating the 750ft-high Mittelberg
hill near Nebra where the disc was found. The site was originally thought to
have been a simple Bronze Age camp, however the archaeologists are now
convinced that it was used as an astronomical observatory and a temple in
which the disc or discs played a central role.
They point out that the images on the disc correlate exactly with what they
have calculated to have been the view of the night sky from Mittelberg hill
during the Bronze Age.
Nebra's 3,000 residents are following the archaeologists' progress with rapt
attention. They hope that what was hitherto a run-down east German backwater
will soon be turned into a tourist attraction featuring the "German
A9 Copyright of Telegraph Group Limited 2002.
* LETTERS TO THE MODERATOR *
(9) OCEANIC IMPACT SIGNATURES AND PERMIAN EXTINCTIONS?
>From Adrian Jones < "email@example.com>
The debate over the PT boundary and possible role of an oceanic impact shows
just how little we know about oceanic impacts; about one dozen oceanic
impact craters are now known, all being in what is, or was, continental
shelf, except for one which is truly oceanic (Eltanin). In the
absence of groundtruth, the following ideas might be useful.
Oceanic crust mineralogy is traditionally estimated by comparison with
ophiolite sequences; ultramafic rock, gabbros and basalts dominate. Quartz
is rare, especially away from continental slopes. Therefore it is true that
one would expect oceanic impacts to be essentially devoid of the
mineralogical indicator shocked quartz. Furthermore, although oceanic crust
contains other minerals potentially susceptible to shock effects, primary
mineral assemblages are largely dominated by plagioclase feldspar, which
transforms to glass (maskelynite) and is unlikely to survive hydrothermal
alteration. Potential mineral indicators of oceanic impact derived from the
target oceanic crust, could include spinels, perhaps with nickel-bearing
and chromium-bearing varieties (Robin et al 2000), and spherules. Because
oceanic crust is so thin (5-10 km) relative to continental crust (30-50 km),
the underlying oceanic mantle must also be considered as target material (eg
if the Vredefort crater had formed instead in oceanic crust, it would be
floored by oceanic mantle!). Most mantle minerals (olivine, pyroxenes,
garnet, spinel, plagioclase) when shocked to high-P, transform to metastable
phases or glass, or may, (depending on geothermal gradient) simply melt due
to their high initial temperatures. Any hot minerals and glass would then be
highly susceptible to seawater alteration, to secondary hydrous minerals.
Thus, the likelihood of resistant minerals with distinctive shock features
to survive over geological time from an oceanic impact, is substantially
lower than for a continental impact. Geologically old fractured impacted
oceanic terrains might show extensive hydrous mineral development.
In our recent paper (Jones et al EPSL (2002) 202, 551-561), we explore the
hypothetical scenario of a terrestrial impact sufficiently large to
auto-obliterate by triggering massive volcanism. Auto-obliteration of all
impact craters >>200 km on Earth might explain their anomalous absence
compared with the terrestrial planets. The critical size to trigger massive
decompression melting would depend on lithospheric architecture and
geothermal gradient. We propose that examples might include the Ontong Java
Plateau (oceanic) and the Siberian Traps (continental). Though, as Koeberl
et al stated (CCNET 19.09.02), impact volcanism has never been demonstrated
to operate, our indicative model leads us to believe that it has been
incorrectly dismissed and hugely underestimated (with some notable
exceptions, eg: Green 1972, Rogers 1982, Glikson 1999). For larger oceanic
impacts, glassy materials should include lower silica compositions, compared
to continental impact glasses. We emphasise that all criteria established
for large terrestrial impacts to date, are restricted to craters in
continental crust, which have undergone some brittle failure and not
penetrated the crust. We have no comparable criteria for a large impact,
which punctured oceanic crust and mantle, though this must have occurred,
and may, we conjecture, have propagated a mantle hotspot. Indeed we further
propose that the thermal anomaly of the induced mantle hotspot, could be so
substantial and long lived as to resemble a conventional mantle plume, or
impact plume (I-plume). Furthermore, we do not know how the morphology of
such a large oceanic impact crater might be further modified through the
massive melting event and the transfer of these melts to the surface.
It would therefore seem premature to discount a large oceanic impact at the
PT boundary, as proposed by Kaiho et al (2002). Extreme partitioning between
nickel and iron is found in microscopic metallic meteoritic debris from
Meteor crater, but the metallic grains reported by Kaiho et al (2002) need
further study to determine whether or not they are extraterrestrial. To test
if our impact volcanism model could apply to the Emeishan lavas, we would
predict the location of ground zero to be close to the maximum original
thickness of the lavas, which might not require an oceanic impact, or a
separate one. This Chinese Emeishan event would represent a separate impact
from that possibly responsible for the Siberian traps a few million years
later. To call for two or more closely spaced large impacts is not a
problem, but might be more difficult to explain with conventional mantle
plume-driven volcanic models.
If impact volcanism can be shown to have operated, the coupled effects of
large impact(s) combined with prolific volcanism obviously provide a rich
double pallette of potential kill mechanisms for extinction scenarios, such
as during and at the end of the Permian era.
Glikson (1999) 27, 387-390
Green D (1972) Earth Planet Sci Lett 15, 263-270
Jones A P et al (2002) Earth Planet Sci Lett 202, 551-561
Kaiho K et al (2001) Geology 29, 815-818
Rogers GC (1982) Nature 299, 341-342
Dr Adrian P Jones
(RL Hayman Reader In Petrology)
Department of Geological Sciences
University College London
Tel: 0207 679 2415/2408
Fax: 0207 387 1612
website: www.ucl.ac.uk/geolsci/research/petrology <http://www.ucl.ac.uk/geolsci/research/petrology>
(10) COMPLIMENTS FOR THOUGHT-PROVOKING CCNET
>From Rich Kulawiecz < "firstname.lastname@example.org> <mailto:email@example.com>
Thank you very much for switching my address over. And let me take a moment,
if I might, to also say thank you for running a wonderfully informative
service. I don't always like the news I read or agree with the viewpoints --
but if I did, then there would be little point in reading it, would there?
No, the best thing about this mailing list is when it brings me news I don't
like or viewpoints I disagree with -- because that's when it makes me
*think*. And, I hope, it helps me to learn.
So, thank you for running a terrific Internet resource!
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