PLEASE NOTE:
*
CCNet 59/2001 - 24 April 2001
-----------------------------
"No one knows how many impacts took place, or when, or with
what
severity, over the past 5 million years. But we know very little
about
specific impacts in this time frame, and virtually nothing at all
about their actual environmental effects. [There is] no evidence
of
an impact associated with a hominid extinction."
--David Morrison, NASA Ames Research Center, 24 April 2001
"The findings by Peiser and Paine are underpinned by a
significant
number of large impact craters. So far, 32 impact craters have
been
discovered that are younger than 5 million years. One is 32 miles
(52
kilometers) in diameter, three are between 6 and 12 miles (10 and
20
kilometers), one is between 3 and 6 miles (5 and 10 kilometers)
and 25 are
less than 3 miles (5 kilometers) in diameter. However, it should
be
noted that it takes very unusual conditions to preserve craters
of
this size for more than a few hundred thousand years."
--Space.com, 24 April 2001
"But regardless of whether cosmic messengers helped make us
who we
are, there is one thing researchers seem to agree on: Given the
evidence that our ancient ancestors were clustered in a
relatively
small area (in Africa) you are somewhat lucky to be reading about
all this.
"Asteroids certainly had the opportunity to wipe out man at
his
roots," said Jack G. Hills, an asteroid specialist at Los
Alamos
National Laboratory. "Only good luck prevented it."
--Robert Britt, Space.com, 24 April 2001
(1) REINVENTING DARWIN AGAIN: HOW ASTEROIDS IMPACTED HUMAN
EVOLUTION
Space.com, 24 April 2001
(2) HUMAN EVOLUTION PUNCTUATED BY COSMIC IMPACTS
SpaceDaily, 24 April 2001
(3) MYSTERY BOOM ROCKS EASTERN AUSTRALIA: AN ATMOSPHERIC IMPACT?
Ron Baalke <baalke@jpl.nasa.gov>
(4) MICRO-METEOROID IMPACTS DAMAGE LEONARDO'S INAUGURAL MISSION
Space.Ref, 23 April 2001
(5) THE LYRIDS METEOR SHOWER OF 2001
Rainer Arlt <rarlt@aip.de>
(6) NEW EVIDENCE FOR A LARGE PALAEOPROTEROZOIC IMPACT
Chadwick B, Claeys P, Simonson B
(7) NEW EVIDENCE FOR RAPID AND SYNCHRONOUS COLLAPSE OF ECOSYSTEM
AT P-TR
BOUNDARY
Twitchett RJ, Looy CV, Morante R, Visscher H,
Wignall PB
(8) A PLAUSIBLE CAUSE OF THE LATE HEAVY BOMBARDMENT
Morbidelli A, Petit JM, Gladman B, Chambers J
(9) GRONDINE'S MISREPRESENTATIONS
Duncan Steel <D.I.Steel@salford.ac.uk>
(10) PLANETARY NOMENCLATURE
Jon Richfield <richfield@telkomsa.net>
(11) VERY EXPENSIVE TELESCOPE TO LOOK FOR EXTRA-SOLAR PLANETS
Michael Paine <mpaine@tpgi.com.au>
(12) AND FINALLY, SOME GRUESOME NEWS: "THATCHER'S REMAINS TO
LIGHT UP THE
NIGHT SKY"
The Guardian, 21 April 2001
===============
(1) REINVENTING DARWIN AGAIN: HOW ASTEROIDS IMPACTED HUMAN
EVOLUTION
From Space.com, 24 April 2001
http://www.space.com/searchforlife/human_evolution_010424.html
By Robert Roy Britt
Senior Science Writer
In the 5 million years or so that it took for apes to become
human, many
human-like branches of the evolutionary tree were lopped off.
Scientists
have long wondered why these other hominid species, estimated to
number a
dozen or more, didn't make it.
Were those who came to travel to the Moon and ponder their very
origin the
logical and inevitable victors in the most important of all
Darwinian
struggles?
Or did we just get lucky?
A newly presented mathematical argument suggests that the birth
of Homo
sapiens was guided by catastrophic asteroid or comet impacts,
which created
climate conditions that competing species, frankly, couldn't
handle.
It also holds that our human ancestors avoided early elimination
by the
statistical skin of their rotting teeth.
"The reason that Homo sapiens have survived in spite of
these global
disasters has little to do with the traditional explanations
given by
neo-Darwinists," said Benny Peiser, a social anthropologist
at Liverpool
John Moores University. "It is sobering to realize that we
are alive due to
cosmic luck rather than our genetic makeup."
Peiser bases his argument on the fact that populations of
hominids and early
modern humans were extremely small. "Had any of these
impacts occurred in
the proximity of these population groups, we might also have gone
the way of
the dodo," he said.
The study's assumptions and calculations have met with strong
caution and
even sharp criticism among scientists who specialize in
evolution, as well
as asteroid experts.
Adaptive advantage
David Balding, a professor of applied statistics at University of
Reading in
the U.K., said the idea that human survival is due to
"cosmic luck" does not
compute:
"Perhaps we were lucky in avoiding a massive impact, but
perhaps it was our
adaptive advantage that helped us survive modest regional impacts
whereas
our hominid cousins did not," said Balding, whose own
research focuses on
human evolution.
But some called the new scenario plausible. It has not been
published in a
peer-reviewed journal but it is based on impact estimates that
are generally
accepted by the asteroid research community, though there are
disagreements
over the precise number of times a large asteroid or comet has
struck our
planet.
Peiser laid the idea out earlier this month at a conference,
"Celebrating
Britain's Achievements in Space." He worked with Michael
Paine, a volunteer
for the Planetary Society in Australia who ran impact scenarios
through a
computer program. (Paine has written freelance stories for
SPACE.com in the
past.)
The researchers concluded that there would have been 20
"globally
devastating" impacts during the past 5 million years, with
effects strong
enough to have had "a catastrophic and detrimental
effect" on human
evolution. Five million years ago is roughly the time when
hominids diverged
from other apes, though some recent controversial evidence puts
the split as
far back as 6 million years ago.
Did space rocks set the human stage?
No one argues that asteroids can be devastating when they tangle
with Earth.
An impact 65 million years ago is widely believed to have spurred
the demise
of the dinosaurs and many other animals and plants.
But efforts to tie other, more ancient mass extinctions to
impacts remain
inconclusive. While extinctions are clearly identifiable in
fossil records,
impact evidence seems not to survive the millennia as well. So
impact
estimates are based largely on the Moon -- a nearby archive of
countless
craters that have not eroded much over time.
Still, because scientists have not witnessed a severe impact, the
presumed
effects are speculative.
If an asteroid larger than a kilometer (0.6 miles) hit the
planet, it would
cause instant death across a wide area near the site of impact,
and
researchers generally agree that drastic climate changes could
last a year
or more. Even our protective ozone layer could be damaged,
studies have
shown.
But the precise consequences of these effects are not known. It
is thought
that long-term climate change could make life impossible for many
species,
which in turn would cause mass death that might move up entire
food chains.
Peiser suggests another possible effect: "The abrupt loss of
the ozone layer
and the sudden release of toxins may even affect the DNA in some
unknown
manner, thus triggering macro-mutations, including the sudden
reorganization
of entire genomes."
Ellen Thomas, a Wesleyan University research professor who
examines how
climate change affects evolution, said few evolutionists would by
this
argument of quick, significant changes in the genetic blueprints.
Instead,
macro-mutations are seen by many as a genetic dead end.
"Macro-mutations can hardly ever lead to evolution,"
Thomas said. "They lead
to non-viable organisms."
Basic numbers questioned
Of course to affect human evolution in any fashion, a space rock
first has
to hit Earth. But "no one knows how many impacts took place,
or when, or
with what severity, over the past 5 million years," said
David Morrison, an
asteroid expert at NASA's Ames Research Center in California.
Morrison told SPACE.com that instead of the 20 potentially
devastating
impacts assumed by the study, he expects there were probably only
five or 10
with enough energy to create global environmental effects.
"But we know very little about specific impacts in this time
frame, and
virtually nothing at all about their actual environmental
effects," Morrison
said, adding that there is "no evidence of an impact
associated with a
hominid extinction."
Morrison did not discount the whole idea, however.
"I would be surprised if impacts had not had some influence
on early hominid
populations and perhaps evolution," he said. "On the
other hand, I am not
convinced that impacts led to numerous extinctions in the past 5
million
years. This is all interesting speculation, but specific data are
lacking on
either impacts or extinction events and there is no known
correlation
between the two."
Peiser counters that the estimates used in the study are
"very
conservative." He acknowledges that shortcomings in the
human fossil record
(fossils on land erode more easily than those in the oceans)
"are far too
big to allow any direct correlation between impact catastrophes
and hominid
extinction." But he said that the study shows that
"impact catastrophes that
occurred during the crucial period of human evolution should no
longer be
ignored."
Still, it is clear that more research will be needed before any
consensus
emerges.
"What [Peiser and Paine] may have added," said Balding,
the statistics
professor, "is some quantitative simulations to make more
precise some well
established speculations."
Speculation about evolution is nothing new. And the more one
delves into the
nitty-gritty of our own past, the stronger the criticism gets
over Peiser's
attempt to reinvent Darwin.
Does Darwin need reinventing again?
If asteroid experts are sometimes a mile apart on their view of
history --
and they are -- then evolutionary theorists live on different
continents.
Followers of Charles Darwin have long believed that failed
branches of our
ancestry reflect a common mode of evolution, whereby species are
gradually
replaced by more advanced species that adapted because of their
superior
genetic fitness.
But in recent decades, a different view called punctuated
equilibria has
taken hold. This theory, first put forth in the 1970s by Stephen
J. Gould
and Niles Eldredge, expects sharp changes in evolution.
In either scenario, luck plays a role. And both fit within the
most famous
of Darwinian themes, survival of the fittest. But the rapid
shifts assumed
in punctuated equilibria, be they caused by sudden disasters or
other means,
are thought to be the mechanism by which one species replaces
another.
"There has been debate for over 100 years on whether
evolution is gradual or
punctuated," said Balding.
And the debate continues. Recent fossil findings have some
researchers
leaning back toward the gradual approach to human evolution.
Peiser said his study supports punctuated equilibria, and helps
explain why
"almost all hominids, i.e. the 14 known species of human
ancestors, have
become extinct during the last 5 million years."
But Wesleyan's Ellen Thomas said it is not even known that there
were 14
species.
"The human fossil record is incomplete, and it is not easy
to agree on which
fossils belong to different species," Thomas said in an
e-mail interview.
"The experts disagree wildly."
Thomas echoed other scientists in pointing out that there is no
fossil
evidence -- neither of human remains in Africa nor marine
organisms, which
leave a much more complete record -- that reveal any mass
die-offs during
the 5 million-year period covered in Peiser's study.
"And if the extinctions affected humans, they should show up
in the
extinction record of other organisms as well," Thomas said.
"The paper just
shows that many impacts, many of which could have been damaging,
possibly
occurred."
But Peiser argues that no expert on near-Earth asteroids, the
space rocks
known to exist in our region of the solar system, questions that
"many such
global disasters must have occurred." Yet he said "all
textbooks on human
evolution completely ignore the occurrence of catastrophic
impacts."
Other forces of evolution
While Peiser and Paine suggest that comets or asteroids are a
driving force
behind evolutionary change, it is the climatic consequences of
impacts that
are the would-be crushing mechanisms for fledgling species. Other
researchers have long debated possible links between climate
change and
human evolution.
For example, cold periods are suspected of forcing migrations
that created
small, isolated groups that could have evolved significantly but
then died
out. One such period may have occurred as recently as 71,000
years ago. But
firm links between climate and serious evolutionary changes elude
researchers.
One recent international study, released earlier this year and
led by Jeremy
Marlow of Newcastle University, showed evidence of a significant
cooling of
the climate 2 million years ago that the authors said "adds
weight to the
theory that climate change played a significant part in the
evolution of
early humans."
Further clouding the possibilities, recent findings have hinted
at the
possibility that the worst extinctions might require multiple
killing
mechanisms, such as when an impact, or perhaps several, happens
to occur
during a time of heavy volcanic activity.
Irony in our existence
In an ironic preface to the whole argument, it's possible that
asteroids and
comets were responsible for life in the first place. A growing
movement
among astrobiologists suggests that rocks from space brought
critical
building blocks that stimulated the initial biological activity
in the
earliest primordial soup billions of years ago.
But regardless of whether cosmic messengers helped make us who we
are, there
is one thing researchers seem to agree on: Given the evidence
that our
ancient ancestors were clustered in a relatively small area (in
Africa) you
are somewhat lucky to be reading about all this.
"Asteroids certainly had the opportunity to wipe out man at
his roots," said
Jack G. Hills, an asteroid specialist at Los Alamos National
Laboratory.
"Only good luck prevented it."
----------------------------------------------------------------------------
----
The following details of the new idea were provided by Benny
Peiser and
Michael Paine and appear here with only minimal editing for style
and
clarity:
The findings are calculated on the basis of the generally
accepted "impact
rate" (i.e. the rate of cosmic impacts calculated from
terrestrial and lunar
impact craters together with the currently observable flux of
asteroids and
comets in the solar system). A computer simulation of cosmic
impacts over a
5 million-year period was chosen to give an indication of the
environmental
disruptions that have occurred during the evolution of our
species.
These consequences can be categorized into:
A. Local -- devastation over a radius of tens of (miles)
kilometers. No
serious regional or global consequences
B. Moderate regional -- devastation over a radius of hundreds of
miles
(kilometers) -- the size of a small country. Short-term regional
climatic
problems.
C. Severe regional -- devastation over 600 miles (1,000
kilometers) (the
size of a large country). Severe regional climatic disruption.
Mild,
short-term global climatic disruption -- year without summer.
D. Moderate global -- devastation over thousands of miles
(kilometers) --
continental. Severe global climate disruption lasting several
years. Global
food chain failures
E. Severe global -- global firestorms from ballistic entry of
impact debris.
Extreme worldwide climate disruption for decades to centuries.
Extinctions.
For everything except the last category, the effects on early
human
populations depend on proximity to the impact -- a matter of
luck. In
addition to climate disruption (mainly darkness and cooling), the
larger
impacts could lead to global warming due to the greenhouse effect
(water and
carbon dioxide), loss of the ozone layer (particularly with ocean
impacts
that propel chlorine into the upper atmosphere), acid rain and
toxins.
The simulation looked at the worst event in each of 5,000
millennia. It
therefore gives an underestimate of the total number of impacts.
The program recognizes five outcomes of an asteroid or comet
colliding with
Earth:
The object skims the atmosphere and flies harmlessly back into
space. This
happened in 2 percent of the millennia.
The object explodes above land in an airburst similar to an
atomic
explosion. This happened in 17 percent of the millennia.
The object impacts the land and forms a crater. This happened in
11 percent
of the millennia.
The object explodes in an airburst above an ocean. This was the
most
frequent outcome, accounting for 41 percent of millennia.
Fortunately, until
recently, most of these impacts would have been harmless to land
dwelling
creatures.
The object impacts the ocean, forming tsunami and, possibly,
ejecting vast
quantities of water and salt into the atmosphere. This happened
in 28
percent of the millennia. (Larger impacts may also reach the
ocean floor and
cause similar effects to a land impact)
Over the period of the simulation some 57 percent of millennia
suffered an
impact that would potentially have consequences for land-dwelling
creatures.
In most cases they would only be affected when they were close to
the impact
site. The situation is different now with significant human
populations
living in low-lying coastal areas.
Size impactor (The letters refer to the typical environmental
consequences.)
1,650 to 2,950 feet (500 to 900 meters) (C): 108 events
0.6 to 0.9 miles (1 to 1.5 kilometers) (C/D): 24 events
1 mile (1.6 kilometers +) (D/E): 13 events
Craters (The letters refer to the typical environmental
consequences.)
Over the 5,000 millennia a total of 552 craters were formed on
land. Of
these:
477 were less than 3 miles (5 kilometers) in diameter (A);
64 were between 3 and 6 miles (5 and 10 kilometers) in diameter
(B);
nine were between 6 and 12 miles (10 and 20 kilometers) in
diameter (C);
two were more than 12 miles (20 kilometers) (D).
There were also six ocean impacts that could be expected to
produce
moderate-to-severe global climate disruption (D/E), particularly
destruction
of the ozone layer. Three of these involved transient craters
more than 31
miles (50 kilometers) in diameter and would probably have
penetrated to the
ocean floor.
Therefore, during this simulation severe climate disruption
occurred, on
average, every million years (i.e., two land impacts and three
ocean
impacts).
The findings by Peiser and Paine are underpinned by a significant
number of
large impact craters. So far, 32 impact craters have been
discovered that
are younger than 5 million years. One is 32 miles (52 kilometers)
in
diameter, three are between 6 and 12 miles (10 and 20
kilometers), one is
between 3 and 6 miles (5 and 10 kilometers) and 25 are less than
3 miles (5
kilometers) in diameter. However, it should be noted that it
takes very
unusual conditions to preserve craters of this size for more than
a few
hundred thousand years.
SEE ALSO: TIME LINE OF HUMAN EVOLUTION
http://www.space.com/php/multimedia/imagedisplay/img_display.php?pic=h_human_evolution_010424_02.gif
Copyright 2001, Space.com
=======
(2) HUMAN EVOLUTION PUNCTUATED BY COSMIC IMPACTS
From SpaceDaily, 24 April 2001
http://www.spacedaily.com/news/asteroid-01e.html
================
(3) MYSTERY BOOM ROCKS EASTERN AUSTRALIA: AN ATMOSPHERIC IMPACT?
From Ron Baalke <baalke@jpl.nasa.gov>
From The Courier Mail, 20 April 2001
http://www.thecouriermail.com.au/common/story_page/0,5936,1912401%255E3102,00.html
Boom shakes, but fails to stir quake sensor
Staff reporters
20apr01
THOUSANDS thought it was an earthquake, others thought it was a
bomb.
Buildings shook, windows rattled, dogs howled.
There were no report of damage, but a mystery boom that rocked a
142km
stretch of the coast in south-east Queensland left lots of
worried residents
in its wake.
Earthquake sensors did not register a disturbance, even though
the 15-second
"boom" hit thousands of homes between Buderim and North
Stradbroke Island.
Earthquake monitoring centres were flooded with calls that a
tremor had hit
just after 3.30pm, but no damage was reported.
Last night the RAAF admitted that one of its F-111s had gone
supersonic east
of Ballina in NSW. But they played down the chances that the jet
was cause
of the boom.
RAAF Wing Commander Rob Lawson said the F-111, flying at 160m,
finished its
manoeuvre 100km off the coast at Beenleigh.
He said he could not rule out the possibility that the jet had
caused the
"tremor". But "we go supersonic there all the time
and people in Brisbane
don't ever notice it," he said.
Air traffic control agency Airservices Australia said last night
there was
an area of air space off the coast where military aircraft were
permitted to
fly faster than sound.
Spokesman Richard Dudley said while that area did not extend as
far north as
Bribie Island, it was possible given certain weather and wind
conditions
that the sound of a sonic boom might travel some distance.
"However, that would not explain vibrations people reported
experiencing,"
Mr Dudley said.
Relieving Moreton Island ranger Scott Rogers said he was in his
office when
the whole building began to shake.
Stradbroke Island resident Mark Davis said his TV shook and his
dogs bolted
when the plane flew over his home yesterday at Point Lookout
yesterday.
"The dogs were sitting on the loungeroom floor and they
freaked, jumped up
and took off out the door," Mr Davis said.
Bongaree resident Darren Jellick said he felt an "enormous
shudder and heard
a loud bang" while working at Bribie Island. "It was
the sort of sound you
hear when a military bomb blows up," he said.
Bribie Island's Rod Bennett was shaken from sleep.
"I was sure someone was trying to break into the house. It
was a really
violent shaking of the windows, I thought they were going to
break," Mr
Bennett said.
Copyright 2001, The Courier Mail
==========
(4) MICRO-METEOROID IMPACTS DAMAGE LEONARDO'S INAUGURAL MISSION
From Space.Ref, 23 April 2001
http://www.spaceref.com/news/viewnews.html?id=327
Photos of Two Minor Debris Impacts Leonardo MPLM Suffered on its
Inaugural
Mission
By Keith Cowing
These pictures were taken of the Leonardo MPLM (Multi-Purpose
Logistics
Module) at NASA KSC after it returned to Earth from its first
mission.
Leonardo is one of three MPLM's provided by Italy and was flown
to the
International Space Station last month on mission
STS-102/ISS-5A.1.
These photos show micrometeoroid damage to a
micrometeoroid/orbital debris
(MMOD) shield panel from MPLM FM1 (Leonardo). The panel was
penetrated in
two spots (the small pinholes in the photos), but did not damage
the
multi-layer insulating blanket beneath. This module was in space
for about a
week.
The strike damage to Leonardo's MDPS (micrometeorite protection
system) is
characteristic of other impacts that have been seen on
spacecraft. However,
the size of particle that penetrated the shield was a bit larger
than
average and was estimated to be traveling rather fast - at least
10
kilometers/second - when it struck Leonardo.
To put this impact into perspective, had this piece of space
debris hit a
Space Shuttle window it would have left a crater approximately 1
inch (2.5
cm) in diameter. If it had hit a someone wearing an EVA spacesuit
it would
have gone partially through the suit and left a bruise on the
person wearing
the suit.
Impacts such as these two are routine for any spacecraft in Earth
orbit. The
Long Duration Exposure Facility (LDEF) which spent 5.7 years in
Earth orbit
had been struck more than 20,000 times by the time its was
brought back to
Earth. The Hubble Space Telescope had nearly 800 impacts by the
time it was
repaired in 1997.
How much debris a spacecraft can expect to collide with - the
orbital debris
flux - is a function of mission duration, the size and
orientation of the
spacecraft (how big of a target it is), the orbital inclination,
altitude,
and the level of solar activity.
Components of the International Space Station are provided with
shielding so
as to reduce the annual risk that impact with a space debris
could cause a
critical failure to less than 0.5% This shielding is also sized
to last
through the expected 15 year operational lifetime of the ISS.
Last year, it was discovered that the Service Module did not have
sufficient
shielding to meet requirements levied upon it by the ISS program.
As such,
additional shielding panels will be delivered and installed on
the exterior
of the Service Module.
Copyright © 2001 SpaceRef Interactive Inc. All rights reserved.
===========
(5) THE LYRIDS METEOR SHOWER OF 2001
From Rainer Arlt <rarlt@aip.de>
-------------------------------------
I M O S h o w e r C i r c u l a r
-------------------------------------
LYRIDS 2001
Very favourable lunar conditions made this shower a highlight
target of
2001. Occasionally heightened activity is observed from the
Lyrids, most
notably in 1982. The 2001 maximum exhibited a slightly enhanced
level of
activity. Observations from 49 observers were collected by April
24, 0h UT.
Such a large number of observations monitoring a shower of
moderate activity
is a fairly nice success of amateur meteor observing. The table
of the
activity graph is given below.
The maximum is broad; highest rates are found near a solar
longitude of
lambda = 32.0 deg with ZHR = 33+-3. The first peak at lambda =
31.7
comprises a number of novice observers
who may have underestimated their limiting magnitudes.
Nevertheless, the
up-and-down or -- more roughly speaking -- the general plateau
shape of the
activity profile appears to be a typical feature of the 2001
Lyrids. This
was already found in recent Lyrid activity profile. This year,
the plateau
may extend over as much as 24 hours. ZHRs in 2000 were lower, 20
at best, in
1999 near 30 as this year, but again significantly lower in 1998
with values
below 20.
-------------------------------------------------------
2001 Time
Sollong nObs nIND
nLYR ZHR
Apr (UT) (J2000)
-------------------------------------------------------
17 0620
27.295
2 1
0 3 +-3
19 0600
29.237
1 1
0 7 +-7
20 0130
30.030
1 1
3 3 +-2
20 2200
30.864
6 2
13 5 +-1
21 0140
31.013
8 5
30 8 +-1
21 1800
31.678
8 7
85 37 +-4
21 2130
31.820 18
13 155 28 +-2
21 2320
31.894 13
13 67 18
+-2
22 0000
31.922 10
10 128 28 +-2
22 0100
31.962 14
12 117 19 +-2
22 0230
32.023 10
10 90 33
+-3
22 0900
32.287
8 5
54 27 +-4
22 2130
32.795
3 2
19 24 +-5
23 2200
33.791
2 2
7 8 +-3
-------------------------------------------------------
We are very grateful to the following observers for their efforts
and quick
reporting of data:
ANTDU Dusan Antic
(Serbia)
MENHU Huan Meng (China)
ARLRA Rainer Arlt
(Germany)
MILAA Ana Milovanovic (Serbia)
BASLU Luc Bastiens
(Belgium) MISKO
Koen Miskotte (Netherlands)
BETFE Felix Bettonvil (Netherlands) MODAM Amruta
Modani (India)
BHANE Neha Bhandari
(India)
NISMA Markku Nissinen (Finland)
BHASU Sushrut Bhanushali (India)
PATSO Sonali Patil (India)
DECGO Goedele Deconink (Belgium)
PEEBJ Bjorn Peeters (Belgium)
DEOPA Parag Deotare
(India)
PRAMA Mayuresh Prabhune (India)
DUBAU Audrius Dubietis (Lithuania) PUNNI Nilesh
Puntambekar (India)
FANYU Yuwei Fan
(China)
RENJU Juergen Rendtel (Germany)
GADSH Shirish Gadkar
(India) SAVBR
Branislav Savic (Serbia)
GEOPE Petros Georgopoulos (Greece) SONWA
Wanfang Son (China)
GEYBE Benny Geys
(Belgium)
SUNHU Huiming Sun (China)
GLIGE George Gliba
(USA)
TRIJO Josep Trigo-Rodriguez (Spain)
GOLDA Darja Golikowa
(Germany) TUKAR Arnold
Tukkers (Netherlands)
HASTA Takema Hashimoto
(Japan) UCHSH Shigeo Uchiyama
(Japan)
JOHCA Carl Johannink (Netherlands) VELKR
Kristina Veljkovic (Serbia)
KULMA Manali Kulkarni
(India) VERJN Jan
Verbert (Belgium)
KULRH Rhikesh Kulkarni
(India) VUJKA Katarina Vujic
(Serbia)
KULVI Vineet Kulkarni
(India) VUJRO Romana
Vujasinovic (Serbia)
LANMA Marco Langbroek (Netherlands) WANSH Shuo Wang
(China)
LINMI Mike Linnolt
(USA)
WISJE Jean-Marc Wislez (Belgium)
LUNRO Robert Lunsford
(USA) ZERZO
Zorana Zeravcic (Serbia)
MARAN Antonio Martinez (Venezuela) ZHUJI Jin
Zhu (China)
MCBAL Alastair McBeath
(UK) ZUPLJ
Ljubica Zupunski (Serbia)
Solar longitudes refer to equinox J2000.0. nObs is the number of
individual
observing periods, nIND is the number of individual observers
providing
them, nLYR is the number of Lyrids seen. The radiant position was
assumed at
alpha=271, delta=+34, the population index used was r=2.9. The
expectation
value of the ZHR,
ZHR = (1 + sum
nLYR) / sum(Teff/C),
was used for the averages here, where Teff is the effective
observing time
and C is the total
correction composed of limiting magnitude, clouds, and zenith
correction.
Times are rounded to
the nearest 10 minutes.
Rainer Arlt & Vladimir Krumov,
2001 April 24
==============
* ABSTRACTS *
==============
(6) NEW EVIDENCE FOR A LARGE PALAEOPROTEROZOIC IMPACT
Chadwick B, Claeys P, Simonson B: New evidence for a large
Palaeoproterozoic
impact: spherules in a dolomite layer in the Ketilidian orogen,
South
Greenland
JOURNAL OF THE GEOLOGICAL SOCIETY 158: 331-340, Part 2 MAR 2001
An unconformable sedimentary succession deposited between c.
2130-1848 Ma on
Archaean gneisses of the foreland of the Palaeoproterozoic
Ketilidian orogen
includes a layer with coarse sand-sized silicate spherules. The
layer is c.
1 m thick and consists mainly of coarse diagenetic dolomite. In
addition to
c. 18% spherules, the layer also contains 3% well-sorted, very
fine
quartzose sand and 6% larger intraclasts of chert and carbonate.
The
spherules were previously interpreted as microfossils (Vallenia
sp.) because
of their spheroidal shapes and inclusions of carbonaceous matter.
The
spherules are reinterpreted as replaced impact ejecta because
they have
shapes typical of splash-form microtektites, some contain
possible examples
of replaced skeletal spinel crystals, perlitic cracks and
devitrification
spherulites, and non-spherical particles with shapes and textures
of typical
glassy and scoriaceous volcanic ash are absent. The carbonaceous
matter is
attributed to hydrocarbons that migrated into the spherule layer
from
elsewhere in the sedimentary succession. The spherules were
reworked after
deposition, probably as a result of turbidity currents or storm-
or
impact-induced waves. Analysis of one spherule-bearing sample
revealed only
0.02 ppb iridium, a value comparable with low iridium abundances
in distal
layers of other terrestrial impact ejecta. The spherules in South
Greenland
are the first distal impact ejecta recognized in mid-Precambrian
strata.
They represent a major impact because their aggregate thickness
exceeds the
thickest spherule accumulations reported from the
Cretaceous-Tertiary
boundary layer. Given their loosely constrained age and the
implied scale of
the impact, the Ketilidian spherules could be distal ejecta from
either the
Vredefort, South Africa, (c. 2025 Ma) or Sudbury, Canada, (c.
1850 Ma)
impacts.
Addresses:
Chadwick B, Univ Exeter, Room 220,Laver Bldg, Exeter EX4 4QE,
Devon, England
Univ Exeter, Exeter EX4 4QE, Devon, England
Museum Naturkunde, Inst Mineral, D-10099 Berlin, Germany
Oberlin Coll, Dept Geol, Oberlin, OH 44074 USA
Copyright © 2001 Institute for Scientific Information
==========
(7) NEW EVIDENCE FOR RAPID AND SYNCHRONOUS COLLAPSE OF ECOSYSTEM
AT P-TR
BOUNDARY
Twitchett RJ, Looy CV, Morante R, Visscher H, Wignall PB: Rapid
and
synchronous collapse of marine and terrestrial ecosystems during
the
end-Permian biotic crisis
GEOLOGY 29 (4): 351-354 APR 2001
A newly studied Permian-Triassic (P-Tr) boundary section in
Jameson Land,
East Greenland, contains an abundant and well-preserved marine
fauna as well
as terrestrial palynomorphs. For the first time it is possible to
compare
the biotic crises of the marine and terrestrial realms using the
same
samples from the same section. The sediments record a negative
excursion in
delta C-13(carb) values of 8 parts per thousand -9 parts per
thousand, and
in delta C-13(org) values of 10 parts per thousand -11 parts per
thousand.
The presence of the conodont Hindeodus parvus, combined with the
delta
C-13(carb) record, enables correlation with the proposed global
stratotype
section at Meishan. This shows that the Greenland section is the
most
expanded P-Tr section known. Collapse of the marine and
terrestrial
ecosystems took between 10 and 60 k.y. It took a further few
hundred
thousand years for the final disappearance of Permian floral
elements.
Collapse of the terrestrial and marine ecosystems began at the
same
stratigraphic level and preceded the sharp negative excursion in
the delta
C-13 record.
Addresses:
Twitchett RJ, Univ So Calif, Dept Earth Sci, Los Angeles, CA
90089 USA
Univ So Calif, Dept Earth Sci, Los Angeles, CA 90089 USA
Univ Utrecht, Palaeobot & Palynol Lab, NL-3584 CD Utrecht,
Netherlands
CSIRO, Inst Minerals Energy & Construct, N Ryde, NSW 2113,
Australia
Univ Leeds, Sch Earth Sci, Leeds LS2 9JT, W Yorkshire, England
Copyright © 2001 Institute for Scientific Information
============
(8) A PLAUSIBLE CAUSE OF THE LATE HEAVY BOMBARDMENT
Morbidelli A, Petit JM, Gladman B, Chambers J: A plausible cause
of the late
heavy bombardment
METEORITICS & PLANETARY SCIENCE 36 (3): 371-380 MAR 2001
We show that at the end of the main accretional period of the
terrestrial
planets, a few percent of the initial planetesimal population in
the 1-2 AU
zone is left on highly-inclined orbits in the inner solar system.
The final
depletion of this leftover population would cause an extended
bombardment of
all of the terrestrial planets, slowly decaying with a timescale
on the
order of 60 Ma. Because of the large impact velocities dictated
by the high
inclinations, these projectiles would produce craters much larger
than those
formed by asteroids of equal size on typical current near-Earth
asteroid
orbits: on the Moon, basins could have been formed by bodies as
small as 20
km in diameter, and 10 km craters could be produced by 400 m
impacters. To
account for the observed lunar crater record, the initial
population of
highly-inclined leftovers would need to be a few times that
presently in the
main asteroid belt, at all sizes, in agreement with the
simulations of the
primordial sculpting of both these populations. Ifa terminal
lunar cataclysm
(a spike in the crater record similar to3.9 Ga ago) really
occurred on the
Moon, it was not caused by the highly-inclined leftover
population, because
of the monotonic decay of the latter.
Addresses:
Morbidelli A, Observ Cote Azur, BP 4229, F-06304 Nice, France
Observ Cote Azur, F-06304 Nice, France
NASA, Ames Res Ctr, Moffett Field, CA 94035 USA
Copyright © 2001 Institute for Scientific Information
============================
* LETTERS TO THE MODERATOR *
============================
(9) GRONDINE'S MISREPRESENTATIONS
From Duncan Steel <D.I.Steel@salford.ac.uk>
Dear Benny,
You have today (April 23rd) carried various comments from Ed
Grondine in
which he has misrepresented my viewpoints as expressed in my
message in
CCNet of April 19th.
>If I interpret Duncan's comments on the Siding Spring
Observatory correctly
Grondine did not (interpret my comments correctly). I simply
pointed out
that the UK already has an operational telescope that might be
equipped in
precisely the same way as its twin at Palomar, the latter having
now been
adapted for NEO searching by the NEAT team and colleagues (and
good for
them). The telescope in question (the UKST) happens to be an
instrument
which many UK astronomers would like to see relinquished so as to
free up
some of the funds required for other astronomical research
activities. It
would represent an invaluable complement to the Oschin Schmidt at
Palomar if
equipped and operated in the same way for NEO searching.
Note that I made no comment at all about "Siding Spring
Observatory", which
is an observatory operated as part of the Australian National
University. It
simply happens to be the location of the UKST, which is operated
as part of
the Anglo-Australian Observatory. By confusing my comments here,
as
elsewhere, Grondine muddies the waters.
>it appears that he has accepted that the UK 3.5 meter
telescope will not be
>built by a government facing very large bills ...
That is not the case at all and it takes some weird jump in
imagination to
derive such a false belief. It is akin to suggesting that
because a bicycle
becomes available for me to pedal to work then it follows that I
will give
up saving to buy a new car.
Similarly Grondine's analysis of my comments on the Associated
Press report
is entirely incorrect. The AP report was misleading because it
made it
appear that the "NASA Spaceguard goal" is 90 percent of
all 1 km plus NEOs
(i.e., including Earth-crossing comets), whereas the goal is
recognised by
all those with close familiarity with the subject to involve only
the NEAs.
And at that, only the NEAs with short-period orbits (because it
is beyond us
to discover those 1 km asteroids with perihelion distances less
that 1 AU
but aphelia beyond Neptune until such time as they enter the
inner solar
system; ipso facto such long-period asteroids are not part of the
population
of which 90 percent is the aim).
I made no expression of any personal belief as to whether that
specific NASA
goal is adequate in the long term: I simply pointed out why
comets and
long-period asteroids are not included in the goal. Indeed, as I
am neither
a US citizen nor a US taxpayer, it is not my business to express
any opinion
about what NASA should be doing. Perhaps Grondine thinks he has
the right to
tell his next-door neighbour whether he (the neighbour) should
buy a new car
or not. I do not presume any such right for myself. What I would
say is
that, as a person who is not directly involved, I think the US
search teams
are doing a wonderful job, and I am happy to lend them my verbal
and moral
support. I can write books and magazine articles, I can appear on
US radio
and TV, but I have no Congressman to lobby or threaten with
losing my vote.
Elsewhere I am pleased to see some NEO activity, such as in Japan
with the
new search and tracking activity, and similarly in Italy where
apart from
NEO observations there is brilliant dynamical work under way. But
it is not
my position to tell the Japanese or Italian astronomers or
governments what
they should be doing. Nor is it my place to criticize the NASA
Spaceguard
goal, especially since it is NASA-funded projects that are
delivering most
of the NEA discoveries. On that basis, congratulations to the US
public for
their support of this endeavour. You are leading the way. But in
the same
way as one might admire the football or baseball team that is
currently
leading the rankings, some of us have ambitions to overtake your
efforts.
As regards what I do think myself, as a citizen of the UK, and a
UK
taypayer, I permit myself to lobby the UK government in various
ways. That
is one of the contributing reasons why the UK NEO Task Force
report made
recommendations for the size limit of NEA discoveries to be set
somewhat
lower than the NASA Spaceguard goal (and that necessitates larger
search
telescopes), and also for scientific studies of the nature of the
NEO hazard
(because a group of us in the UK regard giant comets undergoing
disintegrations as being a larger danger to the terrestrial
environment than
is perhaps realised by researchers elsewhere).
Thus:
>Besides giving in to NASA's rather arbitrary goal for
asteroids, Steel
I do no such thing, and I would thank Grondine not to make such
baseless
statements. What NASA chooses to do is not my business, as I have
written.
Similarly, what I choose to do is not NASA's business, and in the
UK we have
a different target. In the future I hope that the UK and the USA
and many
other nations will be able to work together, but I would expect
that at all
times there will be differing opinions about what the priorities
should be.
Such working together often takes the form of friendly
competition, and if
higher goals are set elsewhere then this might have an influence
upon the
goals set in the US. But, again, it is not my place to criticise
what any
other nation might be doing.
I further wrote (rather clearly, I believe):
>So far as I am aware the majority of very large objects on
>Earth-crossing orbits observed over the history of
astronomical research
>have been comets, mostly in near-parabolic orbits. Finding 90
percent of
>those is not feasible, because they spend most of their time
near aphelion,
>making it possible to find them only as they enter the
planetary region."
To which Grondine stated:
>Carolyn Shoemaker disagrees with him, and is seeking
$170,000,000 for a
>telescope for exactly this purpose.
Again, Grondine has made a false statement based upon his own
lack of
understanding of what is involved, even though it is quite
simple. Spotting
long-period/near parabolic comets as they cross the 3 AU
threshold at which
water starts to sublimate, or rather further out where weaker
comae are
produced by the more-volatile constituents (methane, ammonia, CO
etc.), is
trivial (compared to finding 1 km asteroids at similar
distances). Thus it
is straightforward to
find the majority of such comets that enter the inner solar
system, but only
as they do so. (There are, however, some long-period comets that
are not
easily discoverable well ahead of an impact if only Earth-based
search
systems are employed, for example if they cross the 3 AU
threshold while
near superior conjunction.)
As I wrote, it is not feasible to find any substantial fraction
of the total
numerical population because one cannot spot comets at 10,000 AU
no matter
how much you spend on telescopes, and no-one with half an ounce
of
intelligence has suggested that you can. As I wrote, there are
100 million
comets per square degree that are not discernable as individual
objects.
Spotting the few that enter the inner planetary region each year
is easy, in
most cases.
The problem, as I pointed out previously, is that even if such a
comet were
spotted when still some distance away from impact (say when it is
at the
distance of Saturn), still a timely intercept is not feasible
using
presently-available propulsion systems. You give me a system
capable of
achieving a delta-vee of 100 km/sec in short order (that is, not
an ion
engine that might reach that speed after a three-year gradual
acceleration),
and you have it sitting on a launch pad waiting to go, and I
could intercept
most such comets. The reality, however, is not that. Grondine and
others
interested in looking into this need to start at the beginning,
by examining
the sorts of warning times that are feasible for long-period
comets (see the
chapter by Marsden and Steel in 'Hazards Due to Comets and
Asteroids',
edited by Tom Gehrels, 1994; if we were lucky we might get 250 to
500 days).
Having understood what is involved in terms of the celestial
mechanics, next
they could try to invent an interceptor for some characteristic
cometary
orbits, using presently-available propulsion systems. Good luck.
In the meantime, those wanting to move the subject forward and
decrease the
chance of a major impact taking us unawares will continue to
support the
efforts aimed at tackling the simplest part of the hazard, that
associated
with asteroid impacts predictable on a long-term basis (decades).
All hail
those NEO search programmes that are delivering the goods now,
whilst other
talk and wring their hands. Congratulations to the dynamicists
who have
developed the techniques making impact predictions and
probabilities
calculable. Once the 1 km goal is achieved, then it can be
dropped to half a
kilometre, and then smaller still. The UK NEO Task Force report
indicates
what some of us think our own nation should be aiming for in the
short term
(the next decade or so). Maybe others will follow suit. In the
same way as
we (humankind) have eradicated smallpox, so we can eradicate the
danger
posed by large short-period asteroids. Next we'll move on to
polio, rubella
and measles, or your disease of choice. The fact that we cannot
at present
cure cancer or even the common cold is irrelevant, because by
wiping out
some diseases we do enhance the individual's chance of long-term
survival.
Similarly it is irrelevant that we cannot hope to tackle the
long-period
comets in the near-term, although we'll keep it in mind. When
there are
limited resources available they should be directed to where they
can do
most good. In our own countries, and the larger organisations of
which they
are a part (like the European Community, or the United Nations),
we strive
to enhance the resources allocated to the NEO impact hazard. As I
indicated
previously, there will come a time when the asteroid problem is
solved, and
then long-period comets take over, just as at present there is
very little
spent on tackling smallpox. By then maybe we will have the
propulsion system
necessary, and everything else required.
Getting the NEO impact hazard accepted by the general public and
by
politicians, and then getting the appropriate actions taken to
ameliorate
the danger, require clear and distinct signals to be given. The
Associated
Press story added to the signal, but also enhanced the
noise/confusion level
slightly because in certain aspects it was incorrect. Grondine's
message
contained a number of false statements and incorrect deductions
which
amplify the noise without adding any significant signal.
Duncan Steel
==========
(10) PLANETARY NOMENCLATURE
From Jon Richfield <richfield@telkomsa.net>
Hi Benny,
In response to the remarks of Robin Lloyd:
>Birthright aside, can a planet-sized object that fails to
orbit a
star still be called a planet? The standards-setting
International
Astronomical Union (IAU) recently issued a provisional answer --
no
way. Planets, by their new definition, must orbit a star. That
definition
could be revised as more data come in and the group continues to
meet.<
I can well believe that to call the committee discussions
"contentious" was
putting it mildly. This is about standard for invention of
terminology. One
of the main problems is that such committees seldom start with a
clear
listing of the entities to be named and a basis for
the nomenclature. Perhaps I wrong them, but the outcome seems
about par for
the course. Given the complexity of the situation, one could
simply coin ad
hoc terms as the need arises: how about "Kuiperoids"
and "Oortoids" for a
start?
I am uncomfortable with the limitation of the use of the word
"planet" in
particular, because it means "wanderer", which seems
very suitable to a wide
range of objects, but I suppose that that particular baptism is
now beyond
redemption. "Brown sub-dwarfs" is getting off
lightly on balance...
Abortasters or fetasters seems to me to better, but would you
believe, they
never asked me! Then for wandering non-brown-sub-dwarfs how about
exoplanets
or simply free planets?
This is just a reaction to a lot of about-it-and-abouting that
seems to be
starting to spill right out of the teacup. Bad terminology
can be a real
nuisnace in the long term, as well as grating on the sensitive
ear. Why not
get someone in forum to present a nice, complete list of the
classes of
object under consideration with clear distinctions between them,
and ask for
serious suggestions for a useful terminology? In fact, if the
dimensions of
distinction are clear enough, I could even suggest schemes for
automatically
generating names for each class.
Cheers,
Jon
========
(11) VERY EXPENSIVE TELESCOPE TO LOOK FOR EXTRA-SOLAR PLANETS
From Michael Paine <mpaine@tpgi.com.au>
Dear Benny,
I find NASA's budget priorities a little strange. If this report
is to be
believed then during the next decade $1 billion will be spent on
a telescope
to "to study and potentially discover planets orbiting
distant stars". While
I support the search for extra-solar planets and potential abodes
for other
forms of life it would be nice to see just a fraction of this
money go
towards ensuring that the only life we know of is not wiped out
by a large
asteroid or comet.
regards
Michael Paine
----
Princeton U. scientists design telescope for NASA competition
http://news.excite.com:80/news/uw/010419/tech-30
By Vanessa Woods
The Daily Princetonian
Princeton U.
(U-WIRE) PRINCETON, N.J. -- It is possible that human beings are
only a
decade away from finding out whether or not it is alone in the
Universe, and
Princeton University is playing a large role in this potential
discovery.
A group of six University faculty members, three graduate
students and a
postdoctoral fellow has teamed up with scientists from the Space
Telescope
Science Institute in Baltimore, Md. and Ball Aerospace in
Boulder, Colo. to
form one of four teams in a NASA-run competition.
To participate in the competition, all four groups are required
to design
and create a $1 billion telescope to study and potentially
discover planets
orbiting distant stars. The NASA mission is scheduled to begin
the launching
of the winning telescope as early as 2012.
Assistant professor of mechanical and aerospace engineering
Jeremy Kasdin is
leading the University's team, which has made several advances in
its work
since they began working last summer. Kasdin said he became
involved in the
project a year and a half ago, just a few months after coming to
Princeton.
Kasdin explained that the main purpose of NASA's mission is to
gather as
much information as possible to find the best way to find an
earth-like
planet and "to gather information on whether or not it could
potentially
harbor life."
Kasdin also participated in a NASA space project at Stanford
University and
discovered his current project on NASA's website.
"NASA made it very clear that it wanted industry teamed up
with academia in
this mission," he said.
Princeton is not the only university bringing academia to the
partnership.
The other universities involved include the University of
Arizona, the
University of Colorado and the Massachusetts Institute of
Technology,
according to Kasdin.
However, the University has made some very significant steps
toward
completing NASA's mission. The major breakthrough of Princeton's
team is "a
very unique telescope design that nobody has done before,"
said Kasdin.
Nicknamed "The Pupil," the telescope was designed by
University astrophysics
professor David Spergel. Spergel was unavailable for comment.
Also on the University's team are mechanical and aerospace
engineering
professor Michael Littman and astrophysics professor Edwin Turner
who is in
Tokyo. Both were unavailable for comment.
Though Kasdin noted the team members might not all share the same
view as to
the possibility of other earth-like planets with life forms, he
said he
believes earthlings may find they actually have extraterrestrial
neighbors.
"I lean towards the side of people who believe there is a
very high
likelihood of the [existence of earthlike planets] out
there," he said.
He also noted that some scientists believe it is nearly
impossible for
another planet to have the same life-promoting qualities that
Earth has.
Kasdin also explained that no one has actually seen an earth-like
planet
through a telescope so it is difficult for any scientist to
predict the
possibility of alternate life forms. "No one has any idea
what to expect,"
he said.
Nevertheless, the University's team is certainly trying to make a
great
contribution to science regardless of whether or not an
earth-like planet
with extraterrestrial life is found.
"There's going to be a lot of different kinds of science
done with this,"
Kasdin said.
(C) 2001 The Daily Princetonian via U-WIRE
================
(12) AND FINALLY, SOME GRUESOME NEWS: "THATCHER'S REMAINS TO
LIGHT UP THE
NIGHT SKY"
From The Guardian, 21 April 2001
http://www.guardian.co.uk/uk_news/story/0,3604,476191,00.html
--------------------------------------------------------------------
THE CAMBRIDGE-CONFERENCE NETWORK (CCNet)
--------------------------------------------------------------------
The CCNet is a scholarly electronic network. To
subscribe/unsubscribe,
please contact the moderator Benny J Peiser <b.j.peiser@livjm.ac.uk>.
Information circulated on this network is for scholarly and
educational
use only. The attached information may not be copied or
reproduced for
any other purposes without prior permission of the copyright
holders.
The fully indexed archive of the CCNet, from February 1997 on,
can be
found at http://abob.libs.uga.edu/bobk/cccmenu.html
DISCLAIMER: The opinions, beliefs and viewpoints expressed in the
articles and texts and in other CCNet contributions do not
necessarily
reflect the opinions, beliefs and viewpoints of the moderator of
this
network.
