CCNet 60/2001 - 26 April 2001

"I am convinced that only the largest of impact would have had
potential to seriously shape Human evolution: and with that I am thinking
of the very rare impacts of K/T size, which are not likely to have
happened the past 5 to 8 million years of hominine evolution."
--Marco Langbroek, Leiden University, 25 April 2001

"It's like the question, 'what is the difference between an asteroid
and a comet?' The best answer is probably something like 'an asteroid is a
cosmic body, less than 1000 km in diameter, that appears to be solid
and devoid of a coma or tail, in orbit around a star.' Or, to put it in
more accurate but less formal terms, an asteroid is a body that
astronomers say looks and acts like an asteroid. Let's not get too carried
away with nomenclature. Remember Pluto..."
--John S. Lewis, University of Arizona, 25 April 2001

    Ron Baalke <>

    Mohammad Odeh <>

    SpaceDaily, 24 April 2001

    Andrew Yee <>

    BBC News Online, 25 April 2001

    Jim Benson <>

    Marco Langbroek <>

    Michael Paine <>

    MSNBC, 25 April 2001

     Norbert Giesinger <>
     John S Lewis <jsl@U.Arizona.EDU>

     Richard TAYLOR <>

     Jens Kieffer-Olsen <>

     Barbara Becker <bjbecker@UCI.EDU>

     Allen RL, Bernstein GM, Malhotra R

     Leroux H

     Petrovic JJ

     John Daly, 25 April 2001



From The Times of India, 24 April 2001

Meteorite crashes near mourning Jordanian village
April 24, 2001

AMMAN: Residents of a Jordanian village attending a funeral got an unwelcome
surprise when a fiery meteorite crashed down in their midst, one of them
said on Monday.

"More than 100 of us were gathered on Wednesday at sundown to bury a village
resident when we saw a strange object that looked like a ball of fire," said
Mohammed Nawaf Mikdadi, mayor of Beit Eidess, some 85 km north of Amman.

"The meteor shot through the sky from west to east before a part of it came
down a half km from the village, sparking an explosion and then a fire with
four-meter flames for 10 meters straight," Mikdadi said.

"The villagers thought it was a missile, but when we went to the spot there
weren't any metal scraps," he said.

The mayor expressed relief the meteorite fell on a rocky area near Beit
Eidess and not in a nearby forest, which could have spelled disaster for the



From Mohammad Odeh <>
[as posted on the IMO mailing list]


Residents of a Jordanian village called Bayt Eides said that they saw a
meteorite crashed down in front of more than 100 persons of the residents.

JAS has visited the place, made an interview with an eyewitness and took
several photos for the place! To know more about this event and to see the
photos and hear the interview kindly visit JAS site at:

Best Wishes
Mohammad Shawkat Odeh.
Jordanian Astronomical Society (JAS).
Member of JAS Administrative Board.
P.O. Box 925916 Amman 11110 Jordan.
Fax:  +1-707-2210918 (In USA).
Mobile: +962-79-877225     (JAS URL)       (JAS' WAP URL)

Meteorite Over Jordan?
By Mohammad Odeh

On 18 April 2001 around 19:30 Local Jordanian Summer Time (UT+3), Mr. Jamal
Al-Halabi, the editor in chief of the Associated Press (who is already a
friend of JAS), called JAS member Mohammad Odeh asking him about an object
he saw in the sky from Amman few minutes ago! From his description it seemed
that what he saw was a fireball! Or better a huge fireball! Anyhow, later on
a Jordanian Newspaper mentioned that residents of a Jordanian village called
Bayt Eides saw a meteorite crashed down in front of more than 100 persons of
the residents.

One of the eyewitnesses was Mr. Mohammad Nawwaf Miqdadi, mayor of Bayt
Eides. So JAS had directly phoned him asking him about some details, and
later on JAS decided to visit that place.

A delegation of JAS consisting of Eng. Khalil Konsul (President of JAS),
Mohammad Odeh, and Mohammad Katbeh went to Bayt Eides on Tuesday 24 April.
JAS reached the site around 15 Local Time (LT). Where Mr. Miqdadi welcomed
JAS and joined JAS to the location.

As JAS arrived the site, we made an interview with him asking him about the
details, and JAS took some photos, as well as determining the coordinates of
the site. According the GPS, the site is 54.4 Km to the North of Amman
(Azimuth 345). Regarding the details, Mr. Miqdadi said:-

On Wednesday 18 April around 07 pm, which is before sunset (Sunset occurs
around 07:10 pm) at sundown to bury a village resident, more than 100
persons saw a bright object moving in the sky with a dark yellowish color.
The object was moving from west to east, and then it broke up into two
parts, which felt on a nearby hill (which is about 1.5 Km from the place at
which we were watching!). As the two pieces hit the ground we saw a fire,
initially with a greenish color, and then the fire reached up to 5 meters!
On the very next day I (Mr. Miqdadi) went to that place and I saw the two
locations at which the two parts felt. (Let's call the first location A, and
the second one B).

Now JAS is watching and examining the location A, which no one entered yet!
The ground is full of ash and it is rather black (from the fire) and so are
the stones! What directly brought our attention were two things, the first
was a tree trunk which is broken into two parts (See Photo). Mr. Miqdadi
said this must be from the object which hit the tree! Actually the
appearance of the broken tree trunk is very strange! I don't guess it is a
man-made break! The other thing was a half burnt tree (See photo)!

Concerning the location B, which was visited by two persons before JAS, it
was also full of ash and black. "The location was full of small rock, but
when the object hit the area it made a crater as you can see", Mr. Miqdadi
said. Actually there was no real crater! But it was clear that at certain
place the level of the rocks is lower than the surrounding, and there is a
shape of an arc. Also, a half of a large rock was burnt, while the other
half is normal (See Photo)!

We did our best to find a meteorite but I must say that we failed! So the
question is what felt then? Did the object totally burnt up? Is this ash the
meteorite remnant! Eng. Khalil Konsul said, this is not possible, because if
the ash is a meteorite remnant, then the meteorite would be very large and
this will make a real trouble! Which was not the case!

JAS took a sample of the ash and soil. So we would be glad if the reader of
this report tell us to whom shall we send the sample for analysis ?

Lastly, the coordinates of the of the locations are:-

Location A:-

Longitude: 35:42:55 E
Latitude: 32:26:09 N
Elevation: 707 m
Location B (Which is about 50 meters only away of A):-

Longitude: 35:42:56 E
Latitude: 32:26:08 N
Elevation: 714 m


From SpaceDaily, 24 April 2001

Laurel - April 24, 2001

NEAR mission science team members have concluded that the majority of the
small features that make up the surface of asteroid Eros more likely came
from an unrelenting bombardment from space debris than internal processes.

Details of the research from NASA's Near Earth Asteroid Rendezvous (NEAR)
mission were published this week in Science and are based on the NEAR
Shoemaker spacecraft's Oct. 25-26, 2000, low-altitude flyover of asteroid
Eros that brought the spacecraft to within about 3 miles of the surface of
the asteroid.

"We think that impacts to the asteroid's surface have probably been the
single-most dominant process in shaping the surface texture of the
asteroid," says NEAR Project Scientist Dr. Andrew Cheng of the Johns Hopkins
University Applied Physics Laboratory in Laurel, Md., which managed the
mission for NASA.

"We saw surface details such as regolith [surface dust and debris], craters
and fields of small boulders in incredible detail. We also saw things that
confound us, but we now have a more in-depth picture of Eros that will help
us to decipher the asteroid's history."

During the flyover, simultaneous observations were taken by the spacecraft's
multispectral imager and laser rangefinder over two tracks approximately 1
mile and 2.5 miles long that showed objects the size of a doghouse at three
to four times better resolution than previously obtained.

The data revealed an inordinate number of small boulders, a saturation of
large craters and a dearth of small ones, crater "ponds," and unknown
erosion processes.

A vast number of large craters, 1,630 to 3,280 feet (500 to 1,000 meters) in
diameter, have been imaged, but there is a surprising scarcity of boulders
large enough to make such impacts.

There is more than 100 times the number of 10- to 12-foot (3- to 4-meter)
boulders than there are impact craters in this region. Some angular or
slab-like features were imaged that could indicate they are composed of
stronger material than rounded objects. Some boulder clusters are thought to
be fragments of a larger projectile that hit the asteroid.

The flyover also yielded evidence of an unusually low number of smaller
craters. "There could be some unknown process, possibly something like
seismic shaking following impacts, which is more likely on a small body such
as Eros," says Dr. Joseph Veverka of Cornell University, Ithaca, N.Y., who
heads the imaging team.

"Other possibilities are processes that could erode or erase smaller craters
such as micro-cratering [the pummeling of the surface by smaller objects] or
thermal creep [the erosion of surface material through normal seasonal
heating and cooling of the asteroid] that is eroding the smaller craters."

"We do know there is a substantial amount of regolith from erosion and
impacts that is covering blocks [boulders] and craters possibly to a depth
of several meters. So it could be that many smaller craters do exist but
they're buried under the regolith," says Veverka.

"A thick covering of fine dust that prevents us from seeing what lies
beneath might also be part of the answer to why the asteroid has little
color variation. It is possible that parts of Eros are covered in regolith
as deep as a 10-story building."

The data also revealed ponds -- flat surfaces at the bottom of craters --
formed by regolith deposits. These ponds are intriguing science team members
because of their extremely smooth surfaces.

"The smoothness indicates that there is an efficient process on Eros which
is able to sort out the finest component of the regolith from the coarser,
more blocky portion and concentrate this fine material into some low-lying
areas such as crater bottoms," Veverka says.

Moreover, the laser altimeter found that ponded deposits are not only smooth
but also extremely horizontal -- level relative to local gravity -- as if
formed by fluid-like motions.

"It is astonishing that the total dry regolith of an asteroid like Eros can
apparently be mobilized like a fluid," says Cheng. "There is no water on
Eros, and there has not been any water, for billions of years. However,
seismic shaking caused by impacts may be able to produce fluidized movement
of regolith."

"Aprons" of debris at the base of some of the larger boulders indicate
another phenomenon the researchers are studying: efficient erosion or
disintegration of ejecta boulders (boulders forced out of a crater as the
result of an impact) after they have landed on the surface.

But scientists say they need to study higher resolution images to more
definitively interpret the various forms of regolith that the low-altitude
images have provided. "What causes this efficient disintegration remains a
mystery," Veverka says.

"But one we hope to solve over the coming months by studying the wealth of
data that the NEAR mission has provided."

Copyright 2001, SpaceDaily


From Andrew Yee <>

Department of Public Affairs
University of Toronto


Jerry Mitrovica
Department of Physics, University of Toronto
ph: (416) 978-4946; email:

Alessandro Forte
Department of Earth Sciences, The University of Western Ontario
ph: (519) 661-3188; email:

Communications and Public Affairs
The University of Western Ontario
ph:(519) 661-2111, ext. 85165; email:

U of T Public Affairs
ph: (416) 978-6974; email:

April 25, 2001

A "four-piston engine" drives earth from the inside, new study shows

Upward floating continent-sized plumes of hot rock provide the most
comprehensive model to date

By Carmen Kinniburgh and Janet Wong

Deep beneath Earth's surface, continent-sized plumes of hot rock are
floating upwards, providing a driving force for such phenomena as the
movements of whole continents, earthquakes, volcanism, and even climate
change, according to a new theory by two earth scientists in Ontario.

In a paper appearing in the April 26 issue of Nature, lead author Alessandro
Forte of The University of Western Ontario and co-author Jerry Mitrovica of
the University of Toronto provide an answer to the longstanding mystery of
how the entire Earth, from the deep interior to the surface, is changing
over time.

Their work, which draws together results from many disciplines in the earth
sciences, shows a heat engine is slowly churning deep within the planet's
interior and provides the most comprehensive model to date that explains
physical phenomena occurring at the surface.

"In effect, we have found that the solid Earth is being churned by a
four-piston heat engine with two immense sinking cold slabs and two equally
large rising hot plumes," says Forte. "It really ignites the imagination to
realize how things are changing hundreds of kilometres beneath your feet and
how this change connects to majestic features on Earth's surface."

"This find allows us to move well beyond the drift of continents described
by plate tectonics," says Mitrovica, U of T's J. Tuzo Wilson Professor in
Geophysics. The plate tectonics theory, proposed in the 1960s, suggests
Earth's crust is split up into a few immense plates that constantly shift
and produce earthquakes, but it does not explain how this movement is linked
to processes occurring deep inside the planet, says Forte.

"The first clues to finding that link appeared in the 1980s when earth
scientists obtained images of Earth's internal structure using earthquake
waves that travel deep inside the planet," says Mitrovica. "This method is
similar to medical CAT-scanning used to image the human body. The remarkable
images of the mantle, a region below the crust that extends down 3,000
kilometres to the top of Earth's molten core, turned earth science on its

The images showed that deep below the margins of the Pacific Ocean are two
vast arc-shaped regions where earthquake waves travel faster, while deep
below the central Pacific and below Africa are two equally enormous
plume-shaped regions where earthquake waves are slowed down. Because the
edge of the Pacific is ringed by zones where cold, dense portions of
tectonic plates descend into Earth, the "faster" regions were clearly
marking areas where slabs of heavy material were sinking into Earth toward
the iron core.

A popular view held by earth scientists is that the "slow" regions are
simply immense stagnant blobs of material that have remained essentially
unaltered since the formation of Earth. Now Forte and Mitrovica have proven
that these towering features are actually floating up toward the surface
like hot air balloons. Their proof is based on a diverse array of
observations ranging from incredibly small variations in Earth's rotation
and gravity field to dramatic deflections of continental regions such as
southern Africa, which now sits 1,000 metres higher than North Africa.

The pair's multidisciplinary approach is being hailed as the most unified
model to date for Earth dynamics and one which provides a framework for
modeling of long-term changes in sea-level, topography and climate. The
model may also be used to further understanding of other planets in our
solar system, such as Venus, Mars and Mercury, says Forte. "We have
discovered something grandiose in size and yet remarkably simple and

"It's a road map for resolving a contentious debate that has hampered global
earth science since the plate tectonics revolution," says Mitrovica.

Forte and Mitrovica's research is funded by the Canada Foundation for
Innovation, the Ontario Innovation Trust, the Natural Sciences and
Engineering Research Council of Canada and the Canadian Institute for
Advanced Research Earth Systems Evolution Program.

[Carmen Kinniburgh is with the communications and public affairs office at
the University of Western Ontario. Janet Wong is a news services officer
with the U of T Department of Public Affairs.]

[NOTE: Two images supporting this release are available at

Credit: Images courtesy of A. Forte and J. Mitrovica]


From the BBC news Online, 25 April 2001

By BBC News Online science editor Dr David Whitehouse

A fossil dinosaur has been unearthed that was wrapped from head to tail in

It will add to the debate about birds being descended from dinosaurs and
suggests that the evolution of feathers pre-dates the development of flight.

The 130 million-year-old Dromaeosaur specimen provides the best evidence yet
that some dinosaurs developed primitive feathers - not for flight but
probably to keep warm.

Dromaeosaurs were small predators closely related to the Velociraptor which
starred in the film Jurassic Park.

Dinosaurs may have looked more like weird birds than giant lizards
Like Velociraptor they had a sickle-like claw on the middle toe, sharp
teeth, and a bone structure similar to that of modern birds.

Barbed features

The fossil was unearthed last spring by farmers digging in north-eastern
China's Liaoning Province. It was entombed in two slabs of fine grained

When the slabs were separated they saw a fossil that resembles a large duck
with a long tail and an oversized head.

The fine grained rock allowed minute details to be preserved showing that
its head and tail were covered with downy fibres, while other parts of the
body seemed to have tufts or sprays of filaments resembling primitive

Fine markings reveal the feathers imprint
The arms also seemed to be adorned with branched structures similar to the
barbs of modern bird feathers.

Dr Mark Norell, from the American Museum of Natural History, New York, said:
"This fossil radically modifies our vision of these extinct animals. It
shows us that advanced theropod (two-legged) dinosaurs may have looked more
like weird birds than giant lizards."

Several new species of dinosaur with feather-like structures have been found
in the Liaoning fossil beds since the first, Sinosauropteryx, was discovered
in 1995.

In most cases the fossils were incomplete, making it unclear how the
featherlike structures related to the animal's body.

Most experts believe that modern birds evolved from dinosaurs, and cite the
Liaoning fossils as evidence.

However, critics of the theory have argued that the feather-like structures
are not the remains of primitive feathers, or that the specimens are
mixed-up fossils of early birds and dinosaurs.

The new find may help resolve the debate. It contains details so fine that
scientists will be able to see how the primitive feathers were attached to
the dinosaur's body.


Ji Qiang, from the Chinese Academy of Geological Sciences, Beijing, said:
"This is the specimen we've been waiting for. It makes it indisputable that
a body covering similar to feathers was present in non-avian (flightless)

Dromaeosaurs are more primitive than birds, suggesting that feathers
developed before flight. Scientists think the feathers may have evolved as
insulation to keep the animal warm.

Dr Norell said: "It's conceivable that smaller dinosaurs like this one and
even the young of larger species like Tyrannosaurus rex may have needed
featherlike body coverings to maintain their body temperature."

The Dromaeosaur fossil, on loan from China, is being displayed for the first
time at the American Museum of Natural History.

While in the United States it will also travel to Texas for imaging with a
CAT scanner, which will provide a three dimensional view of the skeleton.

The findings were reported in the scientific journal Nature.
Copyright 2001, BBC


From Jim Benson <>

SpaceDev Participates in NASA Mars Sample Return


In 1999, under contract to JPL, SpaceDev performed a mission and spacecraft
design study for JPL's proposed Mars MicroMissions. Our detailed analysis
showed such Mars missions could be done for less than $50 million.

We teamed with Boeing last year to explore a variety of commercial deep
space mission possibilities based on SpaceDev's micromission design. That
effort resulted in a proposed commercial lunar orbiter that is currently
being marketed.

SpaceDev has now teamed with Boeing again, and as a result, SpaceDev is in a
leadership role in defining for JPL possible approaches for their potential
Mars Sample Return mission.

Poway, Calif., April 23, 2001 - SpaceDev, Inc. (OTCBB: SPDV), the world's
first publicly-traded commercial space exploration and development company,
announced that it is part of a Boeing-led team that was awarded a $1 million
contract from NASA's Jet Propulsion Laboratory in Pasadena, California to
study options for a potential Mars sample return mission.

David B. Smith, SpaceDev Vice President & Chief Technical Officer and
thirty-year JPL veteran of several deep space missions, is leading the
Boeing Mars Sample Return architecture team. "My recent experience as a
member of the Mars architecture team at JPL will provide our team with
insights into past, current and future methods and technologies that will
help us create a unique, innovative and affordable Mars Sample Return
architecture for input into the JPL planning process," said Smith.

The full news release:

Onward and upward!

Jim Benson
SpaceDev CEO

P.S. Website/page owners please feel free to link to our website with any of
the following graphics:  (Making Space Happen
Banner)  (General SpaceDev



From Marco Langbroek <>

Dear Dr. Morrison, dear Dr Peiser, dear Mr Paine,

With interest I've read NEO News 4/24/01 on Impacts & Human evolution, and I
have a few points to say about this. I am a professional archaeologist
(Leiden University, faculty of Archaeology) working in the field of early
human evolution, as well as a high level amateur meteoriticist. I therefore
know both sides of the coin (human evolution & meteoritics) rather well (for
example, I am co-author to a paper on an earth-threatening comet: P.
Jenniskens et al., ApJ 479 (1997), 441-447), and certainly the Human
evolution side. Moreover, I have been pointing to a possible significant
impact with regard to early human presence in Southeast Asia in a paper
published a year ago.

As a side remark in that paper (co-authored by Wil Roebroeks) on the
chronology of the earliest human occupation of Southeast Asia, which
appeared in April 2000 (M. Langbroek & W. Roebroeks: J. Human Evolution 38
(2000), 595-600), in which tektites were an argument, I've pointed out that
a large impact, believed by some to be one of the largest of the past few
million years, occurred in SE Asia 0.8 Ma ago, and that it was of such a
magnitude that it "must have had serious consequences for the
palaeo-environment and biogeographical history (perhaps including local
hominid evolution) of Southeast Asia".

This topic is discussed in more detail in my 1998 Master dissertation, and
will be discussed in more detail in an appendix to my upcoming PhD
dissertation. The impact in question is the impact which created the large
Australasian tektite strewnfield. It is extremely well dated at 0.80 Ma (see
our paper and refs therein). This is well within the time span of human
evolution, and moreover, humans might have been present near or in the
actual impact affected area. The impact is believed to have occurred in the
area of Laos, Cambodia or Thailand, from multiple lines of evidence. Schmidt
& Wasson (Meteoritics 28 (1993), 430) have, from the strewnfield structure,
estimated the strewnfield to be caused by an impact with an energy release
in the order of 5x10^4 to 1x10^5 MT. In the impact hazard assessment model
of Chapman and Morrison (Nature 367 (1994), 33-39), this would be an impact
at the lower limit of the "global effects threshold". Apart from possible
short term effects due to atmospheric dust release, ozone depletion and acid
rains, employing the simple scaling relationships from the Chapman and
Morrison paper also shows that an area of about 150 000 to 200 000 square
kilometer, or an area 500 kilometer in diameter, would be directly affected
by air blast phenomena. Such an area is significant in size: it amounts to
as much as about one third of the longitudinal diameter of the Southeast
Asian peninsula/Sunda shelf at this location. In a larger area of Indochina
roughly 1000 km in size, impact ejecta in the form of large Muong-Nong type
tektites occur. These are believed to have been still plastic and "hot" upon
landing (Fiske, Met. Plan. Sci. 31 (1996), 42-44), creating the possibility
that they started wildfires within this large area which covers a
significant part of the Indochinean peninsula. This is considerable
ecological havoc on a sub-continental scale.

We know that hominids were present in China at about 1.1-1.2 Ma, well before
the impact. Debates are currently raging (and I am in the thick of it)
concerning the earliest occupation of Southeast Asia. Some would have it as
early as 1.8 Ma, which I strongly doubt (see our 2000 JHE paper). But even
my more conservative estimate brings humans in Indonesia at about 1.1 Ma,
which still is before the impact. To get to Indonesia, they had to cross the
area of impact first, hence the impact area would probably have been
"settled" in a broad sense. Yet evidence from the actual impact area
(Cambodia-Laos,Vietnam, Thailand) dating from the time of impact is actually
absent. This seems to have a geological reason as not only traces of human
presence, but faunal assemblages in general are lacking from this area from
this time span: in addition, there is the enigmatic point that the impact
crater itself has not been positively identified yet. This indicates that
deposits from this time span have become inaccessible due to (probably) some
geological reason. Uncertainties concerning the chronology of Quaternary
Sunda make it currently impossible to tie biogeographic events on the Sunda
shelf south of the impact area with possible effects of the impact.

While very significant on a sub-continental scale (which is thus not to be
ignored!) and perhaps (and inevitably if they indeed were present in the
actual impact affected area) leading to the extinction of a local subgroup
of Homo erectus, there is NO evidence that this lead to long term effects in
whatever way, notwithstanding that this was one of the largest impacts in
the time span of human evolution. Detailed study of Deep Ocean Drilling Core
data by Schneider, Kent & Mello (Earth Planet. Sci. Lett. 111 (1992),
395-405) revealed no evidence for significant climatic perturbations on a
timescale of 1 ka: compared with the strong effects of glacial cycles, this
impact was hardly a ripple in the ocean. Likewise, even if local Homo
erectus inhabitants of the impact area were wiped out (as seems likely) on a
sub continental scale, this seems to have had little evolutionary effects.
Once the dust settled, the population was simply restocked by Homo erectus
from outside the impact-affected area. Such abandonment and repopulations of
areas probably were common in the Pleistocene, certainly in this area,
connected to events that had nothing to do with impact but where of similar
scales or even scales surpassing the short-term effects of impact: for
example the strong effects of cyclical flooding and re-emergence of the
Sunda shelf just south of the impact area, due to the cycles of sea-level
change connected to the glacial cycles: or the known waxing and waning of
the Human population of Europe over time (e.g. the depopulation of large
parts of Europe during the height of the last glacial 18 000 years ago) as a
result of the glacial cycles.

This brings me to a concern with the picture such as painted by Peiser and
Paine. I am convinced that only the largest of impact would have had
potential to seriously shape Human evolution: and with that I am thinking of
the very rare impacts of K/T size, which are not likely to have happened the
past 5 to 8 million years of hominine evolution (and at any rate, such an
impact would have yielded clearly discernable signs in the geological and
palaeontological record, in the form of mass extinctions of a considerable
part of the global fauna and flora, as well as widespread (=global) presence
of impact ejecta). Any smaller impacts will simply have had effects which
were insignificant compared to the powerful driving force of the glacial
cycles of the last few million years. Effects would have been very local and
temporary when seen in that context, being hardly more than ripples in the
ocean, whereby an area was temporarily depopulated and then repopulated
again. Where climatic effects (and by inference ecological effects) stay
short-term and do not wipe out significant parts of the global or
continental biomass (and there is no evidence for such non-short term,
non-local effects due to impact in palaeoclimatological and biochronological
proxy data of the past million years, while these effects should be
discernable if they happened), evolutionary effects are very minor and such
things will not lead to profound speciation. As Steve Drury very rightly
pointed out in his comment, Peiser and Paine make a mistake in focusing on
hominid EXTINCTION: what really drove human evolution was an unbound hominid
SPECIATION during the Pliocene and Pleistocene. In the absence of a near
continental ecological wipe-out, which we know did not happen, such
phenomena can come about only through long term trends of ecological
diversification on a large geographic scale, as happened in Africa when a
trend of aridification and increasing seasonality set in at the end of the
Miocene, with some profound accelerations near 2.5 and 1.8 Ma, creating long
term change in the ecology and new directions of ecological developments. In
this sense, I am a bit afraid that Peisser and Paine seem to be ignorant of
what evolution really amounts to. The extinctions they focus upon where an
unimportant side effect created by speciation: hominine species only could
become extinct because they had been created by speciation first, and when
ecological diversification due to long term trends in ecological change
creates speciation events, there inevitably have to be a series of
extinctions following too. Many of the large number of hominine species
Peiser and Paine point out got extinct during the Pliocene and Pleistocene,
were species that were chronologically contemporary, sharing a similar time
span and in general a similar geographical area and grosso modo similar
structured ecology: but filling slightly differing niches within that grosso
modo similar ecology and geographic area. It were long-term changes in the
details of ecological structure which drove evolutionary selection: while on
the other hand an impact of the necessary continental scale (Pliocene
African Australopithecines at 3.5 Ma for example where present in an area
ranging from South Africa via East Africa to Chad!)would have wiped them out
all at once, along with many other mammalian species which emerged and
evolved during the same time span in the same area due to the same
evolutionary processes. That should leave its signs in the record, and the
signs are not there. Therefore, I really strongly doubt whether cosmic
impacts played a major significant role in Human evolution of the past 5 to
8 million years.


Marco Langbroek
Palaeolithic Archaeologist
Faculty of Archaeology
Leiden University
P.O. Box 9515
NL-2300 RA Leiden
the Netherlands

building 1176, room 021
tel. +31 (0)71 5272926
fax  +31 (0)71 5272429

MODERATOR'S NOTE: I very much welcome Marco Langbroek's comments and
critique. Michael and I have now started to write up our hypothesis as a
scientific paper for publication in a peer-reviewed journal. Nevertheless,
we intend to respond in greater detail to Marco's objections and
assumptions, as well as those by other critics, by next week. BJP


From Michael Paine <>

Dear Marco,

Thank you for your comprehensive comments on the issue of impacts and human
evolution. I will study them in details over the next few days but offer a
few quick comments.

I too have looked (briefly) at the 800Ka tektite event in SE Asia and I
prepared a popular-level paper on the subject that was published in the
February 2001 issue of Meteorite. A preprint available at along with a table of
possible environmental effects of impacts. I am an amateur in this field and
do not have good access to resources but I wish I had come across your paper
(do you have an electronic copy that you could send me?). I too am puzzled
by the appearent lack of global effects associated with this event.

There are several possible confounding factors

* It is possible that the assumptions about the size of the impact,
based on the tektite strewn field, are wrong.

* The severe climate consequences would have lasted for a few years,
perhaps decades but the sensitivity of climate analysis techniques is of
the order of centuries (as you point out "no evidence for significant
climatic perturbations on a timescale of 1 ka").

* Similarly a layer of dust/clay from an impact by a 2km diameter
asteroid would only be about 10 microns thick and probably go undetected
(rough calculation by Alan Haris from JPL by scaling the KT event).

* I understand that archaeological dating over this period is very

* The estimates of environmental effects, as set out by Toon and
others (Toon, O.B., K. Zahnle, D. Morrison, R.P. Turco, and C. Covey:
Environmental pertubations caused by the impacts of asteroids and
comets. Reviews of Geophysics 35:41-78 (1997) could be too pessimistic.
There appears to be no easy way to verify some of these predictions. Dr Jay
Melosh from Uni Arizona has expressed to me concerns about uncertainty in
environmental predictions.

Subject to this uncertainty, while the environmental consequences of a 2km
impact only last a few years it could be expected to have a severe effect on
the biosphere, just as it would on today's human population. However, like
the climate record, I doubt if the fossil record is sufficiently sensitive
to show up such disruptions. After all, would we have known about the Black
Death and other major plagues through RECORDED history on the basis of
archaeological evidence alone and yet the human population was decimated at
these times.

I have attached a graph that shows impact events and hominid lines that I
prepared yesterday, after reading the article by Rob Britt.

There is much to be done in this fascinating field.

Michael Paine


Do you think asteroid or comet impacts may have influenced hominid
* 283 responses
Such impacts had no effect on human societies. 5%
Such impacts could have affected societies, but they didn't play a role in
the rise of Homo sapiens. 23%
Such impacts could have played a role in eliminating hominid species. 66%
None of the above (share your view on the Space News Discussion Board). 6%


From Norbert Giesinger <>
Dear Dr. Peiser,

Mr. Paine's article (CCNet 19/4/01) shows that finding the impact site and
more impact traces of the event related to the East Asian/Australian tectite
field is of special value regarding the existence and evolution of Homo
erectus (a side question - how many individulas were in the area at the
time: 100,000 or 10,000 or even fewer individuals?).

For the estimated 2-5 km diameter impactor and a suspected crater diameter
of up to about 100 km, it may be of some interst to look at the antipodal
points. For the upper limit of 5 km of the impactor diameter, I guess
antipodal structures should not be completely ruled out.

For all estimated impact areas, the antipodal areas are near the coast of
Peru, the mayority on the land side.

Suspected impact area      Antipode area

Mekong delta                  Peruvian upland between Ucayali and Urua
river. The hydrographic
structure of the area is quite intersting

Khorat/Thailand              200 km west of the peruvian coast/subduction
zone area

Tonle Sap lake                south of  Lima in the western Cordilliera

Southernmoast Laos        east of Nazca, Peru

An antipodal list for the large impact structures may be also of some
interst. For impacts older than some million years, plate movement must be
taken into account. For ages older than Triassic this may bcome quite
difficult and more and more useless.

Greetings from a chilly Vienna !

Since Sunday before Easter, we have rather arctic weather conditions here
(or is it climate when 16 days in a row?). On Easter, the temperature was
1-3 degree C in Vienna, at 170 m above sea level. Last Year, the temperature
was about 25 C.

Sincerely, Yours

Norbert Giesinger


From John S Lewis <jsl@U.Arizona.EDU>


Regarding the question, "What is a planet?", I can only share the approach I
have taken for several years now. The best distinction I can think of is to
call a "planetary body" that is not in orbit around a star a WORLD. A world
in orbit around a star is a planet; in orbit around a
planet, it is a satellite. Although all distinctions have a degree of
arbitrariness to them, it would probably be useful to stipulate that a world
must have a diameter of at least 1000 km. The other useful criterion for
minimal world-hood might be that it be a chemically differentiated body, but
obviously the 1000-km and differentiation criteria will almost never
coincide perfectly.

It's like the question, "what is the difference between an asteroid and a
comet?" The best answer is probably something like "an asteroid is a cosmic
body, less than 1000 km in diameter, that appears to be solid and devoid of
a coma or tail, in orbit around a star." Or, to put it in more
accurate but less formal terms, an asteroid is a body that astronomers say
looks and acts like an asteroid.

Let's not get too carried away with nomenclature.  Remember Pluto...

John Lewis


From Richard TAYLOR <>

Dear Benny,

Just a brief comment on the extract from CCNet below.

Martyn Fogg and I have adopted a name for free-floating planetary mass
objects proposed by an American Amateur astronomer by the name of Paul D.
Rust. He proposed in Sky and Telescope earlier this year that these new
objects - being a kind of  cross between very small stars and very large
planets ( which they more closely resemble) - should be designated
'planetars'. Its a nice portmanteau contraction of planet and star and
follows in the tradition that gave us pulsar, quasar and the like. Perhaps
we could encourage its use and persuade the IAU to adopt it.

Richard Taylor,
Probability Research Group, and British Interplanetary Society

From CCNet 58/2001 - 23 April 2001: "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. The new definition, released in February, is
the result of a sometimes contentious months-long process. It was
the IAU's first attempt to give an official definition to the word
--Robin Lloyd,, 18 April 2001


From Jens Kieffer-Olsen <>

In CCNet 59/2001 Duncan Steel <> wrote:

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).

Better than launch-pad ready-to-go interceptors are devices in low solar
orbits, which can be given a variety of slingshot nudges from Venus or Earth
or both in order to intercept comets at short notice. Anything less will not
do, unless the observation limit is stretched far beyond the orbit of Pluto,
the Kuiper Belt planet. 

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.

Now this I find a poor comparison. Diseases kill people continuously, so you
do well by tackling them one by one. However, if the large killer object
waiting to impact Earth first is a comet, then all effort spent obviating an
asteroid hitting us is totally wasted. I'm not saying such effort is wrong,
but if the dice don't roll our way then it will end up a futile gesture.

Therefore there is a limit to the expenditure warranted on asteroid
deflection readiness, unless it is in balance with a reduction in the impact
hazard from comets.
As soon as an asteroid detection programme can provide a reasonable (but far
from full) level of protection - implying a rudimentary asteroid intercept
capability - then funds need to be channelled predominantly towards dealing
with comets, even if the task is a hundred times more difficult and costly.

Is the solution outlined (interceptors in low solar orbits ready for
slingshot course  adjustments) a realistic way to plan for the century to

Yours sincerely
Jens Kieffer-Olsen, M.Sc.(Elec.Eng.)
Slagelse, Denmark       


From Barbara Becker <bjbecker@UCI.EDU>
as posted on the HASTRO-L@WVNVM.WVNET.EDU mailing list

Hi everyone!

Another astronomical question has arisen in my plagues class, this one
related to a different plague and a different comet.

In Book XII of his remarkable _General History of the Things of New Spain_,
Fray Bernardino de Sahagun tells of 8 omens observed by the Mexica before
the arrival of Hernando Cortes.

The first (although the word "comet" is not used) seems to me to describe a
comet. The exact year of its apparition is somewhat unclear since it is
variously stated that it appeared ten years before the arrival of the
Spaniards and elsewhere that it appeared two years before.

"Comet" is used to describe the fourth omen, but it sounds more like a
bolide. I'll provide the text for both omens below.

I've used "Redshift" and located a comet that would have appeared on or
above the horizon in Mexico City at midnight from April to August 1506 (a
little more than ten years before Cortes' arrival). The program contains no
ephemerides for a comet in 1517.

Roberta Olsen, in _Fire and Ice: A History of Comets in Art_, mentions (but
doesn't provide) a European illustration of a 1506 comet (on p. 36). On p.
46, she shows the illustration from Duran's _Historia de las Indias...._
which depicts "Montezuma transfixed by a comet in 1519-20".

My question is: does anyone have information about comets recorded or
illustrated around that time -- or possibly a periodic comet that might have
gone unrecorded in Europe but might have made a favorable apparition in
lower latitudes?

Here are the quotes from Sahagun:

When the Spaniards had not arrived, by ten years, an omen first
appeared in the heavens. It was like a tongue of fire, like a flame, as
if showering the light of the dawn. It looked as if it were piercing the
heavens. [It was] wide at the base and pointed [at the head]. To the
very midst of the sky, to the very heart of the heavens it extended; to the
very midpoint of the skies stood stretched that which was seen off to the
east. When it arose and thus came forth, when it appeared at midnight,
it looked as if day had dawned. When day broke, later, the sun
destroyed it when he arose. For a full year [the sign] came forth. (It
was [in the year] Twelve House that it began.) [1517] And when it appeared,
there was shouting; all cried out striking the palm of the hand
against the mouth. All were frightened and waited with dread....

A fourth omen: there was yet sun when a comet fell. It became three
parts. It departed from where the sun set and traveled toward where
he came forth. As if sprinkling live coals, [so] its tail went extended
a great distance. Far did its tail reach. And when it was seen,
great was the uproar; like [the din of] shell rattles [the outcry] was

For any of you who are interested, here's the URL for the Plagues course
website that I've been building:

It's still under construction, so check back periodically.

Here's the URL for the website I made last quarter for the introduction to
history of science survey course. There are some astronomical history
documents on it that you may find interesting and/or useful:

Thanks in advance!!


"Comet-ose" Barb.



Allen RL, Bernstein GM, Malhotra R: The edge of the solar system
ASTROPHYSICAL JOURNAL 549 (2): L241-L244, Part 2 MAR 10 2001

We have surveyed for Kuiper Belt objects (KBOs) in six fields of the
ecliptic (total sky area 1.5 deg(2)) to limiting magnitudes between R = 24.9
and R = 25.9. This is deep enough to detect KBOs of diameter greater than or
similar to 160 km at a distance of 65 AU. We detected 24 objects. None of
these objects, however, is beyond 53 AU. Our survey places a 95% CL upper
limit of Sigma < 5 deg(-2) on the surface density of KBOs larger than
<similar to>160 km beyond 55 AU. This can be compared to the surface density
of similar to6 deg(-2) of greater than or equal to 160 km KBOs at distances
30-50 AU determined from this survey and previous shallower surveys. The
mean volume density of D > 160 km KBOs in the 55-65 AU region is, at greater
than 95% confidence, less than the mean density in the 30-50 AU region, and
at most two-thirds of the mean density from 40 to 50 AU. Thus, a substantial
density increase beyond 50 AU is excluded in this model-independent
estimate. A dense primordial disk could be present beyond 50 AU if it
contains only smaller objects or is sufficiently thin and inclined to have
escaped detection in our six survey fields.

Allen RL, Univ Michigan, Dept Astron, 830 Dennison Bldg,500 Church St, Ann
Arbor, MI 48109 USA
Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA
Univ Arizona, Dept Planetary Sci, Tucson, AZ 85721 USA

Copyright © 2001 Institute for Scientific Information


Leroux H: Microstructural shock signatures of major minerals in meteorites

Shock metamorphism is a fundamental process in the solar system. It is
evidenced by craters on the surfaces of solid planets and asteroids, as well
as by shock-induced microstructural modifications in minerals. This paper
presents review of the main microstructural characteristics of shock
signatures in meteoritic minerals (olivine, enstatite, diopside, plagioclase
and metal) as evidenced by transmission electron microscopy (TEM). The
nature of the shock-induced modifications strongly depends on the material
and the shock conditions (peak pressure and peak temperature). It includes
fracturing, dislocations and twins (evidence of plastic deformation), phase
transformation to high pressure polymorphs, amorphization,
recrystallization, melting and volatilization. The influence of
shock-induced microstructures during post-shock events is also discussed and
further research tracks on the microstructural aspect of shock metamorphism
are outlined.

Leroux H, Univ Sci & Technol Lille, Lab Struct & Proproetes Etat Solide,
CNRS, ESA 8008, F-59655 Villeneuve Dascq, France
Univ Sci & Technol Lille, Lab Struct & Proproetes Etat Solide, CNRS, ESA
8008, F-59655 Villeneuve Dascq, France

Copyright © 2001 Institute for Scientific Information


Petrovic JJ: Mechanical properties of meteorites and their constituents

A review is presented of the mechanical properties of meteorites and
meteorite constituents. Scientific literature data on the strength of stony
and iron meteorites are extremely limited. The average mechanically-measured
stony meteorite compressive strength is 200 MPa, while the average iron
meteorite compressive strength is 430 MPa. However, the best current
estimate of the strength of stony bodies in space may be in the range of
only 1-5 MPa, based on observations of meteorite fragmentation due to
dynamic atmospheric loading upon Earth entry. Mechanical property and
behavior information on both iron-nickel alloy and mineral meteorite
constituents is also surprisingly limited in the metallurgical, rock
mechanics, and ceramics literature. (C) 2001 Kluwer Academic Publishers.

Petrovic JJ, Univ Calif Los Alamos Natl Lab, Div Mat Sci & Technol, Los
Alamos, NM 87545 USA
Univ Calif Los Alamos Natl Lab, Div Mat Sci & Technol, Los Alamos, NM 87545

Copyright © 2001 Institute for Scientific Information


From John Daly, 25 April 2001

The IPCC says sea level has already risen 10 - 25 cm in the 20th century
(disputed) and will undergo an accelerated rise of nearly a metre by 2100.

In an article titled "No Noah's flood" in the Swedish daily Svenska
Dagbladet on 15th April 2001, Dr. Nils-Axel Mörner, professor of
paleogeophysics and geodynamics at Stockholm University, Sweden (and also
president of the INQUA Commission on Sea Level Changes and Coastal
Evolution),  states -

"The IPCC arguments of sea level rise is not in accordance with  modern
scientific knowledge."

"What happens to temperatures is one thing. What happens to the sea is
another matter. The two are not connected in the way the IPCC report

One litmus location has been the Maldives Islands in the centre of the
Indian Ocean, a coral group, which the IPCC says will drown under rising
seas within a few decades (IPCC TAR chapter 11).

The IPCC prediction is based only on computer modelling, but INQUA sent a
scientific expedition to the Maldives last November to find out for sure.

The result: In the Maldive Islands the sea level has risen not so much as a
millimetre during the last century. Instead it has FALLEN by at least 10
centimetres (or 4 inches) within the last 20-30 years.

And in the next 100 years the sea level is unlikely to vary more than around
10-20 centimetres.

Mörner also notes that Chapter 11 on Sea Level Changes of IPCC's TAR report
was written by 33 people, none of them involved in actual sea level

He says that sea level change in the IPCC report is based purely on models,
not observations (a point made forcefully in this report on sea levels ).
When it comes to sea levels, the models have proved to be hopelessly wrong.

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