CCNet 73/2001 -  31 May 2001

"Chemicals trapped in ancient glacial or polar ice can move
substantial distances within the ice, according to new evidence from
University of Washington researchers. That means past analyses of
historic climate changes, gleaned from ice core samples, might not be
entirely accurate."
--Sandra Hines, University of Washington, 30 May 2001

"What fascinated me personally about [Deep Impact] is, as the design
went through, it became clear how little we truly know about comet
--Tom Morgan, program scientist for Deep Impact, 30 May 2001

    Ron Baalke <>

    Ron Baalke <baalke@ZAGAMI.JPL.NASA.GOV>

(3) COMET P/2001 J1 (NEAT)

    Brian G. Marsden <>

    Rainer Arlt <>

    The Baltimore Sun, 30 May 2001  

    Andrew Yee <>

    Andrew Yee <>

(9) TNO (20000) VARUNA
    Javier Andres Licandro Goldaracena <>

     Rolf Sinclair <>

     Duncan A. Lunan <>


From Ron Baalke <>

PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011

Contact: Martha J. Heil      (818) 354-0850

FOR IMMEDIATE RELEASE                         May 30, 2001


The clearest radar pictures of a near-Earth double asteroid system were
taken by astronomers last week using NASA's Goldstone radar telescope,
revealing clues to the system's current structure but raising questions
about its origin and future.

A team of astronomers studied images that show the trail of the smaller
component orbiting a larger object, made with the Goldstone radar, a
70-meter (230-foot) antenna in California's Mojave Desert. The asteroid,
1999 KW4, came within five million kilometers of Earth (over 3 million
miles) on Friday, May 25.

"This system, 1999 KW4, is the third binary near-Earth asteroid pair
revealed by radar, but this is the first time we've been able to image the
system over a complete orbit of one component around the other," said Dr.
Steven Ostro of NASA's Jet Propulsion Laboratory, Pasadena, Calif., leader
of the team that made the discovery. "Goldstone was able to track the
asteroid for up to eight hours daily for a week.  Then we made close-up
images of each component using the Arecibo telescope in Puerto Rico, which
is not as fully steerable but is much more powerful."

The images can be seen at .

The radar team also included Dr. Lance Benner and Jon Giorgini of JPL, Dr.
Jean-Luc Margot of the California Institute of Technology, Pasadena, and Dr.
Michael Nolan of Arecibo Observatory, Arecibo, Puerto Rico.

"The asteroid pair 1999 KW4 is classified a Potentially Hazardous Asteroid
because eventually its path through space could intersect Earth.  However,
the radar measurements, which are accurate to 15 meters (about 49 feet),
indicate there is no significant chance of 1999 KW4 colliding with Earth for
at least a thousand years," said Giorgini. He said the larger component is
spheroidal and roughly 1.2 kilometers (three-quarters of a mile) in average
diameter, while the smaller component is asymmetrical and roughly one-third
as large.

"1999 KW4 is one of fewer than two dozen known asteroids whose orbits cross
the orbits of Mercury, Venus and Earth," said Benner. "However, the only
known solar system bodies that get closer to the Sun and have a more steeply
inclined orbit than 1999 KW4 are comets, so perhaps this object is an
extinct comet nucleus."

"Our first look at the images suggests an orbital period of roughly 16
hours," said Margot.  Later, detailed analysis of all the radar data will
determine very precisely the period, which is the time it takes the smaller
object to orbit the larger one. Using the laws of celestial mechanics, the
team will measure the objects' masses and densities, which will tell what
they are made of and how porous they are. For single asteroids, that kind of
information can only be obtained by sending a spacecraft close to the body,
and so most asteroids' densities, compositions and meteorite associations
are not well known.  "Yet this kind of information is the key to
understanding relationships between meteorites, near-Earth asteroids,
main-belt asteroids and comets," said Margot.

"This might be the first discovery of an ex-comet's density," said Dr. Don
Yeomans, head of NASA's Near Earth Object program office at JPL. Three known
objects are officially designated both an asteroid and a comet.

"The existence of binary near-Earth asteroids raises perplexing questions
about their origins," said Nolan.  "Nobody understands exactly how binary
asteroid systems formed, or even how stable the current binary systems are,
that is, how they might evolve, with the two components either separating
completely or collapsing onto one another to form a contact binary. The
theoreticians really have their work cut out for them now." Nolan said that
the near-Earth binary systems might have formed during certain kinds of
collisions. Or, if they came from loosely bound, unconsolidated piles of
rubble instead of solid rocks, binary asteroids might have formed during
close passages by Earth when gravity pulls them apart.

The first binary asteroid was found in August 1993 when NASA's Galileo
spacecraft took pictures of asteroid Ida and revealed its tiny moon Dactyl.

Current statistics suggest that at least several percent of the near-Earth
asteroids are binaries. Ostro said that the existence of binary asteroids on
potentially hazardous orbits means that we have to start figuring out how to
maneuver spacecraft close to such objects.

"Robotic spacecraft, and eventually people, are destined to go to such
objects someday, either for defense against one of them, to exploit mineral
resources, to satisfy our curiosity about what they're like close-up or
simply for the adventure of exploring a diminutive double world," Ostro

JPL is a division of the California Institute of  Technology in Pasadena.


From Ron Baalke <baalke@ZAGAMI.JPL.NASA.GOV>
[as posted on the HASTRO mailing list [ HASTRO-L@WVNVM.WVNET.EDU ]

IAU Circular 7635 reports on the similarity of newly discovered Comet P/2001
J1 (NEAT)'s orbit with Comet Biela. Comet Biela was first observed in 1772,
and was identified in 1826 by Wilhelm von Biela to have a short periodic
orbit, only the third periodic comet known at the time (after Halley and
Encke). In 1846, Comet Biela surprisingly split up into two fragments. I
believe this was the first time a comet was observed to break up. The two
fragments were observed for some months after the breakup. In 1852, only one
of the fragments was still visible. Comet Biela hasn't been seen since 1852.
In 1872, a large meteor storm was linked to the orbit of Comet Biela. Large
meteor showers in 1885 and 1899 were also attributed to the comet.

Now, it appears that Comet P/2001 J1 (NEAT) may possibly be one of the
fragments of Comet Biela that has been missing for nearly 150 years.

Ron Baalke

(3) COMET P/2001 J1 (NEAT)


Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138,
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)

     B. E. Schaefer, University of Texas at Austin, on behalf of
the QUEST collaboration (cf. IAUC 7387), reports on the discovery
of eleven apparent supernovae discovered with the QUEST 16-CCD
array camera on the Centro de Investigaciones de Astronomia 1-m
Schmidt telescope at Llano del Hato, Venezuela.  The total area
searched was 264 deg^2 between Mar. 25 and Apr. 1 to R = 20.8, with
each clear night receiving independent drift scans through B, V,
and R filters.  Nightly scans continued until Apr. 4, so that the
eleven objects all have well-sampled 3-color light curves over
roughly three weeks.  Each supernova was found by subtraction of
QUEST reference images, and each new object has been confirmed via
six or more independent images taken on three or more nights with
subtractions from three independent reference images.

SN       2001 UT     R.A.  (2000.0)  Decl.     R      Offset
2001bu   Mar. 25  10 45 22.19  - 1 28 44.5   19.4    0" E, 0" N
2001bv   Mar. 25  13 58 09.11  - 1 51 40.9   19.9    0" E, 2" S
2001bw   Mar. 25  14 01 05.50  - 1 08 26.0   19.8    4" E, 4" N
2001bx   Mar. 25  14 54 05.62  - 1 42 04.1   20.0    1" W, 3" N
2001by   Mar. 25  15 25 52.96  - 2 10 28.7   20.3    0" E, 0" N
2001bz   Mar. 25  15 30 13.76  - 0 09 26.0   20.7    2" W, 0" N
2001ca   Mar. 25  15 35 41.15  - 0 16 21.6   19.4    0" E, 0" N
2001cb   Mar. 25  15 38 44.08  - 0 22 56.6   20.5    0" E, 0" N
2001cc   Mar. 25  15 44 13.61  - 1 53 15.5   20.0    0" E, 1" S
2001cd   Mar. 25  15 46 38.83  - 0 23 09.2   19.9    1" W, 1" N
2001ce   Mar. 25  16 39 28.49  - 1 27 17.9   17.9    0" E, 0" N

COMET P/2001 J1 (NEAT)
     As hinted on IAUC 7625, this is a short-period comet, and
observations by C. W. Hergenrother, T. B. Spahr, and M. Nelson with
the 1.8-m f/1 VATT Lennon telescope on May 27 make it clear that
the orbital period is $P$ about 7.5-7.9 years.  Spahr has also
identified the comet with a very faint object (not described as
cometary) discovered by A. E. Gleason with the Spacewatch telescope
on 2000 Oct. 7 and placed on The NEO Confirmation Page but removed
on Oct. 20 for lack of follow-up.  The additional astrometry and
orbital elements ($P$ = 7.64 yr) are given on MPEC 2001-K43.  S.
Nakano has noted some rough similarity to the orbit of comet

                      (C) Copyright 2001 CBAT                   
2001 May 29                    (7635)            Daniel W. E. Green


From Brian G. Marsden <>

Dear Benny,

While I cannot exclude with 100-percent certainty the possibility that the
new comet P/2001 J1 (NEAT) is the long-lost 3D/Biela, I really don't think
it is. Contrary to what Ron Baalke writes, the two components of 3D/Biela
observed in 1846 were also observed--farther apart--in 1852 (and his
identification history should include mention of the fact that Bessel, Gauss
and others thought the 1772 and 1805 comets to be identical long before
Biela found the comet in 1826; the problem was that it was not clear how
many times the comet had been around the sun between 1772 and 1805).

What, indeed, happened to 3D/Biela after 1852?  Did it break up completely?
Some 30 years ago I looked into the possibility of finding that comet again
and published a number of different orbits based on different possibilities
for the action of the nongravitational forces on the comet after 1852. For
an epoch around 1971 these orbits all had perihelion distances under 0.83 AU
and inclinations to the ecliptic under 8.1 degrees.

Coming now to the recent comet, although unusually large inconsistencies
among the observations made it particularly difficult to establish the
orbit, and given that the comet's position in the sky makes it difficult to
observe, I note that some careful observations on May 27 by Carl
Hergenrother and Tim Spahr with the Vatican Advanced Technology Telescope in
Arizona isolated the revolution period to 7.5-7.9 years. Tim then realized that the object
had in fact been reported as unusual--though not of cometary appearance--by
Arianna Gleason at Spacewatch on October 7 last year. The object was then
listed on The NEO Confirmation Page for almost two weeks, although it was
obviously too faint for essentially all of the likely follow-up observers,
and Spacewatch itself evidently just missed the comet's position when it
recorded the region again on October 19.  The October 7 linkage is clearly
correct, and this pins down the current period as 7.64 years.

Running this orbit back gives a moderately close approach to Jupiter (0.8
AU) in 1972, before which the P/2001 J1 perihelion distance was 0.96 AU and
the inclination 11 degrees. While there was tolerably good agreement in
orbital eccentricity, argument of perihelion and nodal longitude, it is
difficult to reconcile the perihelion distance and inclination with the
3D/Biela values.  To get these elements to agree would require the
nongravitational forces to act in some special way, together with the
gravitational effects of occasional approaches to Jupiter.

Whether or not the comets are identical, why was the current comet not
observed earlier in the twentieth century? After all, the perihelion
distance of under 1 AU does allow moderately close approaches to the
earth--with a minimum orbital distance of perhaps 0.15 AU and an actual
minimum distance of perhaps 0.5 AU in 1955. Actually, it is quite clear that
at many passages through perihelion the small elongation from the sun would
completely preclude observations, and by the time the object had moved
around to opposition it would be as faint as when Spacewatch fortuitously
observed it last October. Even under the more favorable circumstances of the
1955 perihelion passage, the best one could hope for at a 90-degree
elongation from the sun would be magnitude 15, and more typically (as this
year), one would have to contend with a maximum elongation of 70-80 degrees
and magnitude 16 if one were lucky. We _were_ lucky that NEAT was observing
this year so far from opposition, and there would have been no observing
program with the capability of making the discovery at the previous
comparable elongation in 1985.  Unless the comet is now anomalously faint,
that it escaped prior detection is fully reasonable--a situation not a bit
like that of 3D/Biela on several occasions in the late eighteenth and early
nineteenth centuries.


From Rainer Arlt <>


            I M O   S h o w e r   C i r c u l a r



Dust trails produced by Comet Schwassmann-Wachmann 3 near its perihelion
passages may get close to the Earth and produce meteor activity.
Computations of the evolution of such dust trails by H. Luthen (Germany)
showed an approach to the 1941  trail for May 30, 2001, 10h UT (solar
longitude 69.04 deg).  The encounter was not very close, and chances to see
a meteor  outburst were slim.

Several observers reported their results from visual and video monitoring in
the nights of May 24 to May 30. Apart from very few possible shower members,
no meteor activity from Schwassmann-Wachmann 3 was observed.  Unfortunately,
no report was received for the time after May 30, 12h UT.

The following observers sent in their observations directly to the Visual
Commission or communicated their results via the mailing list
''. We are very grateful for their quick contributions.

ARLRA  Rainer Arlt (Germany)
BETFE  Felix Bettonvil (the Netherlands, VIDEO)
DECGO  Goedele Decononck (Belgium)
HOLDA  David Holman (USA)
JENPE  Peter Jenniskens (USA)
JOHCA  Carl Johannink (the Netherlands)
KOOMI  Mike Koop (USA)
LANMA  Marco Langbroek (the Netherlands)
LUNRO  Robert Lunsford (USA)
MOLSI  Sirko Molau (Germany, VIDEO)
RENJU  Jurgen Rendtel (Germany)
STORO  Rosta Stork (Czech Republic, VIDEO)
TRIJO  Josep M. Trigo-Rodriguez (Spain)
TUKAR  Arnold Tukkers (the Netherlands)
VERCI  Cis Verbeeck (Belgium)

May  Observer Time (UT)  N   ZHR      hR
2001                    SW3       (app./true)
24   JOHCA    2154-2216  0    -     68/65

25   LANMA    2145-2245  1   1.5    68/64
25   TUKAR    2145-2245  0    -     68/64
25   JOHCA    2145-2305  1   1.2    67/63
25   TUKAR    2245-2345  0    -     63/59
25   LANMA    2246-0000  0    -     62/58
25   JOHCA    2305-0005  0    -     61/56
25   TUKAR    2345-0045  1   2.8    57/51
26   LANMA    0000-0112  0    -     54/48
26   JOHCA    0005-0105  0    -     54/48
26   TUKAR    0045-0115  0    -     52/45

29   STORO    2100-0130  1   (video obs.)
29   MOLSI    2103-0215  0   (video obs.)
29   BETFE    2200-0230  0   (video obs.)
29   DECGO    2250-0020  0    -     60/55
29   VERCI    2258-0020  0    -     60/55
29   RENJU    2300-0036  0    -     55/49
30   ARLRA    0017-0100  0    -     49/41
30   TRIJO    0203-0305  0    -     39/30
30   LUNRO    0830-0933  0    -     54/44
30   LUNRO    0933-1035  0    -     40/31
30   HOLDA     casual    0    -  
30   JENPE     casual    0    -
30   KOOMI     casual    0    -
30   LUNRO    1035-1138  0    -     30/18

Solar longitudes refer to equinox J2000.0. The geocentric radiant position
was assumed at alpha=212, delta=+28, the population index used was r=3.0.
The radiant elevation is given as apparent and geocentric (true) values
which differ strongly for a low-velocity shower such as the SW3-ids with an
entry velocity of V_inf = 17 km/s.

It must thus be noted that shower association might be erroneous as the
radiant does NOT APPEAR at alpha=212, delta=+28 as given theoretically, due
to zenithal attraction. The above values of hR (app./true) indicate
differences of up to 10 degrees.

Rainer Arlt,
2001 May 31


From The Baltimore Sun, 30 May 2001
By Frank D. Roylance
Sun Staff

A University of Maryland, College Park scientist has won NASA's approval to
lead a $279 million space mission that any 10-year-old boy would understand
and applaud.

Astronomer Michael A'Hearn will lead a team that's planning to find out
what's inside comet Tempel 1 by smashing into it with a 771-pound copper
"hammer" -- the biggest they could loft into space.

"It's a guy thing," said College Park astronomer Lucy McFadden,
co-investigator on the project being led by A'Hearn. "It's going to be a
blast, that's for sure."

The mission to put the hammer into orbit is scheduled for launch in January
2004. Impact -- scheduled for July 4, 2005 -- is expected to blow a
seven-story-deep hole in the comet.

As debris from the comet's interior is ejected, sensors on board the main
spacecraft -- 300 miles above the comet -- will analyze the chemistry of the
debris and the crater walls, and radio the results back to Earth.

Scientists will also get video images of the impact and make them available
for display on the Internet and broadcast television.

The event will also be studied from ground-based observatories. It might
produce a sudden brightening of the comet visible to amateur astronomers
with small telescopes.

The 3-mile-wide comet will not be destroyed or knocked from its orbit,
McFadden said.

"It's like if you throw a pebble at a moving car," she said. "You're not
going to knock the car off course, unless you frighten the driver."

Even so, the mission had to pass scrutiny from the National Aeronautics and
Space Administration for violations of the space agency's "planetary
protection" rules. The conclusion, McFadden said, was that the impact would
destroy nothing unique.

"There are millions of comets," she said.

The $279 million mission, called Deep Impact, is one of two space science
missions selected in 1998 for final design review under NASA's Discovery
series of "better, faster, cheaper" space science missons.

Still awaiting NASA's final approval is Messenger, a Discovery mission to
map and photograph the surface of the planet Mercury. The spacecraft would
be built and managed by the Johns Hopkins University Applied Physics Lab in

"What fascinated me personally about [Deep Impact] is, as the design went
through, it became clear how little we truly know about comet interiors,"
said Tom Morgan, program scientist for Deep Impact at NASA headquarters. He
was a member of the group that reviewed the proposal and last week cleared
the team to start building the spacecraft.

Comets, he said, "are important constituents of the outer solar system and
keys to understanding the origins of all solar systems."

Comets are composed of dust and frozen gases that scientists believe are
little changed since the formation of the solar system 4.5 billion years

The precise composition, and relative proportions of that dust and gas, hold
clues to the materials and physical conditions present in the frigid outer
regions of the solar system where comets formed.

But astronomers aren't certain that what they see in their telescopes -- the
relatively large halo, or "coma" of gas and dust that has escaped from the
comet's tiny nucleus -- is "pristine."

Some suspect that the material in the coma comes from surface ices that have
been changed chemically and physically from their primordial composition by
repeated passages around the sun.

If they want to draw reliable conclusions about the composition of the early
solar system, they need a look beneath the surface, at the interior.

"Our idea was to disturb the top surface and expose the pristine material,"
said Alan Delamere, an engineer at Ball Aerospace, the Colorado contractor
where Deep Impact will be built.

He and Michael Belton, of the National Optical Observatory in Tucson,
originated the idea of a comet impact mission.

Images of Halley's comet taken in 1987 showed its surface to be quite black,
suggesting it was covered by dust instead of its primordial ices, Delamere

"Ever since that point, I was really disturbed about what the surface
properties were of the comet, and how little we really knew about the
mechanism that made it as black as it is."

Deep Impact also could shed light on how fragile comets are. Although
several recent comets have been seen to break apart, little is known about
the forces needed to trigger the breakups.

Comet Tempel 1 was discovered in 1867, and it orbits the sun once every 5.5
years. It was chosen because it has had plenty of time for its surface
materials to have been changed by the sun.

After its launch, Deep Impact will orbit the sun for a year, then cruise out
to Tempel 1's orbit for its rendezvous. On July 3, 2005 -- the day before
impact -- it will release its copper cannonball.

That object will navigate on its own to the comet's surface. It carries no
explosives, but its mass and speed relative to the comet -- 22,300 mph --
will deliver energy equivalent to 4.5 tons of TNT.

Pictures and spectroscopic data on the blast will be gathered by instruments
on board the main spacecraft, which will fly past the comet at a safe
distance of more than 300 miles.

"We don't want to get any closer," McFadden said. Small dust particles could
fog Deep Impact's camera lenses. Bigger debris could destroy the spacecraft.

Copyright 2001, The Baltimore Sun


From Andrew Yee <>

Office of News and Information
University of Washington
Seattle, Washington

Sandra Hines, 206-543-2580,
Vince Stricherz, 206-543-2580,


Migrating impurities in ancient ice can skew climate research findings

Chemicals trapped in ancient glacial or polar ice can move substantial
distances within the ice, according to new evidence from University of
Washington researchers. That means past analyses of historic climate
changes, gleaned from ice core samples, might not be entirely accurate.

"The ice cores themselves are wonderful records of climate. Nobody is
questioning that," said Alan Rempel, a post-doctoral research scientist in
the UW Applied Physics Laboratory.

In fact, the research shows that the fingerprint of chemical variations
within ice cores is much sharper than had previously been expected. But it
also shows that substances that are climate signatures -- from sea salt to
sulfuric acid -- travel through the frozen mass along microscopic channels
of liquid water between individual ice crystals, away from the ice on which
they were deposited. The movement becomes more pronounced over time, as the
flow of ice carries the substances deeper within the ice sheet, where it is
warmer and there is more liquid water between ice crystals. By contrast,
oxygen isotopes that can indicate past temperatures are carried mostly
within the ice.

The possible movement of chemical signatures away from the ice on which they
were deposited means scientists must re-examine questions such as whether
warm summers coincided with high levels of sea salt in the air, Rempel said.
But that is only true for ancient ice, since little movement is shown in ice
less than 100,000 years old.

The findings by Rempel; John Wettlaufer, a senior physicist at APL; Edwin
Waddington, a UW professor of Earth and space sciences; and APL visiting
scientist Grae Worster from the University of Cambridge in England are
published in the May 31 issue of the journal Nature.

Ice sheets (large polar glaciers) are built by thousands of years of
accumulated snowfall, to depths of thousands of meters. Each season's
snowfall forms a distinctive layer that can be analyzed chemically after
being extracted in a core sample.

Certain impurities serve as markers that can tell scientists what was going
on climatically at various times. Those substances are found principally in
unfrozen liquid that accumulates at the boundaries of individual crystals
within the ice sheets.

The new research shows those substances migrate deeper into the ice sheet,
where it is warmer, faster than the ice on which they were deposited, said
Wettlaufer, an ice physics expert. The displacement is larger at greater
depths. The result is that substances found 3 kilometers (1.9 miles) deep
could be 50 centimeters (20 inches) or more away from the ice on which they
were deposited many thousands of years ago, a distance that accounts for
about 100 years of snowfall.

"The point of the paper is to suggest that the ice core community go back
and redo the chemistry," said Wettlaufer. "That's a lot of work, and we're
hoping to be involved in that."

The Nature article notes that the best high-resolution climate records over
the past few hundred thousand years have come from ice cores taken from
Greenland and Antarctica. A core from interglacial ice in central Greenland
suggests that a sudden cooling took place in the Eemian period 115,000 to
125,000 years ago. However, the new study shows that impurities used as
climate markers may have moved as much as 20 inches, a distance large enough
to offset the resolution at which the core was examined and alter the
interpretation of the ice-core record.

The Vostok core from Antarctica, which goes back some 450,000 years,
contains even greater displacement because of the greater depth, but it has
not been examined at even the close spatial resolutions of the Greenland
core, Wettlaufer said.

Rempel said the researchers hope to devise models that can help scientists
account for the relative movement of different impurities when making their
ice core measurements.

But in the meantime, said Wettlaufer, scientists doing that climate work
have to take into account how much their measurements might be skewed, and
adjust their findings accordingly.

"That would be what we most would want to influence -- the way people make
their observations," he said. "Since they are doing all that work, they
can't afford to neglect these important physical processes in their


For more information, contact:
Rempel at (206) 543-1274 or
Wettlaufer at (206) 543-1300, (206) 543-7224 or
Waddington at (206) 543-4585, (206) 543-8020 or
Worster at (206) 685-8334 or

ml] Four microscopic liquid channels, each about 100 microns across (roughly
1/250th of an inch), come together at the corner where four ice grains meet.
Because impurities are concentrated in the channels, they stay liquid even
though the temperature is below freezing -- for the same reason that ice
melts on the sidewalk when you throw salt on it. (Note 200 micron scale in
bottom left corner.) Photo credit: Heidi Mader, University of Bristol


From Andrew Yee <>

Pennsylvania State University
University Park, Pennsylvania

A'ndrea Elyse Messer, (814) 865-9481,
Vicki Fong, (814) 865-9481,

May 29, 2001

Tropical Glaciers Formed While Earth Was Giant Snowball

Boston, Mass. -- Glacial deposits that formed on tropical land areas during
snowball Earth episodes around 600 million years ago, lead to questions
about how the glaciers that left the deposits were created.  Now, Penn State
geoscientists believe that these glaciers could only have formed after the
Earth's oceans were entirely covered by thick sea ice.

"There is strong geologic evidence of tropical glaciation at sea level
during those times," Dr. David Pollard, research associate, Penn State
College of Earth and Mineral Sciences' Environmental Institute, told
attendees at the spring meeting of the American Geophysical Union today (May
29) in Boston. "We wanted to determine how low-level tropical glaciers could
have formed."

Ice can accumulate in the tropics only if temperatures are below freezing or
around freezing with large amounts of snowfall. Tropical glaciers exist
today only on high mountain peaks such as the Andes and Mt. Kilimanjaro, and
do not reach anywhere near sea level.

Pollard and James K. Kasting, professor of geosciences, first looked at the
possibility that tropical ice sheets formed before the oceans completely
froze into a snowball Earth, when equatorial oceans were still ice-free and
could supply enough moisture for substantial snowfall.

During the lead-up to a snowball Earth episode, the Earth gradually cools
because the amount of carbon dioxide in the Earth's atmosphere decreases.
Relatively fast weathering of silicate rocks on large tropical landmasses
causes this decrease that locks up carbon.  As the earth cools, the oceans
begin freezing.  The high reflectivity of the snow and ice that covers the
northern and southern oceans, reflects, rather than absorbs, the sun's heat
and further cools the planet.  This cooling takes place slowly until the
oceans are frozen to about 30 degrees latitude, or from the North Pole down
to New Orleans, La. and from the South Pole up to the tip of South Africa.

"This is the coldest that the Earth can get before all the entire ocean
surface freezes," says Pollard.  "Beyond this, there is no stable point at
say 20 or 10-degrees latitude: instead, the ice-reflectivity feedback
becomes unstable and the system collapses rapidly to a snowball Earth with
all oceans ice covered."

The researchers adjusted a global climate model, GENESIS, to the coldest
point just before the collapse and used climate outputs of temperature and
precipitation to drive a dynamic ice-sheet model.  They used paleomagnetic
reconstructions of land mass distributions for 750 and 540 million years
ago, but, because the locations of major mountain chains are unknown that
long ago, they put mountains analogous to the Andes, all around the edges of
tropical land masses in their ice-sheet model.

"Ice sheets did form on the tops of these mountains," says Pollard.
"However, the ice sheets never flowed down to sea level, where we find
glacial deposits. Tropical temperatures were still too warm and melted the
ice before it could flow down from the mountains."

The researchers conclude that it is unlikely that tropical sea level glacial
deposits formed before the collapse into snowball Earth. However, having
them form after the oceans freeze also seemed problematic because once the
oceans are frozen, the rates of precipitation decrease drastically, to only
a few millimeters per year.

"However, in further simulations with the global climate model for full
snowball conditions, snowfall did exceed evaporation of snow and ice in some
land areas, allowing a slow build up of tropical ice sheets that would
eventually flow to the sea," says Pollard.  "It would have taken several
thousand years to form big ice sheets this way, but since it takes several
million years to reverse snowball Earth, there would have been plenty of
time for the ice to form."

Also, snowfall rates would have been gradually increasing during that time
as carbon dioxide built up. Researchers have estimated that it required a
buildup of carbon dioxide by volcanic outgassing to 300 times today's levels
to bring Earth out of snowball Earth, which accounts for the millions of
years necessary to reverse the process.

Some scientists question whether life could have survived a full
snowball-Earth episode, and therefore suggest that the Earth never passed
beyond the critical point with sea ice down to about 30 degrees latitude.
However, the Penn State results imply that full snowball Earth must have
occurred in order to produce the observed tropical glacial deposits at sea
level. Others have suggested that oceanic life could have survived full
snowball episodes below gaps in the ice around volcanic island, or in
tropical oceans where sunlight may have limited sea ice thickness to only a
few meters.


EDITORS: Dr. Pollard is at (814) 865-2022 or at Dr.
Kasting may be reached at (814) 865-3207 or at by


(9) TNO (20000) VARUNA

From Javier Andres Licandro Goldaracena <>

Dear Benny

Regarding to the diameter and albedo determination of TNO (20000) Varuna,
also known as 2000 WR106, by Jewitt et al., let me comment that we have
recently obtained near-infrared (0.9 - 2.4
mic) spectra of this TNO and of 2000 EB173, using the Near Infrared Camera
Spectrograph attached to the 3.56m Telescopio Nazionale Galileo. The paper
has been accepted for publication in Astronomy and Astrophysics Letter, and
is also avaliable in the astro-ph/0105434. One of the most remarcable
results is that we detected water ice in the surface of (20000) Varuna.

NICS-TNG infrared spectroscopy of trans-neptunian objects 2000 EB173 and
2000 WR106.

     Licandro, J. (1), Oliva, E. (1,2), and Di Martino, M. (3)

(1) Centro Galileo Galilei & Telescopio Nazionale Galileo
(2) Osservatorio di Arcetri
(3) Osservatorio Astronomico di Torino


We report complete near-infrared (0.9-2.4 $\mu$m) spectral observations of
trans-neptunian objects (TNOs) 2000 EB173 and 2000 WR106 collected using the
new Near Infrared Camera Spectrometer (NICS) attached to the 3.56m
Telescopio Nazionale Galileo (TNG). Both spectra are very red and with a
quite strong and broad drop extending throughout the K band. However, while
2000 EB173 does not show any evidence of narrow absorption features, the
spectrum of 2000 WR106 has quite deep water ice absorption at 1.5 and 2.0
$\mu$m. Moreover, the latter object is significantly less red than the
former indicating, therefore, that the surface of 2000 WR106 is "cleaner"
(i.e. less processed by particle irradiation) than that of 2000 EB173.

Javier Licandro


From Rolf Sinclair <>

    The New York Times, 29 May 2001

Hi Benny -

You may be interested to know that the first version of this acoustic
bomb-detection array was a secret project that flew a series of balloons
carrying microphones to "listen" for possible nuclear weapon tests. On July
3, 1947, one of these balloons crashed near Roswell, New Mexico, and the
attempts to keep the project secret while recovering the pieces turned
Roswell into the center of the Flying Saucer mythology. [See US Air Force
"Roswell Report: Fact vs. Fiction in the New Mexico Desert", or a shorter
version in Bob Park's "Voodoo Science".]



From Duncan A. Lunan <>

    From Hermann Burchard <>

Dear Benny,

In New Scientist, vol. 73 p.320, there was an article titled 'The World Is a
Bit Cracked' - a news item as I remember. I don't have a note of the date
but it would have been in the 1970's or very early 80's. It stated that in
orbital survey photographs a system of parallel crustal fractures running
north-south had been located in both western Africa and eastern South
America. The implication was that the Earth's rotation rate had been altered
before the continents separated, either by the flyby of a massive object or
more probably by an impact.   However it put the age of the fractures c. 600
million years b.p., so I don't know if it's relevant here.

Best wishes,

Duncan Lunan

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By By Edward A. Byrant, School of Geosciences, University of Wollongong,

The following text is an extract from Edward A. Bryant's new book TSUNAMI:
THE UNDERRATED HAZARD, to be published by Cambridge University Press
(publication c. July 2001).

0 521 77244 3 Hardback 55.00/$74.95
0 521 77599 4 Paperback 19.95/$27.95

For more details and how to order, please visit the CUP website at


In the past decade over ten major tsunami events have impacted on the
world's coastlines, causing devastation and loss of life. Evidence for past
great tsunami, or 'mega-tsunami', has also recently been discovered along
apparently aseismic and protected coastlines. With a large proportion of the
world's population living on the coastline, the threat from tsunami can not
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and describes particular events linked to earthquakes, volcanoes, submarine
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of the text can be read by anyone with a high school education. The book
will appeal to students and researchers in geomorphology, earth and
environmental science, and emergency planning, and will also be attractive
for the general public interested in natural hazards and new developments in

Chapter Contents plus excerpt see:

CCCMENU CCC for 2001