PLEASE NOTE:


*

CCNet DIGEST, 6 May 1998
------------------------

(1) PLANETARY SOCIETY TO AWARD SECOND ROUND OF ASTEROID-DISCOVERY
    GRANTS
    The Planatary Society
    planetary.org/articlearchive/headlines/1998/headln-050598.html

(2) UNIVERIST OF ARIZONA CATALINA SKY SURVEY SPEED UP THEIR SEARCHES
    Andrew Yee <ayee@nova.astro.utoronto.ca>

(3) METEORITE DELIVERY VIA YARKOVSKY ORBITAL DRIFT
    Paolo Farinella <paolof@keplero.dm.unipi.it>

(4) WHY WE STILL DON'T KNOW WHERE HOMO SAPIENS EVOLVED
    S.L. Smith and F.B. Harrold, University of Texas

(5) THE CCNet ARCHIVE
    Benny J Peiser <b.j.peiser@livjm.ac.uk>

=========================
(1) PLANETARY SOCIETY TO AWARD SECOND ROUND OF ASTEROID-DISCOVERY
    GRANTS: GENE SHOEMAKER NEAR-EARTH OBJECT GRANTS ENCOURAGE DETECTION
    OF POTENTIALLY DANGEROUS COMETS AND ASTEROIDS

From The Planatary Society
http://planetary.org/articlearchive/headlines/1998/headln-050598.html

The Planetary Society is seeking applications for the second round of
selections for the Gene Shoemaker Near-Earth Object Grants. The purpose
of the grant program is to increase the rate of discovery and follow-up
studies of asteroids and comets in Earth's vicinity by enabling amateur
observers, observers in developing countries, and professional
astronomers who, with seed funding, could greatly increase their
programs' contributions to this critical research.

The deadline for receipt of applications for the second round of
selections is June 30, 1998. Previous awardees will not be considered
for the present selection and applicants for the first round wishing
consideration in the second selection are requested to submit new,
updated applications. Application forms are available on this web site
<http://planetary.org/articlearchive/headlines/1998/headln-050598.html>

The Society's NEO Grant Program is coordinated by Daniel D. Durda, an
asteroid researcher at the University of Arizona's Lunar and Planetary
Laboratory. An international advisory group, including noted near-Earth
object scientists Richard Binzel of the Massachusetts Institute of
Technology, Clark Chapman of the Southwest Research Institute, Andrea
Carusi of the Spaceguard Foundation, and Brian Marsden of the
Smithsonian Astrophysical Observatory, will advise the Planetary
Society on the selection of awards for the grants.

FACING THE THREAT OF COMETS AND ASTEROIDS

Popular awareness of the threat of comet and asteroid impacts has
increased dramatically in recent months with the report of a close
approach past Earth of the asteroid 1997 XF11 in October 2028 and the
summer release of the movies Deep Impact and Armageddon.

Earth lives in a swarm of near-Earth objects of different sizes and
orbits. Scientists have only recently begun to understand the
significant contribution NEOs have made to the evolution of Earth --
and of life on Earth -- just as impacts from comets and asteroids have
contributed to the evolution of all planets throughout the solar
system.

Less than 200 NEOs have been discovered thus far. Scientists estimate
that there are several thousand such NEOs larger than one kilometer and
150,000 to perhaps 100 million larger than 100 meters in size.

While various astronomical groups and NASA advisory committees have
strongly recommended discovery of these objects be accelerated,
government support for NEO search and follow-up programs remains
modest.

"At the current rate of discovery, it would take decades to find a
majority of even the large NEOS," says Planetary Society Executive
Director Louis Friedman.

The Planetary Society hopes that its NEO Grant Program will help map
the potential hazards of the future, allowing humanity to better
understand the threat of cosmic collisions.

The Society is cooperating with the Spaceguard Foundation, a
European-based international organization, to help fund and promote
discovery of near-Earth objects.

PREVIOUS GRANT RECIPIENTS

The first four Gene Shoemaker Near-Earth Object Grants were awarded at
the Celebration of Life service honoring Shoemaker at the US Geological
Survey Flagstaff Field Center on October 11, 1997. The grants, totaling
more than $35,000, were awarded to Gordan Garradd of Australia, Kirill
Zamarashkin of Russia, Walter Wild of the United States, and Bill
Holliday of the United States for upgrades to their programs to search
for NEOs.

The Society funds for the NEO Grant Program come from its 100,000
members worldwide, whose voluntary dues and donations permit targeted
support to research and development programs.


====================
(2) UNIVERSITY OF ARIZONA CATALINA SKY SURVEY SPEED UP THEIR SEARCHES

From Andrew Yee <ayee@nova.astro.utoronto.ca>

University of Arizona News Services

Lori Stiles
UA News Services
520-621-1877
lstiles@u.arizona.edu

Contact(s):

     Stephen M. Larson
     520-621-4973
     slarson@lpl.arizona.edu

May 4, 1998

UA Catalina Sky Survey to make speedy searches for faint near-earth
asteroids and comets

Astronomers at The University of Arizona in Tucson who in 1992 started
a unique near-Earth asteroid survey in the Santa Catalina Mountains
north of Tucson are about to begin faster searches for fainter objects
in large areas of sky where other such surveys seldom look.

Six years ago, Timothy Spahr and Carl Hergenrother, then UA
undergraduate students, with faculty sponsor Stephen M. Larson of the
UA Lunar and Planetary Laboratory, launched the Bigelow Sky Survey at
the university's 16-inch Schmidt telescope near Mount Bigelow, Ariz. It
has been a part time photographic survey, inspired by and patterned
after the systematic photographic search conducted at the Palomar
Observatory Schmidt telescope in southern California by the late Eugene
Shoemaker of the U.S.Geological Survey and his wife, Carolyn..

With the photographic system, observers took two images, 30 minutes
apart, of the exact same region of the sky, then compared the images
under a stereo microscope. Moving objects appeared to "float" above the
flat star background. It took 60 minutes to thoroughly scan a pair of
films, Larson said.

Program observers Spahr and Hergenrother made the Bigelow survey's most
famous discovery, a near-Earth asteroid 200 meters in diameter, or
roughly four times the size of the impactor that produced Meteor
Crater, Ariz., that missed Earth by about 280,000 miles on May 19,
1996.

Several months ago, Larson's group started a major NASA-funded upgrade
of the system and renamed the project the Catalina Sky Survey.

Ultimately, Larson said, "With current and anticipated improvements, we
will be able to detect an object in one-fortieth the exposure time
needed for photographic observations, or we will be able to detect
objects 14 times fainter while covering the same area as film with our
new system. And this does not include improvements using software to
replace eyeball scanning."

The Catalina Sky Survey is unusual in that program observers hunt for
Earth- orbit crossing asteroids and comets above the plane of the
ecliptic, or the plane in which the planets revolve.

Other surveys, including the productive and pioneering UA Spacewatch,
directed by planetary sciences Professor Tom Gehrels, hunt for
near-Earth asteroids along the ecliptic. Most Earth-crossing asteroids
can be found when their slightly inclined orbits cross the ecliptic
plane twice each orbit so long as they are near enough or bright enough
and are observed for a long enough time. Sometimes, they are close
enough to the Earth that perspective causes them to appear outside of
the ecliptic.

"Away from the ecliptic plane, we don't see as many of these objects
because there are fewer of them," Larson said. "But while we don't find
as many objects, a higher percentage of those we do find have
interesting orbits. We aren't able to detect objects as faint and small
as the larger (36-inch) Spacewatch telescope, but we will cover much
more area for the brighter and potentially more dangerous asteroids."

Larson now is collecting data to test software that operates an
electronic camera on the newly computer-controlled UA Catalina Schmidt
telescope. The heart of the camera is a very large, very sensitive
4,096 by 4,096-pixel charge-coupled device (CCD). It is the same type
of chip used in Eleanor Helin's Near-Earth Asteroid Tracking program,
sponsored jointly by NASA, the NASA Jet Propulsion Lab and the U.S. Air
Force. The device can record light 50 times fainter than can be
captured by the most sensitive photographic film.

The Catalina telescope now electronically images a 3x3-degree field of
view, or a square patch of sky equivalent to six lunar diameters on a
side. It is capable of finding objects as faint as 20th magnitude,
which is approaching the sky background level generated by scattered
city light and auroral airglow that brightens Earth's upper atmosphere.

The astronomers take from three to five electronic images of the exact
same sky region about 30 minutes apart. When they perfect the
performance of the telescope, they will be able to precisely align the
multiple electronic images so that stars and galaxies appear as single
stationary sources of light and moving objects are seen to move across
the screen.

Other proposed improvements to the Catalina Sky Survey include
increasing the telescope's light gathering power with a larger entrance
corrector plate, and to increase computer capacity. Each electronic
image is 32 megabytes and requires near real-time processing to extract
moving objects."We now have this fairly fast computer, but it has to
cope with 16 million pixels per image," Larson said.

John Brownlee, a recent graduate of the UA geosciences program, is
programming the computer to coordinate the telescope and CCD control
with data reduction and object detection. Automation of repetitive
tasks and sequence flexibility to compensate for cloudy weather will be
major goals.

Spahr recently finished his dissertation, which included data from the
Bigelow Sky Survey, and has been awarded his doctorate from the
University of Florida. Graduate school has kept him away from Tucson
during most of the upgrade, but he soon will rejoin the survey effort
he initiated. This time, he will have state-of-the-art survey tools.

The Catalina Schmidt telescope is available to the sky survey team most
of the time, so only the bright moon limits observing time, Larson
added. "With enough money to hire people, which is the big operational
expense, we could observe 21 nights a month."

Ideally, the several near-Earth asteroid surveys could cover the sky
two-to- three times a month, he said. "The Catalina Sky Survey team
anticipates making significant contributions to the NASA near-Earth
asteroid inventory effort."

==========================
(3) METEORITE DELIVERY VIA YARKOVSKY ORBITAL DRIFT

From Paolo Farinella <paolof@keplero.dm.unipi.it>

Paolo Farinella, David Vokrouhlicky and William K. Hartmann: Meteorite
delivery via Yarkovsky orbital drift. ICARUS 132, 378-387, April 1998

ABSTRACT. We provide a unified discussion of the Yarkovsky effect in
both the original, 'diurnal' variant and also for the `seasonal'
variant which has been recently shown by Rubincam (1995) to be
important for meteorite-sized, regolith-free asteroid fragments. After
computing the rate of the corresponding semimajor axis drift as a
function of size and spin rate, and comparing the relevant timescales
with those for collisional disruption and spin reorientation, we
discuss some issues in meteorite science which are put in a new light
by the relevance of the Yarkovsky effect. In particular, this mechanism
provides a good explanation for the fact that meteorite cosmic ray
exposure ages (in particular for irons) are much longer than the
dynamical lifetimes of objects delivered to the Earth-crossing region
through resonances. Thanks to the Yarkovsky effect, small asteroid
fragments in the belt undergo a slow drift in semimajor axis (with a
random-walk component related to their rotational state) and therefore
have enough mobility to reach the resonances after comparatively long
times spent in nonresonant main-belt orbits. Metal-rich fragments have
slower Yarkovsky drift rates than stones, but their much longer
collisional lifetimes may explain why iron meteorites appear to sample
a larger number of asteroid parent bodies compared to ordinary
chondrites.

=======================
(4) WE STILL DON'T KNOW WHERE HOMO SAPIENS EVOLVED (let alone how,    
    .... never mind why)

S.L. Smith and F.B. Harrold: A paradigm's worth of difference?
Understanding the impasse over modern human origins. YEARBOOK OF
PHYSICAL ANTHROPOLOGY, 1997, Vol.40, pp.113-138

UNIVERSITY OF TEXAS, DEPARTMENT OF SOCIOLOGY & ANTHROPOLOGY, ARLINGTON,
TX, 76019

The modern human origins debate within paleoanthropology has become
polarized between two dominant models, Recent African Origin (RAO) and
Multiregional Evolution (MRE). The debate has persisted and shows no
sign of resolution despite the incorporation of new data and dates
during the past decade. We examine the reasons for this stalemate,
focusing on the presentation of these models by their principal
advocates, Christopher Stringer and Milford Wolpoff. In particular, we
consider whether the RAO-MRE dispute is a paradigm crisis. The modern
human origins debate can be placed in the broader context of unresolved
controversies within evolutionary biology (e.g., punctuated equilibrium
vs. gradualism, use of cladistics, and species definitions). While the
two sides hold conflicting views, we argue that such differences do not
constitute a paradigm clash. Since both share a commitment to Darwinian
evolutionary theory, the debate cannot be characterized as a paradigm
clash at the level of, e.g., Ptolemaic vs. Copernican astronomy.
Furthermore, we submit that a debate having historical roots reaching
back into the previous century should not be portrayed as a conflict
between competing paradigms in the Kuhnian sense. Preferences toward
discontinuity or continuity wax and wane, persisting in a variety of
scientific disciplines. We do not predict the quick demise of either
MRE or RAO but are optimistic that careful evaluation of the characters
and data on which claims about modern human origins are based will lead
us toward a resolution of the current impasse. (C) 1997 Wiley-Liss,
Inc.

=====================
(5) THE CCNet ARCHIVE

From Benny J Peiser <b.j.peiser@livjm.ac.uk>

If you are a new list member on the CCNet or you wish to check previous
communication and correspondence posted on the CCNet since its
start in February 1997, you can access and search the Cambridge
Conference Correspondence Menu at

http://abob.libs.uga.edu/bobk/cccmenu.html

Bob Kobres has set up this electronic archive and posts the
communication on the CCNet on the menu on a daily basis.

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