PLEASE NOTE:
*
CCNet DIGEST, 9 March 1999
--------------------------
(1) SOME COMMENTS ON NEODyS
Gareth V. Williams <gwilliams@cfa.harvard.edu>
(2) HOW ASTEROIDS JUMP
The New York Times, March 9, 1999
http://www.nytimes.com/library/national/science/030999sci-observatory.html
(3) BRITAIN TAKES INTEREST IN NEAR-EARTH OBJECTS
Mike DiMuzio <mdimuzio@cisnet.com>
(4) SPACEDEV WINS MICRO-SATELLITE AWARD
Jim Benson <jim@spacedev.com>
(5) MILLENNIAL-SCALE VARIABILITY OF HOLOCENE CLIMATE
G.G. Bianchi and I.N. McCave, UNIVERSITY OF
CAMBRIDGE
(6) SUDDEN EMERGENCE OF THE OXUS CIVILISATION IN THE LATE 3rd
MILLENNIUM BC
B.E. Hemphill, VANDERBILT UNIVERSITY
=================
(1) SOME COMMENTS ON NEODyS
From Gareth V. Williams <gwilliams@cfa.harvard.edu>
The recent CCNet Digest posting on NEODys by Andrea Milani is
written
in a manner that makes it difficult to object to any portion of
it
without seeming to be pro-proprietary data or pro-secrecy.
However,
there are a number of issues that Milani has ignored and that
need to
be mentioned.
A major problem is that NEODys includes, in the form of .rwo
files, the
observations from the Minor Planet Center's database, in full,
that
were used in the orbit determination. Why are these data
included?
Milani argues that it is necessary so that others may repeat and
verify
his calculations. However, if anyone else uses OrbFit, the same
.rwo
file with the same weights and the same planetary perturbation
scheme,
then they are going to end up with exactly the same result as
Milani.
What does this prove about the "trueness" of the
derived solution?
Nothing. It is far more likely that another user will want to use
his/her own code, own weighting scheme and quite possibly a
different
set of planetary positions. Yet the fit of the orbit to the
observations still needs to be demonstrated. This can be
accomplished
by including a residual block as in the Minor Planet Circulars.
We note that the OrbFit software is distributed, freely, under a
rather
specific license that prohibits certain actions on the part of
the
users. In a similar vein, the Minor Planet Center's database of
astrometric observations is distributed, via subscription, under
a
similar license, specifically one that allows personal scientific
use
but that prohibits redissemination in any form. Why should one
license
be adhered to, while another is ignored?
Milani argues that the observational database is in the public
domain
because it contains, almost exclusively, data obtained by third
parties
(the worldwide corps of astrometric observers). What he fails to
appreciate, or seems reluctant to accept, is that the Minor
Planet
Center spends a lot of time making sense of the raw observations
that
are submitted by observers: identifying objects, designating new
objects, identifying and correcting problems (in the designation,
date/time of observation or position), and extracting old
positions
from the literature. It should be noted that many others also do
not
realise that the MPC's principal effort involves making sense of
the
observations. Perhaps we've made it look too easy... Once
order has
been brought to the observations the orbit computations are often
trivial.
Free and immediate access to data is a laudable goal, but it has
to be
remembered that data rarely, if ever, come at no cost. Someone,
somewhere has to be paid to do the work on which others
depend. We
also feel that it is wrong to complain that there is no
"glasnost" in
this field. The observations and orbits computed at the MPC are
published on the MPECs and in the Minor Planet Circulars and
Minor
Planet Supplement. In the MPCs residual blocks are shown for new
computations, allowing the reader to see the fit of the
observations to
the published orbit. The algorithms used by the Minor Planet
Center are
mainly well-known classic methods, taken from the literature (in
some
cases, refereed journals, in others, classic textbooks on
celestial
mechanics). Anyone is free to check any of the MPC's calculations
by
whatever methods they see fit.
Over the past few years, the datasets of the Minor Planet Center
have
been subject to numerous cases of plagiarism and downright
thievery,
actions that would not be tolerated in any other field.
We agree that it is unsatisfactory that the Minor Planet Center
has to
depend on user subscriptions to support its activities, but there
is at
present no other funding solution that satisfies all the relevant
parties and that enables the MPC to maintain its integrity and
the
independence that it requires and that some observers demand.
==============
(2) HOW ASTEROIDS JUMP
From The New York Times, March 9, 1999
http://www.nytimes.com/library/national/science/030999sci-observatory.html
By HENRY FOUNTAIN
Most asteroids lead a benign existence, content to linger in
their main
belt between Mars and Jupiter, following an elliptical orbit
around the
Sun. But some wind up nearer Earth, where the potential for a
life-threatening collision inspires fear and film scripts.
Exactly how an asteroid jumps across Mars orbit to near-Earth
space has
always been something of a mystery. Now, scientists from Italy
and the
Czech Republic, writing in the journal Science, offer an
explanation as to
how small asteroids and asteroid fragments make the leap.
In doing so, the scientists have dusted off a phenomenon first
described a century ago. It is called the Yarkovsky effect, for
the
Russian engineer who discovered it, and holds that spinning
bodies
warmed by sunlight gain heat in a nonuniform manner, which in
turn
leads to small orbital shifts.
Using simulations, the scientists showed that over millions of
years,
the effect can cause an asteroid's semimajor axis (half the long
axis
of the ellipse) to drift a few million miles or so. That is
enough to
bring some asteroids in the inner part of the main belt close
enough to
Mars that other forces take over, slinging the rocks into orbits
that
bring them near Earth.
Copyright 1999, The New York Times Newspapers Ltd.
===================
(3) BRITAIN TAKES INTEREST IN NEAR-EARTH OBJECTS
From Mike DiMuzio <mdimuzio@cisnet.com>
This is from Spaceviews, a list from the National Space Society,
http://www.spaceviews.com.
Mike
----------------------
Britain Takes Interest in Near-Earth Objects
At the request of a member of Parliament, the British government
announced plans this past week to investigate how it can play a
larger
role in the detection of potentially-dangerous near-Earth objects
(NEOs).
John Battle, the Minister for Energy and Industry, told the House
of
Commons near the close of its Wednesday, March 3 session that the
government is willing to talk with British astronomers and other
experts on ways the country can help in the search for near-Earth
asteroids and comets.
Battle's statement came after a statement by Lembit Opik. Opik
called
on the government to pledge support, and money, for the
Spaceguard
Foundation, an international organization that supports searches
for
NEOs. He suggested setting up a UK center for Spaceguard at the
Armagh
Observatory in Northern Ireland, which currently does asteroid
and
comet research.
"To set up the centre and the feasibility study group would
cost about
4.56 million pounds (US$7.3 million) over 10 years; that is less
than
500,000 pounds (US$800,000) a year, and would provide an
important
first step to the larger project," Opik said.
He said the project's cost was only 2 percent that of the
Millennium
Dome, a structure under construction on the banks of the Thames
in
London. "McDonald's has given 12 million pounds (US$19
million)
sponsorship to the dome, which is more than the entire cost of UK
participation in Spaceguard over 10 years," Opik said.
"That is
an amazing statistic."
Opik said he got the runaround from the government when he first
tried
to bring up his concerns about impacts. "When I originally
asked about
the threats, we contacted the Ministry of Defence, which said
that it
was really a matter for the Department of the Environment,
Transport
and the Regions [DETR]. The DETR passed us on to the Home Office,
which
suggested the Department of Trade and Industry."
Battle, though, seemed sympathetic to Opik's request, promising
to
discuss the Spaceguard proposal with other members of the British
government, including Science Minister Lord Sainsbury.
Opik, who represents Montgomeryshire for the minority Liberal
Democrats
party, is the grandson of Ernst Opik, an astronomer who studied
comet
and asteroid impacts from Estonia and, later, the Armagh
Observatory.
====================
(4) SPACEDEV WINS MICRO-SATELLITE AWARD
From Jim Benson <jim@spacedev.com>
Dear Friend of SpaceDev,
I thought you might be interested to see that we are now getting
into a
serious revenue-producing phase, with the award of the contract
described below, to our SIL subsidiary.
This follows closely our contract from NASA's JPL for SpaceDev's
ISS to
furnish JPL with mission and spacecraft designs for Mars
micromissions
costing less than $50 million - exactly the number we have been
advocating since our national press conference in September of
1997.
FOR IMMEDIATE RELEASE
SPACEDEV WINS MICRO-SATELLITE AWARD
Space Innovations Limited To Provide Australian FedSat Research
Satellite Bus
SAN DIEGO, CA -- March 9, 1999 -- SpaceDev (OTC BB: SPDV), the
world's
first commercial space exploration and development company, today
announced that its SIL subsidiary has been awarded a
multi-million
dollar contract to build the Australian FedSat research satellite
bus.
FedSat, an Australian research micro-satellite, is being procured
by
the CRCSS (Cooperative Research Centre on Satellite Systems). The
satellite will be integrated and operated by the CRCSS, a
collaborative
effort by twelve Australian universities, companies and
government
agencies with laboratories in six states and territories.
The
equipment will be provided by SIL (Space Innovation Limited) of
Newbury, England, a wholly owned subsidiary of SpaceDev.
"After an intense international competition and careful
consideration
by the Australian government, the choice of SIL to build the
FedSat bus
indicates SIL has arrived in terms of being a competitor on a
global
scale. We are very pleased with the decision and look
forward to
working with CRCSS to make their mission a
success," said Jim Benson,
Chairman and CEO of SpaceDev.
"I believe that mastery of space and space technology will
be extremely
important in the next century in terms of job creation and
economic
stimulation." Mr. Benson added, "After recent
visits to Australia and
the award of the contract, I see Australia's interest in
space is
growing, and SpaceDev hopes to collaborate closely with
CRCSS over the
next few years to help foster this important development."
"This new scientific satellite will promote Australian space
engineering and scientific research." The Honorable Nick
Minchin, the
Minister for Industry, Science and Resources Centre, said
today, "This
project and the Space Activities Act we introduced last year,
show that
the government has strong faith in the important role space will
play
in Australia's future."
Minister Minchin approved the contract for the supply of a
satellite
platform or bus, together with its ground control system, for the
FedSat experimental micro-satellite that will celebrate
Australian
scientific and technical capability in 2001, the Centenary of
Federation..
"This contract represents a major milestone for the
CRCSS," said its
Executive Director, Dr. Brian Embleton. "We were
established just 13
months ago, with a charter to develop low-cost space projects
relevant
to Australian business, education and research needs.
FedSat will be
the first satellite developed in Australia in thirty years, and
it will
allow a new generation of space engineers, scientists and
businesses to
acquire experience and to develop new products and services that
customers can afford."
This view was echoed by SIL's Marketing Director, Kim Ward, who
stressed the importance of the contract award to the company,
"We see
the FedSat project as a vital next step in SIL's growth. It is
gives us
the opportunity to establish strong relationships with a number
of
important organizations in Australia and to demonstrate to the
space
community the potential of our advanced 3-axis stabilized
spacecraft
bus to many different mission applications in the future."
The FedSat satellite is scheduled to be launched during the last
quarter of the year 2000, in good time to participate in
celebrations
marking the centennial of the Australian Federation in
mid-2001. The
58 Kg spacecraft, Australia's first satellite mission of the new
millennium, will carry experiments for navigation, magnetic field
measurement, profiling the Earth's atmosphere, and testing new
space
computers and new satellite communications technologies. It
will be
placed into orbit some 800 Km above the Earth and should operate
for up
to three years.
SIL, acquired in 1998 by SpaceDev, is a space products company
specializing in design and manufacture of inexpensive satellite
subsystems and turnkey mini- and micro-satellites.
SpaceDev's capabilities include mission and spacecraft design as
well
as construction of small satellites, ground stations, spacecraft
subsystems, and launch vehicles; plus aerospace design and
analysis
services. Headquartered in San Diego, SpaceDev is a
Colorado chartered
corporation with additional sales offices in Washington, DC.
The foregoing press release includes numerous forward-looking
statements concerning the company's business and future prospects
and
other similar statements that do not concern matters of
historical
fact. The federal securities laws provide a limited "safe
harbor" for
certain forward-looking statements. Forward-looking statements in
this
press release relating to product development, business prospects
and
development of a commercial market for technological advances are
based
on the company's current expectations. The company's current
expectations are subject to all of the uncertainties and risks
customarily associated with new business ventures including, but
not
limited to, market conditions, successful product development and
acceptance, competition and overall economic conditions, as well
as the
risk of adverse regulatory actions. The company's actual results
may
differ materially from current expectations. Readers are
cautioned not
to put undue reliance on forward-looking statements. The company
disclaims any intent or obligation to update publicly these
forward-looking statements, whether as a result of new
information,
future events or for any other reason.
Note: News releases and other information on SpaceDev can be
accessed
at:
www.spacedev.com
ISS: www.spaceinc.com
SIL: www.sil.com
===================
(5) MILLENNIAL-SCALE VARIABILITY OF HOLOCENE CLIMATE
G.G. Bianchi and I.N. McCave: Holocene periodicity in North
Atlantic
climate and deep-ocean flow south of Iceland. NATURE, 1999,
Vol.397,
No.6719, pp.515-517
UNIVERSITY OF CAMBRIDGE, DEPT EARTH SCI, DOWNING ST, CAMBRIDGE
CB2
3EQ, ENGLAND
Climate fluctuations during the past millennium are relatively
well
documented(1). On a longer timescale, there is growing evidence
of
millennial-scale variability of Holocene climate, at
periodicities of
similar to 2,500 and 950 years (possibly caused by changes in
solar
flux)(2,3) and similar to 1,500 years (maybe related to an
internal
oscillation of the climate system)(4-6). But the involvement of
deep
water masses in these Holocene climate changes has yet to be
established. Here we use sediment grain-size data from the
Iceland
basin to reconstruct past changes in the speed of deep-water
flow. The
study site is under the influence of Iceland-Scotland Overflow
Water
(ISOW), the flow of which is an important component of the
'thermohaline' circulation that modulates European climate. Flow
changes coincide with some known climate events (the Little Ice
Age and
the Mediaeval Warm Period), and extend over the entire Holocene
epoch
with a quasiperiodicity of similar to 1,500 years. The grain-size
data
indicate a faster ISOW flow when the climate of northern Europe
is
warmer. However, a second mode of operation is observed in the
early
Holocene, when warm climate intervals are associated with slower
ISOW
flow. At that time the melting remnant of land-based, glacial-age
ice
may have provided a sufficient source of fresh water to the ocean
to
reduce ISOW flow south of Iceland. Copyright 1999, Institute for
Scientific Information Inc.
=======================
(6) SUDDEN EMERGENCE OF THE OXUS CIVILISATION IN THE LATE 3rd
MILLENNIUM BC
B.E. Hemphill: Biological affinities and adaptations of Bronze
Age
Bactrians: IV. A craniometric investigation of Bactrian origins.
AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, 1999, Vol.108, No.2,
pp.173-192
VANDERBILT UNIVERSITY, DEPT ANTHROPOL, 221 KIRKLAND HALL,
NASHVILLE,TN,37235
Discovery of a previously unknown Bronze Age civilization (Oxus
civilization) centered on the eases of Central Asia revealed the
presence of large, preplanned urban centers immediately above
sterile
soil. Given the absence of local antecedents, the sudden
appearance and
proliferation of these Oxus civilization urban centers in the
eases of
Bactria and Margiana immediately raised the issue of where the
inhabitants of these urban centers came from. Three hypotheses
have
been offered by archaeologists to account for the origins of Oxus
civilization populations. These include the early influence
model, the
late colonization model, and the trichotomy model. Eleven
craniometric
variables from 12 Aeneolithic and Bronze Age samples,
encompassing 657
adults from Central Asia, Iran, and the Indus Valley, are
compared to
test which if any of these hypotheses are supported by the
pattern of
phenetic affinities possessed by the Oxus civilization
inhabitants of
the north Bactrian oasis. Craniometric differences between
samples are
compared with Mahalanobis generalized distance (d(2)), and
patterns of
phenetic affinity are assessed with two types of cluster analysis
(WPGMA, neighbor-joining method), multidimensional scaling, and
principal coordinates analysis. Results of this analysis provide
no
support for either the late colonization model or the trichotomy
model
but do offer some support for the early influence model.
Nevertheless,
it is clear that the early influence model fails to account for a
shift in interregional contacts, perhaps from western China to
the
north around 2000 BC, that appears to have played a major role in
the
origins of the Oxus civilization inhabitants of the north
Bactrian
oasis. (C) 1999 Wiley-Liss, Inc.
----------------------------------------
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*
LETTERS TO THE MODERATOR, 9 March 1999
--------------------------------------
(1) PROBLEMS WITH YARKOVSKY EFFECT
Vincenzo Zappala <zappala@otoax4.to.astro.it>
(2) A CHIP OFF THE MOON?
Simon Mansfield <simon@spacer.com>
(3) IS SPACEGUARD TOO CHEAP?
Michael Paine <mpaine@tpgi.com.au>
================
(1) PROBLEMS WITH YARKOVSKY EFFECT
From Vincenzo Zappala <zappala@otoax4.to.astro.it>
Dear Benny,
I have read some comments on the origin of Earth-crossing
asteroids
which seem to take into account the Yarkovsky effect only. It
seems
that no other processes are known to do so. I would like to
address the
readers to a recent paper published in Science (Science, Vol.
281,
2022) where other solutions are found. In particular, that paper
shows
a good way for objects as large as several km. For them,
Yarkovsky
cannot work in reasonable time-scales.
Vincenzo Zappala
================
(2) A CHIP OFF THE MOON?
From Simon Mansfield <simon@spacer.com>
Benny,
The recent "chip off the moon" story has got me
thinking again about
our Lagrangian points and the search for Trojan rocks.
I would like to ask the following questions for discussion:
1/ Is there enough gravitational stability in the L4 and L5
points of
either the Earth-Moon or Earth-Sun systems for smaller
asteroids/big
rocks to become captured.
2/ What sort of time scales might then be operating before the
gravitational influence of the Sun or Jupiter might sweep them
out.
3/ Are there any upper or lower limits to the size of captured
bodies
in relation to the mass of the Earth Moon and Sun.
4/ Have there been telescope or radar searches conducted of these
points
I have searched extensively on the net and found only a few
references
to Jupiter and Mars trojans. The recent "chip off the
moon" article is
one of the few extended references to very close objects I've
come
across.
If the maths can give any sort of reasonable prediction that
objects
can be captured and remain in the L4/5 vicinity for some time
then a
serious search of this "uncharted" region of nearby
space should be
conducted.
With the recent success of several lunar fly bys using various
sized
spacecraft (including a Hughes GeoSat) mounting a flyby of the
Earth-Moon L4 or L5 points could be done, possibly even on route
elsewhere.
The key to such a mission is how to observe a large volume of
virtually
empty space for objects that could be anywhere in that space and
measuring from grains of sand to house size rocks.
Apart from the fundamental science such a discovery would find,
the
ability to harness any useful resources would be much easier
given
their nearby location.
Regards,
Simon Mansfield
Editor
SpaceDaily.com
simon@spacer.com
=================
(3) IS SPACEGUARD TOO CHEAP?
From Michael Paine <mpaine@tpgi.com.au>
Dear Benny,
Lembit Öpik and David Johnson have touched on a possible problem
with
the Spaceguard proposal - it might be too cheap for governments
and
philanthropists to take seriously!
With an international cost of about $10million per year for 10
years a
large scale search for NEOs is not going to be an
expensive, glamorous
job compared with most other fields of space research. Maybe we
should
approach it like road maintenance - fixing pot-holes before they
become
hazardous. Of course, the policitians take pride in opening new
bridges
and motorways and totally ignore road maintenance - unless it is
too
late and someone is killed by a big pothole.
My other conjecture is that many scientists working outside of
the NEO
field support the Spaceguard proposal in principle but are
reluctant to
do so publicly because the funds might be diverted from their
area of
research.
In regard to Lembit Öpik's speech in the UK Parliament, I have
had
almost the same sequence of shuffling between
portfolios/departments in
Australia:
Minister Assisting the Minister for Defence,
Department of Industry, Science and Tourism and
Minister for Employment, Education, Training and Youth Affairs!
The bureaucrats don't have a pigeon-hole for Spaceguard so they
keep
shuffling it around. In view of Lembit Öpik's initiative we
should all
now approach our respective governments once again and get the
politicians to direct the bureaucrats to implement Spaceguard.
Michael Paine
-----------------
CCNet-LETTERS is the discussion forum of the Cambridge-Conference
Network. Contributions to the on-going debate about near-Earth
objects,
the cosmic environment of our planet and how to deal with it are
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Benny J Peiser at <b.j.peiser@livjm.ac.uk>.
The fully indexed archive
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