PLEASE NOTE:
*
Date sent: Wed, 04
Feb 1998 11:15:37 -0500 (EST)
From:
Benny J Peiser B.J.PEISER@livjm.ac.uk
Subject: CC
DIGEST, 04/02/98
To:
cambridge-conference@livjm.ac.uk
Priority: NORMAL
CAMBRIDGE-CONFERENCE DIGEST, 4 February 1998
--------------------------------------------
(1) ASTEROID 1620 GEOGRAPHOS
Alan W. Harris awharris@lithos.jpl.nasa.gov
(2) PLANETARY SOCIETY EXPEDITION TO BELIZE GOES ON LINE
Ron Baalke BAALKE@kelvin.jpl.nasa.gov
(3) NEAP MISSION ELIGIBLE FOR NASA FUNDING
Jim Benson jim@spacedev.com
(4) COSMIC DUST DETECTED IN OUTER SOLAR SYSTEM
D.A. Gurnett et al., University of Iowa
(5) DETERMINATION OF ICE COMPOSITION WITH INSTRUMENTS ON
COMETARY LANDERS
W.V. Boynton et al., University of Arizona
================================================
(1) ASTEROID 1620 GEOGRAPHOS
From: Alan W. Harris awharris@lithos.jpl.nasa.gov
Dear Benny,
a) The asteroid's name is 1620 GEOGRAPHOS.
b) Geographos has been extensively observed both optically
(e.g.
Magnusson and 47 other co-authors, Icarus 123, 227-244, 1996) and
by
radar (Ostro et al. Nature 375, 474-477, 1995), and has failed to
reveal the slightest irregularity in its rotational properties
from
these very extensive data sets. Thus it is very likely that the
claimed results of the recent Ukrainian observations are
spurious.
=============================
(2) PLANETARY SOCIETY EXPEDITION TO BELIZE GOES ON LINE
From: Ron Baalke BAALKE@kelvin.jpl.nasa.gov
Planetary Society Expedition to Belize Goes On Line
Society Web Site Offers Daily Reports on Latest Expedition
Investigating the Demise of the Dinosaurs
From now until February 1, 1998, The Planetary Society's third
expedition to Belize is searching for evidence of the asteroid
impact
that ended the age of the dinosaurs 65 million years ago. This
time everyone is invited to participate via this web site,
http://www.planetary.org/hot-topics/belize/
where field reports -- including images -- from the expedition
will
be posted on a daily basis.
Team leaders Adriana Ocampo of the Jet Propulsion Laboratory
and
Kevin Pope of Geo Eco Research are again leading a group of
Planetary
Society volunteers on a geological adventure into the jungles of
Belize. Past Society expeditions to the region collected samples
of
ejecta blanket material -- debris blasted from the Chicxulub
crater
when the asteroid crashed just off the coast of the Yucatan. The
crater, now buried under the accumulated sediment of millions of
years, is 200 to 300 kilometers across (about 124 to 186 miles
across).
Ocampo said, "In this third expedition to Belize, we will
continue
our quest to build a more complete picture of what really
happened
when a comet or asteroid collided with Earth and changed our
world
forever.
"We have been tantalized by unique evidence from the
impact found
only in Belize, and this expedition will allow us to better
understand how impacts affect Earth and the other planets in our
solar system."
Scientific objectives of the 1998 expedition include
collecting
samples; following the ejecta blanket from north to south Belize
to
see how far it extends; and mapping the distribution of
ballistically
deformed materials, such as "Pook's pebbles" -- unique
features that
were discovered in Belize on a prior Society expedition.
This expedition will also work on an analog to Mars by
correlating
their findings in Belize with similar features found on the
martian
surface during the Pathfinder mission.
A digital camera, donated to the Planetary Society by Epson,
will be
used to record images of scientists and volunteers at work, the
sites
being studied, and some of the geological samples discovered.
These
images, along with daily field reports, will be posted on the
Society's web site. Expedition team member Robert Cozzi,
well-known
author of six books on computer programming, and his daughter
Theresa
will post the reports and photograph the expedition.
Discoveries from the 1995 and 1996 trips to Belize include
* The identification of a new species of crab that went
extinct at
the end of the Cretaceous period, named Carcineretes
planetarius in
honor of the Planetary Society;
* Identification of shock quartz in northern Belize;
* Identification of an iridium anomaly at Albion in northern
Belize;
and
* Identification of possible condensate material from the
impact's
vapor plume, including Pook's pebbles.
While this is the Planetary Society's third expedition to
Belize, it
is the fourth sent by the Society to study evidence of the
Chicxulub
impact. Another expedition went to Italy in 1996 to study core
samples from that same time period.
===============================
(3) NEAP MISSION ELIGIBLE FOR NASA FUNDING
From: Jim Benson jim@spacedev.com
Greetings,
Scientists and researchers will be able to submit proposals
for
flying instruments and experiments on NEAP (our Near Earth
Asteroid
Prospector mission), and for purchasing data from SpaceDev's NEAP
instruments under the next NASA Discovery Announcement of
Opportunity, due out on March 20.
Below is the content of a letter to me from the NASA Office of
Space
Science:
National Aeronautics and
Space Administration
Headquarters
Washington, DC 20546-0001
January 22, 1998
Mr. James Benson
P. O. Box 2121
31557 Aspen Ridge Road
Steamboat Springs, CO 80477
Dear Mr. Benson:
The Near Earth Asteroid Prospector (NEAP) mission represents
an
innovative and interesting approach to acquiring scientific data
through a private sector initiative. You have asked us to assess
the
possible place of NEAP in the Discovery program. The Discovery
Program addresses the scientific goals of the Solar System
Exploration Theme and the Extra-Solar Planetary Systems goals of
the
Astronomical Search for Origins Theme. NEAP clearly falls within
this scientific scope. In short, proposals to participate in the
NEAP mission are within the scope of the Discovery Program.
In addition, the Discovery Program objectives (section 2.2 of
the
draft AO) include: as a practical goal "Perform frequent,
high-quality scientific investigations that assure the highest
science value for the cost;" and as a supporting objective
"Pursue
innovative ways of doing business." The basic approach
envisioned by
the developers of the NEAP initiative is clearly an innovative
new
way of doing business. Because this approach is new and untried,
we
cannot, a priori, determine that the particular opportunity
afforded
will be the most cost-efficient. Such a determination must come
from
the detailed review process.
Finally, we note that proposing user provided instruments for
the
available pods [canisters] would appear to be potential
"Mission of
Opportunity" (section 2.3) investigations.
As the present draft is intended for comment, you should
examine the
draft, and may offer suggested changes. We should note that
actual
success or failure of any new concept proposed in response to the
Discovery AO will depend on the quality of the science, the
reasonableness of cost, and other factors, and will be judged in
the
likely context of a number of excellent competing proposals to
the
program.
Sincerely,
Carl B. Pilcher
Science Program Director (Acting)
Solar System Exploration
Office of Space Science
The Discovery program is open to all kinds of organizations
including
universities, for-profit companies, individuals, non-profits,
etc. It
is also open to both domestic and international participation.
This
means that prospects for NEAP are very wide and diverse.
NEAP is an example of adding more missions to those of
traditional
national space agencies, and results in more opportunities for
more
scientists and researchers.
Because Discovery, and therefore NEAP, is open to both science
and
new technology experiments, we expect a variety of proposals to
be
sent to NASA for possible funding of those instruments and
technologies.
If you are a scientist or technology researcher, now is the
time to
be thinking about preparing a proposal for NASA for your
experiment.
I believe it might be possible for NASA to fund one or more
complete
missions, but because of the low cost of rides on NEAP, funding
several experiments for such rides would provide NASA with the
equivalent of an additional complete mission, but at a fraction
of
the cost.
Finally, because the NEAP launch will be insured, NEAP offers
a very
low risk approach to space and planetary exploration. Unlike
government missions, if there is a disaster, insurance will pay
for
replacement instruments and a new launch, and the only loss will
be
time.
Only a short amount of time is available for sending a
proposal to
NASA. The official opening of the Announcement of Opportunity is
scheduled for March 20, and all proposals must be submitted
within
60 days.
Please let me know if you or an associate is thinking about or
planning to submitting a NEAP-based proposal to NASA under the
Discovery program.
Cheers,
Jim Benson
Chairman, CEO
============================================
(4) COSMIC DUST DETECTED IN OUTER SOLAR SYSTEM
D.A. Gurnett*), J.A. Ansher, W.S. Kurth, and L.J. Granroth:
Micron-sized dust particles detected in the outer solar system
by the Voyager 1 and 2 plasma wave instruments. GEOPHYSICAL
RESEARCH
LETTERS, 1997, Vol.24, No.24, pp.3125-3128
*) UNIVERSITY OF IOWA, DEPT PHYS & ASTRON, IOWA CITY, IA, 52242
During the Voyager 1 and 2 flybys of the outer planets it has
been
demonstrated that the plasma wave instrument can detect small
dust
particles striking the spacecraft. In this paper, we examine the
Voyager plasma wave data for dust impacts in the interplanetary
medium at heliocentric radial distances ranging from 6 to 60
astronomical units (AU). The results show that a small but
persistent
level of dust impacts exists out to at least 30 to 50 AU. The
average
number density of these particles is about 2 x 10(-8) m(-3), and
the
average mass of the impacting particles is believed to be a few
times
10(-11) g, which corresponds to particle diameters in the micron
range. Possible sources of these particles are planets, moons,
asteroids, comets, and the interstellar medium. Of these, comets
appear to be the most likely source. The number densities are
only
weakly dependent on ecliptic latitude, which indicates that the
particles probably do not originate from planets, moons, or
asteroids. Comparisons with interstellar dust fluxes measured in
the
inner regions of the solar system by the Ulysses spacecraft
indicate
that the particles are not of interstellar origin. Copyright
1998,
Institute for Scientific Information Inc.
===================================
(5) DETERMINATION OF ICE COMPOSITION WITH INSTRUMENTS ON
COMETARY LANDERS
W.V. Boynton*), L.C.dUston, D.T. Young, J.I. Lunine, J.H,
Waite,
S.H. Bailey, J.J. Berthelier, J.L. Bertaux, V. Borrel, M.F.
Burke,
B.A. Cohen, D.H. Mccomas, J.E. Nordholt, L.G. Evans, and J.I.
Trombka: The determination of ice composition with instruments on
cometary landers. ACTA ASTRONAUTICA, 1997, Vol.40, No.9,
pp.663-674
*) UNIVERSITY OF ARIZONA, TUCSON, AZ, 85721
The determination of the composition of materials that make up
comets
is essential in trying to understand the origin of these
primitive
objects. The ices especially could be made in several different
astrophysical settings including the solar nebula, protosatellite
nebulae of the giant planets, and giant molecular clouds that
predate
the formation of the solar system. Each of these environments
makes
different ices with different composition. In order to-understand
the
origin of comets, one needs to determine the composition of each
of
the ice phases. For example, it is of interest to know that
comets
contain carbon monoxide, CO, but it is much more important to
know
how much of it is a pure solid phase, is trapped in clathrate
hydrates, or is adsorbed on amorphous water ice. In addition,
knowledge of the isotopic composition of the constituents will
help
determine the process that formed the compounds. Finally, it is
important to understand the bulk elemental composition of the
nucleus. When these data are compared with solar abundances, they
put
strong constraints on the macro-scale processes that formed the
comet. A differential scanning calorimeter (DSC) and an
evolved-gas
analyzer (EGA) will make the necessary association between
molecular
constituents and their host phases. This combination of
instruments
takes a small (tens of mg) sample of the comet and slowly heats
it in
a sealed oven. As the temperature is raised, the DSC precisely
measures the heat required, and delivers the gases to the EGA.
Changes in the heat required to raise the temperature at a
controlled
rate are used to identify phase transitions, e.g.,
crystallization of
amorphous ice or melting of hexagonal ice, and the EGA correlates
the
gases released with the phase transition. The EGA consists of two
mass spectrometers run in tandem. The first mass spectrometer is
a
magnetic-sector ion-momentum analyzer (MAG), and the second is an
electrostatic time-of-flight analyzer (TOF). The TOF acts as a
detector for the MAG and serves to resolve ambiguities between
fragments of similar mass such as CO and N-2. Because most of the
compounds of interest for the volatile ices are simple, a gas
chromatograph is not needed and thus more integration time is
available to determine isotopic ratios. A gamma-ray spectrometer
(GRS) will determine the elemental abundances of the bulk
cometary
material by determining the flux of gamma rays produced from the
interaction of the cometary material with cosmic-ray produced
neutrons. Because the gamma rays can penetrate a distance of
several
tens of centimeters, a large volume of material is analyzed. The
measured composition is, therefore, much more likely to be
representative of the bulk comet than a very small sample that
might have lost some of its volatiles. Making these measurements
on a
lander offers substantial advantages over trying to address
similar
objectives from an orbiter. For example, an orbiter instrument
can
determine the presence and isotopic composition of CO in the
cometary
coma, but only a lander can determine the phase(s) in which the
CO is
located and separately determine the isotopic composition of each
reservoir of CO. The bulk composition of the nucleus might be
constrained from separate orbiter analyses of dust and gas in the
coma, but the result will be very model dependent, as the ratio
of
gas to dust in the comet will vary and will not necessarily be
equal
to the bulk value. (C) 1997 Published by Elsevier Science Ltd..
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