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(meteorobs) Excerpts from "CCNet 33/2001, 1 March 2001"
------- Forwarded Message
From: Peiser Benny <B.J.Peiser@livjm.acdot uk>
To: cambridge-conference <cambridge-conference@livjm.acdot uk>
Subject: CCNet,1 March 2001
Date: Thu, 1 Mar 2001 10:19:44 -0000
CCNet 33/2001, 1 March 2001
---------------------------
"My idea could solve the missing smaller craters, the sunken areas
and the angular rocks that may have been eroded out of the ast[e]roid's
surface. Moderate to large impacts could cause an asteroid to vibrate
like a tuning fork, the loose surface dust would ride along the surface
seeking low spots in the weak gravity like a fluid bed. Smaller impact
craters would be filled in while larger craters, or newer smaller craters,
may leave a sunken like look. Rocks could travel along the surface a short
distance (didn't I read once that a rock left a short trail?) loosening
more dust for the next impact exposing angular rock that may be former
impactors or hard accetions within the asteroid."
--Dave English, 28 February 2001
[...]
(3) NEAR SHOEMAKER PHONES HOME FOR THE LAST TIME
Ron Baalke <baalke@jpl.nasadot gov>
(4) LOUIS FRANK CLAIMS TO HAVE FOUND NEW EVIDENCE FOR SMALL COMET THEORY
Andrew Yee <ayee@nova.astro.utorontodot ca>
[...]
(6) NEAR: AWAKENED FROM THE DEAD?
Space.com, 28 February 2001
[...]
(8) DUST MIGRATION ON SMALL BODIES
Dave English <prospector@sd.znet.com>
[...]
=================================================================
(3) NEAR SHOEMAKER PHONES HOME FOR THE LAST TIME
>From Ron Baalke <baalke@jpl.nasadot gov>
For Immediate Release
February 28, 2001
Media Contacts:
Helen Worth
(240) 228-5113
helen.worth@jhuapldot edu
Mike Buckley
(240) 228-7534
michael.buckley@jhuapldot edu
The End of an Asteroidal Adventure
NEAR Shoemaker Phones Home for the Last Time
Tonight at 7 p.m. (EST) NASA's Deep Space Network antennas will pull down
their last Near Earth Asteroid Rendezvous (NEAR) mission data, bringing to a
close the first mission to extensively study an asteroid. NEAR, which was
the first mission in NASA's Discovery Program of low-cost, scientifically
focused space missions, and the first to land on an asteroid, has delighted
astronomy neophytes and scientists alike.
"NEAR has raised the bar," says Dr. Stamatios Krimigis, Space Department
head at The Johns Hopkins University Applied Physics Laboratory in Laurel,
Md., which built the spacecraft and managed the NEAR mission. "The
Laboratory is very proud to have managed such a successful mission and
worked with such a strong team of partners from industry, government and
other universities. The team had no weak links and the result was an
historic mission that surpassed everyone's expectations."
"This mission has been successful far beyond what was in the original
mission plan," says NEAR Mission Director Dr. Robert Farquhar of APL. "We
got the first images of a C-class asteroid when we added a flyby of asteroid
Mathilde in 1997; we added two low altitude series of passes over the ends
of Eros this past October and January that gave us spectacular images from
2.7 kilometers above the surface; and we achieved the first landing of a
spacecraft on an asteroid on Feb. 12. All this at no extra cost. When you
talk about ' faster, cheaper, better,' this is what 'better' means."
On Feb. 12 at 3:01:52 p.m. (EST), NEAR Shoemaker made a gentle,
picture-perfect 3-point landing on the tips of two solar panels and the
bottom edge of the spacecraft body. But the mission wasn't finished yet.
Much to the amazement of the mission team and millions of observers around
the world who were following the descent, the touchdown was so elegant that
the craft was still operating and sending a signal back to Earth even after
landing.
Jumping at the chance to get "bonus science" from the spacecraft, which had
already collected 10 times more data than originally planned, the mission
team asked for and got a 10-day extension and then four more days of DSN
antenna time, enabling NEAR Shoemaker to send back data through Feb. 28. The
extension was granted to allow the gamma-ray spectrometer to collect data
from an ideal vantage point about four inches from the surface. The
spectrometer team quickly redesigned software and uploaded it to the
spacecraft so they could begin collecting elemental composition readings.
The results were spectacular. "This is the first gamma-ray experiment that
has ever been done on the surface of a body other than Earth," says Dr.
Jacob Trombka, of NASA's Goddard Space Flight Center, in Greenbelt, Md., who
heads the gamma-ray spectrometer team. "In fact, we can say it's the first
feasibility study of how to design an instrument to be used on a rover that
could select samples from the surface, look for the presence of water, or
map the surface for the purpose of future mining."
The gamma-ray spectrometer team was able to retrieve data for a period of
seven days after the spacecraft landed. "Right now we know we have good data
with strong signatures," Trombka says. "But it will take months to
scrutinize what we've collected. What we're looking for is information that
will help us more precisely classify Eros and determine the relationship
between the asteroid and meteorites that have fallen to Earth."
NEAR Shoemaker now rests silently just to the south of the saddle-shaped
feature Himeros as the asteroid twists more and more away from the sun with
each rotation, moving the southern hemisphere into its winter season and
temperatures as low as minus 238 degrees Fahrenheit (minus 150 centigrade).
Project Scientist Dr. Andrew Cheng of APL, says the glamorous part of the
mission is over but now scientists can get down to studying the data,
including the more than 160,000 detailed images taken by the spacecraft. "We
solved mysteries, we unveiled more mysteries. Now we're sharing the amazing
amount of data that we collected with scientists all over the world, to sort
through and debate and hopefully to help us discover facts about Eros and
our solar system that no one knows today."
For more information on the NEAR mission, including a gallery of images,
visit Web site: http://near.jhuapldot edu.
=================================================================
(4) LOUIS FRANK CLAIMS TO HAVE FOUND NEW EVIDENCE FOR SMALL COMET THEORY
>From Andrew Yee <ayee@nova.astro.utorontodot ca>
University Relations
University News Services
University of Iowa
CONTACT:
GARY GALLUZZO
(319) 384-0009; fax (319) 384-0024
e-mail: gary-galluzzo@uiowadot edu
Release: Embargoed 1 a.m. EST, March 1, 2001
UI researcher finds new evidence for small comet theory
IOWA CITY, Iowa -- In a paper published in the March 1, 2001 issue of the
American Geophysical Union's Journal of Geophysical Research, University of
Iowa physics professor Louis A. Frank says that he has found new evidence to
support his theory that the water in Earth's oceans arrived by way of small
snow comets.
Frank reports that he obtained pictures of nine small comets among 1,500
images made between October 1998 and May 1999 using the Iowa Robotic
Observatory (IRO) located near Sonoita, Ariz. In addition, he says that the
possibility of the images being due to "noise," or electronic interference,
on the telescope's video screens was eliminated by operating the telescope
in such a manner as to ensure that real objects were recorded in the images.
This operation of the telescope utilized two simple exposure modes for the
acquisition of the images. One scheme used the telescope's shutter to
provide two trails of the same small comet in a single image, and the second
scheme used the same shutter to yield three trails in an image.
"In the two-trail mode for the telescope's camera, no events were seen with
three trails, and for the three-trail mode, no events were seen with two
trails," he says. "This simple shutter operation for the telescope's camera
provides full assurance that real extraterrestrial objects are being
detected." Frank notes these images with the IRO confirm earlier reports of
small comet detection using the ground-based Spacewatch Telescope during
November 1987, January 1988 and April 1988.
The small comet theory, developed in 1986 with UI research scientist John
Sigwarth from data gathered using the Dynamics Explorer 1 satellite, holds
that about 20 snow comets weighing 20 to 40 tons each disintegrate in the
Earth's atmosphere every minute. Over the lifetime of our planet, the comets
would have accounted for virtually all of the Earth's water. The small comet
theory has been controversial almost from the beginning, with some
scientists suggesting that images identified as small snow comets actually
result from electronic noise on satellite sensors and other researchers
asserting that the images represent a real phenomenon. In 1997, Frank
revealed a series of photographs taken by Visible Imaging System (VIS)
cameras designed by Frank and Sigwarth and carried aboard NASA's Polar
spacecraft as further proof of the existence of the small snow comets.
Robert A. Hoffman, senior scientist at NASA's Goddard Space Flight Center,
Greenbelt, Md. and project scientist for both the Dynamics Explorer 1 and
the Polar spacecraft missions, says that because satellite-based imagery
related to the small comet theory has been interpreted in different ways,
ground-based imagery is a good alternative.
"Due to the controversy surrounding the interpretation of the images from
space-borne detectors taken primarily in ultraviolet wavelengths,
ground-based visible observations with sufficient signal-to-noise appear to
be the most practical approach to obtaining clear evidence regarding the
existence of these objects. I hope more such studies will be performed,"
Hoffman says.
Frank, a UI faculty member since 1964, has been an experimenter,
co-investigator, or principal investigator for instruments on 42 spacecraft.
His instruments include those used to observe the Earth's auroras, as well
as those used to measure energetic charged particles and thin, electrically
charged gases called plasmas. He is a Fellow of the American Geophysical
Union and the American Physical Society, a member of the American
Astronomical Society, American Association for the Advancement of Science
and the International Academy of Astronautics, and a recipient of the
National Space Act Award.
Further information, including images of two small comet trails, can be
found at the following web site:
http://smallcomets.physics.uiowadot edu/iro/
(Note to editors and reporters: Frank will be traveling out of the country
from Feb. 26 through March 3 and will be unavailable for interviews during
that time.)
=================================================================
(6) NEAR: AWAKENED FROM THE DEAD?
>From Space.com, 28 February 2001
http://www.space.com/missionlaunches/missions/near_awakening_010228.html
Is it possible that NEAR Shoemaker could survive its long, deep sleep? There
is some speculation at APL that awakening the probe after its long
hibernation might be feasible.
Given full sunlight will fall upon the spacecraft once again in August 2002,
reactivating solar-powered NEAR Shoemaker might be worth thinking about,
said Helen Worth, APL spokeswoman.
"As we've learned with NEAR Shoemaker, the impossible always seems to become
possible. There are no plans at this time to do such a thing. But it
wouldn't be unreasonable to look into the idea," Worth told SPACE.com.
"It would give us another opportunity to learn more about what happens to a
spacecraft. If we can't contact it later, if we tried to, we would learn
something from that too. Whether they're going to even attempt that..dot it
hasn't been decided at this point," Worth said.
In 2002, Eros is much closer to Earth. Reestablishing a radio link with the
asteroid-sitting spacecraft might be reasonable and feasible.
"This idea has not been thoroughly examined. It's something that needs to be
looked at to determine if it's even possible. We're not there yet. I'm sure
there are people who are thinking about it already, but it hasn't been
pursued at this point, or seriously proposed," Worth said.
Copyright 2001, Space.com
============================
* LETTERS TO THE MODERATOR *
============================
(8) DUST MIGRATION ON SMALL BODIES
>From Dave English <prospector@sd.znet.com>
Dear Benny:
I read with interest the report by Jeffery Bell about the lack of small
impact craters on Eros, the apparent erosion of angular rocks to its surface
and J. Fred Singer's well founded idea of electrostatic dust transport, but
it may be much simpler than that.
My idea could solve the missing smaller craters, the sunken areas and the
angular rocks that may have been eroded out of the astroid's surface.
Moderate to large impacts could cause an asteroid to vibrate like a tuning
fork, the loose surface dust would ride along the surface seeking low spots
in the weak gravity like a fluid bed. Smaller impact craters would be filled
in while larger craters, or newer smaller craters, may leave a sunken like
look. Rocks could travel along the surface a short distance (didn't I read
once that a rock left a short trail?) loosening more dust for the next
impact exposing angular rock that may be former impactors or hard accetions
within the asteroid.
If this idea has merit then the size of the last impactor should be able to
be calculated by the appearance of the sunken areas which will reflect the
type of motion and so the energy generated by the impact. I know that in
panning gold many different motions and taps can cause very different
results in the gold pan. I'm not a scientist, just an idea person with
practical knowledge about virbration and fluid bed type motions, which the
dust in the weak gravity should mimic after larger impacts that would
vibrate the asteroid like a tunning fork causing the dust to seek low spots,
exposing new angular rock, and causing further surface erosion by scraping
and pounding by loose rock.
Dave English
Oceanside, California
prospector@sd.znet.com
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