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(meteorobs) Excerpts from "CCNet 44/2001 - 21 March 2001"
Exciting news from NASA of the next planned comet flyby! And even
more exciting, Neil Bone weighs in on meteor jargon and the press. :)
Lew Gramer
------- Forwarded Message
From: Peiser Benny <B.J.Peiser@livjm.acdot uk>
To: cambridge-conference <cambridge-conference@livjm.acdot uk>
Subject: CCNet, 21 March 2001
Date: Wed, 21 Mar 2001 13:14:47 -0000
CCNet 44/2001 - 21 March 2001
-----------------------------
[...]
(2) SCIENTISTS RETURN TO ANCIENT IMPACT CRATER AT CHESAPEAKE BAY
Ron Baalke <baalke@jpl.nasadot gov>
[...]
(4) DEEP SPACE 1 LOADS UP FOR TREK TO COMET
Ron Baalke <baalke@jpl.nasadot gov>
[...]
(6) CHANNEL FIREBALL
Neil Bone <bafb4@central.susx.acdot uk>
(7) CHANNEL FIREBALL
Martin Hoffmann <Martin.Hoffmann@dlrdot de>
[...]
================================================================
(2) SCIENTISTS RETURN TO ANCIENT IMPACT CRATER AT CHESAPEAKE BAY
>From Ron Baalke <baalke@jpl.nasadot gov>
http://www.usgsdot gov/public/press/public_affairs/press_releases/pr1400m.h=
tml
- ------------------------------------------------------------------------=
- ----
News Release Address
Office of Outreach
U.S. Department of the Interior 953 National Center
U.S. Geological Survey Reston, VA 20192
Release Contact Phone Fax
March 15, 2001 Diane Noserale 703-648-4333 =
703-648-6859
- ------------------------------------------------------------------------=
- ----
Scientists Return to Ancient Impact Crater
March will mark the beginning of a new field season for scientists from =
the
U.S. Geological Survey (USGS) and its cooperators who will begin =
drilling a
second core hole into an impact structure created 35 million years ago =
when
an asteroid or comet slammed into the ocean near the present-day mouth =
of
the Chesapeake Bay. The scientists are studying the effect of this =
ancient
event on the modern day regional ground-water system and the quality of
drinking water in southeastern Virginia.
"The asteroid or comet probably measured about 1 to 2 miles in diameter =
and
was traveling at tens of miles per second," said Greg Gohn, USGS Chief =
of
the Chesapeake Bay Impact Crater Project. "It gouged a crater 53 miles =
wide
and fractured bedrock to a depth of well over a mile. Today, those =
disrupted
rock units greatly affect the pattern of ground-water flow throughout
southeastern Virginia. Because we believe that this ancient impact =
might
have rendered the ground water in large areas of the crater unfavorable =
for
development as a water source, the information we are gathering is =
relevant
to managing ground-water resources in southeastern Virginia," said =
Gohn.
Gohn expects to begin drilling at two sites in the Middle Neck of =
Virginia.
Drilling of a core hole 1,500 feet deep at a site in Mathews County,
Virginia near the village of North will likely begin on March 20. This
location is a short distance inside the outer rim of the crater as it =
is
presently mapped on the Middle Neck. Work at a second drill site in =
Mathews
County near Shadow, Virginia is planned to begin in June. This site is
located well within the ring-shaped trough of the impact crater; =
scientists
expect to penetrate the bottom of the crater at a depth between 2,000 =
to
2,500 feet. Last summer, the scientists drilled more than 2,000 feet =
into
the crater's rim at the NASA Langley Research Center in Hampton, =
Virginia.
Science support and funding have been provided in part by the Hampton =
Roads
Planning District Commission and the Virginia Department of =
Environmental
Quality.
As the nation's largest water, earth and biological science and =
civilian
mapping agency, the USGS works in cooperation with more than 2000
organizations across the country to provide reliable, impartial =
scientific
information to resource managers, planners and other customers. This
information is gathered in every state by USGS scientists to minimize =
the
loss of life and property from natural disasters, contribute to the =
sound
conservation, economic and physical development of the nation's natural
resources, and enhance the quality of life by monitoring water, =
biological,
energy, and mineral resources.
================================================================
(4) DEEP SPACE 1 LOADS UP FOR TREK TO COMET
>From Ron Baalke <baalke@jpl.nasadot gov>
MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
http://www.jpl.nasadot gov
Contact: Martha J. Heil (818) 354-0850
FOR IMMEDIATE RELEASE March 20, 2001
DEEP SPACE 1 LOADS UP FOR TREK TO COMET
NASA's Deep Space 1 spacecraft, sailing through the solar system today, has
taken delivery of a new cargo: the latest software for its ambitious
encounter with Comet Borrelly this September.
After successfully finishing its primary mission in 1999 as a testing ground
for important new technologies, NASA approved a risky bonus mission to Comet
Borrelly for Deep Space 1. There the spacecraft will take black-and-white
pictures, use infrared pictures to find out the nature of
the comet's surface, measure and identify the gases coming from the comet,
and measure the interaction of solar wind with the comet. To take pictures
of the comet, Deep Space 1 must upgrade its software's pointing system to
turn the spacecraft from a testbed for advanced technologies to a
chronicler of Comet Borrelly.
"Deep Space 1's previous version of software, which was transmitted to the
spacecraft nine months ago, has proven itself during the surprisingly
successful flight through the solar system since then, but now we're giving
the probe a new assignment," said Dr. Marc Rayman, the project manager.
"And in order to prepare for this exciting and daring comet encounter, the
software needs to be upgraded."
The spacecraft team will be checking the software, radioed to Deep Space 1
throughout the week of March 5. The first check came when the team actually
received a signal from the spacecraft after it shut the main computer off
and restarted it. Since the software sent by the team works well, the
spacecraft sent a signal indicating it is healthy. Now engineers
are giving the spacecraft's new software a thorough physical checkup.
"The process of transmitting the new software to the spacecraft, rebooting
the on-board computer to begin running it, verifying that the spacecraft
is working properly with the new software and restoring the craft to its
cruise configuration, all when the spacecraft is 318 million km
(197 million miles) away, is a complex and tricky operation,"
said Daniel Eldred, the Deep Space 1 mission manager.
The new software contains capabilities that will be needed when the
spacecraft gets to Borrelly. The new commands will include lessons that
Deep Space 1 learned in its 1999 encounter with asteroid Braille about the
behavior of the spacecraft when it gets close to a solar system object.
The spacecraft carries a device, part of the successful new technology
system, which holds two cameras. One uses a conventional charge-coupled
device detector, the other a new technology detector. The test camera,
though performing its initial tests successfully, wasn't equipped to deal
with the very dark object that Braille turned out to be. Small bodies like
asteroids and comets are still a mystery. Since they're so small and
distant, their exact size and shape can't usually be determined from Earth.
Deep Space 1 plans to use its tried- and-true CCD camera to try to snap
photos of Borrelly. The team will send commands to the new software to
stop using the test camera and start using the CCD camera, which will
take a larger picture with more light.
In late 1999, after the successful end of its primary mission, Deep Space 1
lost its star tracker, and the spacecraft had to be reconfigured to use the
photographic camera to orient itself by the stars around it. In order to
take pictures of Borrelly, the camera can't align the spacecraft and snap
photos of the comet at the same time. Instead, the spacecraft will have to
rely on its fiber-optic gyroscopes to help maintain its orientation. But
the gyros are not accurate enough by themselves, so the new software will
try to correct for those inaccuracies. The new software is designed to
help the camera stay pointed at the comet's nucleus during the 15
minutes that the camera will attempt to observe the comet.
Deep Space 1 was launched in October 1998 as part of NASA's New
Millennium Program, which is managed by JPL for NASA's Office of
Space Science, Washington, D.C. The California Institute of
Technology in Pasadena manages JPL for NASA.
Deep Space 1 completed its primary mission testing ion propulsion and
11 other advanced technologies in September 1999. NASA extended the
mission, taking advantage of the ion propulsion and other systems to
target a chance but exciting encounter with the comet in September
2001. More information can be found on the Deep Space 1 Home Page at:
http://nmp.jpl.nasadot gov/ds1/
================================================================
* LETTERS TO THE MODERATOR *
================================================================
(6) CHANNEL FIREBALL
>From Neil Bone <bafb4@central.susx.acdot uk>
Having been away for a couple of days, I'm just catching up on this
one! I have had, forwarded to me, a single report from a BAA member
of a fireball at 18:53 UT on 2001 March 13, which would appear to
be the event reported on CCNet. This was reported as a mag. -5
event descending from the NE at azimuth 160 from Epsom (51.33N,
0.27W) by Peter Mugridge. The direction and description appear
consistent with the putative 'over the Channel'.
The "meteor shower" report is yet another example of the media
minefield in action. Events like this are either a "meteorite"
or a "meteor shower" in the eyes of the press, and it seems to
be a losing battle to try to get the average hack to use the
correct terminology (I've tried, in vain, on many occasions!).
It perhaps further confuses the issue to have as valid
terminology a *meteorite* shower to describe the scatter of
numerous fragments in the fall ellipse on occasons when
something does make it to ground...
Neil Bone
Director, British Astronomical Association Meteor Section
================================================================
(7) CHANNEL FIREBALL
>From Martin Hoffmann <Martin.Hoffmann@dlrdot de>
Dear friends,
Yesterday I read the news of a possible meteor shower in CCNet 42 and
43/2001. Immediately I recalled having seen a bright meteor last week
and having written a remark about it in my notebook. Indeed this
happened to be on March 13, 19:50 GMT +/- 3 minutes. Although it was
low in the northeastern sky it had an estimated brightness of mag -2,
about Jupiter's brightness. It may have reached mag -4 (Venus) where
it has been overhead. That should have occurred somewhere over
northwestern Poland, since I have observed it from just a few
kilometers southeast of the city limits of Berlin. The object was
visible less than 2 seconds and left no visible train despite its
brightness. I had averted vision when it became visible, but the
final parts of its path were pretty exactly north to south in
celestial coordinates in the northern half of the constellation
of Bootes, where it split into two fragments near Epsilon and
Sigma Bootis and disappeared. If this phenomenon is related to
the reports from the channel has to be checked if there are
reports on the paths of those.
Regards,
Martin Hoffmann
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