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(meteorobs) Excerpts from "CCNet DIGEST, 5 May 1999"
------- Forwarded Message
From: Benny J Peiser <b.j.peiser@livjm.acdot uk>
To: cambridge-conference@livjm.acdot uk
Subject: CCNet DIGEST, 5 May 1999
Date: Tue, 4 May 1999 12:35:45 -0400 (EDT)
CCNet DIGEST, 5 May 1999
------------------------
[...]
(3) CHAMPOLLION'S COST-SAVING KEEPS COMET MISSION ALIFE
Ron Baalke <baalke@ssd.jpl.nasadot gov>=20
(4) METEOR MYSTERY MAY BE SOLVED
Boston Globe, 2 May 1999
(5) METEORS DOWN UNDER
NASA Science News <expressnews@sslab.msfc.nasadot gov>=20
[...]
(7) LECTURE ON THE IMPACT OF COMETS AND ASTEROIDS UPON THE EARTH
--------------------------------------------------------------------
(3) CHAMPOLLION'S COST-SAVING KEEPS COMET MISSION ALIFE
>From Ron Baalke <baalke@ssd.jpl.nasadot gov>=20
=20
Fast Response Keeps Champollion On Track=20
By JOHN G. WATSON
JPL Universe
April 30, 1999
=20
Engineering ingenuity and dawn-to-dusk efforts over the past few=20
weeks have resulted in a successful and lifesaving redesign of Space=20
Technology 4/Champollion, a proposed mission to land on a comet=20
nucleus.
=20
The mission will feature a single spacecraft instead of a mother ship=20
and lander as part of newly announced, reconfigured mission=20
architecture. Some of JPL's most creative solutions come out of the=20
crucible of rigid budget and engineering constraints, and Space=20
Technology 4/Champollion has emerged from the fire a leaner and=20
meaner mission.
=20
Changes in the mission plan will allow Space Technology 4/Champollion=20
to accomplish all of its technology validation and science goals=20
while working within budget limits of approximately $158 million,=20
excluding launch costs and operations.
=20
Earlier plans had assumed that industry and/or government agencies=20
would partner with the project in some key areas of technology. When=20
such partners failed to materialize, the mission was faced with a=20
significant funding shortfall.
=20
On March 19, NASA headquarters formally requested a plan on how the=20
ambitious comet rendezvous mission could be kept at its roughly $158=20
million cap.
=20
Project Manager Brian Muirhead and his team rolled up their sleeves=20
and got to work. "Within one week, the team had brainstormed,=20
developed 18 pages of options, narrowed them down, arrived at what we=20
thought was the most likely option to succeed and fleshed that option=20
out," Muirhead said. "We then took two more weeks to detail the=20
concept, estimate its mass and cost it."
=20
A successful pair of presentations to NASA's Office of Space Science=20
on April 8 and 14 led to reauthorization for JPL to proceed with=20
formulating the mission based on the concept as presented.
=20
"The ST4/Champollion team developed a revised mission plan that was=20
capable of meeting the budget constraints," Muirhead said. "We went=20
from a two-spacecraft paradigm to a single spacecraft, which gives us=20
a simpler set of hardware that's easier to test on the ground. The=20
new design is more robust, and our chances of a successful landing=20
are as good or better than they were before.
=20
"We received offers of support from all over the Lab, especially the=20
technical divisions," he added. "JPL is really at its best when it's=20
focused on supporting a project during a crisis."
=20
The lifesaving transformation of the mission recalls similar=20
resurrections of past JPL missions that had been threatened with=20
cancellation. The Galileo mission, for example, was completely=20
replanned several times due to changes made in launch configurations=20
and upper stages, most dramatically after the Space Shuttle=20
Challenger accident in 1986. The Cassini mission, too, was completely=20
restructured in 1992 in response to a new budget squeeze and the=20
cancellation of its sister mission, Comet Rendezvous Asteroid Flyby.
=20
Attempting a feat never done before, Space Technology 4/Champollion=20
will land on a comet's nucleus after surveying and mapping it for=20
several months. The key to the success of this mission is a suite of=20
10 technologies that must work together as a system to deliver a=20
payload safely to the surface of an active comet. These=20
technologies-including multi-engine ion propulsion (building from=20
Deep Space 1), a large, 10-kilowatt, high-efficiency solar array=20
using inflatables and precision guidance and landing using a=20
miniature scanning laser altimeter-have wide application to other=20
future space science missions.
=20
Once on the surface, the spacecraft will take images of its=20
surroundings, drill for material below the surface of the nucleus and=20
perform scientific experiments to determine the composition of this=20
untouched material from the original solar nebula.
=20
For further details about Space Technology 4/Champollion, visit
=20
http://nmp.jpl.nasadot gov/st4
--------------------------------------------------------------------
(4) METEOR MYSTERY MAY BE SOLVED
=20
>From The Boston Globe, 2 May 1999
http://www.boston.com:80/dailyglobe2/122/metro/Meteor_mystery_may_be_sol=
ved+.shtml
=20
By David L. Chandler, Globe Staff, 05/02/99=20
=20
When astronomers at the Cambridge-based international clearinghouse for =
astronomical observations began last November to get reports from=20
around the world of sightings of the annual Leonid meteor shower, it
was clear that something was off.
=20
While the Leonids can sometimes produce a spectacular storm of shooting =
stars at 33-year intervals, the storms are not reliable, and nobody was =
sure if there would be one last year (or possibly this year).
=20
It soon became clear from the sightings that the '98 display was far=20
short of a true meteor storm, but that there had been a totally=20
unexpected peak of spectacular bright meteors called fireballs - about=20
16 hours before the peak activity was supposed to occur.
=20
Now, some British astronomers think they have solved the puzzle of the=20
ahead-of-schedule activity. Knowing that the Leonids are junk left=20
behind by comet Tempel-Tuttle, they carefully analyzed the comet's path =
for the last several centuries to see where fragments shed in the past=20
would have ended up.
=20
It turns out, they wrote this month, that the unexpected fireballs seen =
last fall were composed of bits shed by the comet when it passed the=20
Earth way back in 1333.
=20
The astronomers, David Asher and Mark Bailey of the Armagh Observatory=20
in Northern Ireland, say their work for the first time proves that=20
meteors are associated with complex braid-like streams of debris in a=20
comet's orbit, and they have been able to create computerized maps of=20
these braids from comet Tempel-Tuttle. This should help in forecasting=20
future meteor showers.
=20
The bad news is that their mapping shows that, contrary to many=20
astronomers' hopes, there will be no spectacular meteor storm this=20
coming November, just a slightly-stronger than usual Leonid shower.
=20
=A9 Copyright 1999 Globe Newspaper Company.=20
--------------------------------------------------------------------
(5) METEORS DOWN UNDER
=20
>From NASA Science News <expressnews@sslab.msfc.nasadot gov>=20
=20
NASA Space Science News for May 3, 1999
=20
Meteors Down Under: On May 5th, debris from Halley's comet will strike =
Earth's atmosphere and put on a sky show for southern observers. The=20
eta Aquarid meteor display is the first of two upcoming annual showers=20
caused by the famous comet. FULL STORY:
=20
http://science.nasadot gov/newhome/headlines/ast03may99_1.htm=20
--------------------------------------------------------------------
(7) LECTURE ON THE IMPACT OF COMETS AND ASTEROIDS UPON THE EARTH
By Donald K. Yeomans
Supervisor, Solar System Dynamics Group
Jet Propulsion Laboratory
Monday, May 17, 1999
7:30 p.m. at
GRIFFITH OBSERVATORY
=20
Comets and asteroids have been receiving bad press of late. In two=20
recent movies, they have been portrayed as Earth threatening=20
villains. While comets and asteroids do smack into the Earth from=20
time to time, it is also likely that they helped deliver the water=20
and carbon-based molecules to the early Earth, thus providing the =20
building blocks for the formation of life. Subsequent collisions may=20
have punctuated life's evolutionary cycles allowing only the most=20
adaptable species to evolve further. We mammals may owe our=20
preeminent position atop the Earth's food chain to a collision some=20
65 million years ago that wiped out most of our competition -=20
including the dinosaurs.
Ironically, the same comets and asteroids that can most closely=20
approach the Earth are also the most accessible in terms of=20
exploiting their vast supplies of water and metals. Comets and=20
asteroids could easily supply the raw materials necessary for=20
colonizing the inner solar system in the next century. In addition to=20
the utility of assessing their potential as future threats and=20
resources, there are compelling scientific reasons for studying these=20
primitive leftovers from the solar system formation process.=20
Knowledge of their compositions and structures will provide important=20
clues to the conditions and chemical mix from which the planets=20
formed some 4.6 billion years ago. The nature and chemical =20
composition of these enigmatic objects should soon become clear as=20
spacecraft missions closely study a dozen comets and asteroids in the=20
next 13 years.
At the Jet Propulsion Laboratory, Don Yeomans is a Senior Research=20
Scientist and Supervisor for the Solar System Dynamics Group. Dr.=20
Yeomans is the Project Scientist for the MUSES-CN mission to explore=20
the surface of a near-Earth asteroid and Radio Science Team Chief for=20
the Near-Earth Asteroid Rendezvous (NEAR) mission. He is the current=20
Chairman for the Division of Planetary Sciences and has recently been=20
appointed manager of NASA's Near-Earth Object Program Office. His=20
research work is focused upon the physical and dynamical modeling of=20
comets and asteroids. He has been active in providing the observing=20
community and flight projects with position predictions for hundreds=20
of comets and asteroids including those that have been, or will be,=20
mission targets. In refining the motions of comets and asteroids, he=20
has used data types as diverse as recent radar measurements,=20
Hipparcos-based astrometry, and ancient Chinese observations. Don has=20
received 10 NASA Achievement awards including an Exceptional Service=20
Medal in 1986. He has published three books and over 100 technical=20
papers. Asteroid 2956 was renamed 2956 YEOMANS to honor his=20
professional achievements.
Friends Of The Observatory (FOTO) is the non-profit support group for=20
Griffith Observatory. Currently, one of FOTO's primary goals is to=20
support the renovation and expansion of the Observatory, so that it=20
continues to provide the nearly 2 million visitors and 50,000 school=20
children annually with accurate astronomical and scientific=20
information and programs and remains the internationally recognizable=20
icon of Los Angeles.
=20
Admission: $2 for FOTO members, $5 for non-members; tickets are=20
available at the door. (Children under 5 are not admitted.)
=20
Griffith Observatory Griffith phone: (323) 664-1181
2800 East Observatory Road Griffith fax: (323) 663-4323
Los Angeles, California 90027 USA http://www.GriffithObs.org
mailto:list@GriffithObs.org
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