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(meteorobs) Excerpts from "CCNet, 09/2000 - 24 January 2000"
------- Forwarded Message
From: Benny J Peiser <b.j.peiser@livjm.acdot uk>
To: cambridge-conference@livjm.acdot uk
Subject: CCNet, 24 Janaury 2000
Date: Mon, 24 Jan 2000 11:05:23 -0500 (EST)
CCNet, 09/2000 - 24 January 2000
--------------------------------
QUOTES OF THE DAY
"[We] witnessed an extraordinary bright light in the sky. It
got very dark, then very bright, then it went pitch black and=20
returned to an orange pink colour. Seconds later, a=20
massive explosion was felt, and it was rather traumatic.=94
-- Gina Nagano, on the Yukon impact event
[...]
(1) AIRCRAFT TRIES TO COLLECT METEOR DATA OVER CANADA
ASTRONOMY NOW, 23 January 2000
(2) SKY-HIGH DRAMA MESMERIZES YUKONERS
WHITEHORSE STAR, 21 January 2000
[...]
(6) STARDUST COMPLETES MOST CRITICAL MANEUVER OF=20
COMET-CATCHING MISSION
Space.com, 21 January 2000=20
(7) NEAR MISSION STATUS REPORT, 21 January 2000
NEAR Mission Status Reports <pettee@jhuapldot edu>=20
============================================================
(1) AIRCRAFT TRIES TO COLLECT METEOR DATA OVER CANADA
>From ASTRONOMY NOW, 23 January 2000
http://spaceflightnow.com/news/0001/23nasaer2meteor/
NASA/DFRC NEWS RELEASE
Posted: Jan. 23, 2000
NASA Dryden Flight Research Center, Edwards, Calif., participated in a
data recovery mission for one of the largest meteor events of the past
10 years.=20
One of Dryden's Airborne Sciences ER-2 aircraft flew to the Yukon
Territory of northwestern Canada on January 21, 2000, in an effort to
collect atmospheric samples of a very large meteor that exploded at an
altitude of 25 kilometers (15.6 miles) on January 18, 2000. The region,
near the town of Carcross, is predominantly unpopulated.=20
Samples of the debris cloud and vapor trail were gathered at an =
altitude
of 65,000 feet with an instrument called the Aerosol Particulate =
Sampler
(APS). The APS is a system of two small five-inch by four-inch paddles
that deploy simultaneously from the ER-2's left wingtip. The paddles
have silicone oil on them that, when exposed to the airstream for a
sufficient amount of time, collect particles from the stratosphere. =
Then
the paddles are withdrawn into hermetic enclosures to avoid=20
contamination during the aircraft's return to Dryden. The paddles will
be removed and sent to NASA's Johnson Space Center in Houston, Texas =
for
analysis.=20
Dryden's ER-2 also carried a camera, called the Dual RC-10, capable of
taking black and white photos of eight-mile wide swaths of the region =
in
an effort to locate any impact craters and other scarring of the earth,
such as flattened areas of forest, that may have been caused by the
explosion and impact of meteorites that separated from the meteor.=20
Scientists are very interested in discovering the composition of the
meteor in an effort to learn more about its origins and makeup.=20
The Department of Defense is interested in knowing the composition of
the meteor in order to calibrate sensors that detected the fireball.
Collection of cosmic dust or meteorite samples would permit this.=20
The meteor detonated with the energy of two to three kilotons of TNT.
The extremely bright fireball was detected by defense satellites and
recorded on seismic monitoring instruments. The meteor produced twin
sonic booms and a sizzling sound over Alaska and northwestern Canada.=20
The unexpected visitor ionized the atmosphere as it entered, leaving a
glowing vapor trail that could be seen up to one and a half hours
afterwards. Two bright green flashes were observed. A foul odor could =
be
detected in the region in the hours following the event.=20
On June 30, 1908, a huge explosion occurred in the sky above the =
central
Siberian wilderness near the Tunguska River in Russia. The concussion
from the blast, estimated at 20 megatons of TNT, leveled trees in an
area nearly 40 miles in diameter. Oddly, the explosion produced no
crater or other evidence of impact.=20
Scientists at NASA and the University of Wisconsin conducted a computer
simulation that strongly suggests that the Tunguska culprit was an
asteroid, the most common class of meteorite. The simulation indicated
that an asteroid about 100 feet in diameter and moving at a speed of 10
miles per second would disintegrate at a height of about five miles
above the ground - approximately the same altitude at which the =
Tunguska
object is believed to have exploded. Information gleaned from the
January 18 meteorite in Canada might enhance understanding of the
Tunguska event. =20
(c) 2000 Pole Star Publications Ltd
============================================================
(2) SKY-HIGH DRAMA MESMERIZES YUKONERS
>From WHITEHORSE STAR, 21 January 2000
http://www.whitehorsestar.com
By Sigrun Maria Kristinsdottir
Many Yukoners, Alaskans and northern British Columbians were rattled=20
and mesmerized by a light in the dark morning sky at approximately=20
8:44. Drivers stopped their vehicles to to alight and gape, and=20
school students and staff emptied their classrooms to watch the=20
drama.
=93What you=92ve seen is a very bright meteor of the class known as a=20
fireball,=94 said Dr. Jeremy Tatum, a representative of Meteorites and=20
Impact Advisory Committee to the Canadian Space Agency in Victoria.
=93The description of this light going through the sky, the noises=20
that were heard to accompany it and the trail that was left behind,=20
that=92s all typical of a bright fireball.=94
=20
One witness to the meteorite described sitting in his car, perplexed=20
by what appeared to be an instant change in the amount of daylight.=20
And then it was dark again. But almost instantaneously, there was=20
another flash, as though a street light had blown out. And then=20
another, before the last in the pulsating flashes of light lit up=20
the sky as if it was mid-day. Looking skyward, the burning streak=20
shot southward across the sky and disappeared as quickly as it came.
It was probably a few meters in size, and travelled at 10 times the=20
speed of sound, said Tatum. He said he did not know yet if it or any
fragments of the meteorites hit the ground. The committee will be=20
getting satellite pictures and infra-sound records, said Tatum.
=93If something did land, it=92s almost impossible to find it unless
someone actually saw it land.=94=20
In a press release from the Yukon government, it says that reports
from NAV Canada and seismic information from the Pacific Geo Science=20
Centre indicate a suspected meteorite hit the ground near Carcross=20
this morning. No reports have been filed of any damage or injury,=20
and it appears to have landed away from settled areas, says the=20
press release.
The Yukon=92s Emergency Measures Organization is working with=20
Emergency Preparedness Canada, Natural Resources Canada and the RCMP=20
to gather more information on the object.
Air traffic controller Gerry Kuhn was on duty in the Whitehorse
control tower. =93I was up here, and I saw it actually ... coming down=20
through the sky down the Carcross Valley. It just lit up the whole=20
sky,=94 said Kuhn. He added he got reports from the Takhini Hot=20
Springs Road and Haines Junction that the object had been seen=20
there.
=93So it must have come from that direction,=94 he said. =93(We don=92t =
know) much at this point,=94 Doug Caldwell, an emergency=20
communications officer, said late this morning.
=93I=92m waiting for some other information to come in. Our main =
concern
right now is anybody who is going to go looking for this object,=20
whatever it may be, that they look after their own safety as a=20
priority.=94
EMO officials have said the object landed somewhere in the Carcross=20
area, near or at Caribou Mountain, and Caldwell said there are always
avalanche threats and other mountain related dangers that can occur.
Cpl. Gina Nagano of the Carcross RCMP said the light pulsated.=20
=93Carcross RCMP witnessed an extraordinary bright light in the sky. It
got very dark, then very bright, then it went pitch black and=20
returned to an orange pink colour,=94 said Nagano. =93Seconds later, a=20
massive explosion was felt, and it was rather traumatic.=94
Nagano added geologists are looking in the area for the object, and
that she understood a helicopter was dispatched this morning. =20
Caldwell said EMO anticipates this was a meteor.
=93I=92m assuming this is (a meteor). We=92re not going to know until=20
somebody=92s got something that can show us what it is. All indicators=20
right now are following the basic premise of being a meteorite,=94=20
said Caldwell, adding that it was probably not a very big one.
Meteor is a rock, a piece of a comet or asteroid, that travels=20
through space. It dispatches energy as it comes through the=20
atmosphere, and that=92s the reason for the light meteorites cast,=20
Caldwell explained.
=93Where we=92re at astronomy wise, the planet is orbiting right now=20
through a known belt of debris,=94 he added. =93January 4 (was) the=20
largest meteor shower of the year.=94
If the meteorite landed, it would have burned up all of the hot=20
material on the way, and would have been cold when it hit the=20
ground, Tatum explained. =93People see meteorites in the sky almost=20
every night,=94 said Doug Davidge, an environmental assessment officer=20
with Environment Canada. He added they were trying to figure out=20
where the object landed, if it did in fact hit the ground. Davidge=20
explained the loud noise heard seconds after it passed over could=20
mean either that it hit the ground or it could simply be the noise=20
the object made as it passed through the air.
A smoke trail similar to contrails left by passenger jets, but much=20
more colourful and mystic, could be seen in the sky for many minutes=20
after the object passed over.
The light from the fireball was also seen in Atlin, B.C., said RCMP
Cpl. Mike Stewart, who heard the noise it made. =93This is the second=20
one we=92ve had in a week here reported to us.... We had a report on=20
the 11th (of January) at 4 a.m. Some people south of Atlin, about 30=20
km, they reported a very similar thing as you=92re hearing this
morning,=94 said Stewart.
=93They saw the tail of a meteorite, a big flash. Then they heard a=20
big crash, a =91boom=92 and then it shook their cabin,=94 said Stewart. =
=20
Martin Jasek is one of Yukon=92s UFO investigators. Although he =
didn=92t=20
see the object personally, he said he had gotten reports of it.
=93(This is) fairly common. There was a similar one that was seen by=20
six people in ... December 1998. That was later at night, so not as=20
many people saw it,=94 said Jasek. That meteor was seen all the way=20
from Lake Laberge to Whitehorse, heading in more or less the same=20
north-to-south direction as this one was.
Jasek said that often meteors simply vaporise before they hit the=20
ground, but if they do crash, they can cause damage. Caldwell=20
stressed that if people are going to look for the object, they=20
should let someone know where they=92re going; go with another person;
and be prepared for the winter conditions.
Copyright, Whitehorse Star 1999.
http://www.whitehorsestar.com
============================================================
(6) STARDUST COMPLETES MOST CRITICAL MANEUVER OF COMET-CATCHING =20
MISSION
>From Space.com, 21 January 2000=20
http://www.space.com/space/stardust_update_000122.html
By Andrew Bridges
Chief Pasadena Correspondent
22 January 2000
=20
PASADENA, Calif. - NASA's Stardust successfully completed on=20
Saturday the most critical maneuver of its seven-year mission to=20
return comet samples to Earth, firing its thrusters for the third=20
time in a week to change the shape of its orbit.
Flight engineers at NASA's Jet Propulsion Laboratory said the=20
$165-million Stardust fired its rockets for 33 minutes and 36=20
seconds around 1:30 p.m. EST, all during a communications blackout=20
with Earth.
The operation was the last of a three-part move called a Deep=20
Space Maneuver designed to change the spacecraft's velocity by 561=20
feet (170 meters) per second. The change was so large, engineers=20
chose to break in up in three parts, performed on Dec. 18, 20 and=20
Saturday.
"It went nearly perfectly," said Tom Duxbury, the Stardust deputy=20
project manager and flight director at JPL, of the final maneuver.=20
"It was a nice conclusion to the three burns, so we are quite=20
happy."
Engineers still need to perform a clean-up maneuver to compensate=20
for extremely small errors resulting from the Deep Space Maneuver.=20
Any cleanup burn would involve changing Stardust's velocity by=20
less than 3 feet (1 meter) per second, engineers said.
Stardust will also have to perform two more Deep Space Maneuvers=20
during its mission, although both will be much smaller. One will=20
put it on target to the comet Wild-2; the second to Earth to=20
return samples of the dirty snowball..
"This was by far, by orders of magnitude, more difficult," Duxbury =
said.
Stardust will fly by Wild-2 on Jan. 2, 2004, collecting the=20
first-ever samples of cometary material to be returned robotically=20
to Earth.
Beginning Feb. 22, and again in July 2002, the spacecraft will=20
also collect samples of interstellar dust streaming through space.=20
The spacecraft will trap the minuscule particles in a collector=20
plate packed with lightweight aerogel, a glass foam.
Saturday's move put Stardust right on track to start collecting.
"The idea is to get maximum exposure of the collector to the=20
stream," said Ken Atkins, the Stardust project manager.
The spacecraft will then jettison a capsule containing the samples=20
in 2006, allowing it to parachute to a soft landing in Utah.
Copyright 2000, Space.com=20
============================================================
(7) NEAR MISSION STATUS REPORT, 21 January 2000
>From NEAR Mission Status Reports <pettee@jhuapldot edu>=20
NEAR Mission Status Reports - http://near.jhuapldot edu
MISSION OPERATIONS:
The NEAR spacecraft continued to operate nominally in Operational=20
Mode with Flight Computer #1 and Attitude Interface Unit #2 in=20
control. All instruments remained "ON" during this week. S/C=20
Attitude pointing continues to alternate between Eros pointing,=20
Earth pointing, and Sun pointing as required to conduct Eros=20
approach operations.
NEAR is presently 29,532 Km from Eros (18,351 miles).
The second test of the Eros rendezvous sequence was completed=20
successfully on January 20. Review of the engineering data indicates=20
this second flight test of the 30 hour sequence leading up to Eros=20
orbit insertion (includes NIS Low Phase Flyby) was successful. =20
The MSI Eros Light Curve 2 was conducted as planned on January 18.
It should be mentioned that no significant problems with DSN=20
supports have occurred since the start of Eros approach operations. =20
Many thanks to those at the DSN for the reliable support.
Regular Eros OpNav images were taken this week.
Final preparations and testing of the NEAR command load to start on=20
January 24 are completed. This command load includes all activities=20
planned through January 30. It will be uplinked during tomorrow's=20
DSN track.=20
Upcoming Spacecraft Activities:
In addition to regular DSN tracking and taking of OpNav images, the=20
following are operationally significant activities planned through=20
Eros orbit insertion. Please consult the NEAR Flight Timeline for=20
more details regarding upcoming science activities.
Jan 21 Flight Test of NLR/MSI Co-timing
Jan 28 Eros Satellite Search B
Feb 2 Rendezvous Maneuver=20
Feb 4 Eros Satellite Search C
Feb 8 Rendezvous Maneuver and Momentum Bias
Feb 9 Eros Satellite Search D
Feb 14 Eros Orbit Insertion
----------------------------------------
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