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Дата: 10 ноября 1998 (1998-11-10)
От: Alexander Bondugin
Тема: Cassini Update - November 6, 1998
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Cassini Significant Events
for 10/30/98 - 11/05/98
Spacecraft Status:
The most recent Spacecraft status is from the DSN tracking pass on
Wednesday, 11/04, over the Goldstone tracking station. The Cassini
spacecraft is in an excellent state of health and is executing the C10
sequence normally. The speed of the spacecraft can be viewed on the
"Where is Cassini Now?" web page (http://www.jpl.nasa.gov/cassini/today/).
Spacecraft Activity Summary:
On Monday, 11/02, three activities were performed: the Delta-V Estimator
Flight Software Update was sent up to the spacecraft, the Solid State
Recorder (SSR) record and playback pointers were reset, and the AACS High
Water marks were cleared.
On Tuesday, 11/03, Part 1 of the SSR-A Power Off was performed. Powering
off the SSR will enhance the overall life expectancy of the unit. Part one
consisted primarily of a complete memory test prior to the power off
commands.
On Wednesday, 11/04, Part two of the SSR-A Power Off was performed and the
VIMS Decontamination Heaters were powered up for a 24 hour period.
Upcoming events:
Activities scheduled for the week of 11/06-11/12 include SSR FSW Partition
Maintenance on 11/06, uplink of the C11 sequence on 11/07, and AACS
Attitude Estimator Memory Readout and SSR Pointer Reset on 11/09.
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Дата: 10 ноября 1998 (1998-11-10)
От: Alexander Bondugin
Тема: Automated Rendezvous & Docking Component Completes Successful Test Abo
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June Malone
Media Relations Office
Marshall Space Flight Center
Huntsville, AL 35812
(256) 544-0034
june.malone@msfc.nasa.gov
http://www.msfc.nasa.gov/news
For Release: Nov. 5, 1998
RELEASE: 98-229
Automated Rendezvous & Docking Component Completes Successful Test Aboard
STS-95
The STS-95 Space Shuttle crew completed a series of successful tests on a
new video guidance sensor component Tuesday, Nov. 3. The component -- part
of the Automated Rendezvous and Capture System -- will allow spaceships to
locate each other and rendezvous without human intervention. The sensor
will be used by the International Space Station to simplify routine supply
dockings and separations.
The video guidance sensor, developed by NASA's Marshall Space Flight Center
in Huntsville, Ala., uses a combination of lasers, video and reflectors to
measure the relative position and distance between spacecraft. For testing,
reflectors were mounted on the SPARTAN solar observatory satellite that was
carried into orbit by Discovery Oct. 29. During the STS-95 mission, the
Shuttle-mounted video guidance sensor measured reflected laser light from
SPARTAN to gather rendezvous data.
The satellite was deployed from the Shuttle's payload bay on Sunday, Nov. 1.
The STS-95 crew used the Shuttle's robot arm to position SPARTAN 33 feet, or
10 meters, in front of the video guidance sensor mounted in the payload bay.
The Shuttle's robot arm moved SPARTAN as close as 13 feet, or 4 meters, to
the sensor to gather detailed tracking information prior to releasing SPARTAN
into space for a two-day solar science mission.
On Nov. 3, after a successful SPARTAN science mission, the STS-95 crew began
long-range testing of the Video Guidance Sensor during manual rendezvous and
retrieval operations.
The video guidance sensor was activated and made contact when the Shuttle
moved to within 480 feet, or 146 meters, of the satellite. During approach,
at 360 feet, or 110 meters, the crew performed attitude maneuvers -- changing
the position of the Shuttle to determine the width of the sensor's field of
view. "The video guidance sensor locked-on at 480 feet. That's 120 feet better
than we designed the system to achieve," said Gene Beam, project manager for
the video guidance sensor at Marshall Center.
The crew stopped attitude maneuvers at 246 feet, or 75 meters, from SPARTAN
during the brief orbital nighttime to maintain observation of the nearby
satellite. The Shuttle then moved away to a distance of 600 feet, or 82
meters, to gather more information on the maximum limits of long-range
tracking. Completing the maneuver, the crew moved back into robot arm range
of SPARTAN and successfully captured and re-stowed it in the Shuttle payload
bay for return to Earth.
During long-range testing, data from the Shuttle's hand-held laser range
finder was compared to information from the video guidance sensor. "The
difference in readings between the hand-held laser and the sensor was well
within acceptable levels," said an STS-95 crew member. "The data we collected
looks comparable to the data from the earlier STS-87 mission where we first
tested this sensor." The Space Shuttle Columbia carried the first test into
orbit in November 1997. The operational version of the Automated Rendezvous
and Capture System is expected to be accurate within one-tenth of an inch.
##
Editor's Note: For more information call June Malone at the Marshall Space
Flight Center Media Relations Office at (256) 544-0034 or visit the Marshall
Space Flight Center News Room website at: http://www.msfc.nasa.gov/news
Andrew Yee
Ayee@nova.astro.utoronto.ca
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Дата: 10 ноября 1998 (1998-11-10)
От: Alexander Bondugin
Тема: WDC-A R&S Launch Announcement 12976: Iridiums 2 and 83-86
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COSPAR/ISES
WORLD WARNING AGENCY FOR SATELLITES
WORLD DATA CENTER-A FOR R & S, NASA/GSFC
CODE 633, GREENBELT, MARYLAND, 20771. USA
SPACEWARN 12976
COSPAR/WWAS USSPACECOM NUMBER
SPACECRAFT INTERNATIONAL ID (CATALOG NUMBER) LAUNCH DATE,UT
IRIDIUM 02 1998-066A 25527 06 NOVEMBER 1998
IRIDIUM 86 " 066B 25528 "
" 85 " 066C 25529 "
" 84 " 066D 25530 "
" 83 " 066E 25531 "
DR. JOSEPH H. KING, DIRECTOR, WDC-A-R&S.
[PH: (301) 286 7355.
E-MAIL: KING@NSSDCA.GSFC.NASA.GOV
06 NOVEMBER 1998 19:30 UT]
Further details will be in a forthcoming SPACEWARN Bulletin
Dr. Edwin V. Bell, II
_/ _/ _/_/_/ _/_/_/ _/_/_/ _/_/ Mail Code 633
_/_/ _/ _/ _/ _/ _/ _/ _/ NASA Goddard Space
_/ _/ _/ _/_/ _/_/ _/ _/ _/ Flight Center
_/ _/_/ _/ _/ _/ _/ _/ _/ Greenbelt, MD 20771
_/ _/ _/_/_/ _/_/_/ _/_/_/ _/_/ +1-301-286-1187
ed.bell@gsfc.nasa.gov
SPACEWARN home page: http://nssdc.gsfc.nasa.gov/spacewarn/
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Дата: 10 ноября 1998 (1998-11-10)
От: Alexander Bondugin
Тема: 1998 Leonid Model Prediction
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1998 Leonid Model Prediction
By Peter Brown, UWO Meteor Group. Issued
November 5th, 1998.
Using a total of 12 different models for the ejection of meteoroids from
comet Tempel-Tuttle, a preliminary "best" guestimate for the location of
the strongest peak in activity and its associated ZHR for the 1998
Leonids has been found.
The 12 model approach involves using three major variations in meteoroid
density (0.1, 0.8 and 4.0 g/cm^3 for bulk density of the
meteoroid). For each of these three densities, four different variations
in the initial ejection velocities are also employed - one follows
the distributed production model of Crifo which produces broad
distributions in initial ejection velocity which
has a mean velocity lower than the classical Whipple/Jones ejection
model. In addition to Crifos distributed production model, a
Whipple/Jones ejection velocity model is used, as well as a second
variant of the same with a heliocentric velocity dependance of
r^-0.5 in place of the usual r^-1. The fourth model is again a variant
on the Jones/Whipple model in which the ejection velocity at a
given heliocentric distance is not single-valued in the monte carlo
generating routine, but rather has a parabolic distribution of
probable velocities about the average Jones/Whipple velocity for the
chosen heliocentric distance. See Brown and Jones (1998), Icarus, v.
133, pp. 36 - 68 for more details.
The results of the modelling for the Leonids, using ejections at all
perhelion passages of the comet back to 1499 AD (ie 15
revolutions of the comet prior to the current epoch). A simple summation
of the meteoroids which are then visible at Earth at the
present time from this ensemble and which would produce visually
observable meteors (mass 1 mg) was then computed from all
ejecta. A meteoroid is defined as being Earth-intersecting if its nodal
radius is within 0.005 AU of Earth at the longitude of its
descending node. All models suggested a steep increase in activity
beginning in December, 1997/early 1998 accompanying the
passage of Tempel-Tuttle. The resolution of the modelling is of order 2
months and thus all models suggest that this November will
show significantly increased activity relative to 1997 (when the peak
ZHR reached just short of 100), and likely activity approaching meteor
storm levels (ZHRs of order 1000). Using 1997 as a baseline and taking
the peak ZHR to have been 96 +/- 13 at 235.22 +/- 0.02 (J2000) in 1997
we have extrapolated the relative model difference between the activity
strength predicted by the model in 1997 to that observed and that
predicted for 1998. Using a mean of all models, produces a predicted
location for the peak in 1998 of 235.26 +/- 0.04 (J2000) with a peak ZHR
of 1200 +/- 280. This solar longitude corresponds to Nov 17 at 19:20 UT
with a 1-sigma uncertainty of 60 minutes. We emphasize that due to the
model results sensitive dependance on density of the meteoroids, the
range of possible ZHRs extends from slightly lower than the bound given
above to nearly 10 000 (the higher values associated with the models
using the least dense meteoroids and lowest ejection velocities).
The use of relative modelling difference between 1997 and 1998 implies
that the veracity of the prediction in 1998 relies entirely on the
accuracy of the magniude of the ZHR reported in 1997 under full moon
conditions. As well as the above, the models suggest that broad
activity, persisting for of order a full day centred about this peak
should be noticeably above normal Leonid background levels and should be
rich in larger meteoroids in 1998 most notably after the time of the
peak. The model suggests ZHRs of order 100 or greater in the 3-4 hour
window prior to the peak and ZHRs of order 100-200 persisting for many
hours after the peak.
The mass index near the time of the peak over the visual magnitude range
will be near 1.6 +/- 0.1. It is worth noting that a significant decrease
in the mass index from 1.8 +- 0.1 several hours prior to the peak to
this lower value and then upward again after the peak is visible in most
models.
*********************************************************************
Peter Brown
Meteor Physics Lab
Department of Physics and Astronomy
University of Western Ontario
London, Ontario
N6A 3K7
Canada
Voice:1-519-679-2111 x6458
Fax:1-519-661-2033
*********************************************************************
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Дата: 10 ноября 1998 (1998-11-10)
От: Alexander Bondugin
Тема: Leonid Meteor Shower, Special Lecture At Griffith Observatory
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Griffith Observatory Press Releases
Leonid Meteor Shower
There may be a significant meteor shower on the morning of Tuesday,
November 17 (or, less likely, on the morning of November 18).
Every November 17, when the earth passes near the orbit of Comet
Tempel-Tuttle, we pass through a sparse swarm of comet debris and
experience a minor meteor shower that generally goes unnoticed. Every 33
years, however, the earth passes through a dense knot of this cometary
material, and there is the possibility of a dramatic meteor storm when the
sky might fill with thousands of "falling stars." This year there may be
such a brief meteor storm lasting no more than a few hours. Although the
shower is predicted to be strongest over Asia, enough meteors may fall over
California to make the night very interesting. This is a meteor shower that
sky watchers should not miss.
The best time to observe the shower from the United States will be the few
hours before dawn on Tuesday morning, November 17. There is less likelihood
of a shower on the morning of the 18th. Few meteors will fall before 1 a.m.
Although it is difficult to estimate the actual rate, an observer in a dark
location will likely see dozens of meteors per hour. There may be brief
periods lasting several minutes when quite a few meteors fall, followed by
periods of relative calm.
The meteors radiate from the direction of Leo, the Lion, and for that
reason they are called the Leonids. Leo is low in the east before dawn, but
the meteors will appear all over the sky. Leonid meteors strike the earth's
atmosphere at high speed, 44 miles per second, and often leave smoke
trails. The moon is almost new and out of the way.
Because of the early hour, Griffith Park will not be open for meteor
observing. Observers should plan to be far from city lights. The
Observatory is often asked to recommend an observing location, but the
answer is -- go away from the city to where it is dark.
For additional information on the Leonid meteors please visit these web sites:
International Meteor Organization: http://www.imo.net
Leonid 98: http://www-space.arc.nasa.gov/~leonid.html
Meteor Storm Hazard:
http://leroy.cc.uregina.ca/~astro/Leonids/Leo_1.html
Media i Corporation (live CCD images from Japan):
http://www.media-i.com/www/Milkyway/index.html
Special Lecture at Griffith Observatory on Monday, November 16
On Monday, November 16, 1998, Griffith Observatory will host a special
lecture by Dr. Amir Aczel on "Why There Must Be Intelligent Life in the
Universe."
For thousands of years visionaries and writers have argued that we cannot
be alone -- that there must be intelligent life in the universe. Now, with
the latest information from Mars, the latest discoveries from the Hubble
telescope, and the knowledge about life at the extremes, scientists are
taking up where the visionaries left off.
Dr. Amir Aczel, author of Fermat's Last Theorem, pulls together everything
that science has discovered and mixes in probability theory to argue the
case for the existence of intelligent life beyond our planet.
Dr. Aczel's new book "Why There Must Be Intelligent Life in the Universe"
will be on sale following the lecture, which Dr. Aczel will autograph.
The lecture will be at 7:30 p.m. on Monday, November 16, 1998. The
Observatory will open, and tickets will go on sale at 7:00 p.m. Ticket
prices are $4.00. Children under five are not admitted.
*********************************************************************
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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Дата: 10 ноября 1998 (1998-11-10)
От: Alexander Bondugin
Тема: Sky & Telescope News Bulletin - November 6, 1998
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SKY & TELESCOPE'S NEWS BULLETIN
NOVEMBER 6, 1998
AS THE KBO TURNS
Astronomers at the European Southern Observatory (ESO) announced that they
determined the rotation period of one of the most distant objects in the
solar system. Olivier Hainaut and his four colleagues from La Silla, Chile,
and Paris Observatory took 50 images of minor planet 1996 TO66 -- a bright
member of the class of body called trans-Neptunian objects, or Kuiper Belt
objects (KBO). The astronomers used ESO's 3.6-meter New Technology
Telescope (NTT) to observe 1996 TO66 in August and October 1997 when it was
about 45 astronomical units (6.7 billion kilometers) away from the Sun and
shining feebly at 21st magnitude. The object's light curve suggests that it
rotates every 6 hours 15 minutes. Discussing their finding at a conference
on small bodies in the outer solar system at ESO's Garching, Germany,
headquarters this past week, the astronomers explain that 1996 TO66's
rotation period probably dates from the birth of the solar system. They
note that minor planet 2060 Chiron, which orbits between Saturn and Uranus
but likely originated much farther out, also rotates with a period near 6
hours.
CLUMPS IN WINDY NEBULA
A new image released from the Space Telescope Science Institute on Thursday
reveals the effects of strong stellar winds. The nebula M1-67 is being
shaped by the outflow from the exceptionally hot and luminous star QR
Sagittae. Most of the nebula probably consists of ejecta that the star cast
off during an earlier phase of its evolution. The picture shows many small,
bright knots that may be the first direct images of clumps flying outward
in the stellar wind of a hot star. Details are in *Astrophysical Journal
Letters* for October 20, 1998.
AURORA FOR THE WEEKEND?
Patrick S. McIntosh (HelioSynoptics Inc.) reports that on November 5th a
flare was ejected from an active area on the Sun that may provide a display
of aurora (northern and southern lights). His electronic announcement to
*Sky & Telescope* notes that we should expect major geomagnetic storm
conditions by late November 7th, which should continue through most of the
following day.
COMET GIACOBINI-ZINNER IN AQUILA
Viewing of Comet 21P/Giacobini-Zinner will improve this week, as the bright
Moon leaves the early evening sky. The comet remains at about 9th
magnitude, but may brighten a bit more by the end of the month. This week,
the comet continues its trek through Aquila. It lies about 20 to 40 degrees
above the southwestern to western horizon, depending on your latitude, at
the end of evening twilight. For a finder chart, see page 107 of the
November *Sky & Telescope.* Here are positions for Comet Giacobini-Zinner
for 0 hours Universal Time (2000.0 coordinates) for the coming week:
R.A. Dec.
November 7 19h 23m -06.8 deg.
November 9 19h 32m -07.8 deg.
November 11 19h 41m -08.8 deg.
WINTER STAR PARTY BLOWN AWAY
Every February hundreds of skygazers head to the Florida Keys for the
Winter Star Party, one of the United States's major annual astronomical
conventions. However, WSP's venue, a Girl Scout camp right at the water's
edge, was heavily damaged by Hurricane Georges, which blew through the Keys
in late September. Tippy D'Auria, WSP founder and chairman, originally
thought the damage could be repaired before the February 1999 gathering.
But "in spite of heroic efforts," he says, "it appears that the camp will
not be ready in time." Thus, the event has been cancelled. However, Tom
Clark and Jack Newton are making arrangements to host an alternative to WSP
for the week of February 14, 1999, at Chiefland, Florida. For details,
visit the Calendar of Star Parties in the Resources section of *Sky &
Telescope*'s Web site.
INTRODUCTING THE NEW SKYPUB.COM
And speaking of our Web site, it has a new look! We unveiled Sky &
Telescope's new home page this week. Point your Web browser to
http://www.skypub.com/ to see the improvement. All of your favorite pages
from the old SKY Online Web site are here in an easier-to-use format. The
site is divided into five major categories: NEWS, SIGHTS, TIPS, IMAGING,
and RESOURCES. There are over 30,000 active links on this new site spread
across more than 500 Web pages. You'll also be able to order from among the
more than 200 quality astronomical books and products found in the 1999 Sky
Publishing Catalog using our new online store. Please note that many of our
pages' URLs have changed, so you may need to alter your bookmarks and
Web-page links.
THIS WEEK'S "SKY AT A GLANCE"
Some daily events in the changing sky, from the editors of SKY &
TELESCOPE.
NOV. 8 -- SUNDAY
* Mercury and Antares appear 2 degrees apart this evening and tomorrow
evening. Look with binoculars just above the southwest horizon a half hour
after sunset. Antares is the fainter one, on the lower left.
* Jupiter's Great Red Spot should cross the planet's central meridian
around 9:42 p.m. Eastern Standard Time. Lately the spot has been very pale
tan with a dark outline and a small, reddish-brown patch in its south side.
For a list of all predicted Red Spot transit times this observing season,
see http://www.skypub.com/sights/moonplanets/redspot.html.
* The eclipsing variable star Algol should be in one of its periodic
dimmings, magnitude 3.4 instead of its usual 2.1, for a couple hours
centered on 11:34 p.m. EST. Algol takes several additional hours to fade
and brighten. For a list of its predicted minima through next winter, see
http://www.skypub.com/sights/variables/algol.html.
NOV. 9 -- MONDAY
* The red long-period variable star Chi Cygni in the Northern Cross
should be at maximum brightness, 5th magnitude, around this date. See the
chart in the November Sky & Telescope, page 100.
NOV. 10 -- TUESDAY
* Last-quarter Moon (exact at 7:28 p.m. EST).
* Mercury is at greatest elongation in the evening sky, 23 degrees east
of the Sun.
* Saturn's largest moon, 8th-magnitude Titan, appears four ring-lengths
to Saturn's east tonight through Thursday night. A small telescope will
show it.
* Jupiter's Red Spot should transit around 11:21 p.m. EST.
NOV. 11 -- WEDNESDAY
* Algol should be at minimum brightness for a couple hours centered on
8:23 p.m. EST.
* Jupiter's Red Spot should transit around 7:12 p.m. EST.
NOV. 12 -- THURSDAY
* Ceres, the largest minor planet (asteroid), is drifting near Aldebaran
in the late-evening sky. You can pick it up in binoculars; it's about
magnitude 7.5. Use the finder chart in the November Sky & Telescope, page
109.
* Users of medium-size and large telescopes from Texas to the Great Lakes
have a chance to catch the faint asteroid 145 Adeona occulting a
10.0-magnitude star just south of Capricornus this evening. The occultation
could last for 7 seconds around 1:24 Universal Time November 13th (7:24
p.m. Central Standard Time on the 12th). For a finder chart and any late
updates, see http://www.skypub.com/sights/occults/occults.html.
* Mars appears near the thick waning crescent Moon in the east before
dawn Friday morning.
NOV. 13 -- FRIDAY
* Jupiter's Red Spot should transit around 8:51 p.m. EST.
NOV. 14 -- SATURDAY
* Some doorstep astronomy: Look low in the northeast after dark for
brigh