Дата: 17 ноября 1998 (1998-11-17)
От: Alexander Bondugin
Тема: Освещение метеорного потока Леонид в Internet
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Освещение метеорного потока Леонид в Internet
[NASA] Связь между появлением кометы Темпеля-Таттла и
следующим за ним через 10 месяцев метеорным потоком Леонид была
замечена в 1865 г. (сам поток наблюдался в 1866 г.). В нынешнем 1998 г.
ожидается, что поток Леонид будет иметь самую высокую в этом
столетии интенсивность. Его пик придется на ночь с 16 на 17 ноября.
Лучше всего это явление будет видно в районах Восточной Азии и в
западной части Тихого океана, но и в остальных частях света можно будет
увидеть 20-40 метеоров в час.
Вот несколько адресов в Internet, где можно будет ознакомиться с
информацией об этом грандиозном астрономическом явлении:
1) Web-узел Королевской Гринвичской обсерватории The
Leonids-RGO:
http://www.ast.cam.ac.uk/RGO/leaflets/solar_system/leonids.html
2) Специальная Web-страница сервера NASA - Leonid '98 Meteor
Outburst Page, где будут представлены данные о потоке Леонид,
полученные с помощью разнообразного оборудования, установленного на
борту специального самолета, который поднимется в воздух во время
прохождения Земли через поток Леонид. Здесь также представлена
история наблюдения этого метеорного потока. Планируется публиковать
новости и полученные изображения. http://www-space.arc.nasa.gov/~leonid/
3) Hа узле Live! Leonids 98 (http://www.leonids.net/live/) 17 ноября
будет
вестись "прямой репортаж" о прохождении потока Леонид в формате
RealPlayer, в последующие несколько дней здесь будут размещаться
выборочные изображения метеорного потока. Источник: InfoArt News Agency
Hа сегодня все, пока!
=SANA=
Дата: 17 ноября 1998 (1998-11-17)
От: Alexander Bondugin
Тема: Астрономы всего мира готовы к наблюдению метеорного потока...
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Астрономы всего мира готовы к наблюдению метеорного потока
Леонид и ... к защите от него
[SpaceViews] Леонид - это один из метеорных потоков, через
которые Земля пролетает каждый год, он представляет собой хвост
кометы Темпеля-Таттла (Tempel-Tuttle). Его интенсивность достигает
максимума каждый год 17-18 ноября, но только раз в 33 года он бывает
особенно сильным, и именно в такие моменты имеет смысл говорить о
метеорном дожде. Последний раз это явление наблюдалось в 1966 г. И
вот - новое пришествие.
Пик метеорного дождя, когда в течение часа можно будет увидеть
тысячи вспыхивающих в земной атмосфере метеорных частиц, можно
будет наблюдать на территории от Дальнего Востока до Центральной
Азии.
NASA будет вести наблюдения с двух самолетов, которые будут
летать над территорией Японии. Hа борту этих самолетов установлено
самое разнообразное оборудование, в том числе и для улавливания
органических молекул в метеорных частицах, что позволит прояснить
картину возникновения жизни на Земле, то есть определить, как
космические частицы могли способствовать появлению на Земле
соответствующих условий для зарождения жизни.
В то время как астрономы готовятся к наблюдениям, центры
управления полетами околоземных спутников принимают меры для
защиты своих орбитальных объектов от возможных повреждений
метеорами. Хотя метеоры очень малы, но во время метеорного дождя их
бывает очень много и скорость их составляет порядка 72 км/с. Большой
ущерб могут нанести не сами метеоры (дырку в спутнике они проделать
не смогут), а вторичные эффекты от их ударов. Скорость их так велика,
что частица поверхности попавшегося на пути объекта будет испаряться с
образованием плазмы, то есть ионизованных частиц, электромагнитные
поля которых могут вывести из строя чувствительное электронное
оборудование, установленное на спутнике. Именно из-за таких явлений в
1993 г. Европейское Космическое Агентство потеряло свой спутник после
прохождения метеорного потока Персеид.
Центры управления постараются таким образом ориентировать
спутники, чтобы минимизировать количество попадаемых в них
метеорных частиц. Большинство спутников будут непрерывно вести свою
работу, но на некоторых аппаратура будет выключена, в частности на
Rossi X-Ray Timing Explorer. Космический телескоп Hubble Space Telescope
будет повернут таким образом, чтобы в его зеркала не попадали
метеорные частицы, соответствующим образом будут установлены и
панели солнечных батарей. Однако наблюдения на телескопе не будут
останавливаться.
Станция "Мир" продолжит свою работу во время прохождения
потока Леонид. Hа прошлой неделе во время последнего своего выхода в
открытый космос Геннадий Падалка и Сергей Авдеев установили на ее
внешней поверхности специальный российско-французский
датчик-ловушку космических частиц. Во время максимальной
интенсивности метеорного потока космонавты на всякий случай будут
находится в спускаемом модуле, чтобы в случае возникновения на
станции нештатных ситуаций вернуться на Землю. Источник: InfoArt News
Agency
Hа сегодня все, пока!
=SANA=
Дата: 17 ноября 1998 (1998-11-17)
От: Alexander Bondugin
Тема: Подготовка к старту ракеты-носителя "Протон"
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Подготовка к старту ракеты-носителя "Протон"
Сегодня утром на космодроме "Байконур" началась подготовка к
старту ракеты носителя "Протон", которая должна вывести на орбиту
первый элемент Международной космической станции - управляющий
модуль "Заря" (на снимке).
Запуск состоится в ранее
намеченное время - 20 ноября 1998 г.
Источник: InfoArt News Agency
Hа сегодня все, пока!
=SANA=
Дата: 17 ноября 1998 (1998-11-17)
От: Alexander Bondugin
Тема: Presentation At Pueblo Weisbrod Aircraft Museum
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Who: The Pueblo Weisbrod Aircraft Museum and Home of the International B-24
Museum
What: will present a lecture by Dr. Boyd Baldauf (ED.D) former Professor of
Computer Science at the University of Southern Colorado and Colonel USAFR
(Retired) titled: _Looking at Earth From Space, Listening to Deep Space_.
Topics covered will be military and civilian uses of space, improving
imagery from space, and the Search for Extraterrestrial Intelligence
(SETI).
Where: The museum is located at the Pueblo Memorial Airport 31001 Magnuson
Ave, Pueblo, Colorado 81001. The airport is located approximately 5 miles
east of Pueblo on US Highway 50 E/Colorado State Highway 96 East.
When: The presentation will be on 21 November 1998 at 2:00 PM.
Additional information: Admission is free. A recommended donation of $3 for
adults (persons 12 years and greater) is appreciated but not required. No
one will be turned away. All donations go toward the museum building fund.
Contact the museum at (719)948-9219 or email at pwam@usa.net for more
information.
Jason Unwin
Volunteer
Pueblo Weisbrod Aircraft Museum
Home of the International B-24 Museum
Pueblo, CO 81001
(719)948-9219
Hа сегодня все, пока!
=SANA=
Дата: 17 ноября 1998 (1998-11-17)
От: Alexander Bondugin
Тема: Zarya Briefings And Launch Coverage Set
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Debra J. Rahn
Headquarters, Washington, DC November 16, 1998
(Phone: 256-961-6226 - Russian 586-75-60)
Kyle Herring
NASA Moscow Office
(Phone: 256/961-6225 - Russian 586-75-60)
NOTE TO EDITORS: N98-69
ZARYA BRIEFINGS AND LAUNCH COVERAGE SET
The launch of the first component of the new International
Space Station, the Russian-built, U.S.-owned Zarya Control Module,
will be the subject of a preflight briefing at the Russian Mission
Control Center in Korolev, Russia, outside Moscow, at 8 a.m. EST (
4:00 p.m. Moscow time) on Nov. 17. The news conference will take
place just three days before Zarya is scheduled to be launched
atop a Russian Proton rocket from the Baikonur Cosmodrome in
Kazakstan.
The news conference will be broadcast live on NASA
Television, but questions can only be asked by reporters at the
Russian Mission Control Center.
The participants will include:
Gretchen McClain, Deputy Associate Administrator for Space
Station
Randy Brinkley, International Space Station (ISS) Program
Manager
Mikhail Sinelchikov, Director of Piloted Programs, Russian
Space Agency
Alain Poirier, Director General, Space Systems, Canadian
Space Agency
Frank Longhurst, Head, Manned Spaceflight Program, European
Space Agency
Tsuguo Tadakawa, Deputy Director, Space Utilization Promotion
Dept., National
Space Development Agency of Japan
Two days later, on Nov. 19, video of the final prelaunch
preparations for Zarya and the rollout of the Proton rocket to its
launch pad at Baikonur will be presented on the NASA TV Video File
at noon EST.
Based on Zarya's current planned launch time of 1:40 a.m. EST
(9:40 a.m. Moscow time, 11:40 a.m. Baikonur time,) on Nov. 20,
NASA public affairs commentary and live television coverage of the
countdown and the launch will begin at 1:10 a.m. EST (9:10 a.m.
Moscow time).
A postlaunch news conference will be held at Baikonur with
senior level officials approximately two hours after launch. It
is expected to be broadcast live on NASA Television with questions
from reporters at Baikonur.
A second postlaunch news conference will be held at the
Russian Mission Control Center following the Baikonur conference
to give a technical status report on Zarya. It will be broadcast
live on NASA TV with questions from reporters in Moscow.
Written status reports on Zarya's operation in orbit will be
issued on subsequent days addressing major activation events
leading up to the launch of the Unity connecting module aboard
Endeavour on the first shuttle assembly mission, STS-88, on
December 3. Following the STS-88 mission, with Zarya and Unity
mated as the first Space Station elements, written status reports
and status briefings on the unpiloted flight of the International
Space Station will be provided periodically.
Note: News media planning to attend the news conferences or the
Zarya launch from the Russian Mission Control Center, Korolev, who
are not already accredited, should request press accreditation
from the Russian press office at 011-7-095-187-2344, or by calling
the NASA public affairs office in Moscow at 256-961-6225, 6226, or
Russian line 586-75-60.
-end-
NASA press releases and other information are available automatically
Hа сегодня все, пока!
=SANA=
Дата: 17 ноября 1998 (1998-11-17)
От: Alexander Bondugin
Тема: Encouraging Report On The Leonids
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Forwarded From George Zay (GeoZay@aol.com)
Subject: Leonid fireballs galore! Nov 15/16 ZAYGE
Meteor/Leonid observations for the night of Nov 15/16, 1998
From Descanso, California, San Diego County
I just got back from the best meteor shower I've ever witnessed. I observed
from my descanso, calif. observatory under clear skies with bob lunsford. I
have a teff of about 7.5 hours and an LM near 6.0 for most of the night. I
plotted until about midnight and then just record data without plotting. I
recorded a total of 140 meteors. 77 were leonids, 31 N. Taurids, 2 S. Taurids
and 30 sporadics. But!! out of the 77 leonids I recorded 25 fireballs. I also
recorded a brilliant N. Taurid fireball with a magnitude of -12. I thought
that was gonna be the highlight of the night...but it didn't even come close.
The magnitudes of the leonid fireballs are as follows:
-3,-3,-3,-3,-3, -4,-4,-4,-4, -5,-5,-5, -6,-6,-6,-6, -7,-7,-7, -8,-8, -10, -12,
-12, -15
The trains lasted quite long for a lot of them. One -7 had a train last 30
seconds, then the other two -7's had trains lasting over 100 seconds each, one
of the -8's train lasted over 100 seconds as well. The -10 had a train last
4.5 minutes and the
-15 train lasted over 8 minutes. The -15 and a -12 had persistent trains that
were of magnitudes of around -8 for a few seconds it seemed. They snaked and
twisted all over the place. It was hard to keep count of their durations
because often another fireball would show up. The -15 occurred above and
behind us...the stars totally disappeared and the sky looked like daylight
blue for a second or two. It was pure old excitement. I wanted to go to the
bathroom, but didn't dare because I was afraid I would miss another fireball.
The strange thing about last nights activity, there were very little dim
meteors...that is those that were of around +3 or dimmer. Besides the
fireballs, I also recorded three that had magnitudes of -2 and 8 were of -1
magnitudes. I won't have time to do my report for a few days...but I bet my
mean magnitude will be around -3 or more? Never had this happen before. We
were caught completely off guard for this kind of activity the night before
the leonid maximum. I hope to be out there again tonight for the leonid
maximum...if the weather holds out? Now to get some shut eye...I might have to
do a road trip to an area in the desert near Yuma, arizona if that front comes
down like it might...got my toes crossed.
George Zay
Descanso, California
Hа сегодня все, пока!
=SANA=
Дата: 17 ноября 1998 (1998-11-17)
От: Alexander Bondugin
Тема: Weiler Named NASA's Associate Adminstrator For Space Science
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Douglas Isbell/Don Savage
Headquarters, Washington, DC November 16, 1998
(Phone: 202/358-1547)
RELEASE: 98-204
WEILER NAMED ASSOCIATE ADMINISTRATOR FOR SPACE SCIENCE
NASA Administrator Daniel S. Goldin today named Dr. Edward J.
Weiler as Associate Administrator for NASA's Office of Space
Science, effective immediately.
Weiler has served as acting Associate Administrator since
Sept. 28, following the departure of Dr. Wesley T. Huntress, Jr.
"In his short time as acting Associate Administrator, Ed
Weiler has demonstrated both the management skills and scientific
leadership that this position demands, and I am delighted he has
accepted the offer on a more permanent basis," Goldin said.
In this capacity, Weiler will be responsible for providing
overall executive leadership of NASA's Space Science Enterprise.
This enterprise aims to achieve a comprehensive understanding of
the origins and evolution of the Solar System and the Universe,
including connections between the Sun and the Earth, the
beginnings of life and the question of whether life exists
elsewhere beyond Earth. It also is charged with communicating
this knowledge to the public.
Weiler was appointed as Science Director of the Astronomical
Search for Origins and Planetary Systems theme within the Office
of Space Science in March 1996. He will continue to serve as the
Program Scientist for the Hubble Space Telescope, a position he
has held since 1979, until a replacement for that position is
selected. Weiler joined NASA in 1978 as a staff scientist.
Prior to that, Weiler was a member of the Princeton
University research staff and was based at NASA'S Goddard Space
Flight Center, Greenbelt, MD, as the director of science
operations of the Orbiting Astronomical Observatory-3
(COPERNICUS). Weiler received his Ph.D. in astrophysics from
Northwestern University in January 1976.
Weiler lives in Bowie, MD, and has two children, Gregory,
9, and Allison, 12.
-end-
Hа сегодня все, пока!
=SANA=
Дата: 17 ноября 1998 (1998-11-17)
От: Alexander Bondugin
Тема: Third US Space Station Assembly Crew Named
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Jennifer McCarter
Headquarters, Washington, DC November 16, 1998
(Phone: 202/358-1639)
Doug Peterson
Johnson Space Center, Houston, TX
(Phone: 281/483-5111)
RELEASE: 98-205
THIRD U.S. SPACE STATION ASSEMBLY CREW NAMED
Astronaut James D. Halsell, Jr. (Lieutenant Col., USAF) will
command the third Space Shuttle mission to carry cargo to space
for the International Space Station in August 1999.
Joining Halsell in the flight deck for mission STS-101 aboard
Atlantis will be Pilot Scott J. Horowitz, Ph.D. (Lieutenant Col.,
USAF). Rounding out the crew are Mission Specialists Mary Ellen
Weber, Ph.D.; Edward Tsang Lu, Ph.D.; and Jeffrey N. Williams
(Lieutenant Col., USA).
As the third International Space Station assembly flight, the
mission will carry internal logistics and resupply cargo for
station operations. The equipment will further the outfitting of
the Russian Service Module.
"STS-101 will bring important components and equipment to the
growing Station assembly," said James D. Wetherbee, Director of
Flight Crew Operations and Deputy Director of NASA's Johnson Space
Center, Houston. "This talented crew brings a great deal of
experience and skill to make this key mission a success."
STS-101 will be Halsell's fifth mission, and his third as
commander. Selected as an astronaut in 1990, he flew as pilot on
STS-65 in 1994 and STS-74 in 1995, and as commander on STS-83 and
STS-94 in 1997. Horowitz served as pilot in his two previous
missions: STS-75 in 1996 and STS-82 in 1997.
Weber, a Mission Specialist onboard Discovery on STS-70, will
be on her second space flight. Lu also will be on his second
space trip; his first was STS-84 which docked to the Mir Space
Station. Mission Specialist Williams will be making his first
space flight.
For biographical information on the STS-101 crew and other
astronauts, see the NASA Internet astronaut biography home page
at:
http://www.jsc.nasa.gov/Bios/
For information on the International Space Station, visit the
Space Station home page at:
http://station.nasa.gov/
- end -
Hа сегодня все, пока!
=SANA=
Дата: 17 ноября 1998 (1998-11-17)
От: Alexander Bondugin
Тема: STARDUST Update - November 13, 1998
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STARDUST Status Report
November 13, 1998
Ken Atkins
STARDUST Project Manager
I hope you've noticed from the picture on the homepage we are now
sending them live from Kennedy Space Center (KSC) in Florida:
http://stardust.jpl.nasa.gov/webcam
The spacecraft was packed into its shipping container last week and this
week was transported by truck to Buckley Field in Denver. There, it
was carefully loaded aboard a giant USAF C-17 jet transport and flown
to KSC aboard a USAF C-17. It arrived at 2:00 am on November 12 and was
moved to the Payload Hazardous Servicing Facility (PHSF) for check-out,
some re-installation of electronics and beginning preparations for
mating to the Delta II launch rocket. The spacecraft has been set up
on its handling dolly and the solar arrays, high-gain antenna removed
and the bottom panel removed for access to the interior. A crew filmed
the whole delivery process and KSC released 15 news photos of
STARDUST's arrival at KSC. These have been merged with the JPL press
release and are available now on the web site. We also now have a time
lapse movie of the unpacking sequence at KSC. All this great action is
found at:
http://stardust.jpl.nasa.gov/news/news39.html.
With the arrival at KSC, I understand NASA will be showing some of the
footage on NASA TV. Hope you can catch it there too.
Speaking of pictures, now that STARDUST is at KSC the still images of
activities in the PHSF are back on line. The image is updated every
minute with the last 10 images available at any time.
http://stardust.jpl.nasa.gov/spacecraft/construction.html
For more information on the STARDUST mission - the first ever comet sample
return mission - please visit the STARDUST home page:
http://stardust.jpl.nasa.gov
Hа сегодня все, пока!
=SANA=
Дата: 17 ноября 1998 (1998-11-17)
От: Alexander Bondugin
Тема: The Leonid Sample Return Mission
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The Leonid Sample Return Mission
NASA scientists will try to capture and return a Leonid meteoroid
http://science.nasa.gov/newhome/headlines/ast16nov98_3.htm
November 16, 1998: High above the clouds on November 17th a NASA weather
balloon will lie in wait for the Leonid meteors. The goal: to capture a
meteoroid and return it to Earth intact. "The chances of success are small,
probably less than 10%", says Dr. David Noever, the project leader at NASA's
Marshall Space Flight Center, "but of course the payoff is rather huge." One
of the goals of the experiment is to see if the "Stuff of Life" -- organic
compounds and other molecules -- are present in the debris of comet
Tempel-Tuttle, the source of the Leonid meteoroids.
Amino acids and other organic molecules necessary for life as we know it on
Earth are thought to be common in meteorites and comets. While life probably
doesn't thrive inside comets, the compounds they carry might have
contributed to the genesis of life on Earth billions of years ago.
Scientists would like to know whether the comet, which passed Earth just
last January, contains organic compounds, and if organic molecules are
created when a Leonid meteor burns up in Earth's atmosphere.
To answer these questions researchers from the Marshall Space Flight Center
hope to capture a piece of the comet Tempel-Tuttle. Tuesday's meteor storm
is like "room service for science", says Dr. David Noever, a member of the
Astrobiology Institute. "Instead of us going to the comet, it's coming to
us."
Scientists will use a particle collector made of aerogel carried aloft on a
helium-filled weather balloon. Weather permitting, the balloon is scheduled
for launch from the Marshall Space Flight Center at 2 am Central Standard
Time on November 17th . The payload will include a meteoroid collection
device, and a CCD video camera. The balloon will spend up to 4 hours aloft
and reach a maximum altitude of 100,000 ft.
High above the clouds and far away from city lights the view could be
spectacular. Live video from the flight will be available to the public at
Leonids Live! (http://www.leonidslive.com) in RealVideo format beginning
approximately 0800 UT November 17th (0200 CST). Video and images from the
NASA's East Asia plane flights will also be posted at that web site.
Aerogel is the lightest known solid, and is considered the best substance
available for capturing fragile particles from a comet without damaging
them. When a high-velocity dust particle hits the aerogel, it buries itself
in the material, creating a carrot-shaped track up to 200 times its own
length. Since aerogel is translucent scientists can use these tracks to find
the tiny particles. The track is largest at the point of entry, and the
particle can be collected intact at the point of the cone.
The sample collector on tomorrow's balloon mission will consist of
twenty-four 1" diameter circular wells of aerogel films clustered in a 6"x4"
payload. The aerogel has a mean density around 0.08 g/cc and is
semitransparent. The total weight is less than a few ounces (mainly
container and structural supports, not aerogel), so it should have a
negligible effect on the flight of the balloon.
According to Dr. David Noever, "The drawback I see is that we are forced to
catch everything from ground to 100,000 feet, mainly because we do not have
time to fashion a remote control door that opens or closes to expose the
capture media. This experiment should be considered an engineering test, and
we'll make improvements prior to the 1999 Leonid shower."
Prelude to Stardust
The Leonids Return Mission is an interesting prelude to another NASA mission
with possible connections to Astrobiology: the Stardust Mission. Stardust is
a spacecraft, scheduled for launch in early 1999, designed to collect and
return to Earth particles flying off the nucleus of Comet Wild-2 in January
2004. It will also bring back samples of interstellar dust including the
recently discovered dust streaming into the solar system from other stars.
The spacecraft will count the comet particles striking the spacecraft, and
produce real-time analyses of the composition of the material coming off the
comet. Like the Leonids balloon flight, Stardust will use an aerogel-based
collector to capture bits of the comet.
"The transparency of aerogel is critical to the success of Stardust; tracing
particle tracks by eye or microscope requires a reasonably clear material",
explained David Noever. Aerogel made on earth is not perfectly transparent
because of irregularities in the pores which permeate the substance (aerogel
is 99% empty space). There is some evidence that aerogels manufactured in
low gravity are much clearer, and an experiment was just conducted on space
shuttle mission STS-95 to test the idea.
"Space-manufactured aerogels could significantly improve our ability to
capture comet particles," commented David Noever. "Using centrifuges we can
make aerogel with a density gradient: low density on one side for low damage
particle capture, backed by a denser section to insure nothing escapes out
the other side. This kind of thin-to-dense aerogel is unique in this dust
capture business and may be unique to the way we make aerogel in space. It's
an open question at the moment."
When Stardust swings by Earth in January 2006, the aerogel samples encased
in a reentry capsule will be jettisoned and parachute to a pre-selected site
in the Utah desert.
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Дата: 17 ноября 1998 (1998-11-17)
От: Alexander Bondugin
Тема: 1998 Mars Orbiter, Lander, Microprobes Set For Launch
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1998 MARS ORBITER, LANDER, MICROPROBES SET FOR LAUNCH
November 1998
NASA embarks on a return trip to Mars this winter with two spacecraft
launches that will first send an orbiter to circle the red planet, then
follow with another to land on the frigid, barren steppe near the edge of
Mars' south polar cap. Piggybacking on the lander will be two small probes
that will smash into the Martian surface to test new technologies.
Mars Climate Orbiter, scheduled for launch Dec. 10, and Mars Polar Lander,
scheduled for launch Jan. 3, will seek clues to the history of climate
change on Mars. Both will be launched atop identical Delta II launch
vehicles from Launch Complex 17 A and B at Cape Canaveral Air Station, FL,
carrying instruments to map the planet's surface, profile the structure of
the atmosphere, detect surface ice reservoirs and dig for traces of water
beneath Mars' rusty surface.
The lander also carries a pair of basketball-sized microprobes that will be
released as the lander approaches Mars and dive toward the planet's surface,
penetrating up to about 1 meter (3 feet) underground to test 10 new
technologies, including a science instrument to search for traces of water
ice. The microprobe project, called Deep Space 2, is part of NASA's New
Millennium Program.
The missions are the second installment in NASA's long-term program of
robotic exploration of Mars, which was initiated with the 1996 launches of
the currently orbiting Mars Global Surveyor and the Mars Pathfinder lander
and rover.
The 1998 missions will advance our understanding of Mars' climate history
and the planet's current water resources by digging into the enigmatic
layered terrain near one of its poles for the first time. Instruments
onboard the orbiter and lander will analyze surface materials, frost,
weather patterns and interactions between the surface and atmosphere to
better understand how the climate of Mars has changed over time.
Key scientific objectives are to determine how water and dust move about the
planet and where water, in particular, resides on Mars today. Water once
flowed on Mars, but where did it go? Clues may be found in the geologic
record provided by the polar layered terrain, whose alternating bands of
color seem to contain different mixtures of dust and ice. Like growth rings
of trees, these layered geological bands may help reveal the secret past of
climate change on Mars and help determine whether it was driven by a
catastrophic change, episodic variations or merely a gradual evolution in
the planet's environment.
Today the Martian atmosphere is so thin and cold that it does not rain;
liquid water does not last on the surface, but quickly freezes into ice or
evaporates and resides in the atmosphere. The temporary polar frosts which
advance and retreat with the seasons are made mostly of condensed carbon
dioxide, the major constituent of the Martian atmosphere. But the planet
also hosts both water-ice clouds and dust storms, the latter ranging in
scale from local to global. If typical amounts of atmospheric dust and water
were concentrated today in the polar regions, they might deposit a fine
layer every year, so that the top meter (or yard) of the polar layered
terrains could be a well-preserved record showing 100,000 years of Martian
geology and climatology.
Nine and a half months after launch, in September 1999, Mars Climate Orbiter
will fire its main engine to put itself into an elliptical orbit around
Mars. The spacecraft will then skim through Mars' upper atmosphere for
several weeks in a technique called aerobraking to reduce velocity and
circularize its orbit. Friction against the spacecraft's single,
5.5-meter-long (18-foot) solar array will slow the spacecraft as it dips
into the atmosphere each orbit, reducing its orbit period from more than 14
hours to 2 hours.
Finally, the spacecraft will use its thrusters to settle into a polar,
nearly circular orbit averaging 421 kilometers (262 miles) above the
surface. From there, the orbiter will await the arrival of Mars Polar Lander
and serve as a radio relay satellite during the lander's surface mission.
After the lander's mission is over, the orbiter will begin routine
monitoring of the atmosphere, surface and polar caps for a complete Martian
year (687 Earth days), the equivalent of almost two Earth years.
The orbiter carries two science instruments: the Pressure Modulator Infrared
Radiometer, a copy of the atmospheric sounder on the Mars Observer
spacecraft lost in 1993, and the Mars Color Imager, a new, light-weight
imager combining wide-and medium-angle cameras. The radiometer will measure
temperatures, dust, water vapor and clouds by using a mirror to scan the
atmosphere from the Martian surface up to 80 kilometers (50 miles) above the
planet's limb.
Meanwhile, the imager will gather horizon-to-horizon images at up to
kilometer-scale (half-mile-scale) resolutions, which will then be combined
to produce daily global weather images. The camera will also image surface
features and produce a map with 40-meter (130-foot) resolution in several
colors, to provide unprecedented views of Mars' surface.
Mars Polar Lander, launched a month after the orbiter is on its way, will
arrive in December 1999, two to three weeks after the orbiter has finished
aerobraking. The lander is aimed toward a target sector within the edge of
the layered terrain near Mars' south pole. The exact landing site
coordinates will be adjusted as late as August 1999, based on images and
altimeter data from the currently orbiting Mars Global Surveyor.
Like Mars Pathfinder, Mars Polar Lander will dive directly into the Martian
atmosphere, using an aeroshell and parachute scaled down from Pathfinder's
design to slow its initial descent. The smaller Mars Polar Lander will not
use airbags, but instead will rely on onboard guidance and retro-rockets to
land softly on the layered terrain near the south polar cap a few weeks
after the seasonal carbon dioxide frosts have disappeared. After the heat
shield is jettisoned, a camera will take a series of pictures of the landing
site as the spacecraft descends.
As it approaches Mars about 10 minutes before touchdown, the lander will
release the two Deep Space 2 microprobes. Once released, the projectiles
will collect atmospheric data before they crash at about 200 meters per
second (400 miles per hour) and bury themselves beneath the Martian surface.
The microprobes will test the ability of very small spacecraft to deploy
future instruments for soil sampling, meteorology and seismic monitoring. A
key instrument will draw a tiny soil sample into a chamber, heat it and use
a miniature laser to look for signs of vaporized water ice.
About 100 kilometers (60 miles) away from the microprobe impact sites, Mars
Polar Lander will dig into the top of the terrain using a 2-meter-long
(6-1/2-foot) robotic arm. A camera mounted on the robotic arm will image the
walls of the trench, viewing the texture of the surface material and looking
for fine-scale layering. The robotic arm will also deliver soil samples to a
thermal and evolved gas analyzer, an instrument that will heat the samples
to detect water and carbon dioxide. An onboard weather station will take
daily readings of wind temperature and pressure, and seek traces of water
vapor. A stereo imager perched atop a 1.5-meter (5-foot) mast will
photograph the landscape surrounding the spacecraft. All of these
instruments are part of an integrated science payload called the Mars
Volatiles and Climate Surveyor.
Also onboard the lander is a light detection and ranging (lidar) experiment
provided by Russia's Space Research Institute. The instrument will detect
and determine the altitude of atmospheric dust hazes and ice clouds above
the lander. Inside the instrument is a small microphone, furnished by the
Planetary Society, Pasadena, CA, which will record the sounds of wind gusts,
blowing dust and mechanical operations onboard the spacecraft itself.
The lander is expected to operate on the surface for 60 to 90 Martian days
through the planet's southern summer (a Martian day is 24 hours, 37
minutes). The mission will continue until the spacecraft can no longer
protect itself from the cold and dark of lengthening nights and the return
of the Martian seasonal polar frosts.
The Mars Climate Orbiter, Mars Polar Lander and Deep Space 2 missions are
managed by the Jet Propulsion Laboratory for NASA's Office of Space Science,
Washington, DC. Lockheed Martin Astronautics Inc., Denver, CO, is the
agency's industrial partner for development and operation of the orbiter and
lander spacecraft. JPL designed and built the Deep Space 2 microprobes. JPL
is a division of the California Institute of Technology, Pasadena, CA.
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=SANA=
Дата: 17 ноября 1998 (1998-11-17)
От: Alexander Bondugin
Тема: Galileo - Countdown To Europa
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GALILEO - COUNTDOWN TO EUROPA
November 16, 1998
It is now 5 days and 10 hours to the Galileo spacecraft's next encounter
with Europa.
A special Countdown to Europa home page is available on the Galileo
Home Page:
http://www.jpl.nasa.gov/galileo/countdown/
Launched in October 1989, Galileo entered orbit around Jupiter in December
1995, and completed its primary 2 year orbital tour around the
solar system's largest planet. Galileo has embarked on a two-year extended
mission, called Galileo Europa Mission (GEM). During GEM, Galileo will make
8 close flybys of Europa, four flybys of Callisto, and two close encounters
with Io provided the spacecraft is still alive.
The seventh encounter for GEM is scheduled for Europa on November 22, 1998 at
11:47 UT. With a diameter of 3,138 km, Europa is slighty
smaller than our own Moon and is the smoothest object in the solar system.
On Galileo's previous encounters with Europa, evidence of a possible ocean
were found, including the discovery of ice volcanoes (none active),
probable icebergs, and salt deposits on the surface. Galileo will continue
its attempt to find additional evidence of a liquid ocean underneath Europa's
icy crust and look for signs of active volcanism on the moon's young surface.
On the upcoming encounter, the spacecraft will pass by Europa at a distance of
2,281 km, which is over 320 times closer than Voyager's closest approach.
Galileo will also take in observations of Jupiter, Io and Ganymede.
Highlights of the Countdown to Europa home page:
o A virtual flyby of Europa with computer-generated approach images of
Jupiter and Europa displayed at the top of the home page. These images
are all updated every 5 minutes.
o Flyby animation of the Europa 18 flyby.
o Daily Galileo status reports reporting on the Europa 18 encounter.
o Fact sheets and Europa, Callisto and Io.
o A detailed timeline of events and sequences that the spacecraft will
perform for the Europa 18 encounter.
o Voyager 1 & 2 images of Callisto, Ganymede, Europa and Io.
o Hubble Space Telescope images of the Galilean satellites.
o Pioneer 10 & 11 images of Callisto, Ganymede, Europa and Io.
Ron Baalke
baalke@kelvin.jpl.nasa.gov
Galileo Webmaster
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