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Дата: 29 декабря 1998 (1998-12-29)
От: Alexander Bondugin
Тема: Successful NEAR Flyby Of Eros - Closeup Images Available
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NEAR Spacecraft Makes Planned Flyby of Asteroid Eros
On Dec. 23, at 1:43 p.m. EST, the NEAR spacecraft made a
flyby of Eros designed to provide scientists with
detailed data on the asteroid. In a matter of hours,
mission operations personnel were able to respond to an
aborted scheduled engine burn and program the command
sequence that put the spacecraft on a trajectory
approximately 2,500 miles (4,100 kilometers) from the
surface of the asteroid. Currently (Dec. 23, 3 p.m.
EST), the spacecraft is executing the command sequence
as planned.
Three instruments onboard the spacecraft, the
Multispectral Imager, the Near-Infrared Spectrometer,
and the Magnetometer, are operating as expected. More
than 1,100 images of the asteroid are anticipated, which
will provide scientists with valuable information on the
size, shape, and surface characteristics of Eros and
whether it has any moons.
The first photographs will be posted on the NEAR Web
site on Dec. 24 between 1:00 - 2:30 p.m.
NEAR Sends Back Images of Eros
(December 24, 1998, 2 p.m. EST)
Despite an aborted engine burn that postponed the
January 1999, rendezvous of the NEAR spacecraft with
asteroid Eros, mission operations team members were able
to quickly upload new commands to the spacecraft, making
it possible to obtain valuable information during a
December 23, flyby of the asteroid.
Science data, including multicolor images, spectral
data, and magnetic field measurements taken during the
flyby, are now coming into the Applied Physics
Laboratory's NEAR Science Data Center. Doppler
navigation data and real-time telemetry were collected
that will help determine the mass of the asteroid.
The flyby gave NEAR Mission Operations an opportunity to
test tracking and instrument sequences in preparation of
a rendezvous event, says Mission Operations Center
Manager Mark Holdridge. "The flight recorders, full of
Eros science data, are being played back at the present
time. The spacecraft is healthy and doing just fine and
it has been confirmed that the flyby pointing and
instrument command sequence executed flawlessly to
completion."
In addition to flyby data processing, team members are
also studying data sent by the spacecraft soon after
contact with it was reestablished on Dec. 22, following
27 hours of communication blackout to determine the
exact nature of the software anomaly that led to the
rendezvous burn failure.
NEAR and Eros are now traveling in separate orbits
around the sun as plans are being made for a rendezvous
sometime between August 1999 and April 2000.
Images of Eros taken during the flyby are being posted
on the NEAR Web site as they are processed.
NEAR's First Close-Ups of Eros
http://near.jhuapl.edu/iod/000/index.html
This montage of the asteroid Eros was assembled from
images acquired by the Near Earth Asteroid Rendezvous
(NEAR) spacecraft on Dec. 23, as the spacecraft flew by
the asteroid at a distance of 2,500 miles (4,100
kilometers) at 1:43 p.m. EST. This montage shows the
first nine of 28 views of Eros that were obtained during
the flyby. The images were taken between 10:44 AM and
12:44 PM EST as the spacecraft range closed from 7300
miles (11,100) km to 3300 miles (5300 kilometers).
During that time, the asteroid completed nearly half of
a rotation. The smallest resolved detail is
approximately 1650 feet (500 meters) across.
A firing of the main engine at 5 PM EST December 20,
designed to slow the spacecraft for insertion into orbit
around the asteroid, was aborted by the spacecraft.
Contact with ground controllers was temporarily lost,
but was regained at 8 PM EST December 21 when autonomous
spacecraft safety protocols took over and transmitted a
signal to the ground. All spacecraft systems appear
healthy and operational. Within hours, a flyby
observation sequence was developed and uploaded to the
spacecraft. Over 1100 images were acquired by the
multispectral imager, to determine the size, shape,
morphology, rotational state, and color properties of
Eros, and to search for small moons. The infrared
spectrometer measured spectral properties of the
asteroid to determine what minerals are present, and the
magnetometer searched for a natural magnetic field.
Analysis of the spacecraft radio signal will yield
bounds on the asteroid's mass and density.
Options for rescheduling firing of the main spacecraft
engine are currently being examined, and could lead to
Eros rendezvous and orbit insertion as early as mid-1999
or as late as May 2000. Eros is NEAR's second asteroid
encountered. On June 27, 1997, NEAR flew by the
main-belt asteroid Mathilde at a range of 1212
kilometers (750 miles).
Built and managed by The Johns Hopkins University
Applied Physics Laboratory, Laurel, Maryland, NEAR was
the first spacecraft launched in NASA's Discovery
Program of low-cost, small-scale planetary missions. See
the NEAR web page at http://near.jhuapl.edu for more
details.
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=SANA=
Дата: 29 декабря 1998 (1998-12-29)
От: Alexander Bondugin
Тема: Lunar Prospector Update - December 21, 1998
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Lunar Prospector Mission Status Report #62
December 21, 1998
The Lunar Prospector spacecraft is operating well and all instruments
continue to collect good data.
On Saturday, December 19, the spacecraft was placed into a orbit with an
average altitude of 40 km. This is a transition orbit, between the nominal
mapping orbit (with altitude 100 km) and the extended mission orbit (with
altitude 25-30 km), where the gravity model will be verified.
The timeline is given below:
353/1740 cmd'd thruster heaters on
353/1811 fired A3/A4 thrusters for 46.8 sec
353/1840 cmd'd thruster heaters on
353/1911 fired A1/A2 thrusters for 150.4 sec
353/1917 cmd'd thruster heater on
353/1937 fired T1 thrusters for 0.65 sec
The starting orbit was 77.5 km x 122.5 km. The first burn was at apoapsis
to lower periapsis from 77.5 km to 50.5 km. The second burn was at the
ascending node to set new periapsis altitude to 25 km at desired argument
of periapsis. The resulting orbit was 25 km x 55 km. The gravity field
will tend to circularize it over the next few days. The attitude
reorientation maneuver was cancelled and the third burn trimmed the
spacecraft spin rate back to its nominal value.
There were very high winds in the California high desert and there was
concern that the antenna (DSS 27) would have to be stowed mid-way during
the maneuver, but fortunately the winds stayed below the limits and
everything went on time.
Eclipses started as predicted at 353/2005 but their length will decrease
with time and the season will end before Christmas.
Current spacecraft state (0000 GMT 12/21/98):
Orbit: 4184
Downlink: 3600 bps
Spin Rate: 12.00 rpm
Spin Axis Attitude (ecliptic):
Latitude: -88.0 deg
Longitude: 242 deg
Trajectory:
Periapsis Alt: 29 km
Apoapsis Alt: 52 km
Period: 112 min
Occultations: 10 minutes
Eclipses: 23 minutes
Propellant
remaining: 17.45 kg
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=SANA=
Дата: 29 декабря 1998 (1998-12-29)
От: Alexander Bondugin
Тема: Mars Climate Orbiter Update - December 23, 1998
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MARS CLIMATE ORBITER MISSION STATUS
December 23, 1998
4:00 P.M. (PST)
Earlier today Mars Climate Orbiter successfully completed its last
planned activity for 1998, in which its two science instruments, the
Pressure Modulator Infrared Radiometer (PMIRR) and MARs Color Imager
(MARCI), were powered for their first post-launch health check. Preliminary
analysis of the telemetry data returned indicated that both instruments are
in good operating condition. Further detailed analysis of the health check
data will be perfomed over the next few weeks.
Data collected onboard the spacecraft from both instruments were
transmitted back to Earth over a four and one-half hour period. Due to a
minor error discovered in the telemetry system configuration, one of the
eight MARCI test images was not returned during the scheduled data playback
period. The error has been corrected, and the remaining MARCI data will be
transmitted early next week.
With the completion of this activity, the flight team is now turning its
focus to completion of preparations for launch of the Mars Polar Lander.
Following the launch of the lander, scheduled for January 3, 1999, the next
planned activity for the orbiter is the development of its second
"housekeeping" sequence, followed by a second Trajectory Correction
Maneuver in late January.
For more information on the Mars Surveyor 98 mission, please visit
our website at:
http://mars.jpl.nasa.gov/msp98
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=SANA=
Дата: 29 декабря 1998 (1998-12-29)
От: Alexander Bondugin
Тема: Sky & Telescope News Bulletin - December 24, 1998
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SKY & TELESCOPE'S NEWS BULLETIN
DECEMBER 24, 1998
A WAYWARD NEAR
After a day of anxious worry, ground controllers tracked down and regained
control of the Near Earth Asteroid Rendezvous (NEAR) spacecraft. NEAR fell
silent soon after its main rocket was commanded to fire on Sunday, December
20th. The main engine has not been used since July 1997. Because the engine
failed to slow NEAR's approach speed, the spacecraft coasted past its main
objective, the asteroid 433 Eros, at 1:43 p.m. Eastern Standard Time on
December 23rd at about 1 kilometer per second at a distance of 4,100 km. An
11th-hour upload of instructions commanded the on-board camera to take more
than 1,100 images and to record data from the near-infrared spectrometer
and magnetometer. However, the best possible resolution will be no better
than about 500 meters. The first images of the highly elongated object --
measuring about 40 km long and 14 across -- were expected to be released
today.
According to mission manager Robert Farquhar, reestablishing contact was a
tremendous relief, and in retrospect the spacecraft was nearly lost for
good. A low-voltage condition on board erased crucial engineering data and
thus complicated the recovery effort. Moreover, regaining control of the
tumbling craft depleted about 30 kg of maneuvering fuel. Once project
engineers understand the nature of Sunday's malfunction, they may redirect
the spacecraft to return to Eros and assume an orbit around it as early as
mid-1999, though a rendezvous in the year 2000 is also being considered.
X-RAY OBSERVATORY RENAMED
NASA announced on Monday that the Advanced X-ray Astrophysics Facility
(AXAF) -- scheduled for launch aboard the Space Shuttle Columbia no earlier
than April 8th -- has been renamed the Chandra X-ray Observatory, in honor
of the late Nobel-prizewinning physicist Subrahmanyan Chandrasekhar
(1910-95). The name was selected by "Name NASA's Next Great Observatory
Contest," which ran from April to June 1998. The two winners -- Camarillo,
California, high school physics teacher Jatila van der Veen, and Idaho high
school student Tyrel Johnson -- win trips to see Columbia lift off. The
AXAF team received more than 6,000 entries, from every state in the United
States and more than 60 other countries, each including a short essay
justifying the entrant's suggestion.
Chandra's scientific accomplishments are numerous. In one sense, he was a
successor to Einstein, further developing the great German physicist's
theory of general relativity and, in so doing, revealing its elegance and
widespread applicability. So it is fitting that the Chandra Observatory
should be the successor to the Einstein Observatory, the last major X-ray
telescope orbited by U.S. astronomers.
ALDEBARAN OCCULTATION
On December 30th, the waxing gibbous Moon will occult (cover) the
1st-magnitude star Aldebaran (Alpha Tauri) around sunset for parts of North
America. Observers in the Northeast will find the Moon well up in the
eastern sky and the Sun just below the horizon when the occultation
happens. For Southerners and Midwesterners it happens when the Sun is still
shining and the Moon is low, but the event should still be visible with a
telescope. For more information and a timetable, see
http://www.skypub.com/sights/occultations/lunar/lunar.html.
WAIT A SECOND!
You'll have to wait an extra second for 1999 to begin on December 31st. The
U.S. Naval Observatory will introduce a leap second to keep atomic clocks
in pace with Earth's rotation. The 22nd leap second since 1972 will occur
at 23 hours 59 minutes and 59 seconds Coordinated Universal Time (UTC),
which corresponds to 6:59:59 p.m. Eastern Standard Time.
THIS WEEK'S "SKY AT A GLANCE"
Some daily events in the changing sky, from the editors of SKY &
TELESCOPE.
DEC. 27 -- SUNDAY
* The Moon (just past first quarter) shines near Saturn this evening.
* Saturn's own brightest moon, Titan, can be seen in a small telescope
three or four ring-lengths east of Saturn this evening through Thursday
evening.
DEC. 28 -- MONDAY
* Seen in a medium-sized telescope, Jupiter's Great Red Spot should cross
Jupiter's central meridian (the imaginary line down the center of Jupiter's
disk from pole to pole) around 11:15 p.m. Eastern Standard Time. Lately the
spot has been very pale tan. For a list of all predicted Red Spot transit
times, see http://www.skypub.com/sights/moonplanets/redspot.html.
DEC. 29 -- TUESDAY
* Jupiter's Red Spot transits around 7:06 p.m. EST.
DEC. 30 -- WEDNESDAY
* The waxing gibbous Moon will occult (cover) the 1st-magnitude star
Aldebaran (Alpha Tauri) around sunset for parts of North America. Observers
in the Northeast will find the Moon well up in the eastern sky and the Sun
just below the horizon whent he occultation happens. For Southerners and
Midwesterners it happens when the Sun is still shining and the Moon is low,
but the event should still be visible with a telescope. For the time, see
the table in last January's issue, page 97, or at
http://www.skypub.com/sights/occultations/lunar/lunarchart.html.
* Mars and the 4.4-magnitude star Theta Virginis are in the same
telescopic field before dawn Thursday morning. They appear about 0.2 degree
apart.
DEC. 31 -- THURSDAY
* The shadow of Jupiter's moon Io crosses Jupiter's disk from 7:41 to
9:55 p.m. EST, followed by Io itself from 8:58 to 11:11 p.m. EST.
* Jupiter's Red Spot transits the planet's central meridian around 8:45
p.m. EST.
JAN. 1 -- FRIDAY
* Full Moon (exact at 9:49 p.m. EST).
JAN. 2 -- SATURDAY
* Jupiter's Red Spot transits around 10:24 p.m. EST.
THIS WEEK'S PLANET ROUNDUP
MERCURY appears low in the southeast during dawn, getting lower daily.
Don't confuse it with Antares, which is to Mercury's right early in the
week and to its upper right later in the week.
VENUS is very low in the southwest during early dusk. Look about 30 minutes
after sunset.
MARS, shining at magnitude +1.0 in Virgo, rises around 1 a.m. and is high
in the south by dawn. Spica is the star below it.
JUPITER, magnitude -2.3, is the big, bright "star" high in the
south-southwest at dusk. It gets lower in the southwest later in the
evening and sets around 10:30 p.m.
SATURN, magnitude +0.2, is the yellowish "star" far to Jupiter's upper
left. The two planets appear 35 degrees apart, on opposite ends of dim
Pisces.
URANUS, NEPTUNE, and PLUTO are hidden behind the glare of the Sun.
(All descriptions that relate to the horizon or zenith are written for the
world's midnorthern latitudes. Descriptions that also depend on longitude
are for North America. Eastern Standard Time, EST, equals Universal Time
minus 5 hours.)
More details, sky maps, and news of other celestial events appear each
month in SKY & TELESCOPE, the essential magazine of astronomy. See our
enormous Web site at http://www.skypub.com/. Clear skies!
SKY & TELESCOPE, P.O. Box 9111, Belmont, MA 02478 * 617-864-7360 (voice)
Copyright 1998 Sky Publishing Corporation. S&T's Weekly News Bulletin and
Sky at a Glance stargazing calendar are provided as a service to the
astronomical community by the editors of SKY & TELESCOPE magazine.
Widespread electronic distribution is encouraged as long as these
paragraphs are included. But the text of the bulletin and calendar may not
be published in any other form without permission from Sky Publishing
(contact permissions@skypub.com or phone 617-864-7360). Updates of
astronomical news, including active links to related Internet resources,
are available via SKY & TELESCOPE's site on the World Wide Web at
http://www.skypub.com/.
In response to numerous requests, and in cooperation with the Astronomical
League (http://www.mcs.net/~bstevens/al/) and the American Association of
Amateur Astronomers (http://www.corvus.com/), S&T's Weekly News Bulletin
and Sky at a Glance are available via electronic mailing list too. For a
free subscription, send e-mail to skyline@corvus.com and put the word
"join" on the first line of the body of the message. To unsubscribe, send
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SKY & TELESCOPE, the Essential Magazine of Astronomy, is read by more than
200,000 enthusiasts each month. It is available on newsstands worldwide.
For subscription information, or for a free copy of our catalog of fine
astronomy books and products, please contact Sky Publishing Corp., 49 Bay
State Rd., Cambridge, MA 02138-1200, U.S.A. Phone: 800-253-0245 (U.S. and
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custserv@skypub.com. WWW: http://www.skypub.com/. Clear skies!
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=SANA=
Дата: 29 декабря 1998 (1998-12-29)
От: Alexander Bondugin
Тема: NASA выбирает программы исследований для японской экспедиции
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NASA выбирает программы исследований для японской экспедиции
Solar-B
NASA объявила список из трех научных программ, которые будут
реализовываться в ходе экспедиции по исследованию Солнца Solar-B
Японского института космоса и астронавтики (Japan's Institute of Space and
Astronautical Science, ISAS), старт которой запланирован на 2004 г. В
международной миссии Solar-B кроме Японии примут участие США и
Великобритания.
Основной целью миссии Solar-B является исследование Солнечной
короны и связи между тонкой структурой магнитного поля на поверхности
Солнца, фотосферой и динамическими процессами, происходящими в короне.
NASA для участия в этой экспедиции выбрало 3 программы:
Разработка инструментария для оптического телескопа диаметром 50 см
(устройства формирования изображения с широкополосным и
узкополосным фильтрами и спектрополяриметр).
Рентгеновский телескоп для исследования атмосферы Солнца,
температура которой составляет миллионы градусов.
Спектрометр дальнего УФ диапазона.
Источник: InfoArt News Agency
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=SANA=
Дата: 29 декабря 1998 (1998-12-29)
От: Alexander Bondugin
Тема: Ионный двигатель от Hughes готов к работе в дальнем космосе
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Ионный двигатель от Hughes готов к работе в дальнем космосе
[Business Wire] Объявлено об успешном
завершении испытаний ионного двигателя,
установленного на борту исследовательского
космического корабля New Millennium Deep
Space 1. Теперь он может стать основным
двигателем для будущих научных космических
экспедиций NASA. Создателем ионного
двигателя является Hughes Electron Dynamics -
подразделение корпорации Hughes Electronics.
После включения 24 ноября ионный двигатель проработал более 500 часов, и
теперь Deep Space 1 находится на расстоянии более 9,5 млн км от Земли.
Исследования в области ионных двигателей были начаты в Hughes еще в
60-х годах. В качестве топлива для них испытывались пары цезия и ртути, но
в
итоге для этих целей был выбран газ ксенон. Коммерческие ксеноновые
ионные двигатели системы XIPS от Hughes уже используются в спутниках
связи HS 702 и HS 601HP. Такой двигатель установлен и на борту
телекоммуникационного спутника PAS-6B, запущенного 21 декабря.
Источник: InfoArt News Agency
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=SANA=
Дата: 29 декабря 1998 (1998-12-29)
От: Alexander Bondugin
Тема: Globalstar заключает контракт на запуск спутников с Arianespace
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Globalstar заключает контракт на запуск спутников с Arianespace
[Business Wire] Компания Globalstar заключила контракт на запуск 6
своих
спутников с французской компанией Arianespace. Спутники Globalstar будут
выведены на орбиту ракетой-носителем Ariane 4.
Запуск планируется произвести в сентябре 1999 г. с космодрома Куру во
Французской Гвиане. Ранее Globalstar объявила о намерении использовать для
запуска своих спутников ракеты "Союз" и Delta, каждая из которых должна
была выводить на орбиту за раз по 4 спутника. Всего таким образом
предполагается запустить 32 спутника, коммерческая эксплуатация которых
начнется в третьем квартале 1999 г. К декабрю 1999 г. Globalstar
предполагает
запустить все 52 спутника своей сети глобальной мобильной связи, 48 из
которых будут находиться в рабочем режиме, а 4 будут запасными.
Источник: InfoArt News Agency
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=SANA=
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