Messenger (Даёшь Меркурий!)

[ronatu]

MESSENGER Marks Seventh Anniversary of Launch

....Seven years ago, on August 3, 2004, MESSENGER left Earth aboard a three-stage Boeing Delta II rocket to begin a journey that would take it more than 15 laps through the solar system, through six planetary flybys, and ultimately into orbit around Mercury.

The spacecraft has travelled 5.247 billion miles (8.445 billion kilometers) relative to the Sun, and the team is one-third of the way through the one-year science campaign to understand the innermost planet....

MESSENGER's primary mission is divided into two Mercury solar days, so that lighting conditions can be repeated for filling gaps in imaging, targeted observations can be optimized, and stereo imaging can be accomplished....

[instml]

[sol]

Сабж уже занял рабочую орбиту?

[instml]

Сабж уже занял рабочую орбиту?

Разумеется. Он с 18 марта на ней

[instml]

MESSENGER Team Delivers First Orbital Data to Planetary Data System

Data collected during MESSENGER's first two months in orbit around Mercury have been released to the public by the Planetary Data System (PDS), an organization that archives and distributes all of NASA's planetary mission data. Calibrated data from all seven of MESSENGER's science instruments, plus radio science data from the spacecraft telecommunications system, are included in this release.

"It's a real milestone for the first data ever obtained from orbit around Mercury to be available now in the PDS," says Nancy Chabot, Instrument Scientist for MESSENGER's Mercury Dual Imaging System (MDIS).

"Scientists around the world will use these data to better understand Mercury and the formation and evolution of our solar system as a whole," says Chabot, of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md. "However, to me, one of the most exciting aspects of this release is that these data now in the PDS are just the first of much more to come. MESSENGER continues to send us new data practically every day!"

The science results from these instruments have already shed light on questions about Mercury that have lingered for more than three decades. Many of these results were highlighted in a June 16 press conference at NASA headquarters.

For instance, says MESSENGER Project Scientist Ralph McNutt of APL, "The imaging has highlighted the importance of volcanism in plains formation in the planet's history, and the geochemical remote sensing instruments are providing new insights into formation scenarios for the planet. Geophysics data are yielding new information on Mercury's internal structure, and data from the exosphere and magnetosphere instruments are giving us the first continuous view of Mercury's interaction with its local space environment.

"The availability of these data via PDS will allow scientists around the world to study the data and begin making even more connections and discoveries," McNutt adds.

Since the mid-1990s, NASA has required all of its planetary missions to archive data in the PDS, an active archive that makes available well-documented, peer-reviewed data to the research community. The PDS includes eight university/research center science teams, called discipline nodes, each of which specializes in a specific area of planetary data. The contributions from these nodes provide a data-rich source for scientists, researchers, and developers.

"PDS deliveries are the result of a concerted effort between the MESSENGER team and the PDS that starts well before the release to the public," says APL's Susan Ensor, MESSENGER's Science Operations Center lead. "Approximately 50 MESSENGER team members were actively involved in making this PDS delivery, including instrument team members, developers from Applied Coherent Technology Corporation, and Science Operations Center personnel."

Previous MESSENGER PDS deliveries included data from cruise and flybys of the Earth, Venus, and Mercury. The data for this delivery are archived and available online at http://pds.nasa.gov/subscription_service/SS-20110908.html , and all of the MESSENGER data archived at the PDS thus far are available at http://pds.nasa.gov . As of this release, MESSENGER will have delivered 1.1 terabytes of raw and calibrated data to the PDS, including more than 30,000 images (of which over 18,000 are from orbit).

The team will submit three more PDS deliveries at six-month intervals from MESSENGER's primary mission. "Improved calibrations will be incorporated in these future deliveries," Ensor says. "Advanced products, including Mercury maps, will be included in the final primary mission delivery in March 2013."

The MESSENGER team has created an innovative software tool with which the public can view data from this delivery. ACT-REACT-Quick Map provides a simple, interactive Web interface to MESSENGER data. Developed by Applied Coherent Technology Corporation, Quick Map allows users to examine global mosaics constructed with high-resolution images from this PDS delivery.

The tool also provides weekly updates of coverage for surface-observing instruments, as well as the status of specially targeted MDIS observations. Information is also available that can be used to locate MESSENGER data products at the PDS. QuickMap can be accessed via links on each of the MESSENGER websites at http://messenger.jhuapl.edu/ and http://www.nasa.gov/messenger .

"The MESSENGER team is delighted to share the orbital observations of Mercury with the planetary science community and the public," adds MESSENGER Principal Investigator Sean Solomon, of the Carnegie Institution of Washington. "The first global exploration of our solar system's innermost planet is a wonderful adventure, and there are plenty of front-row seats for all to participate."

http://messenger.jhuapl.edu/news_room/details.php?id=182

[instml]

Messenger успешно пережил испепеляющую жару Солнца. Уже дважды

Космический зонд MESSENGER закончил второй «горячий период» работы на орбите Меркурия и выполнил третью коррекцию орбиты.

В ходе выполнения своей миссии протяженностью в один год MESSENGER вышел невредимым из второго из четырех горячих периодов.

Первый горячий период начался 9 августа и длился около месяца. За это время MESSENGER приблизился к Меркурию и периодически работал на дневной стороне планеты. Тепловой щит аппарата нагревался до температуры 350 градусов по Цельсию и операторы периодически выключали солнечные панели и поворачивали их ребром к Солнцу, чтобы избежать перегрева и поломки главного источника энергии.



Второй горячий период длился с 20 августа по 29 августа, а орбита зонда позволяла периодически «прятаться» в тени планеты. Тем не менее, в «темные» периоды, длящиеся более 35 минут, MESSENGER-у приходится переключаться с солнечных панелей на аккумуляторы и выключать часть научных приборов. По описанию операторов зонда, управление MESSENGER-ом похоже на вождение автомобиля по запутанной трассе с сильнейшими перепадами температуры каждые 12 часов. Поэтому надежность сложной системы электропитания, обусловленная экстремальными условиями вблизи Меркурия, вызывала наибольшее беспокойство инженеров НАСА.

Однако даже с определенными проблемами в управлении системами спутника, ученым удалось точно настроить приборы зонда и наладить непрерывное получение данных с MESSENGER-а. Причем аккумулятор работает отлично, что позволяет использовать два дополнительных инструмента для проведения непрерывных наблюдений в период отключения солнечных панелей. Таким образом, в дополнение к гамма-спектрометру, в течение всего горячего периода работали нейтронный спектрометр и магнитометр.

После второго горячего периода MESSENGER также скорректировал орбиту с высоты 470 до 200 километров. Это третья из пяти ожидаемых корректировок.

http://rnd.cnews.ru/natur_science/news/line/index_science.shtml?2011/09/12/454941

[instml]

[instml]

http://www.nasa.gov/news/media/newsaudio/index.html

NASA News Audio Live Streaming
 
MESSENGER Spacecraft Reveals New Details of Mercury
2 p.m. EDT, Thursday, Sept. 29

NASA will host a media teleconference at 2 p.m. EDT on Thursday, Sept. 29, to discuss new data and images from the first spacecraft to orbit Mercury.

NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft conducted fifteen laps through the inner solar system for more than six years before achieving the historic orbit insertion on March 18.

Briefing participants are:
-- Ed Graykzeck, MESSENGER program manager, NASA Headquarters, Washington
-- James Head, III, professor of geological sciences, Brown University
-- David Blewett, MESSENGER participating scientist and staff scientist, Johns Hopkins University Applied Physics Laboratory (APL), Laurel, Md.
-- Patrick Peplowski, staff scientist, APL
-- Thomas Zurbuchen, professor of space science and aerospace engineering, University of Michigan

[instml]

Immediately before the teleconference, related images and supporting briefing information will be available at: http://messenger.jhuapl.edu/news_room/telecon7.html

http://messenger.jhuapl.edu/news_room/details.php?id=183

[instml]

http://www.nasa.gov/news/media/newsaudio/index.html

[instml]

http://messenger.jhuapl.edu/news_room/telecon7.html

http://messenger.jhuapl.edu/news_room/telecon07_press.html

Orbital Observations of Mercury Reveal Flood Lavas, Hollows, and Unprecedented Surface Details

After only six months in orbit around Mercury, NASA's MESSENGER spacecraft is sending back information that has revolutionized the way scientists think about the innermost planet. Analyses of new data from the spacecraft show, among other things, new evidence that flood volcanism has been widespread on Mercury, the first close-up views of Mercury's "hollows," the first direct measurements of the chemical composition of Mercury's surface, and the first global inventory of plasma ions within Mercury's space environment.

The results are reported in a set of seven papers published in a special section of Science magazine on September 30, 2011.

"MESSENGER's instruments are capturing data that can be obtained only from orbit," says MESSENGER Principal Investigator Sean Solomon, of the Carnegie Institution of Washington. "We have imaged many areas of the surface at unprecedented resolution, we have viewed the polar regions clearly for the first time, we have built up global coverage with our images and other data sets, we are mapping the elemental composition of Mercury's surface, we are conducting a continuous inventory of the planet's neutral and ionized exosphere, and we are sorting out the geometry of Mercury's magnetic field and magnetosphere. And we've only just begun. Mercury has many more surprises in store for us as our mission progresses."

MESSENGER Reveals Flood Volcanism

For decades scientists had puzzled over whether Mercury had volcanic deposits on its surface. MESSENGER's three flybys answered that question in the affirmative, but the global distribution of volcanic materials was not well constrained. New data from orbit show a huge expanse of volcanic plains surrounding the north polar region of Mercury. These continuous smooth plains cover more than 6% of the total surface of Mercury.

The volcanic deposits are thick. "Analysis of the size of buried 'ghost' craters in these deposits shows that the lavas are locally as thick as 2 kilometers" (or 1.2 miles), explains James Head of Brown University, the lead author of one of the Science reports. "If you imagine standing at the base of the Washington Monument, the top of the lavas would be something like 12 Washington Monuments above you."

According to Head, the deposits appear typical of flood lavas, huge volumes of solidified molten rock similar to those found in the few-million-year-old Columbia River Basalt Group, which at one point covered 150,000 square kilometers (60,000 square miles) in the northwest United States. "Those on Mercury appear to have poured out from long, linear vents and covered the surrounding areas, flooding them to great depths and burying their source vents," Head says.

Scientists have also discovered vents, measuring up to 25 kilometers (16 miles) in length, that appear to be the source of some of the tremendous volumes of very hot lava that have rushed out over the surface of Mercury and eroded the substrate, carving valleys and creating teardrop-shaped ridges in the underlying terrain. "These amazing landforms and deposits may be related to the types of unusual compositions, similar to terrestrial rocks called komatiites, being seen by other instruments and reported in this same issue of Science," Head says. "What's more, such lavas may have been typical of an early period in Earth's history, one for which only spotty evidence remains today."

As MESSENGER continues to orbit Mercury, the imaging team is building up a global catalog of these volcanic deposits and is working with other instrument teams to construct a comprehensive view of the history of volcanism on Mercury.

Hollows on Mercury

Images collected by MESSENGER have revealed an unexpected class of landform on Mercury and suggest that a previously unrecognized geological process is responsible for its formation. Images collected during the Mariner 10 and MESSENGER flybys of Mercury showed that the floors and central mountain peaks of some impact craters are very bright and have a blue color relative to other areas of Mercury. These deposits were considered to be unusual because no craters with similar characteristics are found on the Moon. But without higher-resolution images, the bright crater deposits remained a curiosity.

Now MESSENGER's orbital mission has provided close-up, targeted views of many of these craters.

"To the surprise of the science team, it turns out that the bright areas are composed of small, shallow, irregularly shaped depressions that are often found in clusters," says David Blewett, a staff scientist at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., and lead author of one of the Science reports. "The science team adopted the term 'hollows' for these features to distinguish them from other types of pits seen on Mercury."

Hollows have been found over a wide range of latitudes and longitudes, suggesting that they are fairly common across Mercury. Many of the depressions have bright interiors and halos, and Blewett says the ones detected so far have a fresh appearance and have not accumulated small impact craters, indicating that they are relatively young.

"Analysis of the images and estimates of the rate at which the hollows may be growing led to the conclusion that they could be actively forming today," Blewett says. "The old conventional wisdom was that 'Mercury is just like the Moon.' But from its vantage point in orbit, MESSENGER is showing us that Mercury is radically different from the Moon in just about every way we can measure."

Mercury's Surface and Exospheric Composition, Up Close and Personal

Scientists are collecting data about the chemical composition of Mercury's surface that could not have been obtained without the sustained observing perspective that MESSENGER's orbit provides, and that information is being used to test models of Mercury's formation and shed light on the dynamics of the planet's exosphere.
Measurements of Mercury's surface by MESSENGER's Gamma-Ray Spectrometer (GRS) reveal a higher abundance of the radioactive element potassium, a moderately volatile element that vaporizes at a relatively low temperature, than previously predicted. Together with MESSENGER's X-Ray Spectrometer (XRS), it also shows that Mercury has an average surface composition different from those of the Moon and other terrestrial planets.

 "Measurements of the ratio of potassium to thorium, another radioactive element, along with the abundance of sulfur detected by XRS, indicate that Mercury has a volatile inventory similar to Venus, Earth, and Mars, and much larger than that of the Moon," says APL Staff Scientist Patrick Peplowski, lead author of one of the Science papers.
These new data rule out most existing models for Mercury's formation that had been developed to explain the unusually high density of the innermost planet, which has a much higher mass fraction of iron metal than Venus, Earth, or Mars, Peplowski pointed out. Overall, Mercury's surface composition is similar to that expected if the planet's bulk composition is broadly similar to that of highly reduced or metal-rich chondritic meteorites (material that is left over from the formation of the solar system).
MESSENGER has also collected the first global observations of plasma ions in Mercury's magnetosphere. Over 65 days covering more than 120 orbits, MESSENGER's Fast Imaging Plasma Spectrometer (FIPS) made the first long-term measurements of Mercury's ionized exosphere.

The team found that sodium is the most important ion contributed by the planet. "We had previously observed neutral sodium from ground observations, but up close we've discovered that charged sodium particles are concentrated near Mercury's polar regions where they are likely liberated by solar wind ion sputtering, effectively knocking sodium atoms off Mercury's surface" notes the University of Michigan's Thomas Zurbuchen, author of one of the Science reports. "We were able to observe the formation process of these ions, one that is comparable to the manner by which auroras are generated in the Earth atmosphere near polar regions."

The FIPS sensor detected helium ions throughout the entire volume of Mercury's magnetosphere. "Helium must be generated through surface interactions with the solar wind," says Zurbuchen. "We surmise that the helium was delivered from the Sun by the solar wind, implanted on the surface of Mercury, and then fanned out in all directions.

"Our results tell us is that Mercury's weak magnetosphere provides the planet very little protection from the solar wind," he continued. "Extreme space weather must be a continuing activity at the surface of the planet closest to the Sun."

 "These revelations emphasize that Mercury is a fascinating world that is unmatched in the solar system," says Blewett. "We have barely begun to understand what Mercury is really like and are eager to discover what Mercury can tell us about the processes that led to formation of the planets as we see them today."

[instml]

http://www.nasa.gov/mission_pages/messenger/media/Telecon20110929.html

[instml]

Меркурий пережил бурную вулканическую юность, выяснили ученые

МОСКВА, 29 сен - РИА Новости. Горные породы на поверхности Меркурия содержат в 10 раз больше серы, чем на Земле, и значительная часть северного полюса этой планеты "заливалась" лавой из-за катастрофических извержений вулканов в начале ее жизни - к такому выводу пришли несколько групп ученых, которые проанализировали данные, собранные американским зондом "Мессенджер".

В марте 2011 года космический аппарат "Мессенджер" вышел на орбиту Меркурия, и проанализировал его химические и физические свойства при помощи бортовых спектрометров и высокочувствительных камер, работающих в инфракрасном и видимом диапазоне. Несколько научных коллективов проанализировали полученные данные, и привели свои выводы в семи статьях, опубликованных в журнале Science.

Ларри Ниттлер (Larry Nittler) из Института имени Карнеги в Вашингтоне (США) и его коллеги проанализировали химический состав приповерхностных горных пород Меркурия и обнаружили, что он является в своем роде "адской" планетой - содержание серы в коре Меркурия превышает земное примерно в 10 раз.

Ниттлер и его коллеги подтвердили относительно небольшие запасы железа на поверхности Меркурия, как предсказывают современные теории формирования планет земной группы.

С другой стороны, это открытие подкрепляет современные теории "легкоплавкого" ядра Меркурия, которое предположительно состоит из смеси серы и железа.

Группа ученых под руководством Патрика Пепловски (Patrick Peplowski) из университета Джона Гопкинса в городе Лаурель (США) изучили изотопный состав недр Меркурия, проанализировав гамма и рентгеновское излучение "планеты-вестника".

"Содержание калия, тория и урана в недрах Меркурия соответствует их концентрации в метеоритах-хондритах, что подтверждает то, что Земля, Венера, Меркурий и Марс "слеплены" из одного теста", - пояснил Пепловски.

Как отмечается в статье, "нормальное" содержание калия в меркурианских породах исключает "экзотические" теории его происхождения. Любые катаклизмы после рождения планеты и необычные условия во время формирования протопланетного тела отразились бы в повышенном или пониженном содержании калия в современных недрах Меркурия.

Затем ученые "просветили" планету в рентгеновском диапазоне, и обнаружили, что породы Меркурия формировались преимущественно в условиях щелочной среды, что противоречит общепринятому представлению о типично "кислом" характере планет земной группы. Это может объясняться тем, что на атомы кислорода не задерживались долго на орбите Меркурия, так как их "сдувал" солнечный ветер.

Кроме того, ученые обнаружили признаки бурной вулканической юности Меркурия.

Джеймс Хэд (James Head) из Брауновского университета в городе Провиденс (США) и его коллеги нашли "следы" разливов лавы в районе северного полюса планеты.

В отличие от остальных участков поверхности Меркурия, эта зона была в меньшей степени затронута так называемой "тяжелой бомбардировкой" - падением множества астероидов после формирования планеты. По оценкам планетологов, плоские лавовые щиты покрывают до 6% поверхности Меркурия, а их толщина может достигать километра.

Как предполагают ученые, относительно гладкая поверхность приполярных территорий объясняется тем, что астероидные кратеры были "залиты" потоками лавы, которые выплеснулись на поверхность после "тяжелой бомбардировки".

"Вообразите - вы стоите у подножия монумента Вашингтона (обелиск высотой в 170 метров), и смотрите вверх. Так вот, слой лавы на Меркурии будет примерно в 12 раз выше его", - пояснил Хэд.

Зонд "Мессенджер" был запущен американским аэрокосмическим агентством НАСА в 2004 году. Он стал первым аппаратом, который был отправлен к Меркурию после зонда Mariner-10, пролетавшего в непосредственной близости от планеты-"вестника" 16 марта 1975 года.

В июне 2011 года ученые обнаружили, что магнитный центр Меркурия расположен не в центре планеты, а смещен к северу, из-за чего "планета-вестник" носит свое магнитное поле накребень. Кроме того, "Мессенджер" нашел на поверхности Меркурия "крест" из метеоритных кратеров и доказал возможность существования замороженной воды в глубоких кратерах в приполярных регионах планеты.

http://ria.ru/science/20110929/446250853.html

[Константин Дюкарев]

http://science.compulenta.ru/637621/
http://stp.cosmos.ru/index.php?id=1137&no_cache=1&tx_ttnews[tt_news]=1799&cHash=1668116e2eb1850a6e4cc18dac6aa910

[instml]

"Мессенджер" подтвердил наличие на Меркурии водного льда

Астрономы подтвердили наличие на Меркурии водного льда. Об этом ученые доложили на международной конференции планетологов EPSC-DPS во французском Нанте, а краткое изложение доклада приводит ScienceNOW.

В начале 90-х годов прошлого века при помощи радиотелескопов ученые установили, что на полюсах Меркурия имеются регионы с высоким альбедо - отражающей способностью. Тогда же исследователи высказали гипотезу, что это отложения льда, которые "прячутся" от солнечного света в глубоких полярных кратерах.

В рамках новой работы ученые изучили снимки Меркурия, сделанные аппаратом "Мессенджер", который в настоящее время работает на орбите этого небесного тела. В результате в районе полюса им удалось обнаружить кратеры, существование которых было предсказано в 90-х годах прошлого века.

В конце сентября 2011 года в Science вышли сразу семь работ, в которых ученые излагали самые новые результаты о Меркурии. В частности, им удалось обнаружить следы давней вулканической активности, которые сохранились на северном полюсе планеты, а также определить, что процесс формирования планеты происходил так же, как и у остальных каменных планет Солнечной системы.

http://lenta.ru/news/2011/10/06/ice/
http://news.sciencemag.org/sciencenow/2011/10/scienceshot-dark-ice-on-a-hot.html?ref=hp

[ronatu]

Data from the MESSENGER spacecraft's first six months in orbit is providing new information about the physical properties of Mercury

[instml]

A Global View from Orbit

http://messenger.jhuapl.edu/gallery/sciencePhotos/pics/2011-10-28_global_view_MESSENGER.png

http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=681

[instml]

South Polar Close Up

http://messenger.jhuapl.edu/gallery/sciencePhotos/pics/EN0226722230M.map.png

http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?page=1&gallery_id=2&image_id=676

[instml]

Fourth Orbit Adjustment Stretches MESSENGER's Orbit around Mercury

The MESSENGER spacecraft successfully completed its fourth orbit-correction maneuver today to increase the period of the spacecraft's orbit around the innermost planet from 11 hours 46 minutes to a precise 12 hours.

MESSENGER was 198 million kilometers (123 million miles) from Earth when the 159-second maneuver began at 6:12 p.m. EDT. Mission controllers at The Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., verified the start of the maneuver about 11 minutes, 1 second later, when the first signals indicating spacecraft thruster activity reached NASA's Deep Space Network tracking station outside Goldstone, Calif.

This is the fourth of five maneuvers planned for the primary orbital phase of the mission to keep orbital parameters within desired ranges for optimal scientific observations. MESSENGER's orbital velocity was changed by a total of 4.2 meters per second (9.4 miles per hour) to make the corrections essential for continuing the planned measurement campaigns.

Most of the instruments were placed in a passive state during the burn, but the instruments were reconfigured at 7:05 p.m. EDT to resume scientific observations of the planet.

MESSENGER Mission Systems Engineer Eric Finnegan, of APL, said the engine burn was executed as planned. "The team was well-prepared for the maneuver, and MESSENGER is right where it needs to be to continue revealing new details about Mercury," he said.

The next orbit-correction maneuver is scheduled for December 5.

http://messenger.jhuapl.edu/news_room/details.php?id=186

[instml]

Highlighted Team Member
Jim McAdams, MESSENGER Mission Design Lead Engineer

Highlighted Team Member: Annette Mirantes
Software Designer's Work Critical to MESSENGER Mission's Continued Success