Спутник ФКИ. Gravity Probe B. [Редактировать]

Gravity Probe B (GP-B) — американская космическая миссия по измерению чрезвычайно слабых эффектов геодезической прецессии гироскопов на орбите вокруг Земли и увлечения инерциальных систем отсчёта вращением Земли, которые предсказывает общая теория относительности Эйнштейна. Разработкой дьюара, контейнера научной аппаратуры и электронного оборудования для GP-B занимался отдел новых технологий компании «Lockheed Martin». Для изготовления самого космического аппарата Стенфордским университетом была выбрана компания «Lockheed Martin Missiles & Space», Саннивейл.
Спутник был запущен 20 апреля 2004 года, сбор данных начат в августе 2004. На орбите спутник отработал в целом 17 месяцев и завершил свою миссию 3 октября 2005 года. Обработка полученных данных велась до мая 2011 года и подтвердила существование и величину эффектов геодезической прецессии и увлечения инерциальных систем отсчёта, хотя и с точностью, несколько меньшей изначально предполагавшейся.
Спутник Gravity Probe B нёс на борту самые точные на тот день гироскопы в мире. Точность измерений положения оси позволяет обнаружить два эффекта, предсказываемые общей теорией относительности:

  • геодезическую прецессию, возникающую вследствие искривления пространства-времени.
  • прецессию за счёт увлечения инерциальной системы координат вблизи вращающегося массивного тела (Земли).

Геодезическая прецессия возникает из-за искривления пространства-времени Землёй. В искривленном пространстве, если обнести вектор по замкнутому контуру, он не возвратится в исходное положение, а изменит направление на некоторый угол (см. параллельное перенесение). В данном случае роль вектора выполняет спин гироскопа, а орбита спутника выступает в качестве замкнутого контура. Для параметров GP-B, по расчётам, суммарный угол отклонения должен равняться 6,6 угловых секунд в год. Отклонение спина должно наблюдаться в плоскости орбиты спутника.
Прецессия второго типа на два порядка слабее и возникает из-за увлечения пространства вращением Земли. Если поместить горизотнально вращающийся гироскоп на полюсе Земли, он начнёт очень медленную прецессию в направлении вращения Земли (против часовой стрелки на северном полюсе). Интересно, что на экваторе должна наблюдаться обратная картина: пространство ближе к Земле увлекается больше, и прецессия должна происходить в другую сторону, по часовой стрелке, если смотреть со стороны северного полюса. Для GP-B прецессия из-за увлечения инерциальной системы отсчёта должна составить примерно 0,014 угловых секунд в год.
Идея эксперимента достаточно проста. Система из четырёх гироскопов жёстко закрепляется на главный телескоп спутника, телескоп наводится на ведущую звезду и поддерживается в строго фиксированном направлении в течение всего полёта. Вначале гироскопы раскручиваются так, чтобы их оси совпадали с осью главного телескопа. После этого микроскопическое смещение осей можно будет измерить с помощью SQUID (сверхпроводящее квантовое интерференционное устройство). Измеренное таким образом смещение осей гироскопов будет только за счёт ожидаемых эффектов — геодезической прецессии и увлечения инерциальной системы координат.
Спутник движется по свободной от сноса орбите. Это означает, что орбита спутника постоянно (с частотой 10 раз в секунду) корректируется по движению центра масс одного из гироскопов, который, как и три остальных, защищён от всех внешних воздействий (атмосфера, магнитное поле Земли, давление солнечного света и т. д.), кроме взаимодействия с гравитационным полем. Координаты спутника регистрируются с помощью системы GPS. Гироскопы вращаются с угловой скоростью около 4000 оборотов в минуту. Они подвешены электростатически на расстоянии долей миллиметра от стенок полости. Чтобы избежать контакта гироскопа со стенками, позиция полости относительно гироскопа корректируется 220 раз в секунду.
Роторы гироскопов GP-B изготовлены настолько совершенными, что можно исключить из рассмотрения вероятность прецессии из-за механических дефектов или электрических сил. Прибор способен зафиксировать смещение осей вплоть до 0,5 миллисекунд угловой дуги в год. Для сравнения, этот угол будет примерно равен углу, под которым виден человеческий волос с расстояния 32 км. Согласно ньютоновской механике, совершенный сферический гироскоп в отсутствие внешних сил не испытывает прецессии, то есть если вначале его ось была направлена на определённую звезду, она будет оставаться в таком положении всегда. В 1960 году доктор Леонард Шифф из Стенфордского университета на основании уравнений Эйнштейна и уравнений движения частицы со спином, выведенных Папапетру (уравнения Папапетру-Диксона (англ.)), вычислил величину прецессии осей гироскопов и предложил произвести эксперимент, либо в лаборатории на Земле, либо в космосе. Из его расчётов следовало, что эффект в лаборатории будет на несколько порядков меньше, поэтому орбитальный эксперимент более предпочтителен.
Основная научная аппаратура спутника:

  • Основные приборы — корпус гироскопа, телескоп и несущие конструкции — изготовлены из кварцевого стекла. Кварц практически не подвержен тепловому расширению в широком диапазоне температур — расширяется и сжимается очень мало и очень однородно. Кварцевые детали были изготовлены компанией Speedring из города Куллман, штат Алабама.
  • Главный телескоп имеет апертуру 14 см и направлен на двойную звезду IM Пегаса (HR 8703).
  • Техники центра Маршалла (Marshall Space Flight Center) создали совершенное полировочное оборудование, позволившее им выточить самые сферические объекты из когда-либо изготовленных человеком — роторы гироскопов спутника. Шероховатость поверхности сфер составляет всего несколько десятков атомных слоёв — если увеличить их до размера Земли, самая высокая гора или самая глубокая впадина будет всего 2,4 метра в высоту.
  • Инженеры в Стенфорде разработали технологию нанесения тонкой (всего несколько нанометров в толщину) сверхпроводящей ниобиевой плёнки на поверхность сферы.
  • Основное измерительное оборудование GP-B помещено в сигарообразную 2,7-метровую криогенную ёмкость, окружённую слоем сверхпроводящей свинцовой фольги для защиты от внешних магнитных полей. Эта ёмкость, в свою очередь, вместе со сверхпроводящей оболочкой, помещена в сосуд Дьюара, в момент запуска содержавший 2441 л жидкого гелия. Для поддержания ниобиевой плёнки в сверхпроводящем состоянии необходимо поддерживать криогенную температуру 1,8 К.
  • Направление оси вращения гироскопа детектируется по магнитному моменту (Лондоновскому моменту), который генерирует вращающийся сверхпроводник. Детекторами поля служат квантовые интерферометры (СКВИДы) с чувствительностью, позволяющей измерять магнитное поле на 10 порядков более слабое, чем поле Земли.
  • Сверхтекучий гелий в сосуде Дьюара спутника служит не только для поддержки криогенной среды, но и как рабочее тело реактивных микродвигателей для манёвров при точной наводке телескопа.
  • Более 400 электрических проводов, а также звёздный свет, который попадает в криогенную среду, нагревают сосуд Дьюара. Из-за этого тепла жидкий гелий потихоньку выкипает. Поэтому специалисты Стенфорда изобрели специальную «пористую пробку», которая отводит выкипевший газообразный гелий из сосуда Дьюара, оставляя только жидкий гелий и поддерживая необходимую криогенную температуру.
  • Газообразный гелий пропускается через несколько внешних охлаждающих слоёв сосуда Дьюара, а затем выбрасывается в космос одним из восьми микродвигателей на борту спутника. На основании данных телескопа и положения гироскопов, выходящий гелий аккуратно дозируется таким образом, чтобы поддерживать один из четырёх гироскопов строго в центре масс всей системы.

Дополнительные наименования

#НаименованияПоиск в новостяхПоиск в документах
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22004-014AНайтиНайти

Дополнительная классификация

#Наименования
1Тип орбиты - НОО
2Страна оператор(владелец) - США
3Страна производитель - США
4Тип оператора(владельца) - государственный

Новостная лента[Найти информацию в новостях] [Найти информацию в документах]

#Новостная лента.
12005-01-21. Получены отказы от быстрых протоновТэги: Gravity Probe B

Технические характеристики

#ХарактеристикаЗначение
1Масса КА, кг3100
2Габариты, метра6.4x6.2
3Мощность, Вт606
4Мощность (платформа), Вт293
5Мощность (полезная нагрузки), Вт313

Характеристики орбиты

#ХарактеристикаЗначение
1Наклонение, градусов90
2Период, минут97.6
3Апоцентр, км645
4Дата окончания работы2010-12-08
5Перицентр, км641

Пусковые характеристики

#ХарактеристикаЗначение
1Космодром База Ванденберг
2Средство выведения 1x*Delta 2 (7920, 7925)
3Дата пуска2004-04-20
4Код NSSDC2004-014A

Экономические характеристики

#ХарактеристикаДата измеренияЗначение
1Разработчик Lockheed Martin
2Прогнозируемая стоимость (разработки), млн. долл.2000-04-01615
3Прогнозируемая стоимость (разработки), млн. долл.2001-04-01631
4Прогнозируемая стоимость (разработки), млн. долл.2002-04-01667
5Прогнозируемая стоимость (разработки), млн. долл.2003-01-01709.3
6Прогнозируемая стоимость (проекта), млн. долл.2003-01-01734.9

Информация об удачном запуске

#ХарактеристикаЗначение
1Дата пуска2004-04-20 at 16:57:26 UTC
2Полезная нагрузка 1xGravity Probe B
3Ракета-носитель 1xДельта 2

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... capabilities of humans in zero-gravity conditions. This informaiton is essential.... Preliminary strength experiments in zero gravity have been accomplished in aircraft... of cryogenic fluids in zero gravity. This technology is critical to... transfer and understanding of low-gravity fluid behavior. Under the orbiter... stations and a lunar base, low-gravity structures for the moon, propellant... designed to detect pertnrhationa i n the gravity field caused by co!!apsir... for precise spacecraft targeting and probe delivery. These objectives continue to... accuracy necessary for the Galileo probe re!else. This missicr, event... known in order that the probe, when released, will follow the... support during solar conjunctions and gravity wave experiments. The DNS facilities..., technology for transatmospheric vehicles, planetary probe research, life sciences, human factors... industrial exploitation of the micro-gravity environment but represents a low-cost...



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...-Venus-Earth-Jupiter Gravity Assist VVVGA . . . . . . . . . .Venus-Venus-Venus Gravity Assist WFC... experiments; e.g., solar U.V., meteoric impacts. (c) Intermediate gravity tracking for other experiments; e.g., cosmic... finish, data on center of gravity, moments of inertia, dynamic balancing... Observatory has not been started. GRAVITY PROBE-B Gravity Probe-B is designed to be a cornerstone... theory, and alternative hypotheses exist. Gravity Probe-B will measure both the distortion... processes, and to understand how gravity affects and has shaped life... mechanisms by which organisms perceive gravity and transmit the information to..., to determine the role of gravity in reproduction, development, maturation, and... interactions between planetary bodies as gravity. 6 By the early seventeenth century... intelli6. Newton’s famous work on gravity and other physical principles is... that a probe launched to Jupiter could leverage that planet’s gravity to boost it to Saturn, where it would receive another “gravity... scientists to create high-resolution gravity and surface maps of over... support itself against the Venusian gravity. Clearly a large amount of the... control and sensing systems in a gravity-free environment poses special problems... as seismic activity (3-axis seismometer), gravity and tilt, magnetic field, temperature... on Minovitch’s work by calculating gravity-propelled trajectories to the outer... method. NASA planned to use gravity-assisted trajectories as the basis... mission and renamed it Voyager. Gravity-assisted trajectories have also been... derived in this fashion, utilizing gravity perturbations from Jupiter, for reduction... the method “gravity propelled interplanetary space travel” or simply “gravity propulsion.” It is popularly known as “gravity-assist trajectories... as how and when the gravity propelled encounter sequence, Earth-Jupiter... the computer code for my gravity propelled trajectory program, or a description...–109. 5. Minovitch, M. A., “The Invention Of Gravity Propelled Interplanetary Space Travel: A Technical... Propulsion Laboratory,” Oct. 1997. 6. Reichhardt, T., “Gravity’s Overdrive,” Air and Space Smithsonian..., R. L., et al., “The Origin of Gravity-Propelled Interplanetary Space Travel,” 41st.... 90–630. 8. Dowling, R. L. et al., “Gravity Propulsion Research at UCLA and...: (1) the planetary magnetic field, (2) Uranus’ gravity field, [J2] and satellite masses... local relief, elevations, and slopes. Gravity data are required for geophysical..., the baseline mission now includes a gravity assist from Mars. This will... resources mapping mission and a lunar gravity-topography mission, both of which... a 6.7-year Venus-Venus-Earth-Jupiter-Gravity-Assist (VVEJGA) trajectory to Saturn... an 8.8-year Venus-Earth-Earth-Gravity-Assist (VEEGA) trajectory and a backup... a 10.3year Venus-Venus-Venus-Gravity-Assist (VVVGA) trajectory to Saturn... mission to Saturn requires planetary gravity-assist trajectories; and (3) the spacecraft... launch phases and the Earth-Gravity-Assist trajectories) from the primary... and before the final planetary gravity-assist, the spacecraft could eventually... employ a Venus-Venus-Earth-Jupiter-Gravity-Assist (VVEJGA) trajectory to Saturn... 2001 using a Venus-Venus-Venus-Gravity-Assist (VVVGA) trajectory. A backup opportunity... lower risks for the Earth gravity assist (EGA) swingby segment. Both... 2), late launch (Phases 3-8) and Earth Gravity Assist (EGA). The pre-launch.... There are other theories of gravity that agree with Einstein’s within... prediction more accurately led to Gravity Probe A, the first space experiment specifically..., William Fairbanks in 1964 proposed Gravity Probe B (GP-B). Although work was started... the first time. To detect gravity waves longer than those observable... be estimated. Since the surface gravity and resulting pressure decrease together... the influences of wind and gravity or from a balloon. Balloons fly... of external torques due to gravity gradients, magnetic fields, and air.... With access to the reduced gravity environment of space, scientists might... experiments, called Gravity Probes, with which NASA became involved. While Gravity Probe A flew on a sounding rocket in 1976, Gravity Probe C, proposed by the European Space Research Organization, was ultimately cancelled. Gravity Probe... the attached summary document for Gravity Probes that was prepared for... operation in zero gravity, dewar-gyroscope operation in zero gravity, and optical... Very Large Space Telescope (VLST), gravity wave experiments using laser interferometry... is the investigation of relativistic gravity effects to test gravitational theories... gravitational effects in the strong gravity field close to the Sun.... Edmund Nowinski Prof. Bradford Parkinson Gravity Probe B Hansen Experimental Physics Laboratories Stanford... cosmic rays • Measure how strong gravity operates near black holes and..., 612, 618, 621, 624 Earth Gravity Assist, EGA, 486 Earth Observing...



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...». 16 WMAP — Wilkison Microwave Anisotropy Probe; COBE — Cosmic Background Explorer. 17... orbiter) и спускаемого зонда Гюйгенс (Huygens probe), предназначенного для посадки на Титан... замечательным спутниковыми экспериментами являются спутники Gravity Probe А и Gravity Probe B, специально сконструированные для проверки ОТО... потенциал, отклонение описывается параметром µ. Данные Gravity Probe А ∆ 39 Эффект известен как «эффект... данными GPS. По данным спутника Gravity Probe B уже удалось подтвердить эффект де.... Seven-year Wilkison Microvawe Anisotropy Probe (WMAP1) Observations : Cosmological Interpretation // Astrophys.... Nine-year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results... C. M. Theoretical frameworks for testing relativistic gravity. 1. Foundations // Astrophys. J. 1971. Vol. 163... C. M. Theoretical frameworks for testing relativistic gravity. 2. Parametrized Post-Newtonian hydrodynamics, and... System — A Rare Laboratory for Relativistic Gravity and Plasma Physics // Science. 2004.... Bell J. F. A Tighter constraint on postNewtonian gravity using millisecond pulsars // Astrophys. J. 1996... S., De Laurentis M. Extended Theories of Gravity // Phys.Rept. 2011. Vol. 509... S., de Laurentis M. Extended Theories of Gravity // Phys. Rept. 2011. Vol. 509.... P. 023524. 116. Chiba T. 1/R gravity and scalar-tensor gravity // Phys. Lett. B. 2003. Vol... for the R + R2 theories of gravity without torsion // J. Math. Phys. 1983.... P. 2793–2799. 119. Wands D. Extended gravity theories and the EinsteinHilbert action...–280. 120. Whitt B. Fourth-order gravity as general relativity plus matter... of fourth order gravity inspired by scalar-tensor gravity // Phys. Rev. D. 2005... effective cosmological constant in extended gravity theories // Gen. Relativ. Grav. 1998.... Gottlober S., Schmidt H.-J., Starobinsky A. A. Sixth Order Gravity And Conformal Transformations // Class. Quantum... of fourth and higher order gravity // Astron. Nachr. 1991. Vol. 312.... 132. Babak S. V., Grishchuk L.P. Finite range gravity and its role in gravitational.... P. 201102. 134. Rovelli C. Loop Quantum Gravity // Living Reviews in Relativity. 2008... L. An Invitation to loop quantum gravity // Rev. Mod. Phys. 2004. P. 655... J. Black holes in loop quantum gravity // J. of Phys. Conf. Ser. 2009... L. Falsifiable predictions from semiclassical quantum gravity // Nuclear Physics B. 2006. Vol. 742.... Nozari K., Davood Sadatian S. Loop Quantum Gravity Modification of the Compton Effect... hole entropy from loop quantum gravity // Phys. Rev. Lett. 1996. Vol...



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... only through the pull of gravity? INTRODUCTION 5 Could there be particles... force? Perhaps their portraits of gravity, like unfinished masterpieces, require extra... together through the force of gravity. Examining the Coma Cluster (in... signs its name only with gravity’s mark? Early on, scientists supposed... charging full speed ahead. Ordinary gravity cannot account for such acceleration... demonstrated that the strength of gravity varies in inverse proportion to... going in a straight line, but gravity continuously pulls it toward Earth... an essentially circular path. Though gravity is a force, inertia is not... two critical omissions: acceleration and gravity. An avid reader of Mach... same rate? Clearly, he surmised, gravity’s pull cannot just depend on... fashion to his earlier theory, gravity came to Einstein’s attention in... terrestrial gravity, for example; a piece near Jupiter would describe Jovian gravity. All... from other possible theories of gravity. Determining that the Sun’s gravitational... description of the workings of gravity. Nevertheless, many theorists take issue... known as quantum chromodynamics. Yet gravity, the fourth force, remains the... items, but not so for gravity. Gravity, considered on its most miniscule... the correct pathway to quantum gravity. Such theories predict that for... to measurably different results. Thus, gravity would have two different faces... first instants of the universe, gravity could scarcely be distinguished from... another. In those turbulent moments, gravity and the other forces could... centers of collapsed stars, where gravity wears titan’s boots, the conventional... different jobs? General relativity describes gravity as a geometric effect in four... at the same rate under gravity. Refining Eötvös’s concept even further.... An orbiting satellite called GP-B (Gravity Probe B) is currently engaged in a far... him with compelling accounts of gravity’s actions in the universe. “My... experts in highprecision measurements of gravity. The capstone of Weiss’s career... symmetry, or sameness. Then, somehow gravity separated from the other three... inflation (where a field interacts with gravity, causing it to eventually put... constant term. The attraction of gravity overpowered the repulsion of lambda... for the outermost orbits, where gravity tugs weakly. For example, distant.... What are their secret identities? GRAVITY’S LENS One prominent category of.... Using the Einsteinian result that gravity bends light, he developed the... could unite other interactions with gravity into a single model. Meanwhile, Wess... through Earth. Only extremely sensitive gravity wave detectors, well beyond current... and garden variety materials; only gravity could provide a connection. Thus, a particle...” that enables spacecraft to overcome gravity and effortlessly lift off from... (including Randall-Sundrum) postulate that gravity takes a different form on various..., which would naturally explain why gravity seems strictly attractive on the... from the standard law of gravity. Nevertheless, theorists have pressed on... of repulsive force. Over time, gravity would increasingly cower before its... Newton’s inverse-square law of gravity. It too contains a seemingly enduring... ticked, gravity would become slightly weaker. Consequently, by 1040 ticks, gravity would... supporters over the decades. CHANGING GRAVITY Spurred by Dirac’s curious notion... relativity. Another model of changing gravity was developed several years later... dark-energy conundrum. A diminution in gravity’s strength would offer a natural way... Chandrasekhar limiting mass, depend on gravity’s strength. Subsequently, if G varies, the... spin, are sensitive measures of gravity’s strength. Hence, geophysics provides us... a prize-winning essay in the Gravity Research Foundation competition. ATLAS UNBOUND... According to these arguments, if gravity’s strength has decreased with time... test of theories of changing gravity has been whether geophysical evidence.... Kaluza’s theory thus showed how gravity and electromagnetism as four-dimensional... dimensions were required to merge gravity with the other interactions. This... field theory. Attempts to quantize gravity in a similar manner to electromagnetism... this situation by proposing that gravity, at ultrahigh energies, forms part... brane designed to replicate precisely gravity’s distinctive behavior. BRANE BENDERS In... the long-established law of gravity. Such a minute difference could be.... Given the essential relationship between gravity and mass, one might presume... of gravity as a force. Even after Einstein informed us that gravity is... would generate regions of strong gravity. These would serve as spawning... dimensions, Smolin delving into quantum gravity, Linde speaking about inflation, and... arranged by Francis Everitt at Gravity Probe B, at Stanford. His views were... Classical Tests in Kaluza-Klein Gravity,” Astrophysical Journal, vol. 439, p. 548... and Constraints on Higher-Dimensional Gravity,” Physical Review D, vol. 62, p. 102001... Gravity Probe B (GP-B) satellite, 64, 65, 66, 67–68 Gravity Research Foundation, 158 Gravity...



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..., by the NASA-DLR (Germany) Gravity Recovery and Climate Experiment (GRACE... be committed to the Lisa gravity-wave detector, which depends heavily... carry 16 instruments. Using lunar gravity-assist swingbys, they were subsequently... arm’s performance at Earth-normal gravity. Following the flight the teachers... One aircraft operated by Zero Gravity Corporation (USA) from airstrips in..., San Diego, and Washington. Zero Gravity Corporation also conducted five workshops... and for ionosphere, climate and gravity research. Data from the satellites....” J. L. Chen et al. 2006 ‘Satellite Gravity Measurements Confirm Accelerated Melting of... 2006): “Using timevariable gravity measurements from the Gravity Recovery and Climate Experiment..., terrain camera, radar sounder), for gravity studies (VLBI and data relay... orbit in 2009, after multiple gravity assists, to undertake global mapping... combination of electric propulsion and gravity assists, the planned cruise duration... Jupiter in early 2007 for a gravity assist and for scientific studies... variation, albedo, spectrum, mineral composition, gravity, and its main chemical composition... that the cratering process was gravity-dominated, supporting the notion that... to reach the cometary target, gravity assists (accompanied by science studies... study of the magnetic and gravity fields with unprecedented precision, and.... Small-Scale Waves. Small-scale gravity waves play a critical role in... the middle atmosphere. Accurately parameterizing gravity waves in global circulation models... in gravity wave studies include the construction of a climatology of gravity wave... a French and Australian collaborative project, gravity-wave parameters are being extracted... in the mesopause region, and gravity wave activity. The Arecibo Observatory... studies of the evolution of gravity waves, from their excitation level... programme was designed to study gravity wave dynamics and forcing of... revealed considerably greater variability in gravity wave, and in larger-scale... images showing the effects of gravity wave activity and PMC particle... filtering of gravity waves by allowing more eastward-flowing gravity waves to... significantly by changes in gravity wave filtering and gravity wave forcing around... from the variability of the gravity wave sources, planetary waves and...-generated gravity waves are parameterized while a spectrum of non-stationary gravity waves... suppresses the breaking of parameterized gravity waves above about 100 km... by the parameterized non-orographic gravity wave drag. A similar mechanism appears... MLT region without a gravity wave parameterization, but resolved gravity waves in the... with MM5 simulations. In addition, gravity wave instabilities were studied both... and Space Biology focuses on gravity perception, genetic and physiological modifications... response to microgravity or simulated gravity. Genetic studies are typically paired... to understand the effect of gravity on development, generative and vegetative... gravitational loads. The study of gravity perception mechanism and of related... responses and intricate patterns of gravity-dependent processes. Because of the... space exploration. The European Low Gravity Research Association (ELGRA), which is... the way in which reduced gravity affects many physiological systems, including... these systems adapt to a different gravity environment. For instance, even after... when the crew reenters a higher gravity environment, as found on the... of materials. In microgravity, these gravity-driven phenomena are significantly suppressed... be carried out in a ‘zero’ gravity environment, extremely long path lengths... circumstances include the study of gravity and gravitational waves, tests of... launch and successful operation of Gravity Probe B on 20 April 2004. The... fields of geopotential modelling (Earth’s gravity and magnetic fields), oceanography (altimeter... of dynamic models, the Earth’s gravity field in particular. The continuous... (dynamic, reduced-dynamic, kinematic) and gravity field determination (global, local). Significant... modelling the Earth’s (pseudo-static) gravity field with unprecedented precision and... making use of space-borne gravity gradiometry, based on an instrument... Mars orbiters and in conjunction gravity field modelling of these celestial... gravity field models and even to observe temporal variations of Mars’s gravity... first time, the global lunar gravity -193- field (including the far..., the description of shorter-scale gravity waves above Antarctica, and the... geophysical data (e.g. atmospheric, ionospheric, geomagnetic, gravity) through the establishment of a series... Pluto and Charon, with a Jupiter gravity assist (and Jupiter observations) planned... Incoherent Scatter Radar European Low Gravity Research Association Environment Satellite Earth... and Spectroscopic Explorer (NASA) Earth gravity Global Astrometric Interferometer for Astrophysics... (Russia) Global Navigation Satellite System Gravity field and Ocean Circulation Explorer... of Stars Gravity Probe B Global Plasmasphere Ionosphere Density Global Positioning System Gravity Recovery...



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... dance to the tune of gravity, slowly drawing each other in... holes send out ripples of gravity detectable only to the most... at the ultimate limits of gravity and energy? The telescopes in... explore the essence of time, gravity, matter and energy in the... the most extreme conditions of gravity, temperature and magnetic fields that... matter around it with its gravity. Hot gas falling under the... map the global history and probe the causes of star formation...://einstein.stanford.edu/ Gravity Probe B Kit Item Informational brochure Mission Gravity Probe B is a relativity... the heart of Gravity Probe B are questions about spacetime and gravity - questions that... to previously-formed notions of gravity. To this end, we are... structure of the Universe itself. Gravity Probe B will be making the most....gsfc.nasa.gov/ Microwave Anisotropy Probe Kit Items Fact sheet and... the most extreme conditions of gravity, temperature, and magnetic fields. RXTE... to use them as a unique probe into our Universe and into...



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... recent NASA data from the Gravity Recovery and Climate productivity, and... the past 20 years. The Gravity Ontario, Canada, and John Rundle... first confirmation that time variable gravity radar measurements, to re-analyze... without the obscuring effects of gravity. It is the only facility... scientific issues in the low gravity environment of space that enrich... evolved in response to Earth’s gravity and protective environment. But what... answers to the respond to gravity and space following critical questions... study how organisms respond to gravity at the molecular, cellular, developmental... simulators and ISS to determine gravity responses for at least five... and resources. In the a variable gravity centrifuge that will be used... hardware that is already Martian gravity. The first of these experiments... of space. WHY PURSUE OBJECTIVE 4.2? Gravity affects everything humans do on... occurring around the globe. But gravity also blinds humans to a realm... paint or milk—in a low gravity environment. NASA’S PROGRESS AND ACHIEVEMENTS... and began Wilkinson Microwave Anisotropy Probe and the Sloan Digital Sky... to the attractive force of gravity generated by the universe’s mass... universe. NASA missions will also probe to the beginning of time... from the Wilkinson Microwave Anisotropy Probe indicating that these clusters have... impact on using clusters as a probe microwave background. NASA also selected... of the Wilkinson Microwave Anisotropy Probe mission at the L2 Lagrange... by the Wilkinson Microwave Anisotropy Probe team toward constructing the first... 5.11? The greatest extremes of gravity in the universe today exist.... Matter captured by their strong gravity falls inward, accelerating to speeds... elsewhere. shredded by the intense gravity fields, heats up dramatically and... to home, NASA is using Gravity Probe B, launched in April 2004, to...’s theory of space and time. Gravity Probe-B is a polar-orbiting satellite that... 5.11.2: Test Einstein’s theory of gravity and map space-time near... continued testing Einstein’s theory of gravity and mapping space-time near... of black holes by launching Gravity Probe B, confirming Einstein’s principle of the... black hole. Figure 105: The Gravity Probe B spacecraft launches from Vandenberg Air.... NASA researchers used X-ray launched Gravity Probe B on April 20, 2004. Over... Chandra to provide direct evidence probe will test two predictions of... collapse by the force of gravity to form galaxies and clusters... now know this matter, and gravity shapes galaxies and systems of... any mission outside of Earth’s gravity. Without it, the Space Shuttle... science missions including Aqua, Aura, Gravity Probe-B, Launch Vehicle manifest. The the... rely on this same exceptional ■ Gravity Probe B, successfully level of space communications..., researchers have sought to understand gravity in the physical universe and... human physiological reactions to reduced gravity and develop countermeasures to assure... understanding of the role of gravity Gap” experiment on a Progress in... safety and security in low-gravity environments. This includes enhancing life... systems and solutions to low gravity technological challenges to allow the... water, is strongly affected by gravity. In this picture air–water... same flow rates under different gravity levels. NASA researchers must study... systems for low- and fractional gravity with an efficiency in the... of the effects of variable gravity and radiation on humans and...



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... • Explore the ultimate limits of gravity and energy in the universe... System and Earth within it • Probe the origin and evolution of... Explore the ultimate limits of gravity and energy in the universe... and determine the role of gravity in this process • Establish how... how the Solar System evolves Probe the origin and evolution of... 1998, has successfully completed three gravity assist maneuvers, two at Venus... at Earth. A fourth and final gravity assist maneuver at Jupiter in... few years. The Microwave Anisotropy Probe (MAP) Explorer will measure fluctuations... explosions will allow us to probe the intervening infrared background light... composition of these nuclei to probe the diversity of comets. Deep... districts nationwide. The Solar Terrestrial Probe (STP) program is a line of... Big Bang. The Microwave Anisotropy Probe (MAP) Explorer and the ESA... wide-angle light collector could probe the Big Bang itself. Beyond...; Explore the ultimate limits of gravity and energy in the universe...: Explore the ultimate limits of gravity and energy in the universe... the limit of very strong gravity fields. For Possible Implementation After... processes in the universe and a probe of the Big Bang within... of new stellar clusters and probe the structure and basic physical... keen infrared vision, it would probe deeper into protostellar disks and... Sun’s solar wind. An interstellar probe mission would explore the structure... antenna pointed at ESA’s Huygens probe as it reaches the surface... the Discovery program. OBJECTIVE SIX: Probe the origin and evolution of... Saturn in 2004. Its Huygens probe (provided by the European Space... advanced spacecraft. The Solar Terrestrial Probe (STP) program is a line of..., inside its outer atmosphere, Solar Probe will endure extreme conditions to... variations in solar input. Solar Probe will be our first voyage...-environment of our Sun. Solar Probe will make a close flyby of... in a reasonable time. An interstellar probe, traveling more than 30 billion...-term future. Future Solar Terrestrial Probe missions and Sun-Earth connec... Outer Planets Mission Lines Interstellar Probe Astrobiology Initiative To Build a Planet... the universe, the role of gravity in living systems, and Earth... will study the nature of gravity itself within the fossil remnant... Explore the ultimate limits of gravity and energy in the universe... and determine the role of gravity in this process Reveal the... 2003–2007 TPF ■ ❑ SIM ❑ Solar Probe ❑ MMS ❑ GEC Section A-1 Understand the... Entering Implementation 2003–2007 ■ ❑ Solar Probe ❑ ■ MMS ❑ ■ GEC ❑ ■ MagCon NEO ❑ ❑ ■ ❑ ■ SDO... Life finder Planet imager Interstellar probe Energetic x-ray imaging survey telescope... fate ■ ■ ■ ■ ■ Explore the limits of gravity and energy in the universe... (For Possible Implementation After 2007) ■ ■ Probe the origin and evolution of... supporting 27 different investigations to probe the mysteries of the Saturn... orbiter and ESA’s Huygens Titan probe. Chandra X-ray Observatory (CXO)—High.... Cosmic Journeys—Proposed initiative to probe the most profound aspects of... to these extreme states of gravity. The Journey to Dark Matter...



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... THE SOLAR SYSTEM . . . . . 59 Earth’s Gravity Well (61) The Exploration of... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 Earth Spaceport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 Variable Gravity Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 Tethers in Space... pacing problems that depend on gravity. Particularly needed are long-duration... one-sixth gravity of the Moon, and the one-third gravity of... from radiation, and probably some gravity. Technological advances will permit all... with little energy, and artificial gravity can be provided by rotation... at less than Earth-normal gravity, requires more knowledge and the..., and • Space tethers and artificial gravity These base technology and demonstration...? • What is the importance of gravity in physical, chemical, and biological... satellite. (Courtesy M. Chahine and J. Susskind) Gravity field of the world’s oceans... gravity from less than a hundred-thousandth to greater than one Earth gravity by using centrifugal force in a rotating system or by a gravity... a weakened skeletal structure to increased gravity when, for example, humans emerge... than in the past, including gravity, radiation exposure, environmental toxicology, nutrition... space and in controlled artificial gravity at levels between zero and... billions of years under Earth-gravity conditions. Studying its response in... both plants and animals to gravity. 35 Physics, Chemistry, and Biology... accurate results than desired. Reducing gravity by a factor of 100,000... and quantify the effects of gravity on the development, adaptation, and... ground-based research in normal gravity; and new tests of general... experiment in Earth orbit called Gravity Probe B will measure the precession of... of energy. INNER SOLAR SYSTEM GRAVITY WELLS 62 Astronaut Gene Cernan... “cycler” they will experience a rotational gravity somewhere between that of Earth... elements, the energy of sunlight, gravity, and protection from radiation. All... on planetary surfaces, although normal gravity is available only on Earth... space environment, where Earth-normal gravity can be provided by rotation... material requirements: air, water, food, gravity, and protection from cosmic and... inner Solar System. In space, gravity’s equivalent can be provided by...” questions of air, water, food, gravity, and protection from radiation. For...: Normal intensities of sunshine and gravity, a normal day/night cycle, the... heavier than the other and gravity causes separation into two layers..., however, because the effects of gravity are reduced there a millionfold. Controlled... to develop artificial gravity technology, including centrifuge, tether, and gravity-gradient techniques... rotate about a common center of gravity. Such tethers have myriad potential... maintaining propellant tanks at partial gravity for safe storage and ready... a spaceport in low orbit, a variable gravity, research facility, and spaceports in... between Worlds before 2010. Variable Gravity Research As previously noted, early... for humans experiencing Earth-normal gravity simulated by rotation? (See page... questions must be answered. What gravity level is needed to present... return from low g to Earth gravity? Experiments to settle these questions.... In the background is a Variable Gravity (g) Research Facility that will be... of bodies moving through central gravity and magnetic fields. They can... transportation. The generation of artificial gravity via tethers offers another class... together will experience an artificial gravity proportional to their distance from... hundreds of miles, allowing controlled gravity fields up to about 0.2g.... [more...] For this work a variable gravity research facility is required. In... on the effects of low gravity in many scientific disciplines. Thus... structure, and can alter synthetic gravity by varying spin rate via... exposure to less than Earth’s gravity must be fully understood. In... periods of time in low-gravity environments. NASA’s experience suggests that... required 45 days of Earth gravity before muscle coordination allowed them... one-sixth gravity of the Moon, or the one-third gravity of... a variable gravity research facility, the rotation rate and the gravity level will... subsystems. This facility must establish gravity level requirements in time to... which the Gravity of the Earth is Cancelled by the Gravity of... earlier structure, will have artificial gravity. In the case of Mars... all be provided with artificial gravity. Spaceship mass can be reduced... required are: • Earth Spaceport • Variable-Gravity Research Facility; and • Lunar Surface... by NASA. 148 The Variable-Gravity, Research Facility is required within... to understand the required artificial gravity levels necessary for long-duration... simulate various levels of artificial gravity. They should be accessible to...: An extremely low level of gravity. As experienced by shuttle crews..., one millionth the level of gravity on Earth’s surface. Orbital Maneuvering...



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... drag-free missions: Gravity Probe B (GPB) [7], and the Gravity Field and Steady-State..., and (c) demonstrate Precise Orbit and Gravity Determination (POGD) capability at the... such as electromagnetic and self-gravity gradients. Consequently, the contributions of... in 2a 2b and 5a Gravity Aspherical harmonic expansion model for... from the Sun and Moon Gravity gradient disturbance torque fgs , fgp... ms−2 Hz up to 5 Hz. 6 5.1. 5.1.1. Gravity Central Body The aspherical gravitational...] up to degree four. The gravity gradient torque on the satellite... with the Newtonian two-body gravity model [27]: 3µ⊕ rs × Irs . (7) Mgg... in the yaw axis. The gravity gradient torque was essentially negligible... , Kgg|eq is the self-gravity gradient at req , and K is... properties to minimize the self-gravity gradient at a given point. Guided...−10 ; 0; 0] ms−2 , and the self-gravity gradient Kgg|eq was computed... and δfd are the differential gravity and direct perturbation disturbances respectively... a first order approximation to the gravity gradient disturbance torque in (7), the... of the satellite and the gravity gradient calculations. Finally, in order... Space Interferometers.” Classical and Quantum Gravity, Vol. 22, No. 10, p. S287..., G., Silbergleit, A., Holmes, T., Kolodziejczak, J., et al. “Gravity Probe B: Final Results of a Space Experiment... Silvestrin, P. “The Measurement of Earth’s Gravity Field after the GOCE Mission... Small, H. “On-orbit Performance of Gravity Probe B Drag-Free Translation Control and.... “LISA Pathfinder.” Classical and Quantum Gravity, Vol. 25, No. 11, p. 114034..., C. “On-orbit Performance of the Gravity Probe B Drag-Free Translation Control System... System Implications.” Classical and Quantum Gravity, Vol. 22, No. 10, p. S139...