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
128230НайтиНайти
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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....ru/science/trudy/ Interstellar Heliopause Probe H.W. Loeb, K.-H. Schartner, B. Dachwald, A. Ohndorf, W. Seboldt... C3 = 45.1 km2/s2 a heliocentric probe velocity of 10 AU/yr... this distance, provided a close Jupiter gravity assist adds a velocity increment of...; solar electric propulsion; interstellar heliopause probe; mission strategy; radioisotope-electric propulsion... the Interstellar Heliopause Probe (IHP) or the Deep Space Gravity Probe (DSGP). Both... with near-Sun or multiple gravity assists, is unable to perform... reasonable to equip the scientific probe with ion thrusters that start... (C3>0) and single or multiple gravity assists [3]. Such a ballistic/REP combination... The design of our IHP-probe follows more or less other... scan the entire space, the probe will rotate with about 3 RPM... to reduce disturbances by the probe body (right part of Figure... REP-Stage and IHP Probe (Left), IHP-Probe with REP-Stage (Right... BOM, consisting of the IHP probe and the two propulsion stages... between SEP-stage and scientific probe. Note that once the SEP... and thus, accelerating the IHP probe continuously except during 4 phases of... the RTGs supply both the probe and the REP-stage, they... regarded as part of the probe spacecraft. Including the propellant mass... value and due to a Jupiter gravity assist 5 The strategy found by... as well as including a Jupiter gravity assist (JGA), we have chosen... results show that even without a gravity assist, flight times of less... [1] Mewaldt, R.A and Liewer, P.C., “An Insterstellar Probe Mission to the Boundary of... Nearby Interstellar Space”, Report Interstellar Probe Science and Technology Definition Team... Overview of the Interstellar Heliopause Probe”, ESA Techn. Reference Study, SCI...



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... 3.8 Conclusion................................................................................................................................. 79 4. Gravity Acceleration Approximation Method............................................................................ 81 4.1 JGM Earth Gravity Model Overview ....................................................................................... 81 4.1.1 Geopotential Spherical Harmonic Expression.................................................................. 81 4.1.2 Gravity Acceleration and Partials..................................................................................... 83 4.2 A Study of JGM-3 Gravity Acceleration Variation .................................................................. 83 4.2.1 JGM-3 Gravity Acceleration Variation with Respect to (r , λ ,ϕ ) .................................. 84 4.2.2 Polynomial Approximation of Radial Gravity Acceleration Components ....................... 86 4.2.3 3D Gravity Acceleration Interpolation ............................................................................. 90... a Sphere at a Common Height........................................ 95 4.5.2 Gravity Grid ..................................................................................................................... 98 4.5.3 Experiment Result ............................................................................................................ 99............................................................................................................. 101 4.6.2 Orbit Integration Using the Gravity Acceleration Approximation Method.................... 102 4.7 Computional... 2002) ................. 56 Figure 3.7 Comparison of gravity acceleration accuracy using different degree... memory usage comparison. ................................................... 78 2 Figure 4.1 Gravity acceleration variations ( m / s ) with fixed longitude... 7070km to 7090km............................................................................................... 84 2 Figure 4.2 Gravity acceleration variations ( m / s ) with fixed height... 0 to 360 degrees. .................................................................................................. 85 2 Figure 4.3 Gravity acceleration variations ( m / s ) with fixed height... the radial gravity acceleration ( m / s ) against different orders. ............................................................................................................................................ 88 Figure 4.6 Radial gravity acceleration... a common height. ..................................................... 97 Figure 4.10 Gravity acceleration interpolation accuracy compared with... orbit integration using different JGM-3 gravity model truncations. .................................................................................................. 68 Table 3.4 Comparison... model. ................................................................. 77 o o Table 4.1 Height direction gravity acceleration Legendre polynomial fitting results... orientation parametres EPS Satellite Earth-Probe-Sun system FEDSAT Australian Federal... to calculate the Earth gravity acceleration. An Earth gravity acceleration approximation method... Estimation Software development Techniques Simplifications: • Gravity model approximation • Lunar and solar.... Gravity data DE405 Data Celestial Table Calculation Polar motion Data Gravity Acceleration... gravity model, pre-selecting a significant subset of coefficients, and tuning a truncated gravity... onboard orbit determination. 4.1 JGM Earth Gravity Model Overview 4.1.1 Geopotential Spherical Harmonic... Earth gravity filed determination. As a result, the final pre-launch T/P gravity model... expressed as: ⎡ ⎛ ∂U s ⎞⎤ ∂r ′(r , λ , φ ) ∂&r& ∂ ⎜⎜ ⎟⎟⎥ = Θ Tt ⎢ Θt ∂r ⎣ ∂r ′(r , λ , φ ) ⎝ ∂r ′( x, y, z ) ⎠⎦ ∂r ′( x, y, z ) (4.4) 4.2 A Study of Gravity Acceleration Variation with JGM-3 Model... gravity acceleration variation with respect to (r , λ , ϕ ) has been investigated. 4.2.1 JGM-3 Gravity Acceleration.... Figure 4.1 illustrates the variation. Figure 4.1 Gravity acceleration variations ( m / s 2 ) with fixed longitude... with different latitude. 85 Figure 4.3 Gravity acceleration variations ( m / s 2 ) with fixed height... and memory. 4.2.3 3D Gravity Acceleration Interpolation The Earth gravity acceleration recovery result... of Pseudo-centres 4.3.1 Introduction Examining gravity acceleration approximation functions is motivated... truncated 30 × 30 gravity model with the proposed gravity acceleration method. A 6th... using a 30 × 30 gravity model and the gravity approximation method, with the... × 70 gravity model, with 30 × 30 gravity model and the gravity approximation method... force modelling Earth Gravity Model Third body gravity Planet ephemerides Solar pressure...



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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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NATIONAL AERONAUTICS AND SPACE ADMINISTRATION Gravity Probe B Experiment “Testing Einstein’s Universe” Press... GENERAL RELEASE & MEDIA SERVICES INFORMATION .............................5 GRAVITY PROBE B IN A NUTSHELL ................................................................9 GENERAL RELATIVITY — A BRIEF... (400 miles) above Earth, the Gravity Probe B spacecraft will circle the globe... the general theory of relativity, Gravity Probe B will monitor any drift in... II. More information about the Gravity Probe B mission is available at: http... will be available from the Gravity Probe B Public Affairs Office at Stanford... Briefings & Launch The launch of Gravity Probe B from Vandenberg AFB, California, is....edu. In addition, there is a Gravity Probe B section on NASA’s Marshall Space.../index.htm. 8- Gravity Probe B in a Nutshell Brief Summary of the Gravity Probe B Relativity Experiment... force. The experiment aboard the Gravity Probe-B spacecraft is designed to measure... quantify these minuscule relativistic effects. Gravity Probe-B’s measurement of the geodetic effect... directly been measured before, but Gravity Probe-B is expected to determine its... order to carry out the Gravity Probe B experiment. The spherical gyroscopes have... lifespan, spin offs from the Gravity Probe B program have yielded many technological..., but perhaps most important, the Gravity Probe B program has had a profound effect... way to think about gravity. If the Gravity Probe-B experiment corroborates the two... of matter. Whatever the result, Gravity Probe B will provide us another glimpse... studies 1973 Gyroscope experiment becomes "Gravity Probe B" 1973 J.R. Nikirk designs gyro electrical... Pound-Rebka Experiment and NASA’s Gravity Probe A. In 1960, physicists Robert Pound... the redshift was conducted by Gravity Probe A in 1976, a rocket-based experiment.... Will Gravity Probe B Verify or Refute Einstein? Will the results of Gravity Probe B verify... the motion of matter. Will Gravity Probe B Reveal Where “Inertia” Comes From... creates the property of inertia. Gravity Probe B’s investigation of frame-dragging will.... This is the mission of Gravity Probe B: to experimentally measure our local... ever before. The Mechanics of Gravity Probe B The Gravity Probe B experimental design is as...-dragging effect. In other words, Gravity Probe B intends to use gyroscopes and... arcseconds, or 21.6 million milliarcseconds. Gravity Probe B must be able to measure... Space Vehicle All of the Gravity Probe B technologies are integrated into one... specifically for use in the Gravity Probe B mission. Inside the Dewar A Dewar... being readied for launch. The Gravity Probe B Space Vehicle 32- Science Instrument... vacuum chamber inside the probe and Dewar. Before Gravity Probe B was completely integrated... which a satellite is pointing. The Gravity Probe B satellite contains two star trackers... with the guide star. The Gravity Probe B on-board telescope basically performs... Overview The purpose of the Gravity Probe B Relativity Mission satellite is to... from the Gravity Probe B Mission Operations Center (MOC), located in the Gravity Probe B building... 75 minutes after launch, the Gravity Probe B Space Vehicle will separate from... and early orbit mission phase. Gravity Probe B — Launch & Early Orbit Nominal Timeline... timeline of the IOC activities. Gravity Probe B — Nominal Timeline of IOC Activities... L+22 Days) Spinning up the Gravity Probe B gyroscopes is a delicate and complex... Einstein’s theory of general relativity, Gravity Probe B must measure two minuscule angles...’s. The GP-B Science Instrument The Gravity Probe B science instrument takes the shape... and 40.9 milliarcseconds per year— Gravity Probe B needed to build a near-perfect... interfering supports. Spinning Superconductivity Each Gravity Probe B gyroscope is nearly perfectly spherical... metal. Here was the “marker” Gravity Probe B needed. GP-B scientists coated each... axis of the magnetic field, Gravity Probe B knows precisely which direction the... one readout scheme perfect for Gravity Probe B: extremely sensitive, extremely stable, applicable... the greatest technical challenges for Gravity Probe B is to keep its science... Department as an offshoot of Gravity Probe B research. Drag-free technology is... quasars separately, so that the Gravity Probe B gyroscope measurements can be related... determined with high accuracy for Gravity Probe B to be successful. IM Pegasi...” that obscures it. For the Gravity Probe-B experiments, however, that choice was... the precision of the instruments. Gravity Probe B’s four gyroscopes, housings, and telescopes...+ year lifespan, spinoffs from the Gravity Probe B program have yielded many technological... for Commercial Use Spinoffs from Gravity Probe B aren’t limited to aerospace applications... optical systems. Photo-diode Detectors Gravity Probe B engineers created a revolutionary detector mount..., but perhaps most important, the Gravity Probe B program has had a profound effect... minds. As of October, 2003, Gravity Probe B had produced 78 doctoral dissertations...



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... to depletion and ended the probe’s 12-year, two-mission journey... Heavy launch vehicle. The two Gravity Recovery And Interior Laboratory (GRAIL... into orbit by the moon’s gravity on New Year’s Eve 2011... near side of the moon gravity by 100 times and the... scientific instruments on the F L IG H T probe. The Galileo radioisotope thermoelectric generator... the Sun. Launched in 2004, Gravity Probe B (GP-B) gathered data during its... flight probe – were built at the ATC. Inside the flight probe was...



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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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... Operatl Environ Satellite B use GOES 2 Gravity Probe B HEAO B X-258Y- use HEAO 2 Helios... gravitropism gravity use gravitation artificial gravity center of gravity low gravity use microgravity reduced gravity use microgravity specific gravity... gravity use weightlessness high gravity (acceleration) use high gravity environments gravity anomalies gravity use high gravity gravity gravity low gravity gravity use gravity Gravity Gravity... perception Probe B Recovery and Climate Experiment mission use GRACE mission Gravity Recovery... probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe... probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe lunar probe... distribution functions probability theory probe probe probe probe probe probe probe probe probe probe probe probe probe probe probe probe) use Microwave Anisotropy Probe probe probe probe probe probe probe probe probe probe probe Mariner 11 space... plasma pneumatic probe probe Probe probe probe probe probe use Pioneer 4 space probe probe probe probe probe probe probe probe probe probe use Pioneer Venus spacecraft probe use Pioneer 10 space probe probe use Pioneer 11 space probe probe probe probe probe probe probe probe probe probe probe probe probe probe probe probe probe probe probe probe probe probe probe probe probe probe probe probe Probe B probe method... probe) use Microwave Anisotropy Probe space probe space probe space probe space probe space probe space probe space probe space probe space probe space probe space probe space probe space probe space probe space probe space probe space probe space probe space probe space probe space probe space probe space probe space probe... space probe space probe space probe space probe space probe space probe space probe space probe space probe space probe...



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... of lab-based tests of gravity” The workshop will take place... inquiry based lessons on spectroscopy, gravity and stellar evolution. In addition... of the Acceleration Due to Gravity Bill Crummett1 1 Centre College. 068....11 NASA’s Gravity Probe B Mission: Was Einstein Right? Shannon K. Range1 1 NASA’s Gravity Probe B at... Univ.. 230.02 StarSpotz: A Sensitive Probe of the Differential Rotation Profile....04 Measurement of the Surface Gravity of ␩ Boo Gerard van Belle1... in 3-year Wilkinson Microwave Anisotropy Probe Data Kevin M. Huffenberger1, H. K. Eriksen2, F. K. Hansen2... necessarily enhanced by the self-gravity. Their growth may be deteriorated... at the longest wavelengths, which probe the largest redshifts. Analysis of... widely exploited as a radio jet probe. To determine CP variability properties... follow different evolutionary tracks. A principal probe of this evolution are metal... observations are just beginning to probe the detailed chemistry of the... planet formation, we need to probe the physical conditions of protoplanetary... which the signature of inflationary gravity waves ͑or “B-modes”͒ is expected... search for the signal from gravity waves excited during an inflationary... include NASA’s Wilkinson Microwave Anisotropy Probe and the Sloan Digital Sky... phenomena and serve as a sensitive probe of the structure and composition... describes a design concept for such a probe under study at Ball Aerospace... to an operational orientation. Each probe accommodates a payload of several kilograms... excitation or cratering experiments. The probe provides a standard suite of services... the surface of a micro-gravity body. Such a basic probe could become a low... Keck II 10-meter telescope probe deeper atmospheric levels and show... be. Formaldehyde is a proven molecular probe for this purpose. Measurements of... line ratio may become a sensitive probe of physical conditions in Class... needed to make this potential probe a quantitative one. This project was... gravitational lensing. The velocity with gravity alone is calculated in a variety... strength about 0.4 0.8 times that of gravity would provide the needed additional... projections within a looser group. We probe the evolution of galaxies in... rich in absorption features that probe the characteristics of galactic outflows... detailed parameters ͑effective temperature, surface gravity and composition͒ for nearly 1,000... that flew aboard NASA’s zero gravity airplane last May. 043.03... NASA’s Beyond Einstein Program, would probe the physical mechanism responsible for... detector development. Black Hole Finder Probe to EXIST:Surveying Black Holes..., studied as a Black Hole Finder Probe within NASA’s Beyond Einstein Program..., implying that the X-factor can probe sub-cloud structure. While this... AAPT, APS and NASA’s Reduced Gravity Program. My Top Ten List... required to reproduce the trajectory: gravity, buoyancy, the drag force and... of the Acceleration Due to Gravity Inservice Preparation of High School... holes, gravitational lensing, dark energy, gravity waves--are rooted in the... matter, the quarks and leptons. Gravity and particle physics, long separate....gov. NASA’s Gravity Probe B Mission: Was Einstein Right? Shannon K. Range1 1 NASA’s Gravity Probe B at...’s theory of general relativity -the Gravity Probe B mission based at Stanford University... of physics and engineering innovations, Gravity Probe B was ready to go. In... cluster environments feature full 3D gravity and realistic temperature and density... demographics and the behavior of gravity in the strong, non-linear... under the balance between central gravity, centrifugal force and the pressure... it cannot balance against the gravity, making a dense part of the..., Italy. 1 The COMPLETE ͑COordinated Molecular Probe Line Extinction and Thermal Emission... Attitudes about Science Survey to probe students’ beliefs at different stages... full spectral range, important to probe the nature of extrasolar giant... such as composition and surface gravity. All of this recent scrutiny... a massive young star and provide a probe of the stellar environment on... host galaxies offer a powerful, direct probe of the AGNgalaxy connection. We... 21 cm line offer a promising probe of early radiation backgrounds. Anisotropies..., thus providing the needed independent probe of the gigaparsecscale Universe. In... analyzing smaller-scale surveys to probe the late integrated Sachs-Wolfe... Sachs-Wolfe ͑ISW͒ effect to probe the evolution of the gravitational... identified through radio observations which probe relativistic material. Motivated by SN... distance from the center of gravity of NGC 346 will indicate... optical spectropolarimetry as a tool to probe the three-dimensional structure of... the Surface Gravity of ␩ Boo 230.02 StarSpotz: A Sensitive Probe of the... from the MOST investigation, a surface gravity of log gϭ3.817 Ϯ 0.016 ͓cm... equilibristic skills to demonstrate gyroscopics, gravity, inertia and other topics in... differential MIR photometry allows to probe the cool atmospheres of the... in 3-year Wilkinson Microwave Anisotropy Probe Data We discuss the Atacama...



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..., as well as various micro-gravity experiments for several academic institutions... surveys: measuring parameters of Earth's gravity field, creating a highly accurate geodetic... Mach 1.2 under the influence of gravity. During the descent phase, the... to the programme. ESA’s GOCE gravity mission achieved another major milestone..., ILA 2010, to extend the Gravity Recovery and Climate Experiment - 23... towards Earth for its final gravity-assist swingby, scheduled for 13... the orbit of Europe's GOCE gravity-measuring - 44 - satellite in a successful... AND ADVANCES VI.1 Propulsion ESA’s gravity mission GOCE released its first... that the gravity measurements taken by GOCE are of true gravity, the... km could potentially drown the gravity data. This posed a technological challenge... success of GOCE´s ultra-sensitive gravity measurements depends on finely controlling... explore the extreme Universe. >> ESA’s gravity mission GOCE issued its first... gravitational potential defined by the gravity field - crucial for deriving accurate... a robot using a tether under a micro-gravity environment. >> VI.7 Space Research Facilities... dedicated to measuring the Earth’s gravity field and modelling the geoid... mission objectives are to determine gravity-field anomalies with an accuracy... 1-2 cm. Data from this advanced gravity mission will improve our knowledge... calculations, validated with gravity observations from the Gravity Recovery and Climate Experiment..., terrain camera, radar sounder), for gravity studies (VLBI and data relay... for launch in 2012. GRAIL (Gravity Recovery and Interior Laboratory) was... is to map the lunar gravity field with unprecedented precision, using... UT on 6 October 2008, gaining a gravity assist that tightened its orbit... combination of electric propulsion and gravity assists, the planned cruise duration... and, along with high precision gravity data, revolutionized studies and understanding... of the nominal mission (including gravity measurements and seasonal coverage), to... Jupiter in early 2008 for a gravity assist and scientific studies (see... variation, albedo, spectrum, mineral composition, gravity, and the main chemical composition.... After a successful commissioning phase, a Mars gravity assist was successfully performed in... that the cratering process was gravity-dominated, lending to the notion... to reach the cometary target, gravity assists (and accompanying science studies... in late 2005. A third Earth-gravity assist occurred in November 2009... study of the magnetic and gravity fields with unprecedented precision, and... in another. Observations of Titan’s gravity field and spin state are... important ingredient in geospace variability. Gravity waves generated by hurricanes or... frequencies and scales, such as gravity waves, tides, and planetary waves... X-ray sky monitoring and survey. gravity waves sub-mm LISA Pathfinder... Biology Here, we focus on gravity perception, genetic and physiological modifications... response to microgravity or simulated gravity. Genetic studies are typically paired...-based low-G simulation; gravity perception and orientation; gravity scale effects; centrifuge high... plants are light and gravity. With regard to gravity, this is quite... increasing evidence, that changes in gravity are sensed as environmental stress... the involvement of phytohormone transport (gravity-induced changes in the localization... effect in early phases of gravity reception, but can optimize statolithreceptor... (e.g. selfsustained oscillations without impact of gravity), gene expression studies prevail, but... further examine specific steps of gravity sensing and signal transduction, genetically... and Cologne in which artificial gravity, exercises and nutritional measures will... usually negligible with respect to gravity, can dominate fluid behaviour and... reported in the following paragraphs. Gravity Probe-B (US with some data analysis... fields of geopotential modelling (Earth’s gravity and magnetic fields), oceanography (altimeter... strongly supporting mission operations and gravity field determination from a complement of... field of precise orbit and gravity field determinations from Lunar and... improved gravity field models for Mars and a better observation of temporal gravity... NASA for more advanced future gravity field satellites, relying on very... (Category III due to a Mars gravity assist) continues on course, using...’s next Discovery-class mission, the Gravity Recovery and Interior Laboratory (GRAIL... 2016. Juno will map the gravity field, magnetic field and atmospheric... (Category II due to Venus gravity assist), is a joint mission between... Explorer (NASA) fiscal year Earth gravity Global Assimilation of Ionospheric Measurements... Plasma Model Geospace Environment Modelling Gravity and Extreme Magnetism SMEX Geostationary... Model Global Navigation Satellite System Gravity field and steady-state Ocean... Spacecraft Gravity Probe B Global Plasmasphere Ionosphere Density Global Positioning System General Relativity Gravity Recovery and Climate Experiment Gravity Recovery and Interior...



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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...