arXiv subjects

Slava G. Turyshev

Publications and source records attributed to Slava G. Turyshev.

At least 127 records · Page 7Linked to original sources

arXiv2007

Physics Engineering in the Study of the Pioneer Anomaly

The Pioneer 10/11 spacecraft yielded the most precise navigation in deep space to date. However, their radio-metric tracking data received from the distances between 20--70 astronomical units from the Sun has consistently indicated the presence of a small, anomalous, Doppler frequency drift. The drift is a blue frequency shift that can be interpreted as a sunward acceleration of a_P = (8.74 +/- 1.33) x 10^{-10} m/s^2 for each particular spacecraft. This signal has become known as the Pioneer anomaly; the nature of this anomaly remains unexplained. Recently new Pioneer 10 and 11 radio-metric Doppler and flight telemetry data became available. The newly available Doppler data set is significantly enlarged when compared to the data used in previous investigations and is expected to be the primary source for the investigation of the anomaly. In addition, the flight telemetry files, original project documentation, and newly developed software tools are now used to reconstruct the engineering history of both spacecraft. With the help of this information, a thermal model of the Pioneer vehicles is being developed to study possible contribution of thermal recoil force acting on the two spacecraft. The ultimate goal of these physics engineering efforts is to evaluate the effect of on-board systems on the spacecrafts' trajectories.

physics.space-ph↗

arXiv2007

The Laser Astrometric Test of Relativity: Science, Technology, and Mission Design

The Laser Astrometric Test of Relativity (LATOR) experiment is designed to explore general theory of relativity in the close proximity to the Sun -- the most intense gravitational environment in the solar system. Using independent time-series of highly accurate measurements of the Shapiro time-delay (interplanetary laser ranging accurate to 3 mm at 2 AU) and interferometric astrometry (accurate to 0.01 picoradian), LATOR will measure gravitational deflection of light by the solar gravity with accuracy of 1 part in a billion -- a factor ~30,000 better than currently available. LATOR will perform series of highly-accurate tests in its search for cosmological remnants of scalar field in the solar system. We present science, technology and mission design for the LATOR mission.

gr-qc↗

arXiv2006

Williams et al. Reply (to the Comment by Dumin on "Progress in Lunar Laser Ranging Tests of Relativistic Gravity")

A decreasing gravitational constant, G, coupled with angular momentum conservation is expected to increrase a planetary semimajor axis, a, as \dot a/a=-\dot G/G. Analysis of lunar laser ranging data strongly limits such temporal variations and constrains a local (~1 AU) scale expansion of the solar system as \dot a/a=-\dot G/G =-(4\pm9)\times10^{-13} yr^{-1}, including that due to cosmological effects.

gr-qc↗

arXiv2006

General Theory of Relativity: Will it survive the next decade?

The nature of gravity is fundamental to our understanding of our own solar system, the galaxy and the structure and evolution of the Universe. Einstein's general theory of relativity is the standard model that is used for almost ninety years to describe gravitational phenomena on these various scales. We review the foundations of general relativity, discuss the recent progress in the tests of relativistic gravity, and present motivations for high-accuracy gravitational experiments in space. We also summarize the science objectives and technology needs for the laboratory experiments in space with laboratory being the entire solar system. We discuss the advances in our understanding of fundamental physics anticipated in the near future and evaluate discovery potential for the recently proposed gravitational experiments.

gr-qc↗

arXiv2006

The Study of the Pioneer Anomaly: New Data and Objectives for New Investigation

Radiometric tracking data from Pioneer 10 and 11 spacecraft has consistently indicated the presence of a small, anomalous, Doppler frequency drift, uniformly changing with a rate of ~6 x 10^{-9} Hz/s; the drift can be interpreted as a constant sunward acceleration of each particular spacecraft of a_P = (8.74 \pm 1.33) x 10^{-10} m/s^2. This signal is known as the Pioneer anomaly; the nature of this anomaly remains unexplained. We discuss the efforts to retrieve the entire data sets of the Pioneer 10/11 radiometric Doppler data. We also report on the recently recovered telemetry files that may be used to reconstruct the engineering history of both spacecraft using original project documentation and newly developed software tools. We discuss possible ways to further investigate the discovered effect using these telemetry files in conjunction with the analysis of the much extended Doppler data. We present the main objectives of new upcoming study of the Pioneer anomaly, namely i) analysis of the early data that could yield the direction of the anomaly, ii) analysis of planetary encounters, that should tell more about the onset of the anomaly, iii) analysis of the entire dataset, to better determine the anomaly's temporal behavior, iv) comparative analysis of individual anomalous accelerations for the two Pioneers, v) the detailed study of on-board systematics, and vi) development of a thermal-electric-dynamical model using on-board telemetry. The outlined strategy may allow for a higher accuracy solution for a_P and, possibly, will lead to an unambiguous determination of the origin of the Pioneer anomaly.

gr-qc↗

arXiv2006

Science, Technology and Mission Design for the Laser Astrometric Test Of Relativity

The Laser Astrometric Test Of Relativity (LATOR) is a Michelson-Morley-type experiment designed to achieve a major improvement in the accuracy of the tests of relativistic gravity in the solar system. By using a combination of independent time-series of gravitational deflection of light in the immediate proximity to the Sun, along with measurements of the relativistic time delay on interplanetary scales (to a precision respectively better than 0.1 picoradians and 1 cm), LATOR will measure the key post-Newtonian Eddington parameter γwith accuracy of one part in a billion - a factor of 30,000 improvement compared to the present best result, Cassini's 2003 test. LATOR's primary measurement pushes to unprecedented accuracy the search for cosmologically relevant scalar-tensor modifications of gravity by looking for a remnant scalar field in today's solar system. We present a comprehensive discussion of the science objectives, proposed technology, mission and optical designs, as well as the expected performance of this fundamental physics experiment in space.

gr-qc↗

arXiv2005

The Science, Technology and Mission Design for the Laser Astrometric Test of Relativity

The Laser Astrometric Test of Relativity (LATOR) is a Michelson-Morley-type experiment designed to test the Einstein's general theory of relativity in the most intense gravitational environment available in the solar system -- the close proximity to the Sun. By using independent time-series of highly accurate measurements of the Shapiro time-delay (laser ranging accurate to 1 cm) and interferometric astrometry (accurate to 0.1 picoradian), LATOR will measure gravitational deflection of light by the solar gravity with accuracy of 1 part in a billion, a factor ~30,000 better than currently available. LATOR will perform series of highly-accurate tests of gravitation and cosmology in its search for cosmological remnants of scalar field in the solar system. We present science, technology and mission design for the LATOR mission.

gr-qc↗

arXiv2005

Potential Capabilities of Lunar Laser Ranging for Geodesy and Relativity

Lunar Laser Ranging (LLR), which has been carried out for more than 35 years, is used to determine many parameters within the Earth-Moon system. This includes coordinates of terrestrial ranging stations and that of lunar retro-reflectors, as well as lunar orbit, gravity field, and its tidal acceleration. LLR data analysis also performs a number of gravitational physics experiments such as test of the equivalence principle, search for time variation of the gravitational constant, and determines value of several metric gravity parameters. These gravitational physics parameters cause both secular and periodic effects on the lunar orbit that are detectable with LLR. Furthermore, LLR contributes to the determination of Earth orientation parameters (EOP) such as nutation, precession (including relativistic precession), polar motion, and UT1. The corresponding LLR EOP series is three decades long. LLR can be used for the realization of both the terrestrial and selenocentric reference frames. The realization of a dynamically defined inertial reference frame, in contrast to the kinematically realized frame of VLBI, offers new possibilities for mutual cross-checking and confirmation. Finally, LLR also investigates the processes related to the Moon's interior dynamics. Here, we review the LLR technique focusing on its impact on Geodesy and Relativity. We discuss the modern observational accuracy and the level of existing LLR modeling. We present the near-term objectives and emphasize improvements needed to fully utilize the scientific potential of LLR.

gr-qc↗

arXiv2005

The Pioneer Anomaly and Its Implications

The Pioneer 10/11 spacecraft yielded the most precise navigation in deep space to date. However, their radio-metric tracking data has consistently indicated the presence of a small, anomalous, Doppler frequency drift. The drift is a blue-shift, uniformly changing with a rate of ~6 x 10^{-9} Hz/s and can be interpreted as a constant sunward acceleration of each particular spacecraft of a_P =(8.74 +/- 1.33) x 10^{-10} m/s^2. The nature of this anomaly remains unexplained. Here we summarize our current knowledge of the discovered effect and review some of the mechanisms proposed for its explanation. Currently we are preparing for the analysis of the entire set of the available Pioneer 10/11 Doppler data which may shed a new light on the origin of the anomaly. We present a preliminary assessment of such an intriguing possibility.

gr-qc↗

arXiv2005

Lunar Laser Ranging Contributions to Relativity and Geodesy

Lunar laser ranging (LLR) is used to conduct high-precision measurements of ranges between an observatory on Earth and a laser retro-reflector on the lunar surface. Over the years, LLR has benefited from a number of improvements both in observing technology and data modeling, which led to the current accuracy of post-fit residuals of ~2 cm. Today LLR is a primary technique to study the dynamics of the Earth-Moon system and is especially important for gravitational physics, geodesy and studies of the lunar interior. LLR is used to perform high-accuracy tests of the equivalence principle, to search for a time-variation in the gravitational constant, and to test predictions of various alternative theories of gravity. On the geodesy front, LLR contributes to the determination of Earth orientation parameters, such as nutation, precession (including relativistic precession), polar motion, and UT1, i.e. especially to the long-term variation of these effects. LLR contributes to the realization of both the terrestrial and selenocentric reference frames. The realization of a dynamically defined inertial reference frame, in contrast to the kinematically realized frame of VLBI, offers new possibilities for mutual cross-checking and confirmation. Finally, LLR also investigates the processes related to the Moon's interior dynamics. Here, we review the LLR technique focusing on its impact on relativity and give an outlook to further applications, e.g. in geodesy. We present results of our dedicated studies to investigate the sensitivity of LLR data with respect to the relativistic quantities. We discuss the current observational situation and the level of LLR modeling implemented to date. We also address improvements needed to fully utilize the scientific potential of LLR.

gr-qc↗

arXiv2005

Study of the Pioneer Anomaly: A Problem Set

Analysis of the radio-metric tracking data from the Pioneer 10 and 11 spacecraft at distances between 20--70 astronomical units from the Sun has consistently indicated the presence of an anomalous, small, and constant Doppler frequency drift. The drift is a blue-shift, uniformly changing at the rate of (5.99 +/- 0.01) x 10^{-9} Hz/s. The signal also can be interpreted as a constant acceleration of each particular spacecraft of (8.74 +/- 1.33) x 10^{-8} cm/s^2 directed toward the Sun. This interpretation has become known as the Pioneer anomaly. We provide a problem set based on the detailed investigation of this anomaly, the nature of which remains unexplained.

physics.ed-ph↗

arXiv2005

Directly Measured Limit on the Interplanetary Matter Density from Pioneer 10 and 11

The Pioneer 10 and 11 spacecraft had exceptional deep-space navigational capabilities. The accuracies of their orbit reconstruction were limited, however, by a small, anomalous, Doppler frequency drift that can be interpreted as an acceleration of (8.74 +/- 1.33) x 10^{-8} cm/s^2 directed toward the Sun. We investigate the possibility that this anomaly could be due to a drag on the spacecraft from their passing through the interplanetary medium. Although this mechanism is an appealing one, the existing Pioneer radiometric data would require an unexpectedly high mass density of interplanetary dust for this mechanism to work. Further, the magnitude of the density would have to be nearly constant at distances ~ 20-70 AU. Therefore, it appears that such an explanation is very unlikely, if not ruled out. Despite this, the measured frequency drift by itself places a directly-measured, model-independent limit of \lessim 3 x 10^{-19} g/cm^3 on the mass density of interplanetary dust in the outer(~20-70 AU) solar system. Lower experimental limits can be placed if one presumes a model that varies with distance. An example is the limit \lessim 6 x 10^{-20} g/cm^3 obtained for the model with an axially-symmetric density distribution that falls off as the inverse of the distance. We emphasize that the limits obtained are experimentally-measured, in situ limits. A mission to investigate the anomaly would be able to place a better limit on the density, or perhaps even to measure it.

astro-ph↗

arXiv2005

Study of the anomalous acceleration of Pioneer 10 and 11

Our previous analyses of radio Doppler and ranging data from distant spacecraft in the solar system indicated that an apparent anomalous acceleration is acting on Pioneer 10 and 11, with a magnitude a_P ~ 8 x 10^{-8} cm/s^2, directed towards the Sun (anderson,moriond). Much effort has been expended looking for possible systematic origins of the residuals, but none has been found. A detailed investigation of effects both external to and internal to the spacecraft, as well as those due to modeling and computational techniques, is provided. We also discuss the methods, theoretical models, and experimental techniques used to detect and study small forces acting on interplanetary spacecraft. These include the methods of radio Doppler data collection, data editing, and data reduction. There is now further data for the Pioneer 10 orbit determination. The extended Pioneer 10 data set spans 3 January 1987 to 22 July 1998. [For Pioneer 11 the shorter span goes from 5 January 1987 to the time of loss of coherent data on 1 October 1990.] With these data sets and more detailed studies of all the systematics, we now give a result, of a_P = (8.74 +/- 1.33) x 10^{-8} cm/s^2. (Annual/diurnal variations on top of a_P, that leave a_P unchanged, are also reported and discussed.)

gr-qc↗

arXiv2005

A Route to Understanding of the Pioneer Anomaly

The Pioneer 10 and 11 spacecraft yielded the most precise navigation in deep space to date. However, while at heliocentric distance of $\sim$ 20--70 AU, the accuracies of their orbit reconstructions were limited by a small, anomalous, Doppler frequency drift. This drift can be interpreted as a sunward constant acceleration of $a_P = (8.74 \pm 1.33)\times 10^{-8}$ cm/s$^2$ which is now commonly known as the Pioneer anomaly. Here we discuss the Pioneer anomaly and present the next steps towards understanding of its origin. They are: 1) Analysis of the entire set of existing Pioneer 10 and 11 data, obtained from launch to the last telemetry received from Pioneer 10, on 27 April 2002, when it was at a heliocentric distance of 80 AU. This data could yield critical new information about the anomaly. If the anomaly is confirmed, 2) Development of an instrumental package to be operated on a deep space mission to provide an independent confirmation on the anomaly. If further confirmed, 3) Development of a deep-space experiment to explore the Pioneer anomaly in a dedicated mission with an accuracy for acceleration resolution at the level of $10^{-10}$ cm/s$^2$ in the extremely low frequency range. In Appendices we give a summary of the Pioneer anomaly's characteristics, outline in more detail the steps needed to perform an analysis of the entire Pioneer data set, and also discuss the possibility of extracting some useful information from the Cassini mission cruise data.

gr-qc↗

arXiv2005

Optical Design for the Laser Astrometric Test of Relativity

This paper discusses the Laser Astrometric Test Of Relativity (LATOR) mission. By using a combination of independent time-series of highly accurate gravitational deflection of light in the immediate proximity to the Sun along with measurements of the Shapiro time delay on the interplanetary scales (to a precision respectively better than $10^{-13}$ radians and 1 cm), LATOR will significantly improve our knowledge of relativistic gravity. The primary mission objective is to i) measure the key post-Newtonian Eddington parameter $γ$ with accuracy of a part in 10$^9$. $(1-γ)$ is a direct measure for presence of a new interaction in gravitational theory, and, in its search, LATOR goes a factor 30,000 beyond the present best result, Cassini's 2003 test. Other mission objectives include: ii) first measurement of gravity's non-linear effects on light to $\sim$0.01% accuracy; including both the traditional Eddington $β$ parameter and also the spatial metric's 2nd order potential contribution (never been measured before); iii) direct measurement of the solar quadrupole moment $J_2$ (currently unavailable) to accuracy of a part in 200 of its expected size; iv) direct measurement of the ``frame-dragging'' effect on light by the Sun's rotational gravitomagnetic field to one percent accuracy. LATOR's primary measurement pushes to unprecedented accuracy the search for cosmologically relevant scalar-tensor theories of gravity by looking for a remnant scalar field in today's solar system. The key element of LATOR is a geometric redundancy provided by the laser ranging and long-baseline optical interferometry. We discuss the mission and optical designs of this proposed experiment.

gr-qc↗

arXiv2004

Progress in Lunar Laser Ranging Tests of Relativistic Gravity

Analyses of laser ranges to the Moon provide increasingly stringent limits on any violation of the Equivalence Principle (EP); they also enable several very accurate tests of relativistic gravity. We report the results of our recent analysis of Lunar Laser Ranging (LLR) data giving an EP test of Δ(M_G/M_I)_{EP} =(-1.0 +/- 1.4) x 10^{-13}. This result yields a Strong Equivalence Principle (SEP) test of Δ(M_G/M_I)_{SEP} =(-2.0 +/- 2.0) x 10^{-13}. Also, the corresponding SEP violation parameter ηis (4.4 +/- 4.5) x 10^{-4}, where η=4β-γ-3 and both βand γare parametrized post-Newtonian (PPN) parameters. Using the recent Cassini result for the parameter γ, PPN parameter βis determined to be β-1=(1.2 +/- 1.1) x 10^{-4}. The geodetic precession test, expressed as a relative deviation from general relativity, is K_{gp}=-0.0019 +/- 0.0064. The search for a time variation in the gravitational constant results in \dot G/G=(4 +/- 9) x 10^{-13} yr^{-1}, consequently there is no evidence for local (~1AU) scale expansion of the solar system.

gr-qc↗

arXiv2004

Lunar Laser Ranging Science: Gravitational Physics and Lunar Interior and Geodesy

Laser pulses fired at retroreflectors on the Moon provide very accurate ranges. Analysis yields information on Earth, Moon, and orbit. The highly accurate retroreflector positions have uncertainties less than a meter. Tides on the Moon show strong dissipation, with Q=33 \pm 4 at a month and a weak dependence on period. Lunar rotation depends on interior properties; a fluid core is indicated with radius ~20% that of the Moon. Tests of relativistic gravity verify the equivalence principle to \pm 1.4 x 10^{-13}, limit deviations from Einstein's general relativity, and show no rate for the gravitational constant $\dot{G}/G$ with uncertainty 9 x 10^{-13} 1/yr.

gr-qc↗

arXiv2004

The Pioneer Anomaly: The Data, its Meaning, and a Future Test

The radio-metric Doppler tracking data from the Pioneer 10/11 spacecraft, from between 20-70 AU, yields an unambiguous and independently confirmed anomalous blue shift drift of a_t = (2.92 \pm 0.44)\times 10^{-18} s/s^2. It can be interpreted as being due to a constant acceleration of a_P = (8.74 \pm 1.33) \times 10^{-8} cm/s^2 directed towards the Sun. No systematic effect has been able to explain the anomaly, even though such an origin is an obvious candidate. We discuss what has been learned (and what might still be learned) from the data about the anomaly, its origin, and the mission design characteristics that would be needed to test it. Future mission options are proposed.

gr-qc↗