ASTROD (Astrodynamical Space Test of Relativity using Optical Devices) and ASTROD I

Ni, Wei-Tou

doi:10.1016/j.nuclphysbps.2006.12.067

Cited by 17 publications

(12 citation statements)

References 19 publications

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“…This mission concept has one spacecraft carrying a payload of a telescope, five lasers, and a clock together with ground stations (ODSN: Optical Deep Space Network) to test the optical scheme of interferometric and pulse ranging and still give important scientific results. 56,57 The basic scheme of the ASTROD I space mission concept is to use two-way laser interferometric ranging and laser pulse ranging between the ASTROD I spacecraft in solar orbit and deep space laser stations on Earth to improve the precision of solar-system dynamics measurements, solar-system constants and ephemeris, to measure relativistic gravitational effects and to test the fundamental laws of spacetime more precisely, and to improve the measurement of the time rate of change of the gravitational constant. A schematic of the payload configuration of ASTROD I is shown in Fig.…”

Section: Astrod Imentioning

confidence: 99%

Astrod and Astrod I — Overview and Progress

2008

Int. J. Mod. Phys. D

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In this paper, we present an overview of ASTROD (Astrodynamical Space Test of Relativity using Optical Devices) and ASTROD I mission concepts and studies. The missions employ deep-space laser ranging using drag-free spacecraft to map the gravitational field in the solar-system. The solar-system gravitational field is determined by three factors: the dynamic distribution of matter in the solar system; the dynamic distribution of matter outside the solar system (galactic, cosmological, etc.) and gravitational waves propagating through the solar system. Different relativistic theories of gravity make different predictions of the solar-system gravitational field. Hence, precise measurements of the solar-system gravitational field test these relativistic theories, in addition to gravitational wave observations, determination of the matter distribution in the solar-system and determination of the observable (testable) influence of our galaxy and cosmos. The tests and observations include: (i) a precise determination of the relativistic parameters β and γ with 3-5 orders of magnitude improvement over previous measurements; (ii) a 1-2 order of magnitude improvement in the measurement of G; (iii) a precise determination of any anomalous, constant acceleration Aa directed towards the Sun; (iv) a measurement of solar angular momentum via the Lense-Thirring effect; (v) the detection of solar g-mode oscillations via their changing gravity field, thus, providing a new eye to see inside the Sun; (vi) precise determination of the planetary orbit elements and masses; (vii) better determination of the orbits and masses of major asteroids; (viii) detection and observation of gravitational waves from massive black holes and galactic binary stars in the frequency range 50 µHz to 5 mHz; and (ix) exploring background gravitational waves. The baseline scheme of ASTROD is to have two spacecraft in separate solar orbits and one spacecraft near the Earth-Sun L1/L2 point carrying a payload of a proof mass, two telescopes, two 1-2 W lasers with spares, a clock and a drag-free system ranging coherently among one another using lasers. ASTROD I is a first step towards ASTROD. Its scheme is to have one spacecraft in a Venus-gravity-assisted solar orbit, ranging optically with ground stations with less ambitious, but still significant scientific goals. PACS number(s): 04.80.Cc, 04.80.Nn, 95.10.-a, 96.60.Ly 921 Int. J. Mod. Phys. D 2008.17:921-940. Downloaded from www.worldscientific.com by UNIVERSITY OF BRITISH COLUMBIA on 02/04/15. For personal use only.

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Section: Astrod Imentioning

confidence: 99%

Astrod and Astrod I — Overview and Progress

2008

Int. J. Mod. Phys. D

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105

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“…ASTROD (ASTROD II) [2,36,37] will deliver a new unconventional method [2,[37][38][39][40], and references therein] that is capable of achieving this objective. Figure 3 displays various, theoretical and observed, solar velocity amplitudes of the g-modes, as well as the anticipated sensitivities for the spaceinstruments, ASTROD and LISA [32].…”

Section: The Internal Structure and Dynamics Of The Sun [28]mentioning

confidence: 99%

Astrodynamical Space Test of Relativity Using Optical Devices I (ASTROD I)—A class-M fundamental physics mission proposal for Cosmic Vision 2015–2025

et al. 2009

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ASTROD I is a planned interplanetary space mission with multiple goals. The primary aims are: to test general relativity with an improvement in sensitivity of over three orders of magnitude, improving our understanding of gravity and aiding the development of a new quantum gravity theory; to measure key solar system parameters with increased accuracy, advancing solar physics and our knowledge of the solar system; and to measure the time rate of change of the gravitational constant with an order of magnitude improvement and the anomalous Pioneer acceleration, thereby probing dark matter and dark energy gravitationally. It is an international project, with major contributions from Europe and China and is envisaged as the first in a series of ASTROD missions. ASTROD I will consist of one spacecraft carrying a telescope, four lasers, two event timers and a clock. Two-way, twowavelength laser pulse ranging will be used between the spacecraft in a solar orbit and deep space laser stations on Earth, to achieve the ASTROD I goals. A second mission, ASTROD (ASTROD II) is envisaged as a three-spacecraft mission which would test General Relativity to 1 ppb, enable detection of solar g-modes, measure the solar Lense-Thirring effect to 10 ppm, and probe gravitational waves at frequencies below the LISA bandwidth. In the third phase (ASTROD III or Super-ASTROD), larger orbits could be implemented to map the outer solar system and to probe primordial gravitational-waves at frequencies below the ASTROD II bandwidth.

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“…The solar velocity v ⊙ with respect to the barycentre of the Solar system can reach a maximal value of 15.8 m s −1 giving rise to β ⊙ = v ⊙ / c = 5.3 × 10 −8 . Because space missions LATOR and ASTROD are going to measure the parameter with a precision approaching 10 −9 (Turyshev et al 2004; Ni 2007), the explicit velocity‐dependent correction to the Shapiro time delay in the solar gravitational field must be apparently taken into account. Current indeterminacy in the solar velocity vector is about 0.366 m d −1 (Pitjeva, private communication) which yields an error of Δβ ⊙ ≃ 1.4 × 10 −14 .…”

Section: Coupling Of the Ppn Parameters With The Velocity‐dependentmentioning

confidence: 99%

“…However, very long baseline interferometry (VLBI) measurement of the null‐cone gravity retardation effect (Kopeikin 2001, 2004; Fomalont & Kopeikin 2003; Fomalont et al 2009) and frequency‐shift measurement of γ PPN in the Cassini experiment (Bertotti, Iess & Tortora 2003; Anderson, Lau & Giampieri 2004) made it evident that modern technology has achieved the level at which relativistic effects caused by the dependence of the gravitational field on time can be no longer ignored. Future gravitational light‐ray deflection experiments (Kopeikin & Mashhoon 2002), the radio ranging BepiColombo experiment (Milani et al 2002), laser ranging experiments ASTROD (Ni 2007) and LATOR (Turyshev, Shao & Nordtvedt 2004) will definitely reach the precision in measuring and that is comparable with the post‐Newtonian corrections to the static time delay and to the deflection angle caused by the motion of the massive bodies in the Solar system (Plowman & Hellings 2006). Therefore, it is worthwhile to undertake a scrutiny theoretical study of the time‐dependent relativistic corrections to the static Shapiro time delay.…”

Section: Introductionmentioning

confidence: 99%

Post-Newtonian limitations on measurement of the PPN parameters caused by motion of gravitating bodies

Kopeikin

2009

Monthly Notices of the Royal Astronomical Society

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We derive an explicit Lorentz‐invariant solution of the Einstein and null geodesic equations for data processing of the time delay and ranging experiments in the gravitational field of moving gravitating bodies of the Solar system – the Sun and major planets. We discuss the general‐relativistic interpretation of these experiments and the limitations imposed by motion of the massive bodies on measurement of the parameters γPPN, βPPN and δPPN of the parametrized post‐Newtonian (PPN) formalism.

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ASTROD (Astrodynamical Space Test of Relativity using Optical Devices) and ASTROD I

Cited by 17 publications

References 19 publications

Astrod and Astrod I — Overview and Progress

Astrod and Astrod I — Overview and Progress

Astrodynamical Space Test of Relativity Using Optical Devices I (ASTROD I)—A class-M fundamental physics mission proposal for Cosmic Vision 2015–2025

Post-Newtonian limitations on measurement of the PPN parameters caused by motion of gravitating bodies

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