Limitations to testing the equivalence principle with satellite laser ranging

Nobili, A. M.; Comandi, G. L.; Bramanti, D.; Doravari, S.; Lucchesi, David M.; Maccarrone, Francesco

doi:10.1007/s10714-008-0632-6

Cited by 6 publications

(19 citation statements)

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“…Similarly to the WEP test for the Earth-Moon system around the Sun, one might consider a similar test for the Earth-LAGEOS system in the field of the Sun, since in this case the limitation by gravity gradients would be at 10 −13 level, not 10 −9 . However, this test would be a factor 300 less sensitive than in the case of the Moon [29]. In essence, this is because LAGEOS is closer to the Earth than the Moon, therefore its orbit is less affected than the lunar orbit by the Sun, which is also the source mass of a possible violation.…”

Section: State Of the Art And Limitationsmentioning

confidence: 97%

“…Satellite Laser Ranging (SLR) to Laser Geodynamics Satellites (LAGEOS) orbiting the Earth at a distance of about two Earth radii has been suggested as another possibility for testing WEP. In this case, because of the smaller distance from the source body (Earth) laser ranging errors at cm level yield a larger spurious signal of about 3∆a/(2R ⊕ ) 2.4 · 10 −9 [29].…”

Section: State Of the Art And Limitationsmentioning

confidence: 99%

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Relevance of the weak equivalence principle and experiments to test it: Lessons from the past and improvements expected in space

Nobili

Anselmi

2018

Physics Letters A

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Section: State Of the Art And Limitationsmentioning

confidence: 97%

Section: State Of the Art And Limitationsmentioning

confidence: 99%

Relevance of the weak equivalence principle and experiments to test it: Lessons from the past and improvements expected in space

Nobili

Anselmi

2018

Physics Letters A

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“…As a test of the equivalence principle, lunar laser ranging is ultimately limited by the non uniformity of the gravity field of the Sun, a limitation expressed by the dimensionless quantity 3 a/d ( a being the measurement error in the semimajor axis of the orbit of the Moon around the Earth and d the distance of the Earth-Moon system from the Sun) [27]. A 1 cm error in semimajor axis (due to 1 cm accuracy of lunar laser ranging) is consistent with the current level of LLR tests to 10 −13 ; 1 order of magnitude improvement is expected with the capability of the APOLLO facility to perform laser ranging to the Moon at 1 mm level.…”

Section: Testing the Equivalence Principle To Very High Accuracy: Thementioning

confidence: 99%

“Galileo Galilei” (GG) a small satellite to test the equivalence principle of Galileo, Newton and Einstein

et al. 2009

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"Galileo Galilei" (GG) is a small satellite designed to fly in low Earth orbit with the goal of testing the Equivalence Principle-which is at the basis of the General Theory of Relativity-to 1 part in 10 17 . If successful, it would improve current laboratory results by 4 orders of magnitude. A confirmation would strongly constrain theories; proof of violation is believed to lead to a scientific revolution. The experiment design allows it to be carried out at ambient temperature inside a small 1-axis stabilized satellite (250 kg total mass). GG is under investigation at Phase A-2 level by ASI (Agenzia Spaziale Italiana) at Thales Alenia Space in Torino, while a laboratory prototype (known as GGG) is operational at INFN laboratories in Pisa, supported by INFN (Istituto Nazionale di fisica Nucleare) and ASI. A final study report will be published in 2009.

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“…As shown in [8], a nice favourable case is that of the Moon and the Earth freely falling in the field of the Sun (with an average acceleration g 6 · 10 −3 ms −2 ), the Moon's orbit being measured by laser ranging to corner cube reflectors left by astronauts on its surface. In this case the gravity gradient from the Sun is very small thanks to its very large distance (d ⊕ 1.5 · 10 11 m) yielding γ 2g d⊕ 1.3 · 10 −11 g /m.…”

Section: Introductionmentioning

confidence: 99%

Fundamental limitations to high-precision tests of the universality of free fall by dropping atoms

Nobili

2016

Phys. Rev. A

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Tests of the universality of free fall and the weak equivalence principle probe the foundations of general relativity. Evidence of a violation may lead to the discovery of a new force. The best torsion balance experiments have ruled it out to 10-13. Cold-atom drop tests have reached 10-7 and promise to do 7 to 10 orders of magnitude better, on the ground or in space. They are limited by the random shot noise, which depends on the number N of atoms in the clouds (as 1/N). As mass-dropping experiments in the nonuniform gravitational field of Earth, they are sensitive to the initial conditions. Random accelerations due to initial condition errors of the clouds are designed to be at the same level as shot noise, so that they can be reduced with the number of drops along with it. This sets the requirements for the initial position and velocity spreads of the clouds with given N. In the STE-QUEST space mission proposal aiming at 2×10-15 they must be about a factor 8 above the limit established by Heisenberg's uncertainty principle, and the integration time required to reduce both errors is 3 years, with a mission duration of 5 years. Instead, offset errors at release between position and velocity of different atom clouds are systematic and give rise to a systematic effect which mimics a violation. Such systematic offsets must be demonstrated to be as small as required in all drops, i.e., they must be kept small by design, and they must be measured. For STE-QUEST to meet its goal they must be several orders of magnitude smaller than the size - in position and velocity space - of each individual cloud, which in its turn must be at most 8 times larger than the uncertainty principle limit. Even if all technical problems are solved and different atom clouds are released with negligible systematic errors, still these errors must be measured; and Heisenberg's principle dictates that such measurement lasts as long as the experiment. While shot noise is random, hence its reduction becomes apparent as more and more drops are performed, the systematic effect due to offset errors at release must be identified through its specific known signature, and measured in order to be distinguished with certainty from the signal. This requires many well designed measurements to be performed - each to the target precision - for it to be ruled out as a source of violation. Ways may be pursued in order to mitigate the limitations identified here

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Limitations to testing the equivalence principle with satellite laser ranging

Cited by 6 publications

References 0 publications

Relevance of the weak equivalence principle and experiments to test it: Lessons from the past and improvements expected in space

Relevance of the weak equivalence principle and experiments to test it: Lessons from the past and improvements expected in space

“Galileo Galilei” (GG) a small satellite to test the equivalence principle of Galileo, Newton and Einstein

Fundamental limitations to high-precision tests of the universality of free fall by dropping atoms

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