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Aguilera D.N.,German Aerospace Center | Ahlers H.,Leibniz University of Hanover | Battelier B.,French National Center for Scientific Research | Bawamia A.,Ferdinand - Braun - Institute | And 64 more authors.
Classical and Quantum Gravity | Year: 2014

The theory of general relativity describes macroscopic phenomena driven by the influence of gravity while quantum mechanics brilliantly accounts for microscopic effects. Despite their tremendous individual success, a complete unification of fundamental interactions is missing and remains one of the most challenging and important quests in modern theoretical physics. The spacetime explorer and quantum equivalence principle space test satellite mission, proposed as a medium-size mission within the Cosmic Vision program of the European Space Agency (ESA), aims for testing general relativity with high precision in two experiments by performing a measurement of the gravitational redshift of the Sun and the Moon by comparing terrestrial clocks, and by performing a test of the universality of free fall of matter waves in the gravitational field of Earth comparing the trajectory of two Bose-Einstein condensates of 85Rb and 87Rb. The two ultracold atom clouds are monitored very precisely thanks to techniques of atom interferometry. This allows to reach down to an uncertainty in the Eötvös parameter of at least 2 × 10-15. In this paper, we report about the results of the phase A mission study of the atom interferometer instrument covering the description of the main payload elements, the atomic source concept, and the systematic error sources. © 2014 IOP Publishing Ltd.

Guillemot P.,French National Center for Space Studies | Exertier P.,GeoAzur Observatoire de la Cote dAzur | Samain E.,GeoAzur Observatoire de la Cote dAzur | Pierron F.,GeoAzur Observatoire de la Cote dAzur | And 6 more authors.
42nd Annual Precise Time and Time Interval (PTTI) Systems and Applications Meeting 2010 | Year: 2010

The Time Transfer by Laser Link (T2L2) experiment has to perform ground-to-ground time transfer using time tagged laser pulses propagating back and forth between the ground and the Jason-2 satellite. The expected time stability is 1 ps over 1000 s and 10 ps over 1 day and a time accuracy in the 100 ps range. The T2L2 experiment is a joint CNES and OCA space mission. A payload has been installed inside the Jason-2 satellite, which was launched in June 2008. This payload includes some corner cubes (LRA, provided by the JPL), the T2L2 instrument itself, and an ultra-stable quartz oscillator to date the events. The ground network relies on existing laser stations (ILRS network), among them the two stations of the OCA: a fixed one at Grasse and a transportable one currently installed at Observatoire de Paris. Both stations include laser pulses emitter and receptor synchronized on a clock. First ground-to-space time transfers have demonstrated noise levels of some tens of picoseconds 0 and a preliminary time stability of a few picoseconds over integration times of some tens of seconds, clearly limited by the on-board clock [4]. The current campaign began in June 2010 and involved eight laser stations in Europe and Asia. As some laser stations are also equipped by GPS and TWSTFT devices, this campaign should allow the performance comparisons between these systems operating with different wavelengths and, consequently, different atmosphere delays. With the installation of the SYRTE Mobile Atomic Fountain at OCA (Grasse) and the transportable laser station at SYRTE (Paris), we will perform a time and frequency transfer by laser link between the cold atomic fountains 0 with a frequency accuracy in the 10-16 range. The paper will present the first results of the ground-to-ground time transfer, in common clock and non-common-clock configuration, and a first comparison with GPS. © 2010 by Precise Time and Time Interval (PTTI) - Time Service Department.

Cresson J.,University of Pau and Pays de l'Adour | Pierret F.,SYRTE Observatoire de Paris | Puig B.,University of Pau and Pays de l'Adour
Journal of Mathematical Physics | Year: 2015

We study the Sharma-Parthasarathy stochastic two-body problem introduced by Sharma and Parthasarathy in ["Dynamics of a stochastically perturbed two-body problem," Proc. R. Soc. A 463, 979-1003 (2007)]. In particular, we focus on the preservation of some fundamental features of the classical two-body problem like the Hamiltonian structure and first integrals in the stochastic case. Numerical simulations are performed which illustrate the dynamical behaviour of the osculating elements as the semi-major axis, the eccentricity, and the pericenter. We also derive a stochastic version of Gauss's equations in the planar case. © 2015 AIP Publishing LLC.

Guillemot P.,French National Center for Space Studies | Exertier P.,GeoAzur Observatoire de la Cote dAzur | Samain E.,GeoAzur Observatoire de la Cote dAzur | Pierron F.,GeoAzur Observatoire de la Cote dAzur | And 7 more authors.
43rd Annual Precise Time and Time Interval Systems and Applications Meeting 2011 | Year: 2011

The Time Transfer by Laser Link (T2L2) experiment, developed by both CNES and OCA, is aimed at performing ground to ground time transfer over intercontinental distances. The principle is derived from laser telemetry technology with dedicated space equipment designed to record arrival time of laser pulses at the satellite. Using laser pulses instead of radio frequency signals, T2L2 permits the realization of links between distant clocks with time stability of a few picoseconds and accuracy better than 100ps. The T2L2 space instrument on board the satellite Jason 2 has been in operation since June 2008. Several campaigns were done to estimate both the ultimate time accuracy and time stability capabilities. It includes mainly two kinds of experiments: the first involves two SLR stations on the same site and using the same clock, the second involves two remote SLR stations (Grasse and Paris) in common view. These experiments allowed the demonstration of both a time stability lower than a few tens of picoseconds for integration times from 10 s to 100 s and an accuracy lower than 100 ps for the T2L2 time transfer. Some important work has also been done to accurately compare T2L2 with microwave time transfer GPS and TWSTFT. These comparisons are based on laser station calibrations with a dedicated T2L2 event timer designed to accurately set the optical reference of the laser station within the PPS reference of the microwave systems. This paper presents ground to ground time transfer both in common view and non common view configuration, and comparisons between T2L2, GPS and Two-Way systems. Results of the 2010 campaigns are described as well as an insight into the future working plan.

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