N. I. Kolosnitsyn

Project SEE (Satellite Energy Exchange): an international effort to develop a space-based mission for precise measurements of gravitation

Project SEE (Satellite Energy Exchange) is an international effort to develop a space-based mission for precise measurements of gravitation. Gravity is the missing link in unification theory. Because of the unique paucity of knowledge about this, the weakest of all known forces, and because gravity must have a key role in any unification theory, many aspects of gravity need to be understood in greater depth. A SEE mission would extend our knowledge of a number of gravitational parameters and effects, which are needed to test unification theories and various modern theories of gravity. SEE is a comprehensive gravitation experiment. A SEE mission would test for violations of the equivalence principle (EP), both by inverse-square-law (ISL) violations and by composition dependence (CD), both at ranges of the order of metres and at ranges on the order of RE. A SEE mission would also determine the gravitational constant G, test for time variation of G, and possibly test for post-Einsteinian orbital resonances. The potential finding of a non-zero time variation of G is perhaps the most important aspect of SEE. A SEE mission will also involve a search for new particles with very low masses, since any evidence of violations of the EP would be analysed in terms of a putative new Yukawa-like particle. Thus, SEE does not merely test for violations of general relativity (GR); SEE is a next-generation gravity mission.

Project SEE (Satellite Energy Exchange): proposal for space-based gravitational measurements

Project SEE (Satellite Energy Exchange) is an international effort to organize a new space mission for fundamental measurements in gravitation, including tests of the equivalence principle (EP) by composition dependence (CD) and inverse-square-law (ISL) violations, determination of G, and a test for non-zero G-dot. The CD tests will be both at intermediate distances (a few metres) and at long distances (radius of the Earth, RE). Thus, a SEE mission would obtain accurate information self-consistently on a number of distinct gravitational effects. The EP test by CD at distances of a few metres would provide confirmation of earlier, more precise experiments. All other tests would significantly improve our knowledge of gravity. In particular, the error in G is projected to be less than 1 ppm. Project SEE entails launching a dedicated satellite and making detailed observations of free-floating test bodies within its experimental chamber.

Simulation of the procedure for measuring the gravitational constant on an Earth satellite

A simulation is described for measuring the newtonian gravitational constant G in the SEE space experiment. Two methods are examined for estimating G: the two-point method and the integral one. When the two-point method is used, to provide an error not more than ΔG/G ≈ 1·10−6 requires path measurements to be performed with an error of not more than 1·10−8 m=λ/50 (λ is the green line wavelength). In the integral method, the same error in estimating G is attained with an error of measurement different by two orders of magnitude, 1·10−6 m.

NUMERICAL MODELING OF THE TRAJECTORIES OF PARTICLES FOR MEASURING THE GRAVITATIONAL CONSTANT ON AN ARTIFICIAL SATELLITE

The results of numerical modeling of the trajectories of motion of a light body (a “particle”) with respect to a heavier body in the orbit of an artificial satellite are presented [1]. Plane circular and elliptic orbits of the heavy body are considered, ignoring the nonsphericity of the gravitational field of the earth, and also plane circular equatorial orbits taking the quadrupole moment of the earth into account. The sensitivity of the trajectories to small variations of the initial conditions and values of the parameters of the gravitational interaction is investigated. It is shown that for the space experiment carried out in [2] to be successful for determining the gravitational constant G and the parameters of the five-force, and to check the principle of equivalence at large distances, the theoretical model of the motion of a “particle/rd must take into account all the perturbations which lead to a displacement of the trajectories of more than 10−4 mm.

Measurement of gravitational interaction parameters on an earth-orbiting satellite

An analysis is presented of a space experiment whose purpose is to enhance the accuracy of measurement of the gravitational constant G, improve the estimates of the fifth force parameters α and λ,and finally to verify the equivalence principle. The experiment involves exact measurements of the trajectories of a light body relative to a heavy body on a drag-free Earth satellite. Estimations of the possible effect of various factors on the relative motion trajectory are made. The equations of relative motion are derived for various types of satellite orbits. Some preliminary estimates of the accuracy of the measurements are presented which show that the experiment proposed seems to hold promise.

ON TWO-BODY SPACE EXPERIMENTS FOR MEASURING GRAVITATIONAL INTERACTION PARAMETERS

Recently two methods of measuring the gravitational constant G, possible equivalence principle violation (measured by the Eotvos parameter η) and the hypothetic 5th force parameters α and λ on board a drag-free Earth’s satellite were suggested: SEE (Satellite Energy Exchange) and LPH (Libration Point Hitting). These methods are developed and compared. Various particle trajectories near a heavy ball are studied numerically and analytically. Some basic sources of error are analysed. The G measurement procedure is modelled by noise insertion to a “true” trajectory. It is concluded that the presense knowledge of G, α (for λ≥1 m) and η can be improved by at least two orders of magnitude.

Mini-see project to measure the parameters of gravitational interaction using the alpha international space station

The behavior of two bodies interacting gravitationally onboard a drift-free Earth satellite orbiting at the altitudes of the Alpha international space station is investigated. A numerical simulation of the trajectories of the relative motion of aparticle is performed, as a result of which preliminary estimates of the precision of the experiment are obtained. An estimate of the measurement precision of the parameters of gravitational interaction is given.