Abstract
A dedicated mission in low Earth orbit is proposed to test predictions of gravitational interaction theories and to directly measure the atmospheric density in a relevant altitude range, as well as to provide a metrological platform able to tie different space geodesy techniques. The concept foresees a small spacecraft to be placed in a dawn-dusk eccentric orbit between 450 and 1200 km of altitude. The spacecraft will be tracked from the ground with high precision, and a three-axis accelerometer package on-board will measure the non-gravitational accelerations acting on its surface. Estimates of parameters related to fundamental physics and geophysics should be obtained by a precise orbit determination, while the accelerometer data will be instrumental in constraining the atmospheric density. Along with the mission scientific objectives, a conceptual configuration is described together with an analysis of the dynamical environment experienced by the spacecraft and the accelerometer.
Highlights
The near-Earth environment is an important place for performing experiments aimed at testing present models of the gravitational interaction
The range of scales corresponding to the semimajor axis of low Earth orbits (LEO) is a rather well-tested one [6,7], but room is left for improvements
METRIC can be seen as an evolution of CHAMP, keeping the spacecraft segment as simple as possible, compatibly with the mission requirements
Summary
The near-Earth environment is an important place for performing experiments aimed at testing present models of the gravitational interaction. We expand on a proposed concept [14], which we name METRIC (Measurement of EnvironmenTal and Relativistic In-orbit preCessions), to make use of existing technology developed for acceleration measurement in space and state-of-the-art satellite tracking to precisely determine the orbit of a spacecraft with well-defined geometrical and mass characteristics and to measure over a long period of time the drag deceleration (as well as other non-gravitational perturbations) acting on it This will result in a virtually drag-free spacecraft that can be exploited to investigate a number of effects related to gravitational physics and to the near-Earth environment, via a precise analysis of its orbital dynamics. A discussion of the dynamical environment experienced by the spacecraft is a prerequisite for a quantitative assessment of non-gravitational accelerations that will be sensed by the on-board accelerometer
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