Nearby earth astrometric telescope

 

Only extremely-high-precision astrometry, in space, can detect the dynamical effect due to even low mass orbiting planets on their central star, reaching the scientific goals NEAT aims at.


So NEAT will continue the work performed by Hipparcos (1 mas precision) and Gaia (7 μas aimed) by reaching a precision that is improved by two orders of magnitude (0.05 μas, 1 σ accuracy). Focusing its work on small-field, relative, astrometry. The Figure bellow shows an example of the detection of a 1.5 Earth mass planet by the joint-periodogram of its astrometric signal, with a false alarm probability < 1%. 

The observations will be performed by a long focal length telescope (f = 40m) with a single mirror off-axis parabola telescope (D = 1 m). The focal plane and the mirror would fly in two independent spacecraft.


NEAT measurements does not rely on the inaccessible mechanical stability of the instrument or of its focal plane detectors, but on an interferometric calibration of the position of 8 small movable CCDs located around a fixed central CCD in the focal plane. The calibrations are performed by monitoring Young’s fringes originating from metrology fibres located on the primary mirror.