Title: Probing the gravitational redshift with an Earth-orbiting satellite,
Abstract: We present an approach to testing the gravitational redshift effect using the
RadioAstron satellite. The experiment is based on a modification of the Gravity
Probe A scheme of nonrelativistic Doppler compensation and benefits from the
highly eccentric orbit and ultra-stable atomic hydrogen maser frequency
standard of the RadioAstron satellite. Using the presented techniques we expect
to reach an accuracy of the gravitational redshift test of order $10^{-5}$, a
magnitude better than that of Gravity Probe A. Data processing is ongoing, our
preliminary results agree with the validity of the Einstein Equivalence
Principle.