Phobos Will Deflect Mars Express (VIDEO) European Space Agency This video is under embargo. Please login to access this video. To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Caption This animation shows how the orbit of Mars Express has been influenced by the gravitational influence of Phobos during the spacecraft's flybys of the moon in summer 2008. Since the orbital deviation strictly depends on the mass and shape of the moon, scientists could use this very deviation to determine the mass of Phobos with unprecedented accuracy (1.072 1016 kg, or about one billionth the mass of the Earth). Credit MaRS team/Observatoire Royal de Belgique Usage Restrictions For non-commercial use only. For free use only with full credit line indicated. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.