Drag-free deep-space laser ranging missions for fundamental physics

Abstract

Over the next decade the gravitational physics community will benefit from dramatic improvements in many technologies critical to the tests of gravity and gravitational wave detection. The highly accurate deep space navigation, interplanetary laser ranging and communication, interferometry and metrology, high precision frequency standards, precise pointing and attitude control, together with drag-free satellite attitude control will revolutionize the field of experimental gravitational physics. Deep space laser ranging will be ideal for gravitational wave detection, and testing relativity and measuring solar system parameter to an unprecedentend accuracy. We use ASTROD (Astrondynamical Space Test of Relativity using Optical Devices) with three spacecraft and ASTROD I with a single spacecraft as examples for application those technologies. In this paper, we will present the scientific goals and optical requirements of the different mission scenarios, and will summarize the progress of ASTROD / ASTROD I mission studies with emphasis on optical interferometry, the acceleration noises, drag-free attitude control and low-frequency gravitational wave sensitivity.