Laser interferometer space antenna dynamics and controls model

Abstract

A 19 degree-of-freedom (DOF) dynamics and controls model of a laser interferometer space antenna (LISA) spacecraft has been developed. This model is used to evaluate the feasibility of the dynamic pointing and positioning requirements of a typical LISA spacecraft. These requirements must be met for LISA to be able to successfully detect gravitational waves in the frequency band of interest (0.1–100 mHz). The 19-DOF model includes all rigid-body degrees of freedom. A number of disturbance sources, both internal and external, are included. Preliminary designs for the four control systems that comprise the LISA disturbance reduction system (DRS) have been completed and are included in the model. Simulation studies are performed to demonstrate that the LISA pointing and positioning requirements are feasible and can be met.

Time domain simulations of arm locking in LISA

“…; 0:1 mHz f 0:1 Hz: (18) Note that due to the fact that the interior angle of the constellation is not 90 deg, the spacecraft jitter contributions from SC 1 will be partially correlated in the frequency meter signals A12 ðtÞ and A13 ðtÞ. Finally, we note that it would, in principle, be possible to remove the spacecraft jitter by including the short-arm interferometers in both the phase-lock error signals in the far SC and the arm-locking error signals in the master SC.…”

“…The spacecraft jitter noise model is based on simulations of the drag-free control performance of LISA [18]. The jitter can be divided into two orthogonal components in the plane of the LISA constellation that are independent.…”

Current LISA spacecraft design

“…Stringent requirements are placed on the rotational (8 nrad/ Hz) and translational dynamics (1.5 (1+(f/8mHz) 4 ) 1/2 nm/ Hz) of each spacecraft to ensure that the proper sensitivity for science measurements can be achieved. This is implemented by performing a number of control functions [8,9].…”

The LISA integrated model

“…The bulk of the effort is defining in detail the structural and thermal design along with the control systems. The control system model is discussed in the paper by Maghami in these proceedings [5].…”