Mission analysis for the Laser Interferometer Space Antenna (LISA) mission

Abstract

The interplanetary orbits of three pairs of spacecraft, forming three laser interferometers, are designed such that their separations, i.e. the lengths of the interferometer arms, remain nearly constant. Each spacecraft pair is located near the vertex of a rotating equilateral triangle formed by the individual orbits of the spacecraft about the Sun. Feasible spacecraft masses are computed for a scenario with an Ariane 5 launch into a Geostationary Transfer Orbit (GTO) and a three-burn transfer from the GTO to the triangular configuration. The relative motion is perturbed by planetary gravity. However, the arm rate differences degrading the interferometer accuracy can be kept below certain limits by choosing optimum initial conditions and/or by controlling them by occasional orbit adjustment manoeuvres. The achievable orbit determination accuracy is given for systems processing two-way range and Doppler data collected on ground and/or laser interferometer measurements of the rate of change of distance between spacecraft.