Feasibility of utilizing the 200-inch Hale telescope as a deep-space optical receiver

Capturing the very faint optical communications signals expected from the Mars Laser Communication Demonstration (MLCD) experiment to fly aboard the Mars Telecommunications Orbiter (MTO) in 2009 requires a sensitive receiver placed at the focus of a large collecting aperture. For the purpose of demonstrating the potential of deep-space optical communication, it makes sense to employ a large astronomical telescope as a temporary receiver. Because of its large collecting aperture, its reputation as a well-run instrument, and its relative convenience, the 200-inch Hale Telescope on Palomar Mountain is being considered as a demonstration optical 'antenna' for the experiment. However, use of the telescope in this manner presents unique challenges to be overcome, the greatest of which is pointing the telescope and maintaining the communication link to within a few degrees of the Sun. This paper presents our candidate approaches for adapting the Hale telescope to meet the demonstration requirements, modifications to the facilities and infrastructure, the derivation of requirements for baffles and filters to meet the near-Sun pointing objectives, and initial data on the potential of candidate modifications to meet the requirements.