Rescuing Huygens [faulty receiver]

Abstract

This paper describes how the joint Huygens Recovery Task Force (HRTF) was able to fix a communications implementation flaw involving the receiver on the Cassini spacecraft which was tasked with obtaining detailed information and photographs of Titan, Saturn's largest moon. Although the receiver on Cassini captured and correctly interpreted data during tests in which both the Huygens space probe and the Cassini spacecraft would maintain the same relative position, there was substantial data loss when the tests simulated the craft's planned trajectories. Subsequently, additional in-orbit performance mappings could only ascertain the receiver deficiency. An analytical model of the receiver's symbol synchronizer was developed. In addition to explaining the dynamics of cycle slips in the symbol synchronizer, the model provided the Task Force with the remaining operational corridor of the receiver. This combined information formed the crucial basis for evaluating possible recovery scenarios by radically revising the orbiter/probe relative geometry.