N95- 27788 Application of Non-coherent Doppler Data Types for Deep Space Navigation

Recent improvements in computational capability and Deep Space Network technology have renewed interestin examining the possibilityof using one-way Doppler data alone to navigate interplanetaryspacecraft. The one-way data can be formulated as the standard differenced-countDoppler or as phase measurements, and the data can be received at a singlestation or differencedifobtained simultaneously at two stations.A covariance analysisisperformed which analyzes the accuracy obtainable by combinations of one-way Doppler data and compared with similarresultsusing standard two-way Doppler and range. The sample interplanetary trajectory used was that of the Mars Pathfinder mission to Mars. It isshown that differencedone-way data is capable of determining the angular position of the spacecraft to fairlyhigh accuracy, but has relatively poor sensitivityto the range. When combined with singlestation data, the position dispersionsare roughly an order of magitudc largerin range and comparable in angular position as compared to dispersionsobtained with standard data two-way types. It was also found that the phase formulation is lesssensitiveto data weight variationsand data coverage than thc differenced-count Doppler formulation.