Engineering topics

Sybert, Catherine B.

Publications and source records attributed to Sybert, Catherine B..

2 records

NASA NTRS1992

Planetary approach orbit determination using earth-based short and long baseline radio interferometry

This paper describes an investigation and comparison of the approach-phase orbit determination performance of delta-Very Long Baseline Interferometry (delta VLBI) and Connected Element Interferometry (CEI) data types when used in conjunction with conventional two-way Doppler data. Simulated data sets containing Doppler plus delta VLBI data and Doppler plus CEI data are used to calculate approximate orbit determination accuracy statistics for representative approach trajectories drawn from future robotic missions to Mars and Jupiter. The results illustrate the theoretical performance of CEI data acquired from short (20 km) baselines relative to that obtained with delta VLBI using the intercontinental baselines currently available within the NASA/JPL Deep Space Network.

Thurman, Sam W.↗

NASA NTRS1991

Small body mass determination from a flyby

This paper investigates the accuracy with which the mass of a small body can be determined from a flyby. Due to the nearly linear nature of hyperbolic flybys of small bodies, analytic solutions can be derived. Four analytic solutions are developed, each of increasing complexity with different applications. These solutions are compared to a complex computer simulation for accuracy. When these methods are applied to nearly linear trajectories, the analytic solutions agree with the computer simulation results to within 4.0 percent except in one boundary case which is discussed in the text. Also described is the linear range for which these equations are applicable. These solutions are then applied to the proposed asteroid flyby of the CRAF mission to predict the mass estimate accuracy.

Sybert, Catherine B.↗