Sample-return missions to primitive solar system bodies (asteroids, comets, and planetary satellites) can provide a wealth of scientific information and insight into the composition and origins of the solar system. Recent interest in primitive body missions has been driven by the possibility of human near-Earth object missions, Earth conjunction analysis, and scientific discovery. Precision navigation to acquire a sample from a primitive solar system body and return it to Earth presents unique challenges beyond traditional Earth-based and interplanetary missions.

The overall objective of this effort was to develop, analyze, and optimize advanced navigation strategies required to meet the unique challenges for precision navigation to acquire a sample from an asteroid and bring it to Earth. A systematic study of the navigation strategy during proximity operations was performed using simulated data from a design reference mission (DRM). The objective of the DRM was to approach, rendezvous, orbit, and contact the surface of a near-Earth asteroid. A baseline navigation strategy was designed to meet the navigation requirements defined by the DRM. Elements of the baseline navigation strategy include ground station tracking schedules, the utility and frequency of spacecraft-based measurements, and the implementation of spacecraft autonomy. Additionally, the baseline strategy defined the location and frequency of rendezvous maneuvers, as well as the trajectory design for the approach, survey, orbit insertion, and stable orbit mission phases. High-fidelity simulations of the DRM provided data to perform covariance and error analysis on the baseline navigation strategy. Results from the enhanced in-house efforts were compared with results from a parallel analysis performed using flight-tested software for verification and validation.

The nominal design reference mission and navigation strategy provide a baseline to compare future results and optimization. The tools and analyses developed in this study provide a method of generating realistic data and characterizing spacecraft- asteroid relative state errors during proximity operations. Applications include current and future primitive body missions that require precision navigation during proximity operations.

This work was done by Kenneth Getzandanner and Russell Carpenter of Goddard Space Flight Center, Bobby Williams and Jeremy Baumann of KinetX, and Anne Long of AI Solutions. Inc. GSC-16294-1

NASA Tech Briefs Magazine

This article first appeared in the January, 2015 issue of NASA Tech Briefs Magazine.

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