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Loading contentUsing a spacecraft's own camera images of a target body against the background stars to determine its position relative to that body — essential in the final approach to an asteroid, comet, or moon, where ground tracking alone is not precise enough.
Facts on this topic will be cited from these primary and reference sources.
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.
Orbital data, ephemerides, and small-body parameters for planets, asteroids, and comets.