Publications (2)0 Total impact
ABSTRACT: The autonomous optical navigation system technology for the Deep Space 1 (DS1) mission is reported on. The DS1 navigation system will be the first to use autonomous navigation in deep space. The systems tasks are to: perform interplanetary cruise orbit determination using images of distant asteroids; control and maintain the orbit of the spacecraft with an ion propulsion system and conventional thrusters, and perform late knowledge updates of target position during close flybys in order to facilitate high quality data return from asteroid MaAuliffe and comet West-Kohoutek-Ikemura. To accomplish these tasks, the following functions are required: picture planning; image processing; dynamical modeling and integration; planetary ephemeris and star catalog handling; orbit determination; data filtering and estimation; maneuver estimation, and spacecraft ephemeris updating. These systems and functions are described and preliminary performance data are presented.
ABSTRACT: An approach for measuring the triaxial shape of Io from Voyager images is described. Triaxial shape of a satellite is detrmined by comparing the theoretical shape and location of the body's limb and terminator curves with the actual curves observed in the two dimensional images. Limb or terminator points are found by matching a model for the limb profile with the actual appearance of the limb in the digital data. The theoretical model for the limb model depends on the viewing and illumination geometry, the satellite reflection characteristics and the camera 'point spread function'. The method is applied to imaging data taken of Io in the last 25 hours befor Voyager 1's closet approach to the satellite.