The first flight of NASA's New Millennium Program, Deep Space 1, will include a new navigational technology: an autonomous optical navigation system. The DSI Navigation system will be the first use of autonomous navigation in deep space. The task for this system is to 1) perform interplanetary cruise orbit determination, using images of distant asteroids, 2) control and maintain the orbit of the spacecraft using the ion propulsion system (another technology never before applied to deep space) and conventional thrusters, 3) perform approach orbit determination and control using images of the science targets, 4) perform late knowledge updates of target position during close fast flybys in order to facilitate a high degree of quality data return from 2 targets: asteroid McAuliffe and comet West-Kohoutek-Ikemura. Additionally, an encounter with Mars will probably be performed with possibly a close flyby of one of the Martian moons, Phobos or Deimos. Several functional components are necessary to accomplish these tasks. These include picture planning and image processing, dynamical modeling and integration, planetary ephemeris and star catalog handling, orbit determination data filtering and estimation, maneuver estimation, spacecraft ephemeris updates and maintenance, and general interaction with the other onboard autonomous systems. These systems are described, as is the means of their operation onboard. Finally, performance statistics from trial runs of the system are given.

The Deep Space-1 (DS-1) mission to be launched in 1998 will use an autonomous navigation system to guide the spacecraft on a low thrust trajectory to flybys of an asteroid and a comet. The ion propulsion system to be validated on DS-1 will provide low thrust solar electric propulsion to the spacecraft and presents additional challenges to the development of the autonomous navigation system. In order to maintain a trajectory to the designated mission target bodies, the autonomous navigation system must autonomously determine the orbit of the spacecraft, and adjust the thrust profile to be implemented by the ion propulsion system to correct any deviations from the nominal spacecraft trajectory. A detailed description of the component of the autonomous navigation system that controls the low thrust profile of the ion propulsion system is presented, and examples of some tests of this system are used to illustrate its capabilities.

The first fully autonomous deep-space navigation system ever implemented is planned to guide the New Millenium Deep Space-1 mission to an asteroid and comet beginning in mid-1998. This system is based to a large extent on Optical Navigation (OPNAV) technology developed for the NASA/JPL interplanetary exploration probes Voyager and Galileo. This paper describes the structure and algorithmic content of the Autonomous OPNAV system. The system has several major autonomous functions: picture planning, image analysis, orbit determination, manuever design and general interaction with other onboard autonomous systems.

The navigation of the Near Earth Asteroid Rendezvous (NEAR) mission is described. This mission is the first of several low cost missions being planned to study the solar system. The primary purpose of this mission is to orbit the near-Earth asteroid 433 Eros and study it at close range. Elements of the NEAR Navigation System are described including navigation instrumentation, the spacecraft attitude control and propulsion system and the ground system consisting of tracking stations and software. Navigation accuracies are given for spacecraft orbit prediction and control. Key navigation parameters are noted, including the physical parameters that describe Eros such as mass, moments of inertia, and gravity harmonics. We also describe the orbit determination in support of science observations while in orbit about Eros.

A variety of low-cost space missions planned by NASA for flight in the late 1990's and early 2000's will involve rendezvous with, and orbits about, small solar-system bodies such as asteroids and comets. Rendezvous missions of this nature have never been performed, all previous small-body encounters having been flybys. Thus in navigating these missions there are a number of issues and challenges which are new. This paper will identify the different mission phases for small body encounters and the navigation requirements, objectives and goals involved with each phase. In addition, certain practical limitations with respect to mission design will be identified and the scientific information obtained by navigation during the mission discussed.

All previous spacecraft encounters with small solar-system bodies, such as asteroids and comets, have been flybys (e.g. Galileo's flybys of the asteroids Gaspra and Ida). Several future projects plan to build on the flyby experience and progress to the next level with rendezvous and orbit missions to small bodies. This presents several new issues and challenges for navigation which have never been considered before. This paper addresses these challenges by characterizing the different phases of a small body rendezvous and by describing the navigation requirements and goals of each phase. Prior to the encounter with the small body, improvements to its ephemeris and initial estimates of its physical parameters, e.g. size, shape, mass, rotation rate, rotation pole, and possibly outgassing, are made as accurately as ground-based measurements allow. This characterization can take place over years...

Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.