4.3 Celestial Navigation System
209
the ship’s position line by using the altitude difference, to simplify the operational
process of the celestial navigation. The simplified navigation way laid the theoretical
and practical foundation for the modern maritime ship’s celestial navigation, which
has been used up to now.
Since the 1950s, with the rapid development of electronic technology, computer
and space technology, the positioning accuracy based on the celestial navigation has
reached several hundred meters. Thereby, the celestial navigation was applied to
military ships, submarines, medium and long-range bombers and missiles, and its
strategic advantages and military utilization values were demonstrated clearly. The
American Apollo Program and the Soviet projects of space stations directly promoted
the development of celestial navigation technology and its wide application in the
field of spacecraft’s navigation and control technology. In the early 1960s, the U.S.
Air Force initiated the project of studying the autonomous navigation of satellite,
called Program 283. Taking the Earth’s circle disk as the measurement reference
in the Program 283, the navigation system configuration includes attitude reference
system, horizon scanner, onboard computer and clock system, among which the
attitude reference system consists of three strap-down inertial gyroscopes and one
gimbaled star tracker, and thus the satellite’s navigation can be carried out by using
the horizon scanning data of the inertial platform. The system’s navigation accuracy
is mainly limited by the error of the horizon scanner, with the estimated orbit accuracy of 2 km. In addition, a standard space guidance system was developed by the
U.S. Air Force, which takes the fixed ground landmarks as the measurement reference, and adopts three measurement schemes, including horizon scanning, known
landmark tracking and unknown landmark tracking. By using the landmark tracker
to measure the direction vector from the spacecraft to the landmarks, and combining
the attitude reference system, the orbit and attitude parameters of the spacecraft
can be determined, with the estimated navigation accuracy of 0.2−2 km. In 1973,
a spacecraft subsystem that has the integrated capability of onboard orbit determination with attitude determination, called Space Sextant−Autonomous Navigation
Attitude Reference System (SS-ANARS), began to be developed in the United States.
Actually, the Space Sextant is composed of two optical telescopes mounted on the
same three-degree-of-freedom gimbaled platform, one of which is used to track the
Earth’s limb or the Moon’s limb while the other is used to track the known brighter
stars, and the basic observables composed of the angles between the two lines of
sight are used to estimate the navigation parameters by using the Kalman filter with
the onboard digital computer. The demonstration system of the SS-ANARS had been
flown as a sortie payload on the Space Shuttle to prove its autonomous-integrated
orbit and attitude determination capabilities. With the SS-ANARS, the spacecraft’s
position accuracy is 243−366 m for any Earth orbit, and the attitude determination
accuracy relative to the celestial sphere is better than 1 arc-second. In 1979, a lowcost, strap-down and modular attitude reference navigation system, called the Multimission Attitude Determination and Autonomous Navigation (MADAN) program,
was developed by the U.S. Air Force to provide continuous and real-time inertial
attitude and orbit information for advanced spacecraft application, with the property
of full autonomy and long life. By replacing software and hardware modules, the
209
the ship’s position line by using the altitude difference, to simplify the operational
process of the celestial navigation. The simplified navigation way laid the theoretical
and practical foundation for the modern maritime ship’s celestial navigation, which
has been used up to now.
Since the 1950s, with the rapid development of electronic technology, computer
and space technology, the positioning accuracy based on the celestial navigation has
reached several hundred meters. Thereby, the celestial navigation was applied to
military ships, submarines, medium and long-range bombers and missiles, and its
strategic advantages and military utilization values were demonstrated clearly. The
American Apollo Program and the Soviet projects of space stations directly promoted
the development of celestial navigation technology and its wide application in the
field of spacecraft’s navigation and control technology. In the early 1960s, the U.S.
Air Force initiated the project of studying the autonomous navigation of satellite,
called Program 283. Taking the Earth’s circle disk as the measurement reference
in the Program 283, the navigation system configuration includes attitude reference
system, horizon scanner, onboard computer and clock system, among which the
attitude reference system consists of three strap-down inertial gyroscopes and one
gimbaled star tracker, and thus the satellite’s navigation can be carried out by using
the horizon scanning data of the inertial platform. The system’s navigation accuracy
is mainly limited by the error of the horizon scanner, with the estimated orbit accuracy of 2 km. In addition, a standard space guidance system was developed by the
U.S. Air Force, which takes the fixed ground landmarks as the measurement reference, and adopts three measurement schemes, including horizon scanning, known
landmark tracking and unknown landmark tracking. By using the landmark tracker
to measure the direction vector from the spacecraft to the landmarks, and combining
the attitude reference system, the orbit and attitude parameters of the spacecraft
can be determined, with the estimated navigation accuracy of 0.2−2 km. In 1973,
a spacecraft subsystem that has the integrated capability of onboard orbit determination with attitude determination, called Space Sextant−Autonomous Navigation
Attitude Reference System (SS-ANARS), began to be developed in the United States.
Actually, the Space Sextant is composed of two optical telescopes mounted on the
same three-degree-of-freedom gimbaled platform, one of which is used to track the
Earth’s limb or the Moon’s limb while the other is used to track the known brighter
stars, and the basic observables composed of the angles between the two lines of
sight are used to estimate the navigation parameters by using the Kalman filter with
the onboard digital computer. The demonstration system of the SS-ANARS had been
flown as a sortie payload on the Space Shuttle to prove its autonomous-integrated
orbit and attitude determination capabilities. With the SS-ANARS, the spacecraft’s
position accuracy is 243−366 m for any Earth orbit, and the attitude determination
accuracy relative to the celestial sphere is better than 1 arc-second. In 1979, a lowcost, strap-down and modular attitude reference navigation system, called the Multimission Attitude Determination and Autonomous Navigation (MADAN) program,
was developed by the U.S. Air Force to provide continuous and real-time inertial
attitude and orbit information for advanced spacecraft application, with the property
of full autonomy and long life. By replacing software and hardware modules, the