5.2 Progress on Pulsar Navigation
277
5.2 Progress on Pulsar Navigation
5.2.1 The Proposed Concepts
In 1967, the first radio pulsar was discovered by a doctoral student Jocelyn Bell and
her mentor Professor Antony Hewish at the University of Cambridge, the United
Kingdom. In 1972, the Pioneer-10 spacecraft was launched by the NASA to explore
the planets of the outer solar system and the interstellar space. The Pioneer-10 carried
the gold-anodized aluminum plate design by Carl E. Sagan et al., on which the
pattern using 14 radio pulsars to determine the positions of the Sun and Earth in
the Galactic System was drawn. One day, if the Pioneer-10 is intercepted by the
intelligent extraterrestrial civilization, then its launching location and epoch will be
calculated by observing the signals radiated from these pulsars. It is the first attempt to
obtain the position information by using the trigonometric intersection measurement
based on the pulsars and to get the time information based on the change rates of
pulse periods of the pulsars. Afterward, another gold-anodized aluminum plate and
two golden records with the 14-pulsar pattern were also mounted, respectively, on the
Pioneer-11, and Voyager-1 and Voyager-2, to transmit the Earth’s human civilization
information to space out of the solar system.
In 1974, George S. Downs working then at the NASA’s JPL proposed an
autonomous orbit determination method for the spacecrafts in interplanetary space
flight by using the radio pulsars, and estimated the orbit determination accuracy,
about 150 km [3]. There are three defects in this method: firstly, because the radiated
signals from pulsars in radio frequency are extremely weak, a high gain and large
aperture radio telescope are required in order to detect the radio pulse signals, and
typically, the antenna is with a diameter of more than 25 m; secondly, the radio signal
intensity radiated by pulsars are so low that the signal integration time is required
to be as long as 24 h to get enough high SNR; thirdly, most of the celestial radiation and galactic diffusion signals are distributed in the entire radio frequency band,
which submerges the extremely weak signals radiated by the pulsars, so that it is
disadvantageous to detect and extract the useful signals and eliminate the noises.
Downs’s method is difficult in engineering application, and by using the method, the
orbit determination accuracy is so low that cannot meet the requirements of highprecision autonomous navigation for spacecrafts. For all that, Downs is recognized
as the pioneer conducting the studies on the pulsar’s application. For infrared, visible
and ultraviolet pulsars, due to the small number and low luminosity, the large aperture telescope, high pointing accuracy and advanced signal processing technology
are required, so these types of pulsars are not suitable for the autonomous navigations
of spacecrafts [4, 5].
In 1981, the idea of using the X-ray signals radiated from pulsars to navigate
for spacecrafts was first proposed by Chester and Butman [6]. Most of the energy
radiation from the pulsars is concentrated on the X-ray band, which is advantageous
to detect and process, and reduces the time of signal integration. Especially, it is
conductive to the design of miniaturized detection devices, usually with the detection
277
5.2 Progress on Pulsar Navigation
5.2.1 The Proposed Concepts
In 1967, the first radio pulsar was discovered by a doctoral student Jocelyn Bell and
her mentor Professor Antony Hewish at the University of Cambridge, the United
Kingdom. In 1972, the Pioneer-10 spacecraft was launched by the NASA to explore
the planets of the outer solar system and the interstellar space. The Pioneer-10 carried
the gold-anodized aluminum plate design by Carl E. Sagan et al., on which the
pattern using 14 radio pulsars to determine the positions of the Sun and Earth in
the Galactic System was drawn. One day, if the Pioneer-10 is intercepted by the
intelligent extraterrestrial civilization, then its launching location and epoch will be
calculated by observing the signals radiated from these pulsars. It is the first attempt to
obtain the position information by using the trigonometric intersection measurement
based on the pulsars and to get the time information based on the change rates of
pulse periods of the pulsars. Afterward, another gold-anodized aluminum plate and
two golden records with the 14-pulsar pattern were also mounted, respectively, on the
Pioneer-11, and Voyager-1 and Voyager-2, to transmit the Earth’s human civilization
information to space out of the solar system.
In 1974, George S. Downs working then at the NASA’s JPL proposed an
autonomous orbit determination method for the spacecrafts in interplanetary space
flight by using the radio pulsars, and estimated the orbit determination accuracy,
about 150 km [3]. There are three defects in this method: firstly, because the radiated
signals from pulsars in radio frequency are extremely weak, a high gain and large
aperture radio telescope are required in order to detect the radio pulse signals, and
typically, the antenna is with a diameter of more than 25 m; secondly, the radio signal
intensity radiated by pulsars are so low that the signal integration time is required
to be as long as 24 h to get enough high SNR; thirdly, most of the celestial radiation and galactic diffusion signals are distributed in the entire radio frequency band,
which submerges the extremely weak signals radiated by the pulsars, so that it is
disadvantageous to detect and extract the useful signals and eliminate the noises.
Downs’s method is difficult in engineering application, and by using the method, the
orbit determination accuracy is so low that cannot meet the requirements of highprecision autonomous navigation for spacecrafts. For all that, Downs is recognized
as the pioneer conducting the studies on the pulsar’s application. For infrared, visible
and ultraviolet pulsars, due to the small number and low luminosity, the large aperture telescope, high pointing accuracy and advanced signal processing technology
are required, so these types of pulsars are not suitable for the autonomous navigations
of spacecrafts [4, 5].
In 1981, the idea of using the X-ray signals radiated from pulsars to navigate
for spacecrafts was first proposed by Chester and Butman [6]. Most of the energy
radiation from the pulsars is concentrated on the X-ray band, which is advantageous
to detect and process, and reduces the time of signal integration. Especially, it is
conductive to the design of miniaturized detection devices, usually with the detection