JPS6340057B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a three-axis attitude control communication satellite that is transported and assembled in parts to a space station in low orbit using several rockets (or space shuttles).

With advances in rocket technology, geostationary communication satellites have gradually become larger, and in particular, by being equipped with large antennas, spot beams of the same frequency can be divided into multiple areas and radiated, which will only increase frequency reuse efficiency. Rather, by increasing the antenna gain, the transmission output of both the ground and communication satellites can be reduced. Therefore, a communication satellite having such functions and an assembly structure that is easy to implement is desired, and various proposals have been made. As a means of realizing such a communication satellite, the assembled equipment is launched into low orbit using a shuttle orbiter, and then an orbital antenna arm (OAF) is assembled using the orbiter.
There are two options: (1) deploying the folding antenna after placing it in geostationary orbit using a transfer vehicle; and (2) having the antenna completed in low orbit and then quietly transporting it to geostationary orbit using an electric propulsion OTV. (For example, B.
I. Edelson and WLMorgan “Orbital Antenna
Farms”Astronautics and Aeronautics
(Vol. 15, No. 9, September 1977) The antenna farms that have been announced so far employ a method in which the antenna and the mission equipment are installed separately using the beam of the truss structure as a reference.
However, in communication satellites equipped with large, multi-beam antennas with sharp directivity, it is necessary to connect the onboard receivers and transmitters with the antennas using many high-frequency feeders. An integrated structure with communication equipment is superior in terms of ease of manufacture and reliability. In addition, the surface accuracy of the antenna must be approximately 1/30th of one wavelength of the signal frequency or less, otherwise the gain and directivity characteristics will be lost. For example, considering a signal frequency of 10 GHz, this requires an accuracy of 1 millimeter. On the other hand, the diameter of the antenna is 5 to 10
It is necessary to take into account the deformation caused by sunlight and shade. Therefore, it is technically problematic to maintain accuracy of 1 millimeter or less in the folding method. In addition, there is a proposal to connect additional communications mission equipment in geostationary orbit, but since these devices require not only mechanical connections but also numerous electrical connections, there are many technical problems to realize. I can say that.

Based on the above considerations, the present invention provides a three-axis attitude control communication satellite having multiple large antennas that is easy to assemble on a space station in low orbit and has high operational reliability after entering geostationary orbit. The purpose is to

According to the present invention, a common module is disposed in the center, several communication modules having substantially similar structures and two sets of power modules are disposed around the common module, and the common module and the communication modules or power modules are disposed in the center. The modules are connected radially with connecting beams of a predetermined length, and the center of gravity is placed approximately near the central axis of the common module placed in the center, and the center of gravity is placed near the central axis of the common module placed in the center. A three-axis attitude control communication satellite that can be assembled in space is obtained, which is characterized in that the two are connected by support beams for maintaining spacing.

As the payload of communication satellites increases,
The benefits of increasing size are increasing. especially,
Communication satellites equipped with large multi-beam antennas can provide attractive communication systems in terms of frequency reuse and reduced power requirements for onboard transmitters.

However, on the other hand, it is necessary to give sufficient consideration to the disadvantages of increasing the size. That is, the difficulty of maintenance and inspection, and the complexity of integration design and specific work increase. The present invention reduces the above-mentioned problems by creating a structure that is appropriately decentralized using modular connecting beams, and by minimizing assembly work on the space station for electrically and mechanically critical parts.

The present invention will be described in detail below with reference to the drawings.
FIG. 1 is an example of an external view of a large communication satellite to which the present invention is applied in a geostationary orbit, and FIG. 2 is a front view thereof. In addition, Fig. 3 shows a-b of Fig. 2.
FIG. In the figure, 1 is a common module for tracking, telemetry, and
It houses the command (TTC) function, attitude control system, exchange function between communication modules, etc. Further, although 4 to 9 indicate six independent communication modules, it would be practical to set the number to two to eight. 2 and 3 are power modules having exactly the same structure, the side structures of which are shown in FIGS. 3A and 3B.

Figure 3A shows the solar array paddle 21 on the geostationary orbit.
Figure B shows the expanded structure of 31 when it is flying in a transition orbit with OTV10 from the space station. Power modules 2 and 3 are equipped with a charger, fuel for attitude control, and jet nozzles 22/32, 23/33, and 24/34. Further, the power modules 2 and 3 are connected to the common module 1 by connecting beams 101 and 106. Note that an omni antenna 11 for TTC is attached to the common module 1. The strength of the connecting beams 101 to 108 is slightly flexible, and when the thrust of the OTV 10 fluctuates,
Even if the rectangular truss structure is slightly deformed into a parallelogram shape, it can be said that the direction of the central axis of each module remains almost unchanged. Further, the support beams 111-118 are attached to prevent twisting movement of the connecting beams 101-108. This is true in the case of communication modules.
Guarantees that the pointing direction of the antenna does not change. Furthermore, electrical wiring to and from the common module 1 runs through the tubes forming the connecting beams 101 to 108. Further, the lengths of the connecting beams 101 to 108 are determined after the weight of each module is determined, so that the center of gravity is aligned with the central axis of the common module.

FIGS. 4A and 4B show cross-sectional views of the communication module. 4 is a module that accommodates a transmitter/receiver, a modulator/demodulator, an exchange, a large antenna radiator, 414, etc., and the direction of the radiator is semi-fixed after being adjusted on the ground. FIG. 4A shows a Cassegrain type antenna, and FIG. 4B shows an offset type antenna.The mounting position of the radiator 414 is approximately at the center of the module in the Cassegrain type, and at the edge of the module in the offset type.

In addition, the secondary reflector base assembly section 411 of the antenna
is a structure attached to the antenna radiator 414,
Moreover, the dimensions are such that it can be transported using the H1 rocket without being dismantled.

The primary reflector 413, the support arm 415 that supports it, and the secondary reflector additional assembly section 412 are parts that require assembly or adjustment on the space station. The primary reflector 413 is designed to slightly correct the pointing direction of the antenna based on the fluctuations in the attitude of the large communication satellite as a whole, which is mechanically movable. The drive mechanism for this is housed inside the module body.

By applying the present invention, the following effects can be expected.

(1) Each module, excluding the antenna secondary reflector additional assembly, is of a scale that can be transported to the space station by the H1 rocket without disassembly, and each module can be produced in parallel at a specialized factory.

(2) Since the length of the connecting beam can be changed relatively easily, the mounting position of the OTV, which should be the center of gravity, can always be set at the fixed position on the back of the common module.

(3) The flexibility of the connecting beams can alleviate the shock vibrations that the OTV thrust exerts on communication transmission equipment.

(4) Since each module, except for the common module, is arranged as a satellite, assembly, inspection, maintenance, and replacement can be performed in parallel at the space station.

[Brief explanation of the drawing]

Figure 1 is an external view of a communication satellite to which the present invention is applied;
Figure 2 is a front view of Figure 1, Figure 3 is a-a- of Figure 2.
FIG. 4A is a cross-sectional view of a communication module to which the present invention is applied, and FIG. 4B is a cross-sectional view showing another example of a communication module to which the present invention is applied. In the figure, 1...common module, 2, 3...
...Power Module, 10...OTV, 11...
TTC antenna, 21, 31...Solar battery paddle,
4-9...Communication module, 101-108...
...Connection beam, 111-118...Support beam, 411...
...Antenna secondary reflector basic assembly part, 412...Antenna secondary reflector plate additional assembly part, 413...Antenna primary reflector plate, 414...Antenna radiator, 41
5...Antenna primary reflector support part.

Claims (1)

[Scope of Claims] 1. A common module is disposed in the center, and around it several communication modules having substantially similar structures and two sets of power modules are disposed, and the common module and the communication system The module and the power module are radially connected by a connecting beam of a predetermined length, and the center of gravity is provided approximately near the central axis of the common module arranged in the center, and the communication system adjacent to the surrounding An assembly type three-axis attitude control communication satellite for use in space, characterized in that a module and the power module are connected by a support beam for maintaining spacing. 2. The communication system module is assembled in advance by integrating the horn-shaped radiator of the large antenna and the basic assembly of the secondary reflector on the ground, and the primary reflection of the large antenna is carried out on the space station in low orbit. The three-axis attitude control communication satellite in space as claimed in claim 1, further comprising a plate and a secondary reflector additional assembly section.