JPH0284827A - Data relay satellite system - Google Patents

Abstract

PURPOSE:To always secure communication with a user spacecraft and to improve the operationability and the safety of the user spacecraft by arranging a second data relay satellite arranged on a second orbit circulating the earth. CONSTITUTION:The second data relay satellite 3 is arranged on the second orbit 13 circulating the earth in addition to a first data relay satellite 1. When the user spacecraft 2 is located at the orbit hatched between a point A where becomes the shadow of the earth 11 against the satellite 1 and a point B, the communication is performed via the satellite 3 on the orbit 13. ln other words, a communication path is formed as the path to connect the spacecraft 2 from an earth station 4 via the satellite 1 and the satellite 3. In such a case, a condition to select the height of the satellite 3 can be set by locating the position of the satellite 3 in a range among dotted chain lines C, D, and E where both the spacecraft 2 and the satellite 1 can be visualized at a time when the spacecraft 2 enters the point A and locating the satellite 3 on the orbit where is the range between the points D and E at a time when the spacecraft 2 passes the point B. In such a way, it is possible to always secure the communication with the spacecraft 2 and to improve the operationability and the safety of the spacecraft 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a data relay satellite system, and particularly to a data relay satellite system that transmits data from spacecraft orbiting the earth, such as earth observation satellites and space stations.

[Conventional technology]

Satellites such as earth observation satellites and space stations that orbit in low orbits near the earth have a narrow communication area with respect to earth stations installed on the ground, making it difficult to always ensure communication between the satellite and the ground. Therefore, conventionally, as shown in the configuration diagram of FIG. 2, a data relay satellite 1 is provided in a geostationary orbit where communication is possible from an earth station 4 at all times. It is communicating with the user spacecraft 2 orbiting the earth.

[Problem to be solved by the invention]

However, when the user spacecraft 2 comes within the range from point A to B in Figure 2, it will be in the shadow of the earth 11, making communication between the user spacecraft 2 and the data relay satellite 1 impossible, resulting in a communication breakdown and a so-called blackout. do.

In order to alleviate this blackout, a method has been adopted in which another data relay satellite (not shown) on the geosynchronous orbit is located at a different longitude than the data relay satellite 1 on the geosynchronous orbit. However, even in this case, there is a drawback that blackout may occur, which is an extremely important problem in terms of operation and safety, especially when the user spacecraft 2 is a space station and may be manned.

[Means to solve the problem]

The data relay satellite system of the present invention is the first satellite orbiting the earth.
In a data relay satellite system that performs communication between a user spacecraft in orbit and an earth station, a first data relay satellite is placed in a geostationary orbit, and a second data relay satellite is placed in a second orbit orbiting the earth. and a second data relay satellite, and communication between the user spacecraft and the earth station is performed via at least one of the first and second data relay satellites.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a configuration diagram of an embodiment of the present invention. This embodiment shows a data relay satellite 1 in a geostationary orbit, a user spacecraft 2 in an earth orbit, and a user spacecraft 2 in an earth orbit.
Data relay satellite 3 and earth station 4 in another earth orbit
, the earth 11, the first orbit 12 of the user spacecraft 2, and the second orbit 13 of the data relay satellite 3. The communication path between the earth station 4 and the user spacecraft 2 is normally a path between the earth station 4 and the user spacecraft 2 via the data relay satellite 1 in geostationary orbit.

If the user spacecraft 2 is located on the hatched orbit between points A and B in FIG. 1, which is in the shadow of the earth 11 relative to the data relay satellite 1, )
Communication is carried out via the data relay satellite 3 above, that is,
The communication path is from the ground station 4 to the user spacecraft 2 via the data relay satellite 1 in geostationary orbit and the data relay satellite 3 in orbit.

The conditions for selecting the altitude of the data relay satellite 3 on the second orbit 13 are as follows. When the user spacecraft 2 enters point A between hatched A and B in Figure 1, the position of the data relay satellite 3 is such that both the user spacecraft 2 and the data relay satellite 1 in geostationary orbit are visible. Dotted chain line C-D in Figure 1
- E, and when the user spacecraft 2 passes point B, the position of the data relay satellite 3 is assumed to be in the orbit between points DE in FIG. 1 for the same reason.

〔Effect of the invention〕

As explained above, the present invention arranges a second data relay satellite in earth orbit in addition to the first data relay satellite in geostationary orbit! By doing so, it becomes possible to always ensure communication with the user spacecraft, improving the operability of the user spacecraft.
It has a great effect on safety.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional data relay satellite system. 1.3...Data relay satellite, 2...User spacecraft,
4...Earth station, 11...Earth, 12...First orbit, 13...Second orbit, 14.15...Earth orbit direction.

Claims (1)

[Claims] In a data relay satellite system that performs communication between a user spacecraft on a first orbit orbiting the earth and an earth station, the first data relay satellite placed on a geostationary orbit and the first data relay satellite orbiting the earth a second data relay satellite disposed on a second orbit, and communicates between the user spacecraft and the earth station via at least one of the first and second data relay satellites. A data relay satellite system characterized by: