JPH01101299A - Artificial satellite for earth survey - Google Patents

Abstract

PURPOSE: To increase the observation frequency for a target by use of a small number of artificial satellites by calculating a target position as seen from each artificial satellite by use of a computing device in each artificial satellite on the basis of information about orbits and attitudes, and controlling the direction of the viewing field of an observation sensor. CONSTITUTION: When a target position whose image is to be acquired by an observation sensor 2 from the ground is input to a computing device 8 via a command device 7, the relationship between the target position and the position of an artificial satellite is calculated as a function of time on the basis of orbit information about the artificial satellite 1, transmitted from an orbit information device 6. Then, since the attitude of the artificial satellite is always determined by an attitude control device 5, the direction of the target position for image acquisition by the observation sensor 2 can be calculated by the computing device 8 at an angle based on a coordinate system affixed to the artificial satellite 1. When a drive 4 is controlled so that the direction of the viewing field of the observations sensor 2 attains the angle of the target position of the artificial satellite coordinate system, the image of the target position at a certain time of the command from the ground can be acquired and transmitted to the ground by an image data transmission device 3.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an earth observation satellite that is equipped with an optical sensor or a radio wave sensor to acquire images of the earth and transmit them to the ground.

[Conventional technology]

BACKGROUND ART Artificial satellites have been used as an effective means of observing the earth over a wide range, as seen in the examples of Landsat satellites, SeaSat satellites, and Spot satellites in Europe and the United States, and ocean observation satellites in Japan. Figure 2 shows a conventional Earth B satellite.
is an artificial satellite orbiting the earth, (2) is an observation sensor that acquires images of the earth, (3) is an image data transmission device that transmits the images acquired by observation sensor (2) to the ground,
(5) is an attitude control device that controls the attitude of the satellite (1), and (7) is a device that receives, decodes, stores, and transmits command signals from the ground to control the satellite Il+ 4 and onboard equipment. It is a command device.

Note that Figure 2 shows other equipment on the satellite.

For example, a power supply device, a tracking and telemetry device, a gas jet device, a structure, etc. are required, but these are omitted because they are not directly relevant to the explanation of the present invention.

In such earth observation satellites, the viewing direction of the observation sensor (2) is fixed with respect to the satellite (1), and the satellite (11) is placed in a preselected orbit (usually a sun-synchronous orbit). Detect an earth image corresponding to the swath width of the a sub-sensor (2) (width of field of view on the ground surface of the sensor perpendicular to the direction of travel) along the earth trace of the first artificial satellite in flight, using, for example, a synthetic aperture radar. The data is transmitted to the ground and reproduced by the video data transmission device (3) shown in FIG.

[Problems to be solved by the invention] The purpose of all artificial satellites, such as the Landsat satellite and Spot satellite, which have been introduced above, is to acquire images of as wide an area as possible on the ground during the mission period, and they cannot capture images of the earth's surface from the same orbit. You can only get images of the same area. Therefore, as an artificial satellite for the purpose of obtaining ground surface images that are not related to short-term fluctuations such as resource exploration, a simple mechanism can provide sufficient functionality. For example, monitoring short-term fluctuations such as river flooding and forest fire areas, preferably several times at a time.
In order to obtain images from approximately the same location, it would be uneconomical to launch a large number of satellites (because their orbits deviate each time they orbit).

The present invention was made to solve these conventional problems, and aims to provide an earth observation satellite that can increase the frequency of observation of observation targets using a small number of satellites.

[Means for solving problems]

The earth observation satellite according to the present invention has a mechanism that can change the field of view direction of the observation sensor, and an arithmetic unit in the satellite calculates the target position as seen from the satellite based on information on the orbit and attitude of the satellite. Based on the results, the field of view of the a111II sensor is controlled to be directed toward the target position.

[For production]

In this invention, based on the instruction of the image acquisition target position from the ground, the artificial satellite recognizes the relative relationship with the artificial satellite at the specified target position from the position and attitude of the artificial satellite, and matches the viewing direction of the observation sensor with the target position. Observe the same target position or area from multiple different orbits of an artificial satellite.

〔Example〕

Figure 1 shows the earth observation satellite according to this invention.
In the figure, there are 11 satellites, (2) is the observation sensor, (
3) is a video data transmission device, (4) is an observation sensor (2B
A drive device (5) drives the viewing direction of the sun 1. to the target position. Attitude control device that determines the satellite's attitude and simultaneously obtains the satellite's attitude by observing the earth or stars, (6) is an orbit information device that determines the satellite's orbit, and (7) is from the ground. A command device that receives, decodes, stores, and sends all command signals for the satellite (8I is the attitude information from the attitude control device (5), the orbit information from the orbit information device (6), and the command device (7) This is a calculation device that calculates the field of view target direction of the observation sensor (2) and the orbit/attitude relationship of the artificial satellite based on information about the observation target from the ground, and controls the drive device (4). In the figure, other devices 9 generally constituting the satellite, such as a power supply device.

The tracking telemetry device, gas jet device, structure, instrumentation system, etc. are omitted because they are not directly related to the explanation of this invention.

When the target position for which images should be acquired from the ground by the observation sensor (2) is manually input to the calculation unit (8) via the command device (7), the relative positional relationship between the target position and the artificial satellite Ill is determined by the orbit information device (6). ) is calculated as a time function based on the orbit information regarding the artificial satellite 11).

In addition, the orbit information of this orbit information device can be obtained by using a positioning device using an artificial satellite using the global positioning system, or by determining the orbit of the artificial satellite (1) on the ground and sending that information to the artificial satellite Il+. This can be done by either recording the information.

As mentioned above, if the time function of the target position as seen from the satellite Ill is determined, the attitude of the satellite is always controlled by the attitude control device (5).
Therefore, the image acquisition target position direction of the observation sensor (2) can be calculated as an angle with respect to the coordinate system fixed to the artificial satellite 11). By performing the above calculations in the calculation device (8) and controlling the drive device (4) so that the viewing direction of the observation sensor (2) becomes the angle of the target position based on the satellite coordinate system described in 1. It is possible to acquire an image of any target position at any commanded time and transmit the acquired image to the ground using the image data transmission device (3). Although the observation sensor is not specified in the above embodiment, it is possible to For example, optical sensors with various wavelength bands and synthetic aperture radars can be considered.Radio sensors such as microwave radiometers and radio altimeters can be considered.For example, methods for varying the viewing direction of optical sensors include mirror systems and lenses. This can be done by changing the optical axis depending on the system, or by rotating the entire optical system of the optical sensor relative to the satellite itself, or by mechanically changing the beam direction of the antenna in the case of radio sensors.

This can be done by using an active phased array antenna.

〔Effect of the invention〕

As described below, since the earth observation satellite according to the present invention can freely control the viewing direction of the observation sensor, it is possible to observe the same target position from multiple different orbits of the satellite. When applied to frequent remote sensing of specific locations such as disaster prevention monitoring, it is possible to construct an economical Earth observation system because the frequency of a measurement of observation targets can be increased using a small number of artificial satellites.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an earth observation artificial satellite showing an embodiment of the present invention, and FIG. 2 is a configuration diagram showing a conventional earth observation artificial satellite. In the figure, 11) is an artificial satellite, (2) is an affllll sensor, (3) is a video data transmission device, and 1
4) is a drive device, (5) is an attitude control device, (6) is an orbit information device, (7) is a command device, and (8J is an arithmetic device. The same or equivalent parts in the figures are given the same reference numerals. This is an indication.

Claims (1)

[Claims] In an earth observation satellite equipped with an observation sensor on a satellite to acquire images of the earth's surface and transmit them to the ground, an observation sensor for acquiring images of the earth on the artificial satellite and a video signal acquired by the observation sensor. a video data transmission device that transmits or temporarily records and transmits the information to the ground; an attitude control device that detects the attitude of the satellite and controls it to a target attitude; and an orbit information device that stores orbit determination memory or orbit information from the ground. , receive, decipher, store, and receive command signals from the ground related to the target position or area where images should be acquired, and the time.
The target field of view of the observation sensor is determined based on the command device to send, the image acquisition target position or area, information regarding the acquisition time from the command device, the attitude information from the attitude control device, and the trajectory information from the orbit information device. For earth observation, comprising: an arithmetic device that determines a direction; and a drive device that is driven by a drive signal that instructs a target visual field direction for image acquisition from the arithmetic device and controls the visual field direction of the observation sensor. Artificial satellite.