JPS61169400A - Artificial satellite - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a spin-stabilized artificial satellite, and particularly to a spin-stabilized artificial satellite equipped with a despun mechanism for directing observation equipment or antennas toward the Earth. This is related to artificial satellites.

[Background of the invention]

In conventional spin-stabilized artificial satellites, for example, in order to obtain image data on the earth's surface or above the earth,
Using the spin of the satellite itself.

The camera attached to the satellite has the same angular velocity as the satellite,
There is one that rotates in the same direction as the artificial satellite.

For this type of satellite, the Earth is out of the camera's field of view for more than half of the satellite's spin rotation. Also,
This data acquisition method (camera scanning method) is linear, so in order to acquire data on a two-dimensional surface, the camera may be rotated little by little each time a satellite rotates once. Alternatively, a method has been used in which a shaft to which a reflecting mirror is fixed is rotated little by little, and data is acquired using a camera fixed to the light receiving side of the reflecting mirror.

For example, in the case of the meteorological satellite Himawari, which moves in synchronization with the earth's rotation (geostationary satellite), it takes about 25 minutes to acquire this data.

On the other hand, an earth-orbiting satellite that moves relative to the earth,
In order to obtain still image data on the earth's surface or above the earth, optical cameras that can instantly acquire data are used.
A method of photographing is used to print an image on the film surface. In this case, the photographed film is placed above the earth (altitude 1
00+n or more), and it was extremely difficult to do so from an unmanned satellite.

In addition, with the method of attaching the camera to the despan drive, if the distance between the camera and the despan drive is short, the field of view of the camera will be blocked by the despan drive, so a method of mounting the camera away from the despan drive is used. It will be done.

In this case, when the satellite starts its spin motion at the beginning of its operation,
The ratio of the moment of inertia of the satellite around the spin axis and around the direction perpendicular to the spin axis becomes smaller than 1, and the direction of the spin axis changes, potentially causing attitude instability.

Regarding meteorological satellite Himawari, etc., there is a space science journal supervised by Shigefumi Saito of Kosaido Sanpo Publishing, and about unstable phenomena due to inappropriate moment of inertia ratio, NATURE
, vol 182, Sep, 20, 1958
Bracewell and G in pp760-763
“ROTATION OF AR” by arriott
It is discussed in the document titled ``TIFICIAL EARTI+SA SET LITES''.

[Purpose of the invention]

An object of the present invention is to provide an artificial satellite capable of simultaneously acquiring two-dimensional image data on the earth's surface or the sky above the earth in a short time based on the above-mentioned matters.

[Summary of the invention]

In order to achieve the above object, the present invention provides the despan axis of the despan mechanism with a gimbal axis that rotates around an axis different from this axis, and this gimbal axis is provided with a reflecting mirror, and the reflected light is reflected by this reflecting mirror. The despan mechanism is equipped with a solid-state photographic element that receives images.

With this configuration, it is possible to simultaneously obtain two-dimensional data on the earth from the spinning artificial satellite and maintain a stable attitude.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

The drawing shows an embodiment of the artificial satellite of the present invention, and in this drawing, a spin-stable artificial satellite 2 is orbiting around the earth or moving while being relatively stationary.

This artificial satellite 2 is equipped with a despan drive mechanism 12. This despan drive mechanism 12 is provided with a gimbal shaft 8 that is rotatable around an axis different from the despan drive shaft 13. A reflecting mirror 7 is fixedly attached to this gimbal shaft 8. A plurality of solid-state image sensors 11 are arranged on the despan drive mechanism 12 substantially parallel to the gimbal axis 8 .

Next, the operation of the embodiment of the present invention described above will be explained.

The spin-stable artificial satellite 2 rotates at several to several hundred revolutions per minute in order to stabilize the satellite's attitude.

For this reason, in order to direct the equipment that observes the earth's surface or the sky above the earth towards the earth, it is necessary to rotate the observation equipment at least in the opposite direction to the rotation of the satellite itself, at approximately the same speed as the angular velocity of the artificial satellite.

This is performed by the despan drive mechanism 12. In an earth-orbiting satellite in which the earth and the satellite move relative to each other, in order to maintain a certain observation range on the earth for a certain period of time, the gimbal axis 8 is rotated to hold the desired point. Image data 10 of the sky or the earth's surface is a reflection! ! reflected at 7,
The light is guided to a plurality of solid-state photographing elements 11 provided on the despan drive mechanism 12. The data imaged on the solid-state image sensor 11 is stored in a memory (not shown) and then sequentially transferred to the ground using radio waves.

According to this embodiment, it is possible to simultaneously measure all the data on the two-dimensional surface of the earth's surface or the sky above the earth on the solid-state image sensor 11 in a short period of time. Furthermore, by operating the despan drive mechanism and the rotation mechanism of the gimbal axis, the observation range on the earth can be maintained for a certain period of time even if the earth and the satellite are moving relative to each other.

In addition, by attaching a reflector on the despan drive mechanism, the moment of inertia of the entire satellite around the spin axis can be adjusted to allow the camera to be brought closer to the center of gravity of the satellite, so that the reflected te! 7, which is smaller than the case without 7, and has the effect of preventing attitude instability at the start of spin at the initial stage of operation of a satellite.

In another embodiment, if the material of the reflecting mirror 1 is made of a metal 1 having a high specific strength, such as a -Ti-6Aρ-4v alloy, it can withstand the impact when the satellite is launched, and also It is also possible to prevent an increase in the moment of inertia around the axis, and it also has the effect of making the gimbal drive mechanism smaller and lighter.

〔Effect of the invention〕

As described above, according to the present invention, in a spin-stabilized artificial satellite, the m-measurement range on the earth's surface or in the sky above the earth is fixed for a certain period of time by the despan drive mechanism and the gimbal axis drive mechanism, regardless of the satellite orbit. This has the effect of allowing simultaneous observation using a solid-state image sensor. Furthermore, the use of one reflecting mirror has the effect of preventing unstable motion during the initial stage of satellite operation.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view showing an example of a spin-stabilized artificial satellite of the present invention. 2... Satellite main body, 7... Reflector, 8... Gimbal axis, 11... Solid-state image sensor, 12... Despan drive mechanism, 13... Despan axis.

Claims (1)

[Scope of Claims] 1. In a spin-stabilized artificial satellite equipped with a despan mechanism for directing an observation device or an antenna toward the earth, the despan axis of the despan mechanism rotates about an axis different from this axis. An artificial satellite characterized in that a gimbal axis is provided, a reflecting mirror is provided on the gimbal axis, and a despan mechanism is provided with a solid-state image sensor that receives an image reflected by the reflecting mirror. 2. The artificial satellite according to claim 1, wherein the material of the reflecting mirror is a metal whose specific strength (ratio of tensile strength to specific gravity) is higher than that of glass.