JPH11171100A - Passive temperature control device for artificial satellite-mounted equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the temperature of an artificial satellite mounted- observation equipment without fitting an active temperature control device such as an electric heater. SOLUTION: A temperature control device 12 provided with a cylindrical thermal control hood formed of a film with an appropriate surface characteristic is used to surround an artificial satellite mounted-observation equipment 14 exposed to space. Direct sunlight under sunshine is therefore shielded while obtaining moderate heating by infrared rays. The cylindrical thermal control hood surrounding the satellite-mounted equipment 14 reduces radiative cooling caused by the radiation of infrared rays to space in the shade. The temperature control device 12 is provided with a shape memory alloy frame folded in an artificial satellite launching stage and spread in cylindrical shape by solar heat after putting the satellite into an orbit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature controller for a device mounted on an artificial satellite that is exposed to outer space such as an observation device and is mounted on the artificial satellite.

[0002]

2. Description of the Related Art Equipment mounted on the outer surface of a satellite and exposed directly to outer space is exposed to the harsh thermal environment of the universe. Sometimes cools by radiation.

Conventionally, as a method of controlling the temperature of a satellite-mounted device, (1) the device and the satellite main body are attached to the main body of the satellite using a large number of screws while widening the contact area of the mounting surface. To form a strong heat bond,
A method for keeping the temperature of the equipment close to the temperature of the satellite body, which is relatively stable. (2) The equipment is conductively insulated and attached to the satellite body, and an extreme temperature rise occurs even when sunlight directly hits the equipment. In order not to come, infrared radiation rate and sunlight absorption rate have appropriate radiation cooling capacity and sunlight absorption power by sticking heat control material of appropriate value to the surface of equipment, respectively, and When the temperature is low such as in the shade, there is a method of preventing the temperature from decreasing by energizing and heating the electric heater attached to the surface of the device, and (3) a method in which these methods are compromised.

Generally, the method (1) is applied to equipment having a relatively wide allowable temperature range, and the method (2) is suitable for equipment having a narrow allowable temperature range.

[0005] Among the equipment mounted on satellites, those for observing astronomical objects such as space and the earth are exposed to space and mounted on satellites in order to achieve the purpose of observation. This type of equipment often includes a detection unit including an optical lens and an X-ray mirror.

When the allowable temperature range of these parts is relatively wide, the temperature control method (1) can be adopted, but when it is narrow, the method (2) is required.

[0007]

However, an electric heater for active temperature control cannot be attached to a lens or a mirror because it is necessary to transmit or reflect an electromagnetic wave as observation means. In the case where the allowable temperature range is narrow, the temperature control becomes practically impossible, so that the observation accuracy has to be reduced or the acquired data is corrected on the ground.

An object of the present invention is to provide a temperature control device capable of effectively controlling the temperature of an artificial satellite-mounted device, such as an artificial satellite-mounted observation device, to which an electric heater cannot be attached.

[0009]

SUMMARY OF THE INVENTION A temperature control apparatus for a satellite-mounted device according to the present invention has an elongated tubular heat control hood made of a film having appropriate thermo-optical characteristics. By surrounding the spacecraft-equipped satellite device exposed to outer space with this thermal control hood, the sunlight can directly shield the solar device from the solar control hood during sunshine, The mounted equipment is appropriately heated by the radiated infrared rays. In addition, this heat control hood has a long and narrow cylindrical shape,
Since the spacecraft can see only limited space through the opening of the hood, when the satellite is in the shade such as the earth, the emission of infrared light from the spacecraft is limited to space. Radiant cooling of equipment is reduced. Thus, this heat control hood passively performs stable temperature control by reducing the temperature rise during the sunshine and the extreme temperature drop during the shade.

[0010] Since the artificial satellite is launched by a rocket, its load is limited by the fairing size of the rocket, and a large object is not suitable as a load. For this reason,
The passive temperature control device of the present invention is configured to be folded or contracted small at the launch stage, and to be deployed after being put into orbit. For this reason, the passive temperature control device of the present invention includes a foldable or expandable frame for maintaining the tubular shape of the heat control hood. At the satellite launch stage, the hood is folded or shrunk together with the frame, and after the satellite orbit is inserted, the frame is extended to expand the hood into a cylindrical shape so as to surround the equipment mounted on the satellite.

Preferably, the frame is formed of a shape memory alloy, and is expanded by solar heat after being put into a satellite orbit.

In a preferred embodiment, the portion of the heat control hood facing the sun is formed of a film that absorbs sunlight and emits infrared light to heat the satellite-mounted equipment, and the film is made of a film. The inner surface has a high infrared emissivity.

[0013] Preferably, the portion of the heat control hood that does not face the sun is formed of a film that reduces radiant cooling of the satellite-borne equipment, and the surface of the film has a low infrared emissivity.

The above-mentioned features and effects of the present invention, as well as other features and effects, will be further clarified as described in the following embodiments.

[0015]

FIG. 1 shows a passive temperature controller 12 according to one embodiment of the present invention. In the figure, reference numerals 1a, 1b, 1c and 1d denote wires formed of a shape memory alloy, 2 denotes a support ring for arranging the shape memory wires 1a, 1b, 1c and 1d in a cylindrical shape, and 3 denotes a ring. The mounting bracket has a function of a support ring for arranging the shape memory alloy wires 1a, 1b, 1c, and 1d in a cylindrical shape, and a function of mounting the passive temperature control device 12 of the present invention to the satellite body. Shape memory wires 1a, 1b, 1c, 1d
, The support ring 2 and the mounting bracket 3 constitute the frame 20 of the temperature control device 12. The shapes of the shape memory wires 1a, 1b, 1c, and 1d are stored in advance so that the wires become straight when a certain temperature is exceeded.

Referring further to FIG. 1, reference numerals 4a and 4b denote adhesives applied to the side surface of the ring 2 and the side surface of the mounting bracket 3, respectively, 5 denotes a heating cover provided on the side irradiated with sunlight, and 6 denotes a sun cover. This is a heat insulating cover attached to a so-called shade part which is not irradiated with light, and the heating cover 5 and the heat insulating cover 6 are attached to the ring 2 by adhesives 4a and 4b, respectively, so that no gap is formed therebetween. Bracket 3
It is pasted on. The heating cover 5 and the heat retaining cover 6 constitute an elongated tubular heat control hood 22.

Referring to FIG. 2, which is an enlarged view of a portion A of the heating cover 5 shown in FIG. 1, reference numerals 7a and 7b denote a film formed on one surface of a dielectric material on which a metal such as aluminum is deposited.
8a and 8b are metal layers deposited on the dielectric films 7a and 7b, respectively, and 9 is a metal deposited layer 8 on the dielectric films 7a and 7b.
An adhesive for affixing a and 8b to face each other.

Referring to FIG. 3, which is an enlarged view of a portion B of the heat retaining cover 6 shown in FIG. 1, reference numeral 10 denotes a film formed on both sides by a derivative obtained by evaporating a metal such as aluminum;
a and 11b are metal layers deposited on both surfaces of the derivative film 10, respectively.

FIG. 4 is a schematic diagram showing the passive temperature controller 12 of the present invention attached to an artificial satellite.
(A) is a front view, (b) is a side view. Referring to FIG. 1, reference numeral 12 denotes a passive temperature controller of the present invention, and reference numeral 13 denotes a satellite main body. The sunlight is irradiated from the side of the passive temperature controller 12 of the present invention as shown in FIG. The passive temperature controller 12 of the present invention has an axis parallel to the Z axis of the satellite body 13.

FIG. 5A is an enlarged sectional view of a portion C in FIG. In FIG. 1, reference numeral 14 denotes a satellite-mounted device to be temperature-controlled, and the passive temperature controller 12 of the present invention is disposed so as to surround the mounted device 14. The passive temperature controller 12 and the on-board equipment 14 of the present invention are mounted on a satellite structure panel 15.

Next, with reference to FIG. 5B, a description will be given of a change in the configuration of the temperature control device 12 from the launching stage to the orbit injection. Since the satellite is launched by a rocket, the payload is limited by the rocket's fairing dimensions. In particular, those that protrude outside the artificial satellite, such as the temperature control device 12 of the present invention, are directly affected by the restrictions, and the external dimensions must be reduced. Therefore, at the launching stage, as shown in FIG. 5B, the shape memory alloy wires 1a, 1b, 1c, 1d of the frame 20 and the heat control hood 22 are folded. Shape memory alloy wire 1
Since a, 1b, 1c, and 1d are thin, they can be easily folded, and the heating cover 5 and the heat retaining cover 6 can be easily folded because they are based on very thin dielectric films.

After the satellite is put into orbit, the shape memory alloy wires 1a, 1b, 1c, 1d, the heating cover 5,
By irradiating the heat retaining cover 6 with sunlight, the shape memory alloy wires 1a, 1b, 1c, and 1d are heated to a predetermined temperature or more, and the shape memory alloy wires are elongated into a straight shape stored in advance. Sunshine shape memory alloy wire 1
In order to irradiate a, 1b, 1c, and 1d, the heating cover 5, and the heat retaining cover 6, it is easy to control the attitude of the artificial satellite by turning the Z-axis direction in FIG. 4 slightly toward the sun. it can. When the shape memory alloy wires 1a, 1b, 1c, and 1d of the frame 20 extend in this manner, the heat control hood 22 including the heating cover 5 and the heat retaining cover 6 is developed in the Z-axis direction in FIG. As shown in a), the satellite-mounted device 14 is surrounded.

Next, the operation of the passive temperature controller 12 will be described. The passive temperature controller 12 of the present invention mounted on a satellite is in an extended state in orbit as shown in FIG. When the artificial satellite is traveling on an orbit receiving direct sunlight, sunlight enters the heating cover 5.

Since the heating cover 5 has the configuration shown in FIG. 2, first, sunlight enters the dielectric film 7a.
Part of the sunlight is reflected on the surface of the dielectric film 7a into outer space, and the rest reaches the metal deposition layer 8a while being absorbed by the dielectric film 7a. Most of sunlight reaching the metal deposition layer 8a is reflected on the surface of the metal deposition layer 8a because the sunlight absorption rate of the metal is generally low. The reflected sunlight goes backward while being absorbed by the dielectric film 7a,
It is emitted from the surface of the dielectric film 7a into outer space.

Sunlight not reflected on the surface of the metal deposition layer 8a travels in the direction of the adhesive 9 in this deposition layer. However, since metal generally has an extremely large attenuation factor as compared with a dielectric, almost no sunlight is emitted. All are absorbed by the metal deposition layer 8a. The sunlight absorbed by the dielectric film 7a and the metal deposition layer 8a becomes heat.

The heat generated in the dielectric film 7a is conducted to the metal deposition layer 8a. The heat transmitted to the metal deposition layer 8a and the heat generated in the metal deposition layer 8a are both conducted and transmitted to the adhesive 9, the metal deposition layer 8b, and the dielectric film 7b in this order. The heat transmitted to the dielectric film 7b is radiated as infrared rays from the surface of the dielectric film 7b.

The dielectric generally exhibits a high infrared emissivity close to a black body. For example, in the case of an aluminum-deposited polyimide film having a thickness of 25 μm, the polyimide surface has a high infrared emissivity of 0.64. Further, when the thickness is 50 μm, the infrared emissivity is as high as 0.75. When the temperature of an object having a high infrared emissivity is higher than the temperature of another object disposed in the vicinity, the nearby object can be efficiently heated by infrared rays. Therefore, since the dielectric film 7b constituting the heating cover 5 has a high infrared emissivity, it has an excellent infrared heating function.

Infrared rays radiated from the dielectric film 7b directly irradiate the mounting equipment 14 arranged as shown in FIG. It is roughly divided into those radiated from the opening into the universe. The infrared rays emitted into outer space
4 is not heated. However, the infrared radiation that directly irradiates the on-board equipment 14 obviously heats the on-board equipment 14. Further, the infrared rays radiating the heat retaining cover 6 also heat the mounted device 14 by the following mechanism.

As shown in FIG. 3, the heat insulating cover has a metal deposition layer 11a on the inner surface. In general, metals have low infrared emissivity (synonymous with infrared absorptivity). For example, the infrared emissivity of a 1,000-Å-thick aluminum vapor-deposited surface is 0.03, and 97% of infrared light emitted from the outside is reflected. Therefore, the infrared rays radiated from the dielectric film 7b on the back surface of the heating cover 5 and reaching the metal deposition layer 11a inside the heat retaining cover 6 are reflected by the infrared rays 9b.
7% is reflected.

The reflected infrared rays are broadly classified into those that irradiate the mounted equipment 14, those that return to the original heating cover 5, and those that are radiated to the universe through the inner opening of the ring 2. The infrared rays irradiating the on-board equipment 14 naturally heat the on-board equipment. The infrared rays returned to the heating cover 5 are
Since the inner surface of the heating cover 5 is a dielectric film 7b having a high infrared emissivity, most of it is absorbed by the dielectric film 7b to become heat. This heat is again applied to the dielectric film 7b.
Are emitted as infrared rays, and partly contribute to the heating of the mounted equipment 14. These mechanisms occur at substantially the same time because infrared light propagates at the speed of light, and some of the infrared light radiated from the heating cover 5 to the heat retaining cover 6 also heats the mounted equipment 14.

The dielectric used for the dielectric films 7a and 7b forming the heating cover 5 can be selected from those having appropriate infrared emissivity and solar absorptance by selecting the type and thickness. By selecting the type and thickness of the dielectric film, the amount of heat applied to the mounting device 14 by infrared rays can be easily optimized.

On the other hand, when the artificial satellite is traveling in an orbit out of the sun as a shadow of a planet, the heat control hood 22 of the passive temperature controller 12 of the present invention has a heat retaining effect. The operation is as follows.

The heat of the mounted equipment 14 is always radiated as infrared rays. The infrared rays are broadly divided into those that radiate to the heating cover 5, those that radiate to the heat retaining cover 6, and those that are emitted to the universe through the inner opening of the ring 2.

The infrared radiation directly emitted from the inner opening of the ring 2 into space does not return to the mounted equipment 14 again. Therefore, the mounted equipment 14 is cooled by the amount of heat lost by the infrared rays.

The infrared radiation emitted from the mounting equipment 14 to the heating cover 5 is absorbed by the dielectric film 7b on the inner surface, and a part of the infrared light is reflected and returned to the mounting equipment 14 again, or irradiates the heat retaining cover 6. . The infrared light absorbed by the dielectric film 7b becomes heat, and a part of the infrared light is returned to the dielectric film 7b.
Is re-emitted from the surface of the device to the mounting equipment 14, the heat retaining cover 6, etc., and the rest is transferred from the dielectric film 7b to the metal vapor deposition layer 8b, the adhesive 9, the metal vapor deposition layer 8a, and the dielectric film 7a in order, Infrared rays are again emitted from the surface of the dielectric film 7a and emitted to outer space. From these facts, a considerable amount of the infrared light emitted from the mounting equipment 14 is reflected or re-emitted as infrared light again from the inner surface of the heating cover 5 and irradiates the mounting equipment 14, so that the heating cover 5 Also works as

Similarly to the infrared radiation emitted to the heating cover 5, the infrared radiation radiated from the mounting equipment 14 to the heat retaining cover 6 is reflected or re-emitted as infrared rays from the inner surface of the heat retaining cover 6 again, and Irradiate. However, as shown in FIG. 3, the inner surface of the heat insulating cover 6 has a metal deposition layer 11a.
, The infrared emissivity is low. Therefore, most infrared rays are reflected on the surface of the metal deposition layer 11a. Also, since the outer surface of the heat retaining cover 6 is also a metal deposition layer 11b,
The surface emits very little infrared radiation into space.
For these reasons, the heat retaining effect of the heat retaining cover 6 is much better than that of the heating cover 5.

As described above, the radiation cooling that occurs when the satellite is navigating behind the planet can be greatly reduced by the heat-retaining effect of the heating cover 5 and the heat-retaining cover 6, and the temperature of the on-board equipment 14 decreases. Is less.

In order to further improve the heat retaining effect, it is sufficient to reduce the effective radiative coupling between the mounted equipment and the outer space. Therefore, the shape memory wire frame 20, the heating cover 5, the heat retaining cover 6, and the like are used. What is necessary is just to increase the height of the cylinder to be formed, and to reduce the factor by which the mounted device 14 directly looks at outer space.

Although a specific embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications and changes can be made. For example, the heat control hood 22 of the passive temperature controller 12 has been described as being expanded and deployed by restoring the shape of the frame 20 made of a shape memory wire.
Thermal control hood 2 by releasing spring after orbital injection
2 can also be developed.

[0040]

According to the present invention, it is possible to effectively control the temperature of an optical system, such as a lens or a mirror, to which an electric heater for active temperature control could not be pasted, and to obtain a high observation accuracy. Or temperature compensation on the ground can be eliminated. Further, since the passive temperature control device of the present invention does not use an electric heater, power is not required for controlling the temperature of the device, and power, which is a limited resource for the satellite, can be saved.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a passive temperature control device of the present invention.

FIG. 2 is an enlarged view of a portion A in FIG.

FIG. 3 is an enlarged view of a portion B in FIG. 1;

FIG. 4 is a schematic view showing a state where the passive temperature control device of the present invention is attached to an artificial satellite, (a) shows a front view,
(B) shows a side surface.

5A and 5B are enlarged cross-sectional views of a portion C in FIG. 4, wherein FIG. 5A shows a state where the temperature control device is expanded, and FIG.

[Explanation of symbols]

 5: Cover for heating the hood 6: Cover for keeping the food warm 12: Temperature control device 14: Satellite-mounted device 20: Frame of the temperature control device 22: Heat control hood of the temperature control device

Claims (6)

[Claims] 1. A passive temperature control device for controlling the temperature of an artificial satellite-mounted device, comprising a film having appropriate thermo-optical characteristics, and an elongated cylindrical thermal control for surrounding the artificial satellite-mounted device. A hood, and a foldable or telescopic frame for maintaining the cylindrical shape of the hood. The artificial hood is constructed by folding or contracting the hood together with the frame at the satellite launch stage and extending the frame after satellite orbit. A passive temperature control device for an artificial satellite-mounted device, wherein a hood is deployed in a cylindrical shape so as to surround the satellite-mounted device. 2. The frame is made of a shape memory alloy,
The passive temperature control device according to claim 1, wherein the passive temperature control device is extended by solar heat after being put into a satellite orbit. 3. A portion of the hood facing the sun,
The passive temperature control device according to claim 1, wherein the passive temperature control device is formed of a film that heats a satellite-mounted device by absorbing sunlight and emitting infrared light. 4. The passive temperature control device according to claim 3, wherein the inner surface of the film forming the sun-facing portion of the hood has a high infrared emissivity. 5. The passive temperature control according to claim 1, wherein a portion of the hood that does not face the sun is formed of a film that reduces radiant cooling of an onboard satellite device. apparatus. 6. The passive temperature control device according to claim 5, wherein a surface of a film forming a portion of the hood not facing the sun has a low infrared emissivity.