DEBRIS REMOVAL DEVICE AND DEBRIS REMOVAL SYSTEM

Abstract

A debris removal device includes: a body part; an adhesion part to let the space debris adhere to the body part; a braking part to generate braking force in a specific direction, to act on the space debris adhering to the body part via the adhesion part during circling of the body part around the orbit together with the space debris; and a timing control part to control generation timing of the braking force. The timing control part generates the braking force, during circling of the body part together with the space debris around the orbit, when the body part is located at a specific region on the orbit where a direction of the braking force is substantially parallel to an orbit plane including the orbit and substantially parallel to a tangential line of the orbit, and in substantially an opposite direction of a circling direction of the space debris.

Claims

1. A debris removal device that removes space debris circling around a predetermined orbit about the earth, comprising: a body part; an adhesion part to let the space debris adhere to the body part; a braking part to generate braking force in a specific direction so as to act on the space debris adhering to the body part via the adhesion part during circling of the body part around the orbit together with the space debris; and a timing control part to control generation timing of the braking force, wherein the timing control part generates the braking force, during circling of the body part together with the space debris around the orbit, when the body part is located at a specific region on the orbit where a direction of the braking force is (i) substantially parallel to an orbit plane including the orbit and (ii) substantially parallel to a tangential line of the orbit, and (iii) in substantially an opposite direction of a circling direction of the space debris.

2. The debris removal device according to claim 1, further comprising a direction control part configured to, when the direction of the braking force is not in a direction of passing through gravity center of a rigid body that is combination of the space debris and the debris removal device, change the direction of the braking force so that the direction of the braking force is in the direction of passing through the gravity center.

3. The debris removal device according to claim 1, wherein the body part includes at least one face, the braking part includes a plurality of thrusters that are disposed at the face of the body part in a dispersed manner, and the plurality of thrusters are configured to burn individually with solid fuel.

4. The debris removal device according to claim 1, wherein the adhesion part includes a disk part attached to the body part, and an adhesive layer disposed on a surface of the disk part, and the adhesive layer includes adhesive or glue and an impact buffer member.

5. The debris removal device according to claim 1, wherein the timing control part is loaded at the body part.

6. The debris removal device according to claim 1, wherein the timing control part includes: a signal generation/transmission part configured to generate and transmit a control signal to control the braking part so that the braking force is generated when the body part is located at the specific region; and a signal reception/control part configured to receive a control signal transmitted from the signal generation/transmission part to control the braking part, wherein the signal generation/transmission part is disposed on earth, and wherein the signal reception/control part is loaded at the body part.

7. A debris removal system comprising: the debris removal device according to claim 1; and a mother unit that can carry the debris removal device and is configured to release the debris removal device into the space.

8. The debris removal system according to claim 7, further comprising a guide part configured to guide the debris removal device released from the mother unit to the space debris until the body part of the debris removal device adheres to the space debris.

9. The debris removal system according to claim 8, wherein the guide part is disposed at the mother unit or on earth, and wherein the debris removal device includes a reception part to receive a guide signal from the guide part.

10. The debris removal system according to claim 7, wherein the debris removal device is configured to move to the space debris autonomously after being released from the mother unit.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0028] FIG. 1 describes the configuration of a debris removal system according to one embodiment of the present invention.

[0029] FIG. 2 is a perspective view of the debris removal device according to one embodiment of the present invention (viewed from the adhesion part).

[0030] FIG. 3 is a perspective view of the debris removal device according to one embodiment of the present invention (viewed from the braking part).

[0031] FIG. 4 is a side view of the debris removal device according to one embodiment of the present invention.

[0032] FIG. 5 is a front view of the debris removal device according to one embodiment of the present invention (viewed from the adhesion part).

[0033] FIG. 6 is a rear view of the debris removal device according to one embodiment of the present invention (viewed from the braking part).

[0034] FIG. 7 describes the direction or the like of a braking force generated by the braking part of the debris removal device according to one embodiment of the present invention.

[0035] FIGS. 8A and 8B describe the posture or the like of space debris during circling.

[0036] FIG. 9 describes a region where the braking force is to be generated by the braking part of the debris removal device according to one embodiment of the present invention.

[0037] FIG. 10 is a perspective view of the debris removal device according to another embodiment of the present invention (viewed from the adhesion part).

[0038] FIG. 11 is a perspective view of the debris removal device according to another embodiment of the present invention (viewed from the braking part).

DESCRIPTION OF EMBODIMENTS

[0039] The following describes embodiments of the present invention, with reference to the drawings.

[0040] Firstly, the configuration of a debris removal system 1 according to the present invention is described.

[0041] The debris removal system 1 is to remove space debris D (FIG. 7) circling around a predetermined orbit O about the earth E, and as shown in FIG. 1, it includes a mother unit 2, a debris removal device (slave unit) 3 that the mother unit 2 carries and releases in the space, and a ground system 4 to guide and control the mother unit 2 and the debris removal device 3.

[0042] The mother unit 2 is attached to a cosmonautic vehicle such as a rocket while carrying the debris removal device 3, and is configured to be launched into the space. The ground system 4 is disposed at a base station installed on earth, which is configured to receive sensor signals from the mother unit 2 and the debris removal device 3 or to transmit various command signals to the mother unit 2 and the debris removal device 3 via predetermined communication means. The ground system 4 includes a guide part 5 to guide the debris removal device 3 separated from the mother unit 2 to space debris D to let the debris removal device adhere to the space debris D. The guide part 5 may be provided at the mother unit 2.

[0043] As shown in FIGS. 2 to 6, the debris removal device 3 includes a body part 10, an adhesion part 20 to let space debris D adhere to the body part 10, a braking part 30 to generate braking force in a specific direction, a timing control part 40 to control the timing when the braking force is generated, a direction control part 50 to control the direction of the braking force, and a reception part 60 to receive a guide signal from the guide part 5.

[0044] As shown in FIGS. 2 to 4, the body part 10 has a cylindrical shape, at one end face 10a of which the adhesion part 20 is attached via a shaft 11. At the other end face 10b of the body part 10, the braking part 30 is disposed. The body part 10 internally stores the timing control part 40 and the direction control part 50 made up of a computer or the like. The size of the body part 10 is set appropriately depending on the size of the cosmonautic vehicle and the mother unit 2 carrying the body part 10. The shape of the body part 10 is not limited to a cylindrical shape, which may be various shapes including a cubic shape, a rectangular parallelepiped shape, and a polyangular tubular shape.

[0045] As shown in FIGS. 2 to 5, the adhesion part 20 includes a disk part 21 that is attached to the one end face 10a of the body part 10 via the shaft 11, and an adhesive layer 22 disposed on the surface of the disk part 21. In the present embodiment, the adhesive layer 22 is made up of silicone adhesive and an impact buffer member. Since the silicone adhesive has heat insulation property, heat transmitted from space debris D can be shielded. The adhesive making up the adhesive layer 22 is not limited to silicone adhesive, and other types of adhesive may be used. Instead of adhesive, glue may be used. A mechanical capturing unit may be provided together with adhesive or glue (or instead of adhesive or glue). The disk part 21 may be made of a metal material, and a foam material may be used as the impact buffer member.

[0046] The braking part 30 is to generate braking force P in a specific direction D.sub.P so as to act on the space debris D adhering to the body part 10 via the adhesion part 20 during circling of the body part 10 on an orbit O together with the space debris D. In the present embodiment, as shown in FIGS. 3 and 6, the braking part 30 includes a plurality of (twenty-one) thrusters 31 disposed on the other end face 10b of the body part 10 in a dispersed manner. The thrusters 31 are configured so as to burn individually with solid fuel. The positions and the number of the thrusters 31 are not limited those illustrated in the present embodiment, and they may be set appropriately depending on the weight and the shape of the body part 10.

[0047] The braking part 30 in the present embodiment is configured so that the braking force P in the direction D.sub.P as shown in FIG. 7 acts on the space debris D circling around the orbit O about the earth E in the circling direction D.sub.R. The direction D.sub.P of this braking force P depends on the position where the debris removal device 3 (body part 10) adheres to the space debris D. In the present embodiment, as shown in FIG. 7, the debris removal device 3 (body part 10) adheres to the space debris D on the extended line of the axis of rotation A.sub.D of the space debris D, so that the direction D.sub.P of the braking force P generated by the braking part 30 coincides with the extending direction of the axis of rotation A.sub.D of the space debris D. With this configuration, even when the space debris D rotates during circling, the braking force P in a fixed direction can always act on the space debris D.

[0048] As shown in FIG. 7, the timing control part 40 controls the timing when the braking force P by the braking part 30 is generated so that the braking force P is generated, during circling of the debris removal device 3 together with the space debris D around the orbit O, when the debris removal device 3 is located at a specific region R on the orbit O where the direction D.sub.P of the braking force P is (i) substantially parallel to the orbit plane (circling orbit plane) including the orbit O and (ii) substantially parallel to the tangential line N of the orbit O, and (iii) is in substantially the opposite direction of the circling direction D.sub.R of the space debris D.

[0049] Referring to FIGS. 8 and 9, the following describes the reason why the timing control part 40 sets the timing when the braking force P is generated as stated above.

[0050] It is known that space debris D that circles around a predetermined orbit O about the earth E and does not have a posture-control function does not circle around so as to always direct a specific plane S.sub.D to the center as shown in FIG. 8(A), but the posture thereof changes because of a plurality of disturbances. That is, it is known that a mode of changing the posture and a mode of the rotation of the space debris D are determined based on one or more factors including (1) gravity gradient that occurs if the space debris D is not a true circle, (2) solar irradiation, (3) air resistance, (4) earth magnetism, and (5) other reasons.

[0051] In this way, since the space debris D circles about the earth E while changing the posture due to various factors, when the debris removal device 3 adheres to the space debris D at the position and with the posture as shown in FIG. 8(B), for example, there are two regions where the direction D.sub.P of the braking force P generated by the braking part 30 becomes parallel to the tangential line N of the orbit O (region R and region R). The present inventor found that, when the braking force P is generated at the region (specific region) R between these two regions R and R where the direction D.sub.P of the braking force P is in the opposite direction of the circling direction D.sub.R of the space debris D, the circling speed (energy) of the space debris can be decreased the most effectively. Herein assume that the direction D.sub.P of the braking force P is located in the orbit plane including the orbit O of the space debris D (the direction D.sub.P of the braking force P is at least parallel to the orbit plane).

[0052] Such braking force P generated at the specific region R leads to a decrease in the circling speed of the space debris D, and as a result, the orbit of the space debris D will shift to the orbit O.sub.2 close to the earth E from the original orbit O.sub.1 as shown in FIG. 9. Braking force P is generated at the specific region R in the orbit O.sub.2 after the shifting as well, whereby the circling speed of the space debris can be decreased and so the orbit can shift to the orbit O.sub.3 closer to the earth E. Repeating this, the space debris D can enter the atmosphere finally for burning and removal.

[0053] In the present embodiment, considering the case where the direction D.sub.P of the braking force P may not pass through the gravity center of the rigid body that is the combination of the space debris D and the debris removal device 3 (rigid-body gravity center), the body part 10 includes the direction control part 50 to change the direction of the braking force P. If the direction D.sub.P of the braking force P does not pass through the rigid-body gravity center, the direction control part 50 activates a specific thruster 31 of the braking part 30 to change the direction of the braking force P so that the direction D.sub.P of the braking force P passes through the rigid-body gravity center. Braking force P may be generated once on a trial basis after the debris removal device 3 adheres to the space debris D so as to check whether the direction of the braking force P passes through the rigid-body gravity center or not.

[0054] Next, the following describes a method for removing space debris D using the debris removal system 1 according to the present embodiment.

[0055] Firstly, a cosmonautic vehicle carrying the mother unit 2 and the debris removal device 3 is launched, and the mother unit 2 is moved close to space debris D circling around an orbit O about the earth E (mother unit guide step: S1). In the mother unit guide step S1, the mother unit 2 may be moved relatively close (e.g., the position of a few kilometers from the space debris D) to the space debris D by GPS navigation, for example, the mother unit 2 may be brought close to the space debris D at a position of a few tens to hundreds of meters from the space debris using a star tracker or the like, and then the mother unit 2 may be brought closer to the position of a few meters by an optic camera or the like.

[0056] Next, the debris removal device 3 is released from the mother unit 2, and the debris removal device 3 is guided to the space debris D to adhere to the space debris D (device adhesion step: S2). In the device adhesion step S2, the debris removal device 3 receives a guide signal transmitted from the guide part 5 of the ground system 4 at the reception part 60, and moves close to the space debris D in accordance with the received guide signal and adheres to the space debris D at a specific position (on the extended line of the axis of rotation A.sub.D of the space debris D) so that the direction D.sub.P of the braking force P generated by the braking part 30 coincides with the extending direction of the axis of rotation A.sub.D of the space debris D.

[0057] Subsequently, the timing control part 40 of the debris removal device 3 monitors the position of the debris removal device 3 and the space debris D circling around, and controls to generate braking force P when the debris removal device 3 is located at a specific region R (braking step: S3). Repeating the braking step S3 as needed, the circling speed of the space debris D can be decreased effectively, whereby the space debris D can enter the atmosphere finally for burning and removal.

[0058] In the debris removal device 3 according to the embodiment as stated above, the body part 10 can adhere to the space debris D via the adhesion part 20. Then, the braking force P is generated, during circling of the body part 10 together with the space debris D on the predetermined orbit O about the earth E, when the body part 10 is located at the specific region R on the orbit O where the direction D.sub.P of the braking force P is (i) substantially parallel to the orbit plane (circling orbit plane) including the orbit O and (ii) substantially parallel to the tangential line N of the orbit O, and is (iii) in substantially the opposite direction of the circling direction D.sub.R of the space debris, and this braking force P is allowed to act on the space debris D. In this way, the braking force P is generated when the direction D.sub.P of the braking force P is parallel to the predetermined orbit plane and to the tangential line N of the orbit O, and is in substantially the opposite direction of the circling-around direction D.sub.R of the space debris D, whereby the circling speed of the space debris D can be decreased effectively so as to allow the space debris D to enter the atmosphere for burning and removal.

[0059] In the debris removal device 3 according to the embodiment as stated above, if the direction D.sub.P of the braking force P does not pass through the gravity center of the rigid body that is the combination the space debris D and the debris removal device 3 (rigid-body gravity center), the direction control part 50 can control the direction D.sub.P of the braking force P so that the direction D.sub.P of the braking force P passes through the rigid-body gravity center. If the direction D.sub.P of the braking force P does not pass through the rigid-body gravity center, moment will act on the rigid body and the rigid body will start another rotation. On the contrary, when the direction control part controls the direction D.sub.P of the braking force P so that the direction D.sub.P of the braking force P passes through the rigid-body gravity center, then the generation of such another rotating force on the rigid body can be prevented.

[0060] In the debris removal device 3 according to the embodiment as stated above, the braking part 30 includes the plurality of thrusters 31 disposed on the end face 10b of the body part 10 in a dispersed manner. Since these thrusters 31 burn individually, the braking force P can be generated a plurality of times. Further, each of the thrusters 31 includes solid fuel with low toxicity, and so they can be loaded on various types of cosmonautic vehicles, such as a rocket.

[0061] In the debris removal device 3 according to the embodiment as stated above, the adhesion part 20 has the adhesive layer 22 disposed on the surface of the disk part 21 that is attached to the body part 10, and the adhesive layer 22 includes silicone adhesive and an impact buffer member, and therefore the debris removal device can adhere to the space debris D favorably.

[0062] In the debris removal device 3 according to the embodiment as stated above, since the body part 10 includes the timing control part 40, there is no need to provide facility for timing control on earth separately, and so the cost for the facility can be saved.

[0063] In the debris removal system 1 according to the embodiment as stated above, since the debris removal system includes the debris removal device 3 that includes the body part 10 or the like and the mother unit 2 that can carry the debris removal device 3 and is configured to release the debris removal device 3 into the space, the mother unit 2 is moved relatively close to space debris D (e.g., the position of a few kilometers from the space debris D), and then the debris removal device 3 can be released from the mother unit 2 so as to adhere to the space debris D.

[0064] In the debris removal system 1 according to the embodiment as stated above, the debris removal device 3 can be guided remotely by the guide part 5 installed on earth, and therefore there is no need to provide the debris removal device 3 with a guide part. This can make the debris removal device 3 smaller and more lightweight.

[0065] The above embodiment shows the example where the body part 10 of the debris removal device 3 includes the timing control part 40 and the direction control part 50. In another example, a control signal to control the generation timing of braking force P and a control signal to change the posture of the body part 10 may be generated on earth or at the mother unit 2, and these control signals may be transmitted to the debris removal device 3 to control the braking part 30.

[0066] For instance, a signal generation/transmission part may be disposed on earth or at the mother unit 2, which is to generate a control signal to control the braking part 30 so that braking force P is generated when the debris removal device 3 is located at the specific region R or to generate a control signal to control the direction D.sub.P of the braking force P so that the direction D.sub.P of the braking force P passes through the rigid-body gravity center. In such a case, the debris removal device 3 (body part 10) may include a signal reception/control part, which is to receive a control signal transmitted from the signal generation/transmission part to control the braking part 30.

[0067] With this configuration, the signal reception/control part of the body part 10 can receive a control signal transmitted from the signal generation/transmission part on earth or at the mother unit 2 to control the braking part 30. Therefore there is no need to provide the debris removal device 3 with a large-sized arithmetic circuit, and so the debris removal device 3 can be made smaller and more lightweight.

[0068] The above embodiment shows the example where the debris removal device 3 released from the mother unit 2 is guided to the space debris D by the guide part 5 until the body part 10 of the debris removal device 3 adheres to the space debris D. In another example, the debris removal device 3 may include a mechanism to move to the space debris D autonomously after being released from the mother unit 2. Without using the guide part 5 or the autonomous movement mechanism, the debris removal device 3 may be simply released from the mother unit 2 so as to adhere to the space debris D.

[0069] In the debris removal device 3 according to the embodiment as stated above, the adhesion part 20 having the disk part 21 is shown as one example, and the shape and the configuration of the adhesion part are not limited to this. For instance, as shown in FIGS. 10 and 11, a starfish-shaped member 25 having a center part 23 of a predetermined area and a plurality of (e.g., five) legs 24 extending from the center part 23 radially with a predetermined width and by a predetermined length may be used instead of the disk part 21, and the adhesive layer 22 including adhesive and an impact buffer member may be disposed on the surface of the member 25. The starfish-shaped member 25 may be made of a metal material, for example, and the shape of the starfish-shaped member 25 may be changed freely with wire or the like.

[0070] The present invention is not limited to the embodiments as stated above, and design modifications to these embodiments, which will be made by a person skilled in the art as appropriate, are also included in the scope of the present invention as long as they have the features of the present invention. That is, each element in the above embodiments and the arrangement, materials, conditions, shapes, dimensions, etc., thereof are not limited to those described above and may be modified as appropriate. Each element in these embodiments can be combined as long as such combination is technically possible, and such a combination also is included in the scope of the present invention as long as they have the features of the present invention.

REFERENCE SIGNS LIST

[0071] 1 Debris removal system

[0072] 2 Mother unit

[0073] 3 Debris removal device

[0074] 5 Guide part

[0075] 10 Body part

[0076] 10b End face

[0077] 20 Adhesion part

[0078] 21 Disk part

[0079] 22 Adhesive layer

[0080] 30 Braking part

[0081] 31 Thruster

[0082] 40 Timing control part

[0083] 50 Direction control part

[0084] 60 Reception part

[0085] D Space debris

[0086] D.sub.P Direction of braking force

[0087] D.sub.R Circling direction of space debris

[0088] E Earth

[0089] N tangential line of orbit

[0090] O Orbit

[0091] P Braking force

[0092] R Specific region