Protection system, assembly comprising a protection system and a telescope, and a spacecraft

Abstract

The invention relates to a system (2) for protecting a telescope that can be installed on board a spacecraft, comprising: - a frame (4); - a cover (6) which is mounted so as to pivot with respect to the frame between an open position and a closed position of the telescope; - an elastic element (10) which is tensioned to push the cover towards the closed position; - a drive device (12) which is movable between the closed position and the open position, the drive device comprising a support element which is configured to push the cover into the open position and tension the elastic element, and an actuator (14) which is capable of driving the support element; - a retaining mechanism (18) which is designed to hold the cover in the open position and release it on receipt of a control signal; - an end-of-travel damping stop (32) which stops the cover in the closed position.

Description

[0001] DESCRIPTION

[0002] TITLE: PROTECTION SYSTEM, SET INCLUDING A PROTECTION SYSTEM AND A TELESCOPE, AND A SPACECRAFT

[0003] Technical field of the invention

[0004] The invention relates to the field of optical systems. In particular, the invention relates to a protection system for a space telescope.

[0005] Prior art

[0006] Space telescopes are generally equipped with protective systems designed to shield the objective lens from dust or incoming sunlight.

[0007] We are familiar with documents CN116661124 and CN110737084, which propose shutters to protect the telescope from dust. However, such shutters might prove insufficient for protection against solar radiation, particularly in the event of sudden solar exposure, for example, during changes in the satellite's attitude.

[0008] This highlights the need to propose a new system for protecting an optical system.

[0009] Summary of the invention

[0010] The present invention relates to a protection system for a telescope suitable for installation in a spacecraft, comprising:

[0011] - a fixed frame relative to the telescope,

[0012] - a hood mounted pivoting relative to the frame around a first axis of rotation between an open position in which the hood is clear of an optical beam from the telescope and a closed position in which the hood blocks the telescope beam,

[0013] - an elastic element tending to push the hood towards the closed position,

[0014] - a movable drive device between a first position corresponding to the closed position and a second position corresponding to the open position, the drive device comprising a support element configured to push the hood into the open position and tension the elastic element, and an actuator for driving the support element, the support element being able to be separated from the hood in the open position, - a retaining mechanism, separate from the support element, adapted to hold the hood in the open position, the retaining mechanism being capable of releasing the hood upon receipt of a closing command signal emitted by a control module,

[0015] - a damping end stop that stops the hood in the closed position. Advantageously, the protection system according to the present invention allows for very rapid hood closure, in particular in less than 1 second, for a large-diameter hood, for example, at least 750 millimeters. The system according to the invention handles the closing and opening functions of the telescope separately. The elastic element allows for rapid closure while limiting the power required from the actuator. The hood is opened slowly by the low-power actuator. Consequently, the low-power actuator has a low weight and a small footprint.

[0016] Another advantage of the invention is that it allows the implementation of a hood of significant mass, while retaining actuators with low weight and requiring low energy input.

[0017] Advantageously, the eddy current braking device increases braking force as hood speed increases. It also automatically reduces closing speed and, at the end of travel, further minimizes rebound against the end stop. Furthermore, the eddy current braking device can operate independently of the electronic control module.

[0018] Another advantage is that the damping stop helps to absorb the shock of the shutter cover when it reaches the end of its travel in order to limit the rebound so that the beam remains completely closed.

[0019] The features described in the following paragraphs may optionally be implemented. They may be implemented independently or in combination with each other:

[0020] - The system also includes an eddy current braking device designed to slow the movement of the hood to limit the speed to a predetermined threshold.

[0021] - The drive device includes an eccentric articulated to the support element in the form of a support arm; said actuator in the form of a motor comprising an output shaft for driving the eccentric, the support arm in the form of a support rod; the support rod comprising a support end guided in rotation about the first axis of rotation.

[0022] - The hood extends along a plane perpendicular to the first axis of rotation.

[0023] - The retention mechanism includes an electromagnetic suction cup.

[0024] - The elastic element comprises a pair of torsion springs supported on one side against the frame and on the other side against the hood, the torsion springs being arranged symmetrically with respect to a median plane of the hood.

[0025] The invention relates to an assembly comprising a telescope and a telescope protection system conformed according to the characteristics mentioned above, the protection system being fixedly mounted relative to the telescope.

[0026] The invention relates to a spacecraft comprising a telescope and a protection system for said telescope conformed according to the characteristics mentioned above.

[0027] Brief description of the figures

[0028] [Fig. 1] is a schematic perspective view of part of a telescope and a protection system according to the invention in a hood opening position;

[0029] [Fig. 2] is a schematic perspective view of part of the telescope and the protection system illustrated in Figure 1 in a hood-closed position;

[0030] [Fig. 3] is a top view of the protection system illustrated in figures 1 and 2 in the hood open position;

[0031] [Fig. 4] is a top view of the protection system illustrated in figures 1 and 2 when the hood is opened;

[0032] [Fig. 5] is a top view of the protection system illustrated in figures 1 and 2 during the resetting of the protection system drive device.

[0033] Detailed description of the invention

[0034] In the various figures, the same reference numerals designate identical or similar elements. For the sake of brevity, only the elements necessary for understanding the described embodiment are shown in the figures and are described in detail thereafter. The protection system according to the invention will be described in a non-limiting manner in the coordinate system shown in Figures 1 and 2. Figure 1 schematically represents an example of a protection system 2 for a telescope. The protection system 2 is intended to be carried on the spacecraft carrying the telescope 8. The telescope 8 includes, in particular, a body, for example cylindrical 8A, and an optical system, not shown, located within the telescope body. In Figure 1, only one end of the cylindrical body 8A of the telescope is schematically represented, as well as the optical beam F of the telescope entering through the end of the telescope 8 to be processed by the optical system.

[0035] As shown in Figure 1, the protection system 2 comprises a frame 4 and a cover 6 hinged to the frame. The frame 4 is schematically represented by a plate 3 fixed around the telescope body and a post 5 extending perpendicularly from the plate. A portion of the frame reaches the height of the telescope opening at the point where it connects to the cover. A part of the frame is thus adjacent to the telescope body. The frame is, for example, fixed relative to the outer casing of the telescope.

[0036] Alternatively, one could also consider a hood blocking the beam inside the telescope body and upstream of the optical system receiving the incoming light beam.

[0037] As shown in Figure 1, the cover 6 comprises a shutter plate 7, for example circular, and a support arm 9 carrying the shutter plate at its end. The arm and the shutter plate are rotatable relative to the frame around an axis 13, for example parallel to the telescope axis. The shutter plate 7 extends, for example, in a plane parallel to the (x, y) plane, the telescope axis extending parallel to the Z-axis normal to the (x, y) plane. The plane of the rear face of the shutter plate is positioned in front of the telescope aperture. As shown in Figure 1, the shutter plate covers an area larger than the telescope diameter. The diameter of the cylindrical shutter plate is, for example, larger than the telescope diameter. The shutter plate 7 has, for example, a diameter of 750 mm for a telescope with a diameter of 700 mm.Larger plate diameters can also be considered, particularly depending on the diameters of the telescopes to be covered.

[0038] The cover 6 is movable relative to the frame 4 between an open position, as shown in Figures 1 and 4, in which the cover 6 is unobstructed from an optical beam F entering the telescope 8, and a closed position, as shown in Figures 2, 3, and 5, in which the cover 6 blocks the beam F entering the telescope. In the open position, the cover 6 is positioned next to the telescope. In the closed position, the cover 6 covers the telescope aperture and blocks the optical beam.

[0039] As shown in Figure 1, the cover 6 is held in the open position by a holding mechanism 18, for example, of the hold-down and release (HRM) type. The holding mechanism 18 can release the cover and can be reused to hold it again. The HRM mechanism may, for example, be a permanent magnet holding the arm attached to the cover. This magnet is deactivated, for example, by a controlled current in a coil to create a magnetic field that cancels out the effect of the permanent magnet. The support arm includes a ferromagnetic element, for example, located on one of its sides, so that it can be held by the magnetic field. Alternatively, the holding mechanism is a fastener, such as a hook, actuated by an electric motor.

[0040] As shown in Figure 1, the protection system 2 further includes an elastic element 10 that tends to push the cover 6 towards the closed position. The elastic element 10 is designed to act between the frame 4 and the cover 6. Preferably, the elastic element comprises a lower torsion spring 10A and an upper torsion spring 10B. A spring member, for example, bears against the movable cover so as to pull the cover towards the closed position. The spring member is, for example, a torsion spring held around the axis Z1 of the cover and bearing on the frame, symbolized here by the upright 5, and on a lug 15 attached to the cover.

[0041] The stiffness of the elastic element is chosen according to the mass of the hood. Advantageously, the elastic element allows for very rapid hood closure, in less than 1 second, even for a large diameter hood, for example, at least 750 millimeters.

[0042] As shown in Figure 1, for example, an eddy current braking device 21 is attached to the hood arm and generates a resisting torque along the hood's axis of rotation. The eddy current braking device 21 is designed to brake the hood's movement to limit its closing speed below a predetermined threshold. The braking device comprises a rotor fixed to the hood and a stator fixed to the frame 4. Advantageously, the eddy current braking device increases the braking force as the hood's speed increases. The eddy current braking device also automatically reduces the closing speed and, at the end of its travel, further reduces the rebound against the end stop. Advantageously, the eddy current braking device operates automatically, i.e., without being controlled by an electronic control module.

[0043] A support element on the hood is, for example, in the form of a movable arm 24 which is driven to move the hood into the open position, as shown in Figure 1. The arm is, for example, in the form of a connecting rod, one end of which bears on the hood and is guided in rotation by another arm 22, and the other end of which is articulated around a rotating drive element 28. The rotating drive element 28 is, for example, controlled by an electric motor 14. An electronic control module 20 controls, for example, the retaining mechanism 18 and the drive motor 14.

[0044] For example, a damping end stop 32 is provided adjacent to the telescope and corresponds to the closed position of the shutter cover. Advantageously, the damping stop absorbs the shock of the shutter cover as it reaches the end of its travel and limits the cover's rebound. Thus, the telescope aperture remains fully closed.

[0045] Referring to Figure 2, the cover 6 is, for example, integral with a connecting profile 11 comprising an internal wall with a circular cross-section for rotational guidance about the axis Z1 and a bearing wall against the arm 9 integral with the cover. The profile is, for example, integral with at least one bearing 30, located on a mid-section of the shaft, providing rotational guidance relative to the shaft. The shaft is, for example, supported at its ends. For example, bored portions 19 and 23 are provided integral with the frame to receive the shaft. The shaft of the eddy current braking mechanism is, for example, driven by an L-shaped piece integral with the cover and fixed to the end of the shaft at the output of the braking mechanism.

[0046] In one variant, the profile is, for example, attached to a circular rod guided along the axis Z1 of rotation of the hood by bearings, arranged, for example, at the ends of the axis. The circular rod is, for example, aligned and fixed to the axis at the output of the braking mechanism and directly drives the eddy current braking mechanism. As shown in Figure 2, a pair of springs wound around the axis of rotation Z1 of the hood 6 and arranged on either side of the arm 9 attached to the hood 6 are provided. A first and a second ear, attached to the hood, are each provided with a support lug with a spring, each spring also bearing against the frame. Each torsion spring has, for example, a first strand bearing against the lug of an ear 15, 16, and a second strand bearing against the frame.The lower torsion spring 10A is positioned between the connecting profile 11 and the fixed lower bearing 19. The upper torsion spring 10B is positioned between a guide arm 22 and an upper portion 23 that receives the shaft and is integral with the frame. The presence and positioning of these two springs allow for symmetrical distribution of the forces on the hood. Preferably, the torsion springs 10A and 10B are located on either side of a median plane of the hood. Preferably, the torsion springs have a stiffness between 5 Nm and 10 Nm.

[0047] As shown in Figure 2, the damping stop 32 includes, for example, a pair of springs acting on a pusher that moves in translation relative to the frame.

[0048] As shown in Figure 2, in the closed position, the arm 24 pushing the hood is recessed or in contact with an element attached to the hood.

[0049] The support element 24 is thus ready to push the hood while having a position that does not interfere with its closing.

[0050] As shown in Figure 2, the protection system 2 includes a drive device 12 for moving the cover relative to the frame between the first position, corresponding to the closed position of the telescope, and the second position, corresponding to the open position of the telescope. The drive device 12 comprises the actuator 14, which may, for example, be an electric motor with an output shaft capable of driving an eccentric 28 articulated with the arm 24 that pushes the cover. The actuator comprises a main body fixed relative to the frame and a drive shaft movable relative to the frame. The support arm 24, driven by the eccentric 28, can thus push the cover 6 into the open position and simultaneously tension the elastic element 10.

[0051] The support arm 24, for example, has its support end 26 guided in rotation by another arm 22, the support arm then taking the form of a connecting rod. The guide arm 22 is, for example, articulated on one side about the axis Z1 of the hood and on the other side with respect to the support connecting rod 25.

[0052] The support end 26 of the support element is also designed to disengage and move away from the hood by a reverse movement of the drive mechanism's reset. The term "disengage" means that the support element is moved away from the hood, and in particular from the hood arm, during the reset movement.

[0053] As shown in Figure 2, the pivot axis Z2 of the motor shaft is, for example, parallel to the pivot axis Z1 of the hood.

[0054] Alternatively, the electric motor and eccentric are replaced by a linear actuator, for example a pneumatic actuator.

[0055] Alternatively, the guide arm 22 is replaced by a cam track. Advantageously, the protection system according to the invention manages the closing and opening functions of the telescope separately. The hood is opened by an actuator that can have low power requirements, as the opening can be performed at low speed. Because the actuator can have low power requirements, it can be lightweight and compact, which is very advantageous in the field of spacecraft. The elastic element, on the other hand, allows for rapid closing.

[0056] Another advantage of the invention is that the actuator can move a hood of significant mass, while having a low weight and requiring little energy input.

[0057] As shown in Figure 2, the retaining mechanism 18 is not connected to the cover and is positioned to hold the cover 6 in the open position, which can then be released upon receipt of a closing command signal. For example, the retaining mechanism 18 includes an electromagnetic suction cup. Figures 3 to 5 show the protective device 2 from a top view. In these figures, the upper torsion spring 10B, the upper part 23, and the first tab 15 have not been shown to simplify understanding.

[0058] In Figure 3, the protective device 2 is shown in a closed position. In this position, the cover 6 covers the opening of the cylindrical body of the telescope 8.

[0059] Referring to Figure 4, to position the cover 6 in the open position, the actuator 14 is activated. The drive shaft of the actuator 14 rotates around the second axis of rotation Z2, for example, clockwise. This rotational movement is limited, for example, to an angular range of less than 180 degrees. The eccentric 28 is then driven in rotation around the second axis of rotation Z2 by the drive shaft. The eccentric 28 causes the support arm 24 to move. The end 26 of the support arm 24 then approaches the support arm 9 of the cover and makes contact with it. The end 26 of the support arm 24 then pushes the support arm 9. The support arm thus rotates around the axis of rotation Z1, for example, clockwise. Under the action of this thrust, the hood 6 pivots relative to the frame 4 around the first axis of rotation Z1.The tension springs 10A, 10B are compressed during the rotation of the hood. When the hood 6 reaches the open position, the retaining mechanism 18 comes into contact with the support arm 9 and holds the hood in the open position.

[0060] Referring to Figure 5, when the cover 6 is held in the open position, the actuator 14 moves the support arm 24 into the so-called cocking position. For this purpose, the drive shaft of the actuator 14 pivots in the opposite direction, for example, counterclockwise. The support rod 25 is thus moved away from the support arm 9. During this movement, the cover 6 remains in the open position because it is held in position by the retaining mechanism 18. The arm then moves into the position corresponding to the closed position.

[0061] Next, to position the cover 6 in the closed position, the control module 20 sends and transmits a closing command signal to the retaining device 18. Upon receiving this signal, the retaining device 18 releases the cover 6. The cover 6 is then rotated around the first axis of rotation Z1 by the action of the springs, for example, clockwise. The rotational speed of the cover 6 increases under the action of the springs during the closing movement. To prevent damage to the cover during closing, the eddy current braking device 21 slows the speed of the cover to keep it below a predetermined threshold.

[0062] At the end of the stroke, the damping stop 32 dampens the movement of the hood and stops it in the closed position, as shown in figure 3.

[0063] The invention also relates to an assembly comprising a telescope 8 and a telescope protection system 2 as described above.

[0064] Finally, the invention relates to a spacecraft comprising a telescope 8 and a telescope protection system 2 as described above.

Claims

DEMANDS 1. A protection system (2) for a telescope suitable for use on a spacecraft, comprising: - a fixed frame relative to the telescope (4), - a hood (6) mounted pivotally relative to the frame (4) around a first axis of rotation (Z1) between an open position in which the hood is clear of an optical beam from the telescope (8) and a closed position in which the hood blocks the telescope beam, - an elastic element (10) tending to push the hood (6) towards the closed position, - a movable drive device (12) between a first position corresponding to the closed position and a second position corresponding to the open position, the drive device (12) comprising a support element (24) configured to push the hood (6) into the open position and tension the elastic element, and an actuator (14) suitable for driving the support element, the support element (24) being able to be disjointed from the hood in the open position, - a retaining mechanism (18), separate from the support element, adapted to hold the hood (6) in the open position, the retaining mechanism being capable of releasing the hood upon receipt of a closing command signal emitted by a control module (20), - a damping stop (32) at the end of travel stopping the hood in the closed position.

2. System according to claim 1, further comprising an eddy current braking device (21) suitable for braking the movement of the hood to limit the speed to a determined threshold.

3. System according to any one of claims 1 and 2, wherein the drive device (12) comprises an eccentric (28) articulated to the support element in the form of a support arm (24); said actuator (14) in the form of a motor comprising an output shaft for driving the eccentric, the support arm (24) in the form of a support rod (25); the support rod comprising a support end (26) guided in rotation about the first axis of rotation (Z1).

4. System according to claim 3, wherein the hood (6) extends along a plane perpendicular to the first axis of rotation (Z1).

5. A system according to any one of claims 1 to 4, wherein the retention mechanism (18) comprises an electromagnetic suction cup.

6. A system according to any one of claims 1 to 5, wherein the elastic element (10) comprises a pair of torsion springs (10A, 10B) bearing, on the one hand, against the frame (4) and, on the other hand, against the cover (6), the torsion springs being arranged symmetrically with respect to a median plane of the cover.

7. Assembly comprising a telescope (8) and a telescope protection system (2) conformed according to any one of the preceding claims, the protection system (2) being fixedly mounted relative to the telescope (8).

8. Spacecraft comprising a telescope (8) and a protection system (2) for said telescope conformed according to any one of claims 1 to 6.

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