Multi-orbit space surveillance device

Abstract

In an apparatus 1 for monitoring an object in an orbit around the Earth, the apparatus 1 includes a chassis 2, a plate 3, at least three optical survey modules 4, and a power supply and control block 5 that is at least partially housed inside the chassis 2. The plate 3 is attached to the chassis 2. Each of the at least three optical survey modules 4 is attached to the plate 3 and has a rotating turret 400, an imaging sensor 408 attached to the rotating turret 400, and a passive optical system 410 attached to an entrance of the imaging sensor 408. The rotating turret 400 is configured to rotate by 360° or more about a first axis perpendicular to the plane in which the plate 3 extends, and to rotate by 90° or more about a second axis that is perpendicular to the first axis and perpendicular to the plane in which the plate 3 extends. Apparatus 1.

Description

Technical Field

[0001] The present invention relates to a space surveillance system for exploring the near-Earth and deep-Earth space from the ground, which detects objects located in this space, determines their exact orbits, and monitors these orbits.

[0002] With the above space surveillance system, the development of the orbits of objects can be followed, and these objects and their orbits can be cataloged.

Background Art

[0003] The near-Earth space is defined as the part of the space existing at a location up to several hundred thousand kilometers from the Earth. Therefore, the investigation of the near-Earth space is essentially, but simply, related to the detection of objects existing generally on orbits around the Earth, typically from 100 km to 36,000 km from the Earth's surface.

[0004] The background of the present invention is the increase in the number of observation targets within the orbit around the Earth. These observation targets are, for example, debris, operational satellites, or meteorites.

[0005] The present invention particularly targets objects in the low Earth orbit (LEO) of 200 km to 2000 km. The number of these objects induces an increased risk of collisions that can lead to a long-term increase in the deterioration of the situation, and in the case of operational space assets, regardless of military, scientific, or commercial applications, it particularly attracts risks. In order to control these risks, it is essential to catalog all potentially dangerous objects and associate them with effective orbital parameters that can characterize their orbits.

[0006] When observed from a fixed point on the Earth, objects in the low Earth orbit have the characteristic of moving rapidly across the celestial sphere. Furthermore, at any moment, several objects cross the celestial sphere at several locations. Depending on their orbital parameters, the time interval between two objects continuously crossing the local celestial sphere can vary from several tens of minutes to several hours.

[0007] Orbits are affected by various influences such as tides, atmospheric drag, radiation pressure, and irregularities in the Earth's gravitational field. This prevents these orbits from being accurately characterized in the long term by an invariant set of orbital parameters.

[0008] Furthermore, the size distribution of objects varies, for example, from characteristic radii such as propulsion, paint residues, meteorites, etc., up to several tens of meters, especially for satellites or artificial orbital systems, whether or not they are operational.

[0009] To conduct an investigation of objects in Earth orbit, even without deductive knowledge of the presence and position of objects in low orbit, detecting the objects, defining the orbit or orbital parameters with an accuracy suitable for the intended use, and updating over time the integration of the detected objects' orbital parameters into a tracking catalog are involved.

[0010] It is further necessary to re-acquire the same object and re-read the measurement of their orbital parameters each time this same object passes within the field of view of the observation means, so as to maintain the accuracy according to the use for which they must be made, for example, identifying and aggregating (tracking) the collision risk or carrying out the process of mapping and monitoring (surveying) cosmic objects.

[0011] Finally, this system must be able to refine, according to the requirements, the accuracy of the knowledge of the orbital parameters of a given object so that it can determine its position as accurately as possible, typically within a few days in the near future.

[0012] To perform these monitoring functions, a wide field of view, the sensitivity to enable the detection of the object of interest, and sufficient accuracy in the measurement of the spread of objects across the field of view to estimate the orbital parameters at the required performance level are required.

[0013] The orbital parameters are estimated based on a time series of measurements of the position / velocity vector of an object acquired during the passage of the object within the field of view.

[0014] Patent Document 1 (U.S. Patent No. 7,319,556) deals with a wide-field telescope adapted to a system that performs these functions.

[0015] The main technologies currently envisioned and implemented for conducting low-Earth orbit surveys are the radar for the U.S. Department of Defense's Space Fence, the GRAVES radar (phased array, or bistatic radar, continuous emission) implemented by the French Ministry of Defense, ground-based radars such as missile defense warning radars (monostatic phased array radars, pulse emission), etc.

[0016] Although they offer many advantages (a wide field of view that can cover an area of 180° in azimuth exceeding several tens of degrees in elevation, simplification of access to velocity information by Doppler measurement, insensitivity to weather and day-night cycles, etc.), the solutions using radars mainly have problems in terms of their development, operation, maintenance costs, and their ecological balance. The frequencies used are high (in the L band), large magnetic losses occur, tens of megawatts of power are required and the efficiency is low, Similar to high-power electrical equipment, the mean time between failures (MTBF) of radars is low, which causes high maintenance costs. The number of orbits accessible by each radar is adjusted according to the location on the Earth and is located in the equatorial zone, which results in severe temperature and humidity conditions for electrical and electronic components, and as a result, many disadvantages such as increased operation and maintenance costs are incurred.

[0017] Alternatively, this optical system has already been considered for space surveillance. This optical system is purely passive and its principle lies in the detection of sunlight reflected by natural or artificial objects in orbits around or beyond the Earth, such as asteroids and planets. The above system provides, for example, access to the time series of the measurement of the angular position of an object in azimuth and elevation.

[0018] Various methods are applied to measure these positions, such as, in particular, methods based on the measurement at every instant of the position of the detected object with respect to the stars present in the field of view, the positions of the stars being known with very high precision.

[0019] The main advantages of the optical system over radar systems are its low cost in terms of development, manufacture, operation, and maintenance, its reliability, and its ease of implementation.

[0020] Also, being purely passive, it requires very few infrastructure, energy, buildings, and means of transportation.

[0021] The optical system is usually used to monitor the geostationary Earth orbit (GEO), but is also used to monitor the medium Earth orbit located between LEO and GEO. This is because the objects on these two Earth orbits have the particularity of hardly moving across the celestial sphere, which facilitates the long observation times required for the detection of small objects and / or very low light intensities.

[0022] The US Air Force's "GEODSS" system is an example of the operation of such a system. This mainly consists of metering telescopes with a small field of view of about one degree. In these GEO and MEO applications, long integration (exposure) times of one to several seconds can be used, which allows the signal-to-noise ratio to be increased in order to detect small objects with a characteristic diameter of several tens of centimeters.

[0023] An example of an embodiment of a multi-sensor is described in Patent Document 2 (US Patent Application Publication No. 2009 / 0147238).

[0024] In addition, several studies have been initiated to identify solutions that can monitor LEO.

[0025] For example, the French experimental system SPOC (Probationary System for Observation of the Sky) integrated four small telescopes with an aperture of 10 cm, each providing a field of view on the order of 10°, oriented according to four basic points with an elevation of several tens of degrees.

[0026] In other concepts, a measurement aperture or a more sensitive catadioptric system called a wide-field catadioptric system on the order of 5° dedicated to the investigation of LEO, such as the system described in the aforementioned Patent Document 1 (U.S. Patent No. 7,319,556), is proposed.

[0027] However, the aforementioned and currently proposed solutions do not address the fundamental difficulties and constraints associated with LEO investigations, namely, In particular, the need for rapid (within a few days) detection of any new objects to identify in-orbit fragmentation and explosion phenomena, the need for frequent reacquisition (every few days) of each object, and the update of orbital parameters to maintain the accuracy of the available orbital parameters, especially the need regarding the operational assessment of the collision risk, the detectability of objects that is interdependent with the geographical location of the optical system and the orbit (especially the inclination) of the objects related to its illumination conditions, optical observations related to local weather conditions (cloudy).

[0028] Due to these constraints, LEO investigations also require a specific optical system with very good sensitivity, excellent resolution, and a large field of view. Indeed, existing telescopes usually have high sensitivity with a large aperture and / or long integration time and high resolution that is detrimental to a wide field of view. This is because these telescopes are intended for classical astronomy or monitoring applications of minor planets or asteroids. Therefore, they are not compatible with the monitoring of objects in LEO.

[0029] Furthermore, the principle of this monitoring does not provide object tracking. Thus, during LEO observations, a long integration time does not improve the detectability of objects, which is evaluated in relation to the signal-to-noise ratio at each illuminated pixel. This is because, in the case of classical integration (second integration), the object crosses several pixels of the sensor (CCD or CMOS) over the integration time, penalizing not only the determination of the position and its chronometry, but also the integration noise, and thus degrading the signal-to-noise ratio once the pixel has been crossed.

[0030] From another point of view, the known solutions are not adapted to the detection conditions in LEO and thus do not guarantee the observation of all observable objects with an adapted revisit time.

[0031] Finally, wide-field telescopes remain limited, especially like those known from Patent Document 3 (U.S. Patent Application Publication No. 2009 / 009897) or Patent Document 4 (European Patent No. 1772761).

[0032] Other examples of telescopes are described in Patent Document 5 (U.S. Patent No. 7045774), Patent Document 6 (U.S. Patent Application Publication No. 2007 / 0188610), and Patent Document 7 (U.S. Patent Application Publication No. 2009 / 0015914).

[0033] Space surveillance systems for the investigation of the space near the Earth are also known from Patent Document 8 (European Patent No. 2593366), Patent Document 9 (European Patent No. 2593367), and Patent Document 10 (European Patent No. 2593368).

Prior Art Documents

Patent Documents

[0034]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Patent Document 9

Patent Document 10

Summary of the Invention

Problems to be Solved by the Invention

[0035] Therefore, the main object of the present invention is to provide a passive optical device having a wide survey field of view with a capacity of at least 120° of azimuth aperture for monitoring objects on an Earth orbiting trajectory in low Earth orbit, medium Earth orbit, and geostationary Earth orbit.

Means for Solving the Problems

[0036] According to one object of the present invention, in a device for monitoring an object in a cosmic orbit around the Earth, The device comprises a chassis, a plate, at least three optical investigation modules, and a power supply and control block at least partially housed inside the chassis. The plate is attached to the chassis, and each of the at least three optical investigation modules is attached to the plate and has a rotating turret, an imaging sensor attached to the rotating turret, and a passive optical system attached to the entrance of the imaging sensor. The rotating turret is configured to rotate by 360° or more about a first axis perpendicular to the plane in which the plate extends, and to rotate by 90° or more about a second axis perpendicular to the first axis and perpendicular to the plane in which the plate extends. A device has been proposed.

[0037] Thus, the device according to the present invention forms a device equipped with a passive optical system for exploring cosmic objects. Since the at least three optical modules provide a large number of simultaneous exploration optical fields, the time required to detect an object in a low Earth orbit can be shortened. Therefore, the number of objects that can be detected within a given time can be increased.

[0038] In a first embodiment of the present device, the rotating turret can be an electric turret comprising at least one motor for actuating rotation along two rotation axes, and the power supply and control block has a control unit for each rotating turret configured to control the rotating turret independently of other rotating turrets.

[0039] Thus, these optical modules can be controlled by automation and / or remote control, and they can be controlled independently of each other, thereby possibly enabling the tracking of an object detected by an optical module while another optical module moves or does not move in a different direction.

[0040] According to the second embodiment of the present device, the chassis can be provided with height-adjustable legs, and these legs are adjustable between at least two different lengths such that they have a plate that can be positioned between a first height of 1000 mm and a second height of 2030 mm.

[0041] With these adjustable legs, while maintaining appropriate dimensions and weight, the height of the plate can be adjusted according to the installation environment, and the optical device can be placed in the best state to obtain the clearest possible observation field of view.

[0042] According to the third embodiment of the present device, the plate can be provided with a central orifice through which power cables and data cables connected between the optical investigation module and the power supply and control block pass.

[0043] The central orifice of the plate enables all cables connected to different optical investigation modules to be concentrated at the center of the device, directed towards the power supply and control block, thus reducing the volume of the device and reducing the risk of cables entering one of the observation fields within the optical investigation module.

[0044] According to the fourth embodiment of the present device, the rotating turret is preferably made of aluminum in order to reduce the weight of the rotating turret and thus the total weight of the device. As a variant embodiment, in order to reduce manufacturing costs, the rotating turret can also be made of stainless steel.

[0045] According to the fifth embodiment of the present device, the rotating turret is preferably uniformly distributed on a circle having a diameter smaller than the inscribed circle of the plate.

[0046] By uniformly distributing the optical modules along the circumference of the circle, the observation field of view can be optimized and the overlapping area of the observation fields of view of different optical modules can be reduced.

[0047] According to the sixth embodiment of the present device, the present device can further include a temperature adjustment block that is fixed on the power supply and control block and is configured to adjust the temperature of the power supply and control block between +13°C and +23°C. The power supply and control block can be formed by forming a power supply bay having a control unit.

[0048] The temperature adjustment block enables the device to be placed and used in an environment where the conditions are not usually very favorable for the proper operation of the device. The temperature control block can be a heating block or a cooling block configured to heat or cool the power supply and control block according to environmental conditions, or an air conditioning unit.

[0049] According to the seventh embodiment of the present device, the present device can further include a humidity adjustment block that is fixed on the power supply and control block and is configured to adjust the humidity at a humidity level configured between 30% and 60% inside the power supply and control block.

[0050] The humidity adjustment block makes it possible to place and use the device in an environment where the conditions are not usually favorable for the proper operation of the device.

[0051] In one embodiment, the temperature adjustment block can be a heating block, and the humidity adjustment block can be an air conditioning block configured to cool the power supply bay and adjust its humidity.

[0052] According to the eighth embodiment of the present device, the device preferably includes six optical inspection modules uniformly distributed in a circle having a diameter smaller than the diameter of the inscribed circle of the plate.

[0053] By using six optical modules, an optimized optical target range can be obtained.

[0054] According to the ninth embodiment, the rotary turret can limit the minimum rotation of the amplitude to 10° around the first axis, can reach a maximum rotation of 360°, has a displacement pitch of 1°, and can reach a pitch of up to 0.1°.

[0055] Other features and advantages of the present invention will become apparent from the following description, which illustrates one exemplary embodiment thereof, with reference to the accompanying drawings, without any limitation.

Brief Description of the Drawings

[0056]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0057] FIG. 1 schematically shows a perspective view of an apparatus 1 for monitoring an object within an orbital path around the Earth according to one embodiment of the present invention.

[0058] The apparatus 1 includes a chassis 2, a plate 3, six optical survey modules 4, a power supply and control block 5, and an operation adjustment block 6.

[0059] As shown in FIG. 3 showing a perspective view of the chassis 2 and plate 3 of the apparatus 1 of FIG. 1, the chassis 2 includes a U-shaped base 200 having three segments 202 and four assemblies 204, and these four assemblies 204 are respectively bolted to one end or corner of the base 200, and are intended to fix the base 200 to the ground where the apparatus 1 is fixed.

[0060] The chassis 2 further includes four legs 206 screwed to the base 200 at the first end 2060. The four legs 206 equipped with vibration damping devices are arranged at the four corners of a square extending in a plane parallel to the plane in which the base 200 extends. Two of the first legs 206 are fixed to each other by a first crossbar 208, and two of the second legs 206 different from the first legs are fixed to each other by a second crossbar 210.

[0061] Each leg 206 includes a lower part 206a and an upper part 206b that partially fits into the lower part 206a. The first crossbar 208 is fixed to the lower part 206a of the first two legs 206, and the second crossbar 210 is fixed to the lower part 206a of the second two legs 206.

[0062] The upper part 206b of each leg 206 slides along the lower part 206a to which it is related, and the lower part 206a slides inside the upper part 206b. Therefore, in order to ensure that the field of view of the optical module is clear, the height of each leg 206 can be adjusted between a low position and a high position according to the environment of the device 1.

[0063] Each leg 206 includes a second end 2065 fixed to the plate 3. The first end 2060 of each leg 206 corresponds to one end of the lower part 206a that is not covered by the upper part 206b, and the second end 2065 of each leg 206 corresponds to one end of the upper part 206b.

[0064] As illustrated in FIG. 2 showing a top view of the device 1 in FIG. 1, the plate 3 is disk-shaped and includes a lower surface 300 facing the chassis 2 to which the plate 3 is fixed and an upper surface 302 opposite to the lower surface 300. The optical inspection module 4 is mounted on the upper surface 302 of the plate 3.

[0065] Plate 3 further includes a central orifice 304 that traverses the center of a disk with a cover 306 having a hexagonal bottom surface, and has an upper surface 308 parallel to the upper surface 302 of plate 3 and six lateral surfaces 310 that extend perpendicularly to plate 3 between the upper surface 302 of plate 3 and the upper surface 308 of cover 306. Each lateral surface 310 of cover 306 is perforated with an orifice 312 so that a cable can pass through the orifice 312 of the lateral surface and the central orifice 304 of plate 3.

[0066] The optical modules 4 are evenly arranged on the periphery of a circle whose diameter is smaller than the outer periphery of the disk formed by plate 3. Accordingly, each optical module 4 is separated from the adjacent optical module 4 by an angle of 30° measured with respect to the center of the disk of plate 3. This separation angle between the plurality of modules may vary depending on the configuration.

[0067] If this plate has a shape other than a disk, for example, a polygonal shape, the circle on which the optical inspection modules 4 are arranged will have a diameter smaller than the diameter of the circle inscribed in the polygonal shape of plate 3.

[0068] Each optical module 4 includes an aluminum electric rotating turret 400 in order to maintain the lightest weight possible at a reduced cost. Each turret 400 includes a support 402 fixed on plate 3, and the support 402 has legs 404 placed thereon. The legs 404 can rotate around a first axis perpendicular to the plane in which plate 3 extends. Plate 3 extends parallel to a plane having directions X and Y, and the first axis extends along a direction parallel to direction Z as illustrated in FIG. 1.

[0069] In addition, the turret 400 of each optical module 4 includes an arm 406 connected to the leg portion 404 of the turret 400. The arm 406 is rotatably mounted on the leg portion 404 about a second axis that is perpendicular to the first axis and extends parallel to a plane including directions X and Y.

[0070] An imaging sensor 408 connected on its optical entrance to a passive optical system 410, such as a lens assembly, is mounted on the arm 406 of each turret 400.

[0071] Therefore, each assembly composed of the imaging sensor 408 and the associated passive optical system 410 can be oriented along two directions, namely, a first direction and a second direction.

[0072] The leg portion 404 of the turret 400 can rotate 185° in one direction and 185° in the other direction around the first axis, i.e., the Z axis, and thus can cover 370° in a plane parallel to the XY plane. The arm 406 of the turret 400 can rotate 90° in one direction and 90° in the other direction around the second axis, and thus can cover 180° in a plane perpendicular to the XY plane.

[0073] Note that the cables connecting the optical survey module 4 to the power supply and control block 5 are not shown for clarity. Each cable passes through the central orifice 304 of the plate 3 and then through the orifice 312 in the side surface 310 of the cover 306 before being sent to the power supply and control block 5. Therefore, the power supply and control block 5 can control the power supply to the motor of the turret 400 and the imaging sensor 408 of the optical module, the orientation of the leg portion 404 and the arm 406 of each turret, and the acquisition of images by the imaging sensor 408.

[0074] The power supply and control block 5 is shaped such that it is arranged inside the volume defined by the chassis 2 and the plate 3, particularly between the plurality of legs 206 of the chassis 2. The power supply and control block 5 further includes a control module for each turret 400 that can control each turret 400 independently of the other turrets 400.

[0075] The operation adjustment block 6 is thermodynamically connected to the power supply and control block 5 and is configured to adjust the temperature and humidity inside the power supply and control block 5. Accordingly, the temperature inside the control block 5 can be maintained at a temperature configured between +13°C and +23°C and a humidity of less than 60% for optimal operation of the device 1.

Claims

1. In an apparatus (1) for monitoring an object in an orbital path around the Earth, the apparatus (1) comprises a chassis (2), a plate (3), at least three optical survey modules (4), and a power supply and control block (5) at least partially housed inside the chassis (2), the plate (3) is mounted on the chassis (2), each of the at least three optical survey modules (4) is mounted on the plate (3) and has a rotating turret (400), an imaging sensor (408) mounted on the rotating turret (400), and a passive optical system (410) mounted at the entrance of the imaging sensor (408), the rotating turret (400) is configured to rotate by 360° or more about a first axis perpendicular to the plane in which the plate (3) extends, and to rotate by 90° or more about a second axis perpendicular to the first axis and perpendicular to the plane in which the plate (3) extends, apparatus (1).

2. the rotating turret (400) is a plurality of electric turrets each comprising at least one motor for actuating the rotation along two rotation axes, the power supply and control block (5) has a control unit for each rotating turret (400) configured to control the rotating turret (400) independently of the other rotating turrets (400), apparatus (1) according to claim 1.

3. the chassis (2) comprises height-adjustable legs (206), and the legs (206) are adjustable between at least two different lengths such that the plate (3) has a positionable plate (3) between a first height of 1000 mm and a second height of 2030 mm, apparatus (1) according to claim 1 or 2.

4. the plate (3) comprises a central orifice (304) through which power and data cables connected between the optical survey module (4) and the power supply and control block (5) pass, apparatus (1) according to any one of claims 1 to 3.

5. the rotating turret (400) is made of aluminum, apparatus (1) according to any one of claims 1 to 4.

6. the rotating turrets (400) are uniformly distributed on a circle having a diameter smaller than the inscribed circle of the plate (3), apparatus (1) according to any one of claims 1 to 5.

7. The device (1) according to any one of claims 1 to 6 further comprises a temperature adjustment block (6) fixed on the power supply and control block (5) and configured to adjust the temperature of the power supply and control block (5) between +13°C and +23°C.

8. The device according to any one of claims 1 to 7 further comprises a humidity adjustment block (6) fixed on the power supply and control block (5) and configured to adjust the humidity at a humidity level configured between 30% and 60% inside the power supply and control block (5).

9. The device according to any one of claims 1 to 8 comprises six optical inspection modules (4) uniformly distributed in a circle having a diameter smaller than the diameter of the inscribed circle of the plate (3).

10. The device (1) according to any one of claims 1 to 9, wherein the rotary turret (400) has a displacement pitch centered on the first axis, with an amplitude limited to 10° and a displacement pitch of 1°.

Images