RU2761957C1 - Method for pulse laser clearing of space from single small objects of space debris and pulse laser system for implementation thereof - Google Patents

Abstract

FIELD: cosmonautics.

SUBSTANCE: group of inventions relates to space equipment and can be used for clearing near-earth space from particles of space debris (SD) contaminating said space. The method for pulse laser clearing of space from single small SD objects includes detection of a single SD object, determination of the parameters thereof, guidance and focusing of laser emission on the SD object. Detection of SD objects subject to removal from the orbit, focusing of laser emission thereon and exposure to laser emission are executed in at least two opposite directions, both on the SD object flying towards the pulse laser system and one flying in the trace thereof. The pulse laser exposure mode is automatically selected for each selected object individually. Each object is exposed to laser emission in a series of pulses. Ignition and maintenance of the burning of plasma in a vapour cloud near the surface of the SD are ensured. An area of increased pressure is formed in the vapour cloud with a shock wave capable of changing the velocity modulus of the SD object and reducing the time for removal thereof from orbit to Earth.

EFFECT: efficiency of SD removal is increased.

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Description

The invention relates to space technology and can be used for cleaning near-earth space from space debris (CM) contaminating it.

According to earlier studies by Eichler et al. [1-4], most of the CM is located at altitudes from 400 km to about 2000 km with two peaks about 800 km and 1500 km. There are proposals from various world centers for the utilization of large, medium and small CM, which have been in the stage of comprehensive discussion for a long time in terms of relevance and efficiency, as well as technical and financial feasibility, for example, [3, 4] and others.

Currently, several projects are being developed to remove CM from near-Earth orbit using high-power lasers. One of such projects is ORION, proposed by the Photonics Associates Company and supported by NASA (USA) [5, 6]. The following directions of using high-power laser systems for CM removal can be distinguished.

Laser on Earth. Ground-based laser systems must ensure reliable passage of the laser beam through the atmosphere. A necessary requirement for this is a high power and quality of the output radiation, which provides a beam divergence close to diffraction. For the most effective impact on CM, it is proposed to use high-frequency repetitively pulsed DF lasers with a wavelength of 3.8 μm, or solid-state lasers with a wavelength of 1.06 μm. In this case, the peak values of the intensity of the radiation incident on the CM increase by orders of magnitude in comparison with the continuous mode. Pulsed lasers, with their ability to reach maximum peak power, can deliver pulses from the earth's surface, slowing down space debris, which can then quickly enter the Earth's atmosphere, burn up or fall into the ocean. However, the level of technology development available at this stage will require costs for one facility up to $ 1 million.

Laser in orbit. There are proposals for the complete destruction of CM by laser evaporation, requiring the placement of a superlaser attached to a space telescope in orbit, as well as methods of slowing down or changing the direction of CM motion. In the research of V.V. Appolonov. [7] it was shown that the modulation frequency, optimal from the point of view of the highest energy output and effective overcoming of the plasma screen, is ~ 100 kHz, and the excess of the peak power over the average is 2-3 orders of magnitude. The duration of the pulses in both cases is in the range of 10 ^-7 - 10 ^-8 s. An experimental version of such a system is being prepared in China and Russia for experiments on the ISS, where it is planned to deliver a telescope record for space with a mirror diameter of 3 meters and a laser with 10,000 optical fibers.

Fang [8] describes an example of using a pulsed laser located on a space laser platform to remove centimeter-sized CM debris. Potential risks of collisions between the ISS and hazardous debris in low Earth orbit are discussed. As a result of long-term repetitively pulsed laser irradiation of CMs of centimeter sizes, which are in high-speed motion (up to 8-10 km / s) in low Earth orbit, the CM perigee height decreases slightly (up to 244.2 km).

The disadvantages of the proposed method is that the slowing down of the CM is achieved by repeated and long-term irradiation with laser pulses (more than 5000). In this case, the periods of irradiation are specially determined when favorable conditions arise (and the so-called windows appear), and the threat of collision between the fragments of the spacecraft and the ISS decreases.

Known inventions under patents [9] RU 2001109184 B64G 9/00, 05.04.2001, and [10] RU 2001109185, 05.04.2001, applicant RSC Energia im. S.P. Korolev, where devices for clearing space from CM are described. The devices contain a power plant, a system for detecting particles to be destroyed, a device for generating laser radiation with a cooling system, and a system for directed energy transfer to a particle to be destroyed. According to the invention, the device for generating laser radiation is made in the form of a pulsed gas-discharge laser based on atomic transitions with a laser medium in the form of metal vapors excited by an electric discharge. These patents propose a concept of space cleaning from small debris (meteoric particles) with a size of 0.1 to 10 millimeters using a maneuvering spacecraft (SC) with a nuclear electric propulsion system (NEPPU) with a power of 150 kW and a laser system powered by it, providing remote transmission energy of an evaporated meteoric particle at a distance of up to 10 km. The goal is to clean up space from small-sized technogenic debris in the altitude range from 800 to 1500-2000 km. The objects of influence are meteoric particles of artificial origin, less than 3 mm in size and more than several hundred microns. Particles of this size are beyond the limits of possible cataloging using a tracking system for near-Earth space, but above a threshold size that poses a danger to the integrity of spacecraft systems (space suits, pressurized compartments, etc.). The disadvantage of the proposed method is a significant limitation of the size of the CM to millimeter sizes.

Schall [11] recommends the use of high-power lasers to remove small CM fragments up to 10 cm in diameter. It is assumed that the data for the most probable orbit of collision with fragments is known. The real velocities of the ejection of vapors of the fragments under laser irradiation are estimated, and the acceleration of the fragments is calculated. This allows you to change the orbit of the fragments and ensure their re-entry into the Earth's atmosphere or, on the contrary, complete exit from the Earth's gravitational field. However, with the advent of very powerful lasers, a method may become available that uses such lasers to completely destroy (by evaporation) most of the small debris in Low Earth Orbit (LEO) and possibly even geostationary orbit (GEO). Schall [11], a megawatt-class laser will be required for objects up to 10 cm in size. Megawatt-class lasers are rather large (large in size) and are not usually used in space for civilian purposes. The disadvantage of this method is the ability to transfer the object to a higher orbit. The complete evaporation of small debris is also not effective, because it is necessary to launch into orbit or use a permanently installed on Earth laser with increased power, dimensions and weight.

A small-sized laser with repetitively pulsed radiation, described in the work of Soulard et al. [12], was chosen as a prototype for the proposed technical solution.

The subject of this technical solution is small objects of space debris (up to and about 10 cm) in low Earth orbit (up to 800 km), which are of particular concern because they are many and difficult to track or even detect on an ongoing basis. One of the rational solutions for today, in our opinion, is the placement of a small-sized laser with repetitively pulsed radiation and a power of 25, 50 or 100 kW in near-earth orbit.

A sensor system with artificial intelligence, developed on the basis of neural networks, and installed together with a laser on a carrier platform (ISS or satellite), allows detecting, recognizing and recording parameters (speed, size, trajectory, etc.) of single CM objects falling into the light field laser radiation.

The objective of the proposed technical solution is to increase the productivity and efficiency of removing small CM fragments from near-earth orbit using a high-frequency repetitively pulsed laser system.

The task is solved thanks to the proposed method of pulsed laser cleaning of outer space from single small objects of CM, which is carried out thanks to the constructive solution of the pulsed laser system.

The method of pulsed laser cleaning of space from single small CM objects includes detecting a single CM object to be removed from orbit, determining its parameters, determining the parameters of laser radiation guidance and focusing on the CM object and automatically selecting a certain mode of pulsed laser action on the CM object, and implementing the actual impact itself. According to the invention, detection of CM objects to be removed from orbit, focusing of laser radiation on them and exposure to laser radiation are carried out in at least two opposite directions, both on the CM object flying towards the pulsed laser system and flying in its wake, while automatic selection of the optimal mode of pulsed laser action is carried out individually for each selected object, then the action of laser radiation on each object is carried out in series of pulses: at the beginning, laser pulses of a certain duration are applied - τ _in (several milliseconds) with an intensity below the plasma formation threshold with a duration up to the moment of formation dense cloud of vapor around the surface of the CM object, then they are exposed to pulses with a duration shorter than the initial pulse - τ << τ _in with an intensity higher than the plasma ignition threshold, providing ignition and surfaces of the CM, capable of transferring additional laser energy to the vapor plasma and forming a region of increased pressure in the vapor cloud with a shock-wave effect capable of changing the modulus of the CM object and reducing the time of its removal from orbit to the Earth.

The method implements a pulsed laser system for cleaning outer space from single small objects of space debris CM, located on the space platform of the carrier, for example, the ISS and containing a block of a laser radiation source associated with an automatic control unit for laser radiation parameters, a unit for detection, recognition and registration of parameters of single CM objects , to be removed from orbit, and a block for pointing and focusing the transmission of laser radiation energy to the detected CM objects. According to the invention, a high-frequency repetitively pulsed laser (VIP laser) is used with at least two laser radiation leads opposite to each other, connected to a detection unit and a unit for aiming and focusing laser radiation on CM objects, made with two telescopic reflectors opposite to each other and two movable mirrors installed with the ability to automatically change their curvature and, accordingly, the direction of the wave vector of laser radiation by means of communication with the automatic control unit for laser radiation parameters and selection of the optimal mode of pulsed laser action that is optimally consistent with the parameters of the CM object to be removed from orbit.

The positive effect of the technical solution lies in the constructive solution of the laser, which allows at least in two directions to detect and focus radiation on CM objects, which makes it possible to increase the observation area of CM objects, and to increase the degree of protection of the carrier from unwanted collisions with CM objects, and also automatic selection of the optimal mode of pulsed laser action individually for each selected object, capable of changing the velocity modulus of the CM object and reducing the time of its removal from orbit to the Earth.

FIG. 1 schematically shows a pulsed laser system that can be placed on a space platform of a carrier, for example, the ISS or a satellite (not shown in the figure) with two laser radiation leads opposite to each other and with two telescopic reflectors opposite to each other, focusing laser radiation on single CM objects, both in front of the carrier and in its wake. FIG. 1 also depicts solar cells as a possible power supply for powering a laser system.

FIG. 2 is a functional diagram of a pulsed laser system;

FIG. 3 shows the dependences of the change in the ratio of the initial "life" time in the near-earth orbit T ₀ , without impact, to the "life" time T _v (ordinate axis) with a sudden decrease in the orbital velocity of spherical aluminum particles (CM objects) by a given value ΔV (abscissa axis) with a variation in particle size from 1 mm to 10 cm.

FIG. 4 shows the results of experiments [13] on ablation of various materials (metals and non-metals), which demonstrate the behavior of the specific coupling coefficient C _m of the laser energy with a force pulse depending on the absorbed radiation power density I _ab , while the duration of the laser pulse is limited to 5 nanoseconds.

FIG. 5 shows an exemplary diagram of time-separated pulse profiles for one laser "shot" at a target.

The Table shows the lifetimes T _{0 of} metal macroparticles (steel and aluminum) of various diameters D in a circular near-earth orbit at an altitude of about 400 km.

The method of pulsed laser cleaning of outer space from single small objects of CM is carried out thanks to the constructive solution of the pulsed laser system.

Pulsed laser system (Fig. 1), includes: an energy unit with a high-frequency pulse-periodic laser (VIP laser) 1; automatic control unit 2 for laser radiation; a unit for detecting 3 CM objects to be removed from orbit; block for aiming and focusing 4 VIP-laser 1 on the detected CM object.

A small-sized VIP laser 1 with a power of up to 100 kW provides a remote transmission of sufficient energy to an evaporated CM object, up to 10 cm in diameter, at a distance of up to 10 km.

VIP laser 1 contains at least two outputs for outputting radiation to CM objects, oppositely directed with respect to each other.

The automatic control unit 2 for laser radiation 1 connects units 3 and 4 with the unit for laser radiation 1; controls the curvature of telescopic reflectors and mirrors to change the direction of the wave vector of laser radiation, and also automatically selects the optimal mode of pulsed laser exposure individually for each CM object selected for removal. The automatic control unit 2 processes these parameters of the CM object, received from the unit 3, such as geometry, dimensions, speed and direction of movement, and develops the "tactics" of affecting the CM object. Observation of the object begins already from the distance L = D ² / λ, which is 1070 km, for the diameter of the mirror reflector D = 1 m and the radiation wavelength λ = 1.07 μm.

The laser effect is limited by the focusing spot diameter, which is determined by the formula: d _s = kθ _dif L, where L is the distance to the CM object, θ _dif = 2.44λ / D is the angle of diffraction beam divergence, depending on the wavelength λ and the mirror diameter D , k is the ratio of the real divergence to the diffraction one. If we assume that the radiation divergence is equal to two diffraction limits (i.e., k = 2), then for λ = 1.07 μm, D = 1 m, at a distance L = 10 km we obtain d _s = 0.0488 m. This means that the first laser pulses can be applied to the CM object from a distance of about 10 km.

The 3 CM object detection unit detects CM objects to be removed from orbit, both in front of the carrier of the pulsed laser system and in its wake, in the opposite direction to the direction of movement of the carrier and transmits information to the automatic control unit 2 for analysis and acceptance the optimal solution individually for each object, taking into account its parameters.

The block for aiming and focusing 4 of the laser 1 on the detected CM object contains at least two telescopic (mirror) reflectors 5 and 6, oppositely directed towards each other with movable parabolic mirrors fixed in front of them, 7 and 8, respectively, with automatically variable curvature, through communication with the automatic control unit 2 parameters of laser radiation, to correct the slope of the wave vector of laser radiation.

Telescopic reflector 5 is designed for early detection and focusing of CM objects flying towards the carrier platform and 6 for near detection and focusing of CM objects flying in the wake of the carrier platform.

FIG. 1, CM objects 9 and 10 are also shown to be removed from orbit (small sizes up to 10 cm), onto which laser radiation is focused by reflectors 5 and 6.

Reflectors 5 and 6 and, respectively, movable mirrors 7 and 8 are connected by a drive with an automatic control unit 2 for laser radiation, which changes the overall curvature of the mirrors and allows focusing of the reflected laser radiation on objects CM 9 or 10. Reflector 5 with a diameter of up to 1 m is intended for detection , laser processing (according to a special impulse scenario) and, if necessary, subsequent evasion (due to maneuvering of the carrier) from a possible collision with CM objects flying towards. Reflector 6 with a diameter of up to 0.5 m is designed for detection and laser processing (according to a special impulse scenario) and subsequent evasion (due to carrier maneuvering) from a possible collision with KM 10 objects flying in the carrier's wake. The operation of the reflector 6 in the wake, where the difference in velocities between the CM object and the carrier is minimal, makes it possible to have more time to register and process the data of the CM object, and, if necessary, to carry out a maneuver of the carrier in order to produce a series of laser pulses that provide a frontal and most effective irradiation of the CM object.

The method of pulsed laser cleaning of space from single small CM objects is based on the mechanism of laser evaporation of material from the surface of the CM object and the formation of a dense vapor cloud around the object. A series of pulses creates the subsequent ignition of a high-pressure plasma, which initiates a shock wave, which transmits a pressure pulse to the CM object and decelerates the CM object.

Laser ablation technology is considered the most effective way to remove small CM objects in near-Earth space. For laser ablation of CM objects, a repetitively pulsed laser with a wavelength of 1.06 μm is used, since it provides acceptable intensities, and their rapid readjustment to work out a certain scenario of pulsed laser action on CM objects. The use of, for example, a fiber-optic laser can allow the use of multiple laser leads.

The method is carried out as follows.

Information from the unit for detecting, recognizing and registering 3 CM object to be removed from orbit is sent to the guidance and focusing unit 4 of VIP lasers 1 and to the automatic control unit 2 of laser pulses to process the received information about the parameters of the CM object and transmit a signal to start work VIP laser 1 on the detected CM object moving in front of the carrier platform or at the same time when the CM object is detected in the trail of the carrier platform (see Fig. 2).

High-frequency repetitively pulsed laser 1 on command from the automatic control unit 2 according to an individual design scenario calculated for each detected CM object (the parameters of the object are taken into account: movement speed, size, trajectory), produces a series of impulse effects. The first laser pulse (see Fig. 5) of a certain duration - τ _in several milliseconds (1-2 ms) with an intensity below the plasma formation threshold forms a dense vapor cloud near the surface of the CM object. The resulting recoil pressure will not be enough to significantly slow down the velocity of the CM object, or deviate it from its orbital trajectory. Then a series of high-frequency pulses (see Fig. 5) are applied with a shorter duration than the initial pulse - τ << τ _in with an intensity higher than the plasma ignition threshold, providing ignition and maintenance of plasma combustion in a vapor cloud near the CM surface. In a vapor plasma, laser radiation is almost completely absorbed, which makes it possible to increase the efficiency of using laser energy and to form a shock wave with an increased pressure in the vapor cloud, which can significantly change the velocity modulus of the CM object.

The first pulse should be on the order of a millisecond with an intensity of 10 ⁶ -10 ⁷ W / cm ² . During this time, a steam cloud is formed with a temperature of 1800-2300 K for steel. The steam velocity is:

Pressure

илиDensity:

or

Subsequent impulses 10 ⁹ -10 ¹² W / cm ² can be nano- or picosecond so that the total time corresponds to the time of passage of the shock wave to the body surface.

It is enough to decelerate the velocity of a CM object weighing up to 4 ÷ 5 kg by the value ΔV = 100 m / s, after which the time of its fall to the Earth (“life time”) is reduced to ten thousand times, which does not exceed one hour. FIG. 3 shows the graphs for calculating the ratio of the initial "life" time in a near-earth orbit T ₀ (without laser exposure) to the "life" time T _v with a sudden decrease in the orbital velocity of spherical aluminum particles by a given value ΔV.

The method of pulsed laser cleaning of space from single small CM objects is carried out when a CM object is detected in the trail of the carrier or simultaneously with the CM object moving in front of the carrier platform.

The table shows the calculation data for the "life" time in a circular near-earth orbit of spherical particles made of steel and aluminum with sizes from 1 micron to 10 cm. The orbital altitude is 400 km, the speed is 7 ÷ 8 km / s.

The data given in the Table were calculated at the Institute of Theoretical and Applied Mechanics named after S.A. Khristianovich SB RAS.

Table - time of "life" T ₀ (in seconds) and total days of existence of metal particulates in a circular near-earth orbit at an altitude of about 400 km.

Despite the fact that the technical feasibility of the proposed method is limited by the small size of the CM objects from 1 mm to 10 cm, it is energetically justified due to the sufficiency of a small series of laser pulses separated in time, and providing first the evaporation of a part of the CM object surface and the formation of a dense vapor cloud, and then the ignition and maintenance of the combustion of the optical discharge in the vapor plasma and the generation of a shock wave that dynamically affects the CM and slows down its orbital motion by the magnitude of the modulus of velocity ΔV up to 100 m / s.

Thus, the laser-irradiated small-sized CM object located at an altitude of 400 km above the Earth in less than 1 hour (see Table and Fig. 3) passes from an orbital trajectory to a ballistic one, and then burns up in dense layers of the atmosphere. Combustion products, being the centers of crystallization of water vapor present in the atmosphere, form rain clouds, which fall in the form of precipitation, and completely purify the Earth's air atmosphere.

The positive effect of the technical proposal lies in the efficiency of laser irradiation of CM fragments and a significant reduction in their "lifetime" (existence) in near-earth orbit.

The positive effect of the technical solution also lies in the proposed scheme of two outputs of laser radiation and the placement of telescopic reflectors of the system in two directions with controlled curvature of mirrors (see Fig. 1), capable of providing both defocusing (expansion) of laser radiation for detecting CM objects at distant distances, and focus it on the detected CM objects in the wake, which allows you to increase the observation area, and increase the degree of protection of the carrier from unwanted collisions with CM.

It should be noted that work to remove CM in the wake of a laser system, when the direction of movement of the laser system is co-directed with the movement of CM, can be especially effective. In this regard, the removal efficiency can also be increased by placing the laser system on a controlled spacecraft-cleaner, in an area of high CM concentration, or in higher orbits, where the orbital velocities of CM objects will not be so high. At the same time, the requirements for laser power and sizes of telescopic reflectors can be significantly reduced.

Sources of information

1. Eichler et al. / 1 Eichler P.D. Report No. R8840. Institut fur Weltraumtechnologie und Reaktortechnologie, Technical University of Braunschweig, Germany, (1988).

2. Johnson N.L., in "Orbital Debris from Upper-Stage Breakup", Ed. J.P. Loftus Jr., Progress in Astronautics and Aeronautics, Vol. 121 (1989), Ch. 2.

3. Pikalov P.C., Yudintsev B.B. Review and selection of means for removing large-sized space debris // Proceedings of the MAI. 2018. Issue No. 100.

4. Nosov A.V. The problem of debris in space orbit: threats and countermeasures projects // Peer-reviewed scientific journal "Trends in the development of science and education." August 2019 No. 53, Part 3. P. 33-37.

5. Campbell J.W. Project ORION: Orbital Debris Removal Using Ground-Based Sensors and Lasers. NASA Technical Memorandum 108522. Marshall Space Flight Center. Alabama. 1996.

6. Phipps C.R. L'ADROIT - A spacebome ultraviolet laser system for space debris clearing // Acta Astronautica 104 (2014) 243-255.].

7. Apollo B.B. Destruction of space debris and natural objects by laser radiation. Quantum Electronics, 43, No. 9 (2013) 890-894.

8. Fang Y., Pan J., Luo Y., Li C.-W. Effects of deorbit evolution on space-based pulse laser irradiating centimeter-scale space debris in LEO // Acta Astronautica 165 (2019) 184-190.

9. Patent RU 2001109184. Sinyavsky V.B., Yuditsky V.D. Spacecraft for cleaning outer space from small debris. JSC RSC Energia named after S.P. Queen. Filed 05.04.2001. Publ. 20.05.2003.

10. Patent RU 2001109185 Yuditsky V.D., Sinyavsky V.V. Apparatus for cleaning outer space from debris. JSC RSC Energia named after SP Korolev. Filed 05.04.2001. Publ. 20.05.2003.

11. Schall W.O. Orbital debris removal by laser radiation // Acta Astronautica, Volume 24,1991, Pages 343-351.

12. Soulard R., Quinn M.N., Tajima T., Mourou G. ICAN: A novel laser architecture for space debris removal // Acta Astronautica 105 (2014) 192-200.

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Claims (2)

1. Method of pulsed laser cleaning of space from single small objects of space debris, including the detection of a space debris object (CM) to be removed from orbit, determination of its parameters, determination of the parameters of guidance and focusing of laser radiation on the CM object and automatic selection of a certain mode of pulsed laser impact on the CM object and the actual action itself, characterized in that the detection and focusing of laser radiation on CM objects to be removed from orbit is carried out in at least two opposite directions, both on the CM object flying towards the pulsed laser system, so and flying in its wake, then the parameters of the detected CM objects are automatically processed and the optimal mode of pulsed laser action is selected individually for each selected CM object, while the action on each object is carried out with a series of pulses: first, laser pulses are applied. of a certain duration τ _in with an intensity below the plasma formation threshold with a duration up to the moment of formation of a dense vapor cloud on the surface of the CM object, then they are exposed to pulses of a shorter duration than the duration of the initial pulses τ << τ _in , with an intensity higher than the plasma ignition threshold, and provide the transfer of additional laser energy to maintain plasma combustion in a vapor cloud, which initiates a shock wave and transmits a pressure pulse to the CM object and decelerates it. 2. A pulsed laser system for cleaning outer space from single small objects of space debris, located on the space platform of the carrier, for example, the ISS, and containing a laser radiation unit associated with an automatic control unit for laser radiation parameters, a unit for detecting, recognizing and registering parameters of single CM objects, to be removed from orbit, and a block for pointing and focusing laser radiation on the detected objects CM, characterized in that they use a high-frequency repetitively pulsed laser, made with at least two oppositely directed relative to each other laser radiation leads connected to the object detection unit CM, and a block for aiming and focusing laser radiation on CM objects, including at least two telescopic reflectors opposite to each other with mirrors installed with the possibility of changing their curvature by means of communication with b an automatic control unit for laser radiation parameters to change the focusing of the direction of the wave vector of laser radiation and select the optimal mode of pulsed laser action corresponding to the parameters of the selected CM object to be removed from orbit.

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