CN111547273B

CN111547273B - Thin film spacecraft

Info

Publication number: CN111547273B
Application number: CN202010407582.0A
Authority: CN
Inventors: 李东旭; 刘望; 吴军
Original assignee: National University of Defense Technology
Current assignee: National University of Defense Technology
Priority date: 2020-05-14
Filing date: 2020-05-14
Publication date: 2021-05-25
Anticipated expiration: 2040-05-14
Also published as: CN111547273A

Abstract

The invention discloses a thin-film spacecraft, which belongs to the technical field of spacecraft design. The thin-film spacecraft includes a multifunctional body platform, a thin-film propulsion device, a thin-film camera, a thin-film antenna, a thin-film battery, a thin-film sensor, and a thin-film actuator. The thin film sail is stretched into a huge regular hexagonal sail surface, and the flight power is obtained under the action of solar light pressure, and the thin film camera can perform high-resolution imaging of the observation target. The invention integrates the functions of thin-film propulsion, thin-film imaging, thin-film communication, thin-film power generation, thin-film sensing and actuation, etc., and can complete long-duration and large-scale space flight missions. The advantages of functional structure technology, through the deep integrated design of structure and load, further realizes the weight reduction and energy increase of the spacecraft structure and the improvement of the function ratio, which can better meet the spacecraft's demand for high performance and long life.

Description

Thin film spacecraft

Technical Field

The invention belongs to the technical field of spacecraft structure design, and particularly relates to a thin film spacecraft.

Background

With the continuous improvement of the performance requirement of the spacecraft, the spacecraft puts forward an urgent need of larger scale and size for the size of structures such as a platform, a solar cell array and an antenna of the spacecraft, however, in order to meet the limitation of the launching capability of the current rocket carrier, the size of the spacecraft needs to be enlarged, and meanwhile, the spacecraft needs to be lighter in weight and smaller in volume as much as possible. Therefore, the increase in size and weight of the structural platform of the spacecraft and the reduction in volume in a collapsed state have been the goals of spacecraft designers in various countries. The film structure has the characteristics of light weight, small collection volume, easy realization of an oversized space structure and the like, has good application prospects in the aspects of propulsion, communication, energy and the like of the spacecraft, becomes a favored space flight structure material, and can provide a good design idea and a great exertion space for the design of a novel spacecraft.

The document "thin film-future spacecraft structure" (author: penford; type: conference paper; conference name: second international space science forum and 2007 academic annual meeting of the astronavigation society of Shanghai city; year: 2007) discusses the application of the thin film structure on the spacecraft, analyzes the related key technology of the space thin film structure, and points out the development trend of the thin film of the future large-scale spacecraft.

Patent CN 104058105B (grant publication date: 2015.12.30) discloses a deep space solar sail spacecraft driven by sunlight pressure, which comprises a support frame, four support arms, four isosceles right triangle sail surfaces, solar cells, an etching antenna, a rolling shaft stabilizing mechanism and the like, wherein the sail surfaces are unfolded and supported by 4 support arms with self-unfolding performance, the sail surfaces are stretched by a 5-point connection mode, a small surface-to-mass ratio is realized, and the spacecraft quality is reduced by adopting an open type support packaging structure, self-expending support arms and applying a wireless communication technology.

Patent CN 105711857B (grant publication date: 2017.11.03) discloses a unfolding and locking mechanism of a film spacecraft, which comprises a rotary hinge assembly, side plates, a bottom plate, a top plate, a constraint assembly and the like, wherein potential energy stored by a torsion spring is used as an unfolding power source, and the unfolding and locking functions are integrated into a whole, so that the unfolding and locking mechanism can be applied to a film spacecraft platform.

The document "design verification of a membrane spacecraft deployment and locking mechanism" (author: sun, civilization, etc.; journal: mechanical design and manufacturing project; time: 7 months in 2019; rolling period: 48 (7); page number: 67-70) indicates in the introduction that a membrane spacecraft platform utilizes the pressure of sunlight to carry out space flight, does not need fuel as power, can carry more loads, is a novel spacecraft which is widely concerned at home and abroad, and gives two basic deployment types of the membrane spacecraft platform, one is frameless and adopts the rotary centrifugal force for deployment, and the other is framed and adopts inflation for deployment.

In summary, the existing literature mainly develops research on the aspects of the application of the thin film structure to the spacecraft, the related key technology of thin film development, the spacecraft represented by the solar sail and the design of the unfolding mechanism thereof, and the like, and clarifies the importance of the spacecraft toward thinning, but a deep integrated thin film spacecraft integrating multiple functions such as thin film propulsion, thin film imaging, thin film communication, thin film power generation and the like is not reported yet, and the existing spacecraft structure is difficult to better realize the requirements of the spacecraft on high performance and long service life.

Disclosure of Invention

The invention mainly aims to provide a film spacecraft, which integrates film propulsion, film imaging, film communication, film power generation and other functions into a whole, so as to solve the problems that the existing spacecraft is difficult to realize the film technology with various different functions into a whole and cannot well realize the requirements of the spacecraft on high performance and long service life.

The invention provides a film spacecraft, which comprises a multifunctional body platform, a film propelling device and a film camera;

the multifunctional body platform is positioned in the center of the spacecraft, comprises a top plate, a bottom plate and side plates, is in a regular hexagonal prism shape, and has the functions of bearing load, installing equipment, providing configuration, passive thermal control and connecting and separating stars and arrows;

the film propulsion device comprises a storage box, a support rod and an isosceles trapezoid film sail, the overall shape of the film propulsion device is in a regular hexagon shape in an unfolded state, and the film propulsion device can provide power for the flight of a spacecraft; the storage box is arranged on the multifunctional body platform and is used for storing and unfolding the supporting rod; two vertexes of the film sail, which are positioned at the upper bottom edge, are respectively connected to two adjacent containing boxes, while two vertexes of the film sail, which are positioned at the lower bottom edge, are respectively connected to the tail ends of two adjacent supporting rods, and the film sail is unfolded through the unfolding traction of the supporting rods;

the film camera comprises an extension rod, a relay lens, an achromatic lens and a diffraction film primary mirror, is arranged at the bottom of the multifunctional body platform, and is used for imaging an observation target by adopting a large-aperture film diffraction imaging technology;

the film propelling device is positioned above the film camera and can be used as a light shield when the film camera works in an unfolded state.

Further, the film sail comprises a working layer and a base layer:

the working layer comprises a light reflecting coating and a first polyimide substrate, and the light reflecting coating is positioned above the first polyimide substrate;

the base layer comprises a flexible circuit layer, a second polyimide substrate and an anti-static conductive plating layer, wherein the flexible circuit layer is arranged above the second polyimide substrate, and the anti-static conductive plating layer is arranged below the second polyimide substrate;

the working layer is located above the base layer, and the working layer and the base layer are integrally compounded through an adhesive process.

Further, the thin film spacecraft further comprises a thin film antenna; the film antennas are adhered to the surface of the film sail, and the plurality of film antennas form an antenna array which is used for the measurement and control and data transmission requirements of the spacecraft;

further, the thin film spacecraft also comprises a thin film battery piece; the thin film cell piece adopts a thin film gallium arsenide solar cell, is attached to the front surface of the thin film sail, is close to the multifunctional body platform, is positioned on the working layer, and is used for obtaining sunlight and realizing thin film power generation.

Further, the thin film spacecraft also comprises a thin film sensor and a thin film actuator; the thin film sensor and the thin film actuator are both embedded in the thin film sail and positioned between the first polyimide substrate of the working layer and the flexible circuit layer of the base layer; the film sensor is used for sensing a structural deformation signal of the film sail, and the film actuator is used for realizing the control of the structural deformation of the film sail.

The multifunctional body platform comprises a structure and mechanism subsystem, a power supply subsystem, a satellite affair subsystem, a pose control subsystem, a measurement and control and data transmission subsystem and a thermal control subsystem;

the structure and mechanism subsystem comprises a multifunctional structure substrate, a satellite and arrow connecting and separating device, a fastener and a cable;

the power supply subsystem comprises a storage battery pack, a storage battery controller, a power supply controller and a body-mounted solar battery array;

the satellite affair subsystem comprises an on-board computer and a routing and processing unit;

the position and pose control subsystem comprises a flywheel, a flywheel controller, a fiber-optic gyroscope, an analog sun sensor, a digital sun sensor and a star sensor;

the measurement and control and data transmission subsystem comprises a measurement and control and data transmission all-in-one machine and a measurement and control and data transmission antenna;

the thermal control subsystem comprises a heating sheet, a plurality of layers of thermal insulation materials and a thermal control coating;

the multifunctional body platform adopts a multifunctional structure battery, a multifunctional structure computer and a multifunctional structure cable.

Preferably, the support rod is made of a carbon fiber reinforced resin matrix composite material, the cross section of the support rod is in a symmetrical double-omega shape in an unfolded state, and the support rod can be folded in a curling mode after being flattened.

Preferably, the film antenna is a large-aperture sub-wavelength film antenna structure, and is designed by adopting a three-layer structure of a feed network layer, a patch antenna array and a sub-wavelength structure lens layer.

Preferably, the thin film sensor adopts a film type strain gauge; the film actuator adopts PVDF electroactive polymer material.

Further, a monitoring camera is arranged on the top of the multifunctional body platform and used for observing and monitoring the unfolding condition of the supporting rods in the film propelling device.

The beneficial effects of the technical scheme of the invention are mainly embodied in the following aspects:

firstly, the film spacecraft integrates the functions of film propulsion, film imaging, film communication, film power generation, film sensing, actuation and the like, is a working medium-free propulsion mode because the sunlight pressure is utilized to obtain power, and can realize long-time navigation and large-range flight tasks, such as deep space detection tasks like asteroid detection and on-orbit service tasks like space target observation;

secondly, the invention integrates the advantages of the thin film structure and the multifunctional structure technology, further realizes the weight reduction and energy increase of the spacecraft structure, realizes the improvement of the load ratio and the volume ratio, and the improvement of the effective load ratio, the function ratio and the efficiency by adopting the multifunctional structure battery, the multifunctional structure computer, the multifunctional structure cable and other structures and the deep integrated design technology of the load in the body platform, thereby better meeting the requirements of the spacecraft on high performance and long service life;

thirdly, the film sail is designed into a multifunctional film structure, so that the light pressure for pushing the spacecraft to fly can be obtained by reflecting sunlight, the film sail can also be used as a light shield when a film camera works, meanwhile, a part of the surface of the film sail is attached with a film battery piece capable of generating electricity, so that electric energy is provided for the spacecraft, and in addition, a plurality of film sensors and a plurality of film actuators are embedded inside the film sail, so that the sensing and control of the structural deformation of the film sail can be realized. Therefore, the film sail integrates multiple functions of light pressure propulsion, solar power generation, structural deformation measurement and control and the like, and high multi-functionalization of the film structure is effectively realized;

in addition, the invention adopts various thin film structure technologies, so that the spacecraft has the advantages of light structure mass and high storage ratio, and the launching cost of the spacecraft is greatly reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a membrane spacecraft of the present invention in an unfolded state;

FIG. 2 is a schematic structural view of another view of the thin film spacecraft of the present invention in an unfolded state;

FIG. 3 is a view in three directions of the thin-film spacecraft of the present invention in an unfolded state, wherein FIG. 3(a) is a side view; FIG. 3(b) is a top view, i.e., a view of FIG. 3(a) in the A direction; fig. 3(c) is a bottom view, i.e., a view of fig. 3(a) in the direction B;

FIG. 4 is a schematic structural diagram of the membrane spacecraft of the present invention in a collapsed state;

FIG. 5 is a schematic structural diagram of a multi-functional body platform of the thin film spacecraft of the present invention;

FIG. 6 is a layout view of the major components of the multi-function body platform;

FIG. 7 is a schematic view of a single membrane sail;

FIG. 8 is a schematic structural view of the support rod;

FIG. 9 is a schematic view of the film advancing device in a tensioned state;

fig. 10 is a functional partition and cross-sectional views of layers of the film sail structure, wherein fig. 10(a) is a schematic view of the overall functional partition, and fig. 10(b) is a schematic view of the cross-sectional views of the layers.

The invention is illustrated by the reference numerals:

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Aiming at the requirements of long-time navigation and large-range space tasks on a spacecraft with long service life and high performance and simultaneously meeting the higher requirements of the space tasks on response time and manufacturing cost, the invention provides a film spacecraft based on a novel aerospace film structure technology and a structure load depth integration technology, which comprises a multifunctional body platform 1, a film propelling device 2, a film camera 3, a film antenna 4, a film battery piece 5, a film sensor 6, a film actuator 7 and the like, and is shown in figures 1-4.

Fig. 1 and 2 are structural diagrams of the thin film spacecraft of the invention in an unfolded state, and only the viewing angles of the two diagrams are different. FIG. 3 is a three-dimensional view of the thin-film spacecraft in an unfolded state, wherein FIG. 3(a) is a side view; fig. 3(b) is a top view, and fig. 3(c) is a bottom view. As can be seen from fig. 1 to 3, the overall shape of the film spacecraft of the invention in the unfolded state is a regular hexagon, and six identical isosceles trapezoid film sails 23 are stretched into a huge regular hexagon sail surface by the stretching of six support rods 22, which can generate the power required by the spacecraft for flying under the action of sunlight pressure; the multifunctional body platform 1 provides a mounting and supporting platform, energy, posture, track, working environment and the like required by the loads of the film propelling device 2, the film camera 3 and the like, and can operate the loads of the film camera 3 and the like.

Fig. 4 is a configuration diagram of the invention in a folded state, which only shows the configuration of the membrane spacecraft in an undeployed state of the membrane propulsion device 2. The movable unfolding mechanism of the film spacecraft mainly comprises a film propelling and unfolding mechanism and a film camera folding and unfolding mechanism. In the state shown in fig. 4, given a configuration in which the six storage boxes 21 employed in the present embodiment are respectively used for storing six support rods 22, as can be seen from fig. 4, the six support rods 22 are respectively stored in the six storage boxes 21 for storing and unfolding the support rods, and at this time, the film sail 23 is stored between two adjacent storage boxes 21 (not shown) after being folded in a certain manner. Of course, the storage box 21 may be designed as an integral structure connected to the multi-function body platform 1. It should be noted that the extension rod 31 of the film camera 3 is also a foldable structure, which after being folded can make the main diffraction film mirror 32 of the film camera 3 close to the bottom of the multifunctional body platform 1, so as to further reduce the folded volume of the spacecraft in the height direction, but is not shown in fig. 2.

It can be seen that whether the supporting rods 22 can be smoothly extended from the storage box 21 is a key factor affecting the success or failure of the spacecraft task, and therefore, a monitoring camera 11 can be further arranged on the top of the multifunctional body platform 1 for observing and monitoring the extension condition of the supporting rods of the film propelling device.

The multifunctional body platform of the spacecraft and several functions of the thin films formed by applying the thin film structure technology will be described in detail below.

(1) Multifunctional body platform

The multifunctional body platform 1 of the film spacecraft disclosed by the invention is configured as shown in fig. 5, the shape of the multifunctional body platform is a regular hexagonal prism structure and consists of a bottom plate, a top plate and six side plates, the enveloping size of the platform in the embodiment is designed to be phi 400mm, and the height of the platform is designed to be 300 mm.

The main functions of the multifunctional platform 1 are as follows: bearing a load; installing equipment; providing a configuration; passive thermal control; connection and separation of stars and arrows, and the like. Main components to be mounted On the multifunctional body platform 1 include a storage battery, an On-Board computer (OBC), a Power Controller (Power Control Unit, PCU), a routing and processing Unit, a measurement and Control data transmission, a flywheel Controller, and the like, and in this embodiment, the main components are distributed On a platform component Board as shown in fig. 6. Fig. 6 is an exploded view of the bottom plate and 6 side plates of the multi-functional body platform 1.

From the system composition, the multifunctional body platform 1 comprises six subsystems, namely a structure and mechanism subsystem, a power supply subsystem, a satellite affair subsystem, a pose control subsystem, a measurement and control and data transmission subsystem 18, a thermal control subsystem and the like, and is specifically shown in the following table 1.

TABLE 1 subsystem constitution of a multifunction body platform

The structure and mechanism subsystem comprises a multifunctional structure substrate, a satellite-rocket connecting and separating device, a fastener and a cable, and in the embodiment, the separation form of the film spacecraft and the carriers such as a carrier rocket adopts a cutting ejection separation mode;

the power supply subsystem comprises a storage battery pack 16, a storage battery controller, a power supply controller 15 and a body-mounted solar battery array 12, wherein the body-mounted solar battery array 12 is arranged at the top of the multifunctional body platform 1, namely on a top plate, so that the requirement of the spacecraft on electric energy is better met;

the satellite affair subsystem comprises an on-board computer 17 and a routing and processing unit 19;

the position and pose control subsystem comprises three groups of flywheels 13, three groups of flywheel controllers 14, a fiber-optic gyroscope, an analog sun sensor, a digital sun sensor and a star sensor;

the measurement and control and data transmission subsystem 18 comprises a measurement and control and data transmission integrated machine and a measurement and control and data transmission antenna;

the thermal control subsystem comprises two types of active thermal control measures and passive thermal control measures, wherein the active thermal control measures adopt heating sheets, and the passive thermal control measures mainly adopt a plurality of layers of heat insulation materials and thermal control coatings.

In order to further realize the weight reduction and energy increase of the platform structure and the improvement of indexes such as effective load ratio, function ratio and the like, the invention integrates a structure and load deep multifunctional integration technology in the flat design, and particularly, the multifunctional body platform 1 adopts a multifunctional structure battery, a multifunctional structure computer and a multifunctional structure cable.

The storage battery pack 16 is arranged on the side deck, and a multifunctional structure battery technology (see patent CN 105947235B, multifunctional structure for electric energy and mechanical environment management, published as 2017.05.17) in the prior art of the patent applicant is applied, and is integrally designed with a platform structure, so that the storage battery pack can provide energy for the whole spacecraft and can also be used as a main bearing frame of the spacecraft. That is, the battery pack 16 is integrated with the structure and embedded inside the platform side plate to form a multifunctional structure battery;

the arrangement of the satellite-borne computer 17 applies the multi-functional structure computer technology (see patent CN 106970689B, "curved surface type flexible aerospace multi-functional structure computer", published as 2018.07.20) in the previous period of the present patent applicant, and forms an integrated flexible multi-functional structure computer with an active electronic circuit and a cabin board structure mechanical structure fused by reconstructing functional circuits such as a CPU, a data storage, a field bus and the like into a plurality of multi-chip modules (MCM) and MCM plug-ins, thereby effectively solving the problem of volume swelling of the satellite-borne computer equipment and greatly reducing the parasitic quality of the system. In this embodiment, the on-board computer 17 and the side plates are organically integrated in structure to form a multifunctional structural computer.

In addition, the arrangement and design of the cable also apply the prior multifunctional structure battery technology of the patent applicant (see patent CN 106848954B, multifunctional structure cable for spacecraft and the preparation method thereof, published as 2018.02.09), the structure and the cable are integrated, the bearing function of the original composite material structure of the spacecraft is not lost, the cable has the functions of electric conduction, information transmission and the like, and the parasitic mass and the passive volume of the traditional cable are eliminated. The cable is also embedded in the structure, and the multifunctional structure cable is formed.

(2) Film advancing

The film spacecraft provided by the invention utilizes the film propelling device 2 to obtain the flying thrust under the sunlight pressure, the film propelling device 2 comprises six containing boxes 21, six supporting rods 22 and six isosceles trapezoid-shaped film sails 23, and the six identical isosceles trapezoid-shaped film sails 23 are stretched into a huge regular hexagon sail surface capable of obtaining the sunlight pressure through the stretching of the six supporting rods 22. The overall appearance of the film propelling device 2 in the unfolded state is in a regular hexagon shape; the six storage boxes are uniformly arranged on six sides of the multifunctional body platform, and are mechanisms for storing and unfolding the support rods, as shown in fig. 4.

The profile of the single film sail 23 is shown in fig. 7 as an isosceles trapezoid, which can also be considered as a truncated triangle. The single membrane sail 23 passes mainly through four points P₁、P₂、P₃And P₄Hanging is carried out with two vertices P at the upper base of the trapezoid₁And P₂Two vertexes P of the lower base of the trapezoid respectively connected to the outer walls of two adjacent containers 21₃And P₄Respectively, to the end points of two adjacent support rods 22. By the unfolding of the support rods 22, the film sail 23 can be pulled out.

Because the film structure is a light flexible structure, the film structure has no fixed profile, and the determined profile can be formed only under the action of external tension force, the film sail 23 needs to be unfolded and formed under the traction of the support rods 22, so that the film structure becomes a tensioning film structure with internal stress. The common support rod 22 structure mainly includes a pod rod, an inflation rod, etc. As shown in figure 8, the pod rod is an expandable tubular rod structure with light weight, high rigidity, high folding efficiency and reliable expansion process, and is a popular support rod structure at present. The pod rod is usually made of carbon fiber reinforced resin matrix composite materials and is a thin-wall tubular rod which can be flattened and curled. When the pod rod is unfolded, the pod rod is restored to be in a long pipe shape from a flat rolling state by means of self elasticity, and the cross section of the pod rod is in a symmetrical double-omega shape. In this embodiment, pod rods made of carbon fiber composite material are used as the support rod structure of the film sail 23.

The film sail 23 is stretched into a large sail surface in the shape of a regular hexagon by stretching the pod rods, and the film sail 23 is in a structure with internal pretension due to the tension of the pod rods, and at this time, the edge lines of the film sail 23 are not straight, but are in a curved state, as shown in fig. 9.

The film sail 23 is mainly used for generating light pressure, has other functions such as film power generation and the like, and is a multifunctional film structure. In this embodiment, the film sail 23 is designed to be a single-layer or partially multi-layer film, as shown in fig. 10, where fig. 10(a) is a general functional partition diagram of the multifunctional film sail, and fig. 10(b) is a cross-sectional view of each layer.

As can be seen from fig. 10(b), the film sail 23 can be divided into two layers: a working layer 231 and a base layer 232.

The first layer is a working layer 231 for reflecting sunlight to obtain light pressure, and mainly comprises a light reflecting coating 231a, a first polyimide substrate 231b, and the like. The reflective plating layer 231a is located above the first polyimide substrate 231b, mainly plays a role of reflecting sunlight, and has a thickness less than 1 μm; the first polyimide substrate 231b is a main body material of a film sail structure, has certain strength and certain toughness, and has an expansion coefficient smaller than 5ppm and a thickness smaller than 20 μm.

The second layer is a base layer 232, and mainly comprises a flexible circuit layer 232a, a second polyimide substrate 232b, an antistatic conductive plating layer 232c, and the like, wherein the flexible circuit layer 232a is arranged above the second polyimide substrate 232b, and the antistatic conductive plating layer 232c is arranged below the second polyimide substrate 232 b. In the base layer 232, the second polyimide substrate 232b is also a force bearing layer, and the thickness thereof is less than 50 μm; the antistatic conductive plating layer 232c is used for preventing the accumulation of static electricity on the bottom layer, and the thickness is less than 1 mu m; the flexible circuit layer is a flexible circuit provided for the purpose of arranging the deformation sensors and actuators inside the membrane sail, and has a thickness of less than 20 μm.

(3) Thin film imaging

The main structure of the film camera 3 is shown in fig. 4, and mainly includes three extending rods 31, a relay lens, an achromatic lens, and a diffractive film primary mirror 32, and is installed at the bottom of the multifunctional body platform 1 for imaging an observed target. Since the film advancing device 2 is installed above the film camera 3, the film advancing device 2 in the unfolded state can be used as a light shield when the film camera 3 is operated.

In this embodiment, the thin film camera 3 adopts a large-aperture thin film diffraction imaging technology, that is, the diffraction thin film primary mirror 32 is used to replace the traditional reflector and lens to realize lightweight thin film imaging, the used base film material is also a polyimide thin film, the thermal expansion coefficient of the thin film within the temperature range of-50 to 250 ℃ is only-1.9 ppm/DEG C, the visible light transmittance is more than 85%, the camera has centimeter-level resolution in imaging within the range of 50m to 50km, the size of the CCD pixel of the camera is 8.75 mu m, the system focal length F is 0.875m, the aperture of the designed system is 80mm, the ground static MTF of the system at 57lp/mm (corresponding to 50km resolution 50cm) can reach 0.22 when the system F number is 10.9, and the spatial observation MTF can reach 0.1.

The system index parameters of the film camera 3 are shown in table 2 below.

TABLE 2 System parameter index for thin film cameras

Index parameter name	Numerical value
		Bore diameter	80mm
Spectral range	0.486～0.656μm
		Field of view	0.2°
Focal length	0.875m
		System F number	10.9
Systematic MTF	57lp/mm@50cm
		Length of light path	351mm

(4) Thin film communications

As shown in fig. 10(a), the surface of the film sail 23 is further adhered with the film antenna 4, and the plurality of film antennas 4 form an antenna array to realize film communication, which is used as a requirement for measurement and control and data transmission of the film spacecraft of the invention.

In this embodiment, the film antenna 4 is a large-aperture sub-wavelength film antenna structure, and the film antenna is designed to be a three-layer structure, namely, a feed network layer, a patch antenna array layer, and a sub-wavelength structure lens layer, by using a group-array type space-borne film antenna design method. The unequal power divider is adopted for designing the feed network, and the port power distribution conforms to the Chebyshev polynomial, so that the antenna side lobe is reduced, and the antenna performance is improved. Meanwhile, structural impedance analysis and impedance matching design are carried out, and the insertion loss of the feed network is reduced; the antenna adopts a feed mode and adopts coupling feed, and the design of the broadband sub-wavelength structure antenna is realized based on a parasitic patch and a notch structure design method. According to the invention, the film antenna can simultaneously reduce the realization difficulty and the feed loss of the antenna feed network and ensure reliable communication on the premise of meeting various requirements such as low cost, high performance, high flexibility and the like.

(5) Thin film power generation

As shown in fig. 10(a), a thin film cell 5 capable of generating electric energy under the sun is further attached to the front surface of the thin film sail 23 and close to the multifunctional body platform 1, that is, the inner side edge region of the working layer of the thin film sail structure, so as to realize thin film power generation. On the surface of the thin-film battery sheet 5, a light-transmitting plating layer 231c, see fig. 10(b), for transmitting sunlight while preventing static electricity from accumulating, may also be provided, the thickness of which is less than 1 μm.

In the embodiment, the thin film cell piece 5 is a flexible thin film gallium arsenide solar cell, the photoelectric conversion efficiency of the solar cell is high, and meanwhile, the substrate layer can be peeled off and transferred to other substrates, so that the solar cell is a reversely grown lattice mismatch flexible triple-junction solar cell. The photoelectric conversion efficiency of the thin-film cell 5 can reach 30% at most, and the power generation rate is more than 5%; the surface density reaches 200g/m²(ii) a A thickness of about 60 μm, less than 160 μm, taking into account the glue layer; can be transversely and longitudinally curled, the curvature radius is less than or equal to 0.05m, and the efficiency attenuation before and after rolling is less than or equal to 4 percent; the surface area of the single thin-film battery piece 5 is less than 10cm x 100 cm. The thin film battery piece 5 is used for receiving sunlight for power generation, the generated current is supplied to 1 section of 10Ah 3.7V solid-state lithium battery for charging, and the charging is automatically cut off when the charging is 4.15V.

The basic parameters of the thin film battery sheet 5 in this example are shown in table 3 below.

TABLE 3 parameters of flexible thin film gallium arsenide solar cells

Due to the effects of charged particle irradiation, temperature impact, space debris or micrometallite impact, electrostatic discharge breakdown and the like, the flexible film gallium arsenide solar cell can cause the performance reduction of the cell and the output power reduction, but can not cause serious consequences. In the embodiment, the safety of the thin film battery piece is improved by adopting means of surface-mounted anti-particle irradiation materials, flexible adhesives and processes, designing a stress reduction structure for battery interconnection, adding an anti-static coating design and the like.

(6) Thin film sensing and thin film actuation

The thin film structure is a flexible structure, the structure is easy to deform under the action of external load, in order to further improve key technical indexes such as flatness of the thin film sail, the thin film sail structure deformation control device further utilizes the thin film sensor to sense a structural deformation signal of the thin film sail, and utilizes the thin film actuator to realize the control of the structural deformation of the thin film sail.

The film sensor and the film actuator are both embedded inside the film sail, as shown in fig. 10 (b).

The film sensor adopts a film type strain gauge, is specifically positioned between the first polyimide substrate of the working layer and the flexible circuit layer of the base layer, and is used for acquiring the structural strain of the film sail; the film actuator adopts PVDF (polyvinylidene fluoride) electroactive polymer, is also positioned between the first polyimide substrate of the working layer and the flexible circuit layer of the base layer, is a piezoelectric film material, and can deform under the action of an electric field so as to adjust the deformation of the film sail structure.

In this embodiment, the thickness of the film sensor for measuring the structural strain is less than 10 μm, and the thickness of the film actuator for increasing the stiffness of the film sail is controlled within 10 μm.

In summary, the invention provides a thin film spacecraft, and the following positive effects are achieved:

firstly, the film spacecraft disclosed by the invention integrates multiple functions of film propulsion, film imaging, film communication, film power generation, film sensing and actuation and the like, can realize long-time navigation and large-range flight tasks by utilizing a working medium-free propulsion mode of acquiring power by utilizing sunlight pressure, and typical examples comprise deep space detection tasks such as asteroid detection and the like, on-orbit service tasks such as space target observation and the like;

in addition, the invention adopts various thin film structure technologies, so that the designed thin film spacecraft has the advantages of light structural mass and high storage ratio, and the launching cost of the spacecraft is greatly reduced.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A film spacecraft is characterized by comprising a multifunctional body platform, a film propelling device and a film camera;

2. The thin film spacecraft of claim 1, wherein the thin film sail comprises a working layer and a base layer;

3. The thin film spacecraft of claim 1, wherein the thin film spacecraft further comprises a thin film antenna; the film antennas are adhered to the surface of the film sail, and the plurality of film antennas form an antenna array which is used for measurement and control and data transmission of the spacecraft.

4. The thin film spacecraft of claim 2, wherein the thin film spacecraft further comprises a thin film battery plate; the thin film cell piece adopts a thin film gallium arsenide solar cell, is attached to the front surface of the thin film sail, is close to the multifunctional body platform, is positioned on the working layer, and is used for obtaining sunlight and realizing thin film power generation.

5. The thin film spacecraft of claim 2, wherein the thin film spacecraft further comprises thin film sensors and thin film actuators; the thin film sensor and the thin film actuator are both embedded in the thin film sail and positioned between the first polyimide substrate of the working layer and the flexible circuit layer of the base layer; the film sensor is used for sensing a structural deformation signal of the film sail, and the film actuator is used for realizing the control of the structural deformation of the film sail.

6. The thin film spacecraft of any one of claims 1 to 5, wherein the multi-function body platform comprises a structural and mechanical subsystem, a power subsystem, a satellite subsystem, a pose control subsystem, a measurement and control and data transmission subsystem, and a thermal control subsystem;

7. A membrane spacecraft as claimed in any one of claims 1 to 5, wherein the support rods are pod rods made of carbon fibre reinforced resin matrix composite material, which in an unfolded state are symmetrical double Ω -shaped in cross-section and which can be collapsed in a curled manner after flattening.

8. The thin film spacecraft of claim 3, wherein the thin film antenna is a large-aperture sub-wavelength thin film antenna structure and is designed by adopting a three-layer structure of a feed network layer, a patch antenna array and a sub-wavelength structure lens layer.

9. The thin film spacecraft of claim 5, wherein the thin film sensor employs a film strain gauge; the film actuator adopts PVDF electroactive polymer material.

10. The membrane spacecraft of claim 1, wherein a surveillance camera is further disposed on a top portion of the multi-functional body platform for observing and monitoring deployment of support rods in the membrane propulsion device.