JP2020001696A5 - - Google Patents

Description

Spacecraft

 The present invention relates to a space vehicle such as an artificial satellite.

 Patent Literature 1 discloses attitude control of an artificial satellite. The satellite disclosed in Patent Literature 1 discloses an earth sensor that scans the earth, which serves as a reference for the attitude, in order to detect the attitude with respect to the earth.

JP-A-7-2194

  The disclosed spacecraft may include a spherical imaging device. Here, the whole celestial sphere refers to the entire surface of the sphere when a sphere drawn around a spacecraft is assumed. The omnidirectional imaging device disclosed herein is a device that can capture the entire surface of a sphere drawn on a spacecraft as a center, assuming that the sphere is drawn around the spacecraft. The disclosed celestial sphere photographing apparatus can perform photographing with almost no blind spots in all directions in the up, down, left, right, front and rear directions around the spacecraft.

It is a perspective view of an artificial satellite. It is a block diagram which shows the structure of an artificial satellite. FIG. 2 is a block diagram of a photographing device and an image processing processor. It is a flowchart for process selection. It is a flowchart of a 1st process. It is a flowchart of a 2nd process. It is a flowchart of the process using two images. It is a flowchart of a posture control.

 [1. Space vehicle]

 (1) The spacecraft according to the embodiment is, for example, an artificial satellite or an interplanetary vehicle. The artificial satellites are, for example, communication satellites, broadcast satellites, weather observation satellites, earth observation satellites, and positioning satellites, but their types are not particularly limited. The artificial satellite may be for commercial use or research use, and the use is not particularly limited. Although the size of the artificial satellite is not particularly limited, it may be a small satellite or a microsatellite. Here, a small satellite has a weight of 500 kg or less, and a microsatellite has a weight of 100 kg or less. The microsatellite is preferably 50 kg or less, more preferably 10 kg or less, and even more preferably 5 kg or less.

 The microsatellite may be, for example, a 1U CubeSat, a 2U CubeSat, or a 3U CubeSat. Here, the 1U CubeSat is an artificial satellite having a size of 100 × 100 × 100 mm (height × length × width; the same applies hereinafter). 2U CubeSat is a 200 × 100 × 100 mm artificial satellite. 3U CubeSat is an artificial satellite having a size of 300 × 100 × 100 mm.

 The microsatellite may be, for example, a 1P PocketSat, a 1.5P PocketSat, or a 2P PocketSat. Here, the 1P PocketSat is a 50 × 50 × 50 mm artificial satellite. The 1.5P PocketSat is an artificial satellite having a size of 89 × 50 × 50 cm. The 2P PocketSat is a 153 × 50 × 50 cm artificial satellite.

 A satellite generally goes into orbit after being released from a satellite release mechanism mounted on a space station or rocket. The satellite release mechanism is, for example, a Picosatellite Orbital Deployer (POD). Microsatellites often spin as they are ejected from the satellite ejection mechanism.

 The spacecraft according to the embodiment can include a spherical imaging device. Here, the whole celestial sphere refers to the entire surface of the sphere when a sphere drawn around an artificial satellite is assumed. The omnidirectional photographing device is a device that can photograph the entire surface of the sphere when a sphere drawn around an artificial satellite is assumed. The omnidirectional photographing apparatus can perform photographing with almost no blind spots in all directions of up, down, left, right, front and rear directions around an artificial satellite. The spherical camera is also called a spherical camera.

 The omnidirectional imaging device is configured to include, for example, two hemispherical cameras. A half celestial sphere is half of a full celestial sphere. The celestial sphere camera photographs the celestial sphere. By photographing one hemisphere of the whole celestial sphere with the first hemisphere camera and photographing the other hemisphere of the whole celestial sphere with the second hemisphere camera, it is possible to photograph the whole celestial sphere. The omnidirectional photographing device may perform photographing of the omnidirectional sphere with three or more cameras.

 The celestial sphere photographing device may be one that performs photographing by sensing visible light, or one that performs photographing by sensing infrared light. Here, the infrared light may be far infrared light or near infrared light.

 [2. Example of microsatellite]

 FIG. 1 shows an example of a microsatellite 10. The satellite 10 is, for example, a 1 U CubeSat, and is a communication satellite that performs wireless communication with a ground station on the earth. The data transmitted from the satellite 10 is, for example, image data captured by the satellite 10.

 The image data may be still image data or moving image data. The moving image data is, for example, a live space video taken from an artificial satellite. To transmit a large amount of data such as moving image data, a large wireless transmission band is required. For high-capacity data transmission, for example, a high-frequency region such as a Ku band is preferably used. Since the wavelength is short in a high frequency region such as the Ku band, the communication antenna can be downsized. Small antennas are suitable for microsatellites.

 The satellite 10 has an earth-oriented surface 11a. The earth directing surface 11a is a surface of the satellite 10 that should face the earth. A communication antenna 30 for communication with a ground station on the earth is provided on the earth directing surface 11a. The antenna 30 is preferably a circularly polarized antenna. In order to transmit sufficient radio signal power to the ground, it is necessary to accurately direct the antenna 30 to the ground antenna. The attitude of the satellite 10 according to the embodiment is controlled with high accuracy so that the antenna 30 is accurately directed to the ground antenna. By highly accurate attitude control, the earth directing surface 11a on which the antenna 20 is provided is accurately directed to the ground antenna.

 It should be noted that another device corresponding to the type of the satellite 10 may be provided on the earth directing surface 11a instead of the antenna 30 or in addition to the antenna 30. Another device is, for example, a sensor for observing the earth.

 In FIG. 1, the direction traveling along the orbit of the satellite 10 is X, the direction from the satellite 10 to the center of the earth is Z, and the direction orthogonal to X and Z in the right-handed orthogonal system is Y. The satellite 10 in FIG. 1 has a cubic shape, and has on its surface six surfaces 11a, 11b, 12a, 12b, 12c, and 12d including an earth directing surface 11a.

 In FIG. 1, the z-axis of the satellite 10 is orthogonal to the earth-directional plane 11a and the opposite plane 11b. Hereinafter, the z-axis is also referred to as a yaw axis, and the z-axis direction is also referred to as a yaw direction. When the z-axis faces the center of the earth, the z-axis direction coincides with the Z direction. When the z-axis direction is coincident with the Z direction, the axis that coincides with the X direction is the x-axis, and the axis that coincides with the Y direction is the y-axis. Hereinafter, the x-axis is also referred to as a roll axis, and the x-axis direction is also referred to as a roll direction. The y-axis is also called a pitch axis, and the y-axis direction is also called a pitch direction.

 The satellite 10 has a first surface 12a and a second surface 12b orthogonal to the x-axis, and a third surface 12c and a fourth surface 12d orthogonal to the y-axis. The fisheye lens 21 and the fisheye lens 22 of the omnidirectional photographing device 50 are provided on the first surface 12a and the second surface 12b, respectively. The fisheye lens 21 is for photographing the hemisphere on the fisheye lens 21 side, and the fisheye lens 22 is for photographing the hemisphere on the fisheye lens 22 side. With the two fisheye lenses 21 and 22, the whole celestial sphere centered on the satellite 10 can be photographed with almost no blind spot.

 The fisheye lenses 21 and 22 may be provided on the surface 12c and the surface 12d, or may be provided on the earth directing surface 11a and the opposite surface 11b. However, by arranging the lenses 21 and 22 on a surface other than the earth directing surface 11a, a large installation space for the antenna 30 and the like can be secured on the earth directing surface 11a.

 In the embodiment, a photovoltaic panel 40 is provided on the surface 12c. The photovoltaic panel 40 generates electric power for the operation of the satellite 40. The solar panel 40 may be provided on the surface 11d and the surface 12d.

 As shown in FIG. 2, the satellite 10 includes a controller 70. The controller 70 is built in the satellite 10 and controls the attitude of the satellite 10 and the like. The controller 70 is configured by a computer including a processor 71 and a memory 72. The processor 71 executes a computer program 73 stored in the memory 72. The program 73 has various processing modules such as an attitude analysis module 73a, an attitude control module 73b, and a communication processing module 73c of the satellite 10. The memory 72 also has an area 74 for storing an image photographed by the photographing device 50.

 The satellite 10 includes an actuator 80 for attitude control. The actuator 80 controls the attitude of three axes xyz. The actuator 80 has, for example, a magnetic torquer. A combination of a two-axis magnetic torquer and a complementary one-axis drive device, for example, a momentum wheel, enables three-axis attitude control. Since the magnetic torquer is small, it is suitable for attitude control of a micro satellite. The actuator 80 is not limited to a magnetic torquer, and may be, for example, a thruster. The thruster can also perform three-axis attitude control. Further, even in combination with a three-axis momentum wheel, three-axis attitude control can be performed.

 The actuator 80 is connected to the processor 71 of the controller 70 via the interface 76. The controller 71 supplies a control signal for attitude control to the actuator 80. The actuator 80 operates according to a control signal from the controller 80.

 The satellite 10 includes an imaging device 50 for analyzing the attitude of the satellite 10. The photographing device 50 photographs the whole celestial sphere centering on the satellite 10. The photographing device 50 can photograph at least the earth as a celestial body serving as a reference for the posture. The image obtained by the photographing device 50 is subjected to image processing by the image processing processor 60 and is provided to the controller 70. The image processing processor 60 is connected to the processor 71 via the interface 75. The controller 70 can store the obtained image in the image storage area 74. The controller 70 analyzes the attitude of the satellite 10 based on the movement and position of the earth as a reference celestial object in the obtained image. The posture analysis process is performed by the posture analysis module 73a.

 If the earth is moving without rest in the image, the satellite 10 is spinning. The attitude analysis module 73a can calculate the spin angular velocity and the spin direction of the satellite 10 based on the speed and direction of the movement of the earth in the image. Even if the earth is stationary in the image, if the position of the earth in the image deviates from the position where the earth directing surface 11a is correctly pointing the earth, the satellite 10 has an attitude error. is there. The attitude analysis module 73a can determine the attitude error of the satellite 10 from the position of the earth in the image.

 The image used by the controller 70 for the posture analysis is a spherical image. In the celestial sphere image, even when the satellite 10 is spinning or when the attitude is largely collapsed, the earth as the reference of the attitude is always shown. Therefore, the controller 70 can always perform attitude analysis including satellite motion such as spin. Note that the captured image may be transmitted from the antenna 30 to the earth.

 The attitude control module 73b controls the attitude of the satellite 10 based on attitude analysis information such as the angular velocity, spin direction, and attitude error of the satellite 10. The attitude control module 73b outputs a control signal for operating the actuator 80 to the actuator 80 based on the attitude analysis information. The controller 70 controls the actuator 80 so that the spin of the satellite 10 is suppressed and the earth-facing surface 11a is directed toward the earth. The controller 70 controls the actuator 80 so that the z-axis direction orthogonal to the earth directing surface 11a faces the ground antenna. As a result, the antenna 20 is directed to the terrestrial antenna, and good satellite communication becomes possible.

 The wireless communication device 100 is connected to the controller 70 via an interface 77. The wireless communication device 100 includes an antenna 30. The radio communication device 100 generates a radio frequency signal from the communication signal provided from the communication processing module 73c, and transmits the signal from the antenna 30 to the ground antenna. The wireless communication device 100 can also receive a signal transmitted from a ground antenna.

 Electric power supplied to each unit of the satellite 10 such as the imaging device 50, the image processing processor 60, the controller 70, the actuator 80, and the wireless communication device 100 is generated by the solar power generation panel 40. The generated power is stored in the battery 90, and power is supplied from the battery 90 to each unit.

 FIG. 3 shows an example of the photographing device 50. The photographing device 50 shown in FIG. 3 acquires a visible light image and an infrared image. However, the photographing device 50 may acquire only a visible light image, or may acquire only an infrared image.

 The photographing device 50 includes the first lens 21 and the second lens 22 for photographing the whole celestial sphere, as described above. The first lens condenses the light of the field of view of the first semi-celestial sphere of the full celestial sphere. The second lens collects light in the field of view of the second hemisphere, which is the remaining hemisphere of the full sphere. In addition, it is preferable that the visual field converged by the lens 21 and the visual field condensed by the lens 22 partially overlap to facilitate generation of a single spherical image.

 The light in the field of view of the first hemispherical sphere collected by the first lens 21 is provided to the image sensors 53a and 54a via the splitter 52a. The splitter 52a reflects visible light and transmits infrared light. The image sensor 53a converts visible light into an electric signal. That is, the image sensor 53a outputs the first visible light image 201 corresponding to the first hemisphere. The image sensor 54a converts an infrared ray into an electric signal. That is, the image sensor 54a outputs the first infrared image 301 corresponding to the first hemisphere.

 Light in the field of view of the second hemispherical sphere collected by the second lens 22 is provided to the image sensors 53b and 54b via the splitter 52b. The splitter 52b reflects visible light and transmits infrared light. The image sensor 53b converts visible light into an electric signal. That is, the image sensor 53b outputs the second visible light image 202 corresponding to the second hemisphere. The image sensor 54b converts infrared rays into an electric signal. That is, the image sensor 54b outputs the second infrared image 302 corresponding to the second hemisphere.

 The images output from the image sensors 53a, 54a, 53b, 54b are provided to an image processor 60. The image processor 60 combines the first visible light image 201 and the second visible light image to generate a single visible light omnidirectional image 203. Further, the image processor 60 combines the first infrared image 301 and the second infrared image 302 to generate a single infrared spherical image 303. The image processor 60 transmits the images 203 and 303 to the controller 71. The attitude analysis module 73a of the controller 70 analyzes the attitude of the satellite 10 using one or both of the images 203 and 303.

 As shown in FIG. 4, in step S1, the posture analysis module 73a performs a first process S2-1 for performing a posture analysis using the visible light omnidirectional image 203, and a posture analysis using the infrared omnidirectional image 303. To be executed is selected. This selection is performed in order to use an image more suitable for the posture analysis among the plurality of images 203 and 303 for the posture analysis. The selection may be made based on, for example, time, or may be made based on an evaluation of which image captures the earth more clearly.

 Since the infrared image 303 can project the contour of the earth regardless of the day or night of the earth, it is suitable for posture analysis in many time zones. However, when the earth being photographed is in the daytime, the visible light image can obtain more accurate information indicating the pattern on the earth's surface (information on the topography and the position of cities, countries, etc.), so a more accurate attitude Suitable for control. From this viewpoint, in the selection processing in step S1, processing using an image more suitable for the posture analysis is selected.

 FIG. 5 shows an example of the first process S2-1. In the first process S2-1, the attitude analysis module 73a reads out the visible light spherical image 203 in step S12, and analyzes the movement and position in the earth image 203, which is the reference celestial body, in step S13. 10 posture analysis information is obtained. The attitude analysis information includes the angular velocity, spin direction, attitude error, and the like of the satellite 10 as described above. At step S14, the attitude control module 73b operates the actuator 80 based on the attitude analysis information.

 FIG. 6 illustrates an example of the second process S2-2. In the second process S2-2, the attitude analysis module 73a reads out the infrared spherical image 303 in step S22, and analyzes the movement and position in the earth image 303, which is the reference celestial body, in step S23. Obtain posture analysis information. The attitude analysis information includes the angular velocity, spin direction, attitude error, and the like of the satellite 10 as described above. At step S24, the attitude control module 73b operates the actuator 80 based on the attitude analysis information.

 FIG. 7 shows a procedure when the attitude analysis module 73a performs an attitude analysis using both the visible light omnidirectional image 203 and the infrared omnidirectional image. At step S31 and step S32, the posture analysis module 73a reads the visible light omnidirectional image 203 and the infrared omnidirectional image 303. At step S33, the posture analysis module 73a performs posture analysis using both images 303. In the posture analysis using the two images 303, for example, information obtained from the visible light spherical image 203 is used for a bright portion (daytime portion) of the earth, and far-infrared light is used for a dark portion (nighttime portion). Information obtained from the spherical image is used. When a bright part and a dark part coexist on the photographed earth, more accurate attitude analysis information can be obtained by complementarily using information obtained from both images 203 and 303. The posture error can be obtained with high accuracy. At step S34, the attitude control module 73b operates the actuator 80 based on the attitude analysis information.

 FIG. 8 shows the attitude control processing in steps S13, S24, and S34. In step S41, the attitude control module 73b determines whether or not the earth, which is the reference celestial object (first astronomical object), is moving in the images 203 and 303 (whether or not the position in the images is changing). . Whether it is moving or not is determined, for example, based on information on the angular velocity and the spin direction included in the posture analysis information. If it is determined that the earth in the images 203 and 303 is moving, the satellite 10 is spinning around the x-axis (roll axis) and / or the y-axis (pitch axis). Therefore, in step S42, the attitude control module 73b operates the actuator 80 to suppress spin around the roll axis and / or the pitch axis. The control amount for spin suppression is determined based on the angular velocity and the spin direction.

In step S43, the attitude control module 73b determines whether the position of the earth (first celestial object) in the images 203 and 303 is correct. The spherical images 203 and 303 used for this position determination have, for example, the formats shown in FIGS. 5 and 6. Fig In 5 and the image 203 and 303 of FIG. 6, the horizontal direction theta ₁ corresponds to the horizontal orientation to + 180 ° from -180 °, longitudinal theta ₂ corresponds to the vertical direction up to + 90 ° from -90 ° ing. The horizontal direction theta ₁ is the azimuthal angle in the xz plane, longitudinal theta ₂ is the azimuthal angle in the y-axis direction.

For example, when the earth orientation plane 11a faces the earth and the z axis is oriented at the center of the earth in a correct posture, the center positions of the earths E1 and E3 in the images 203 and 303 are (θ ₁ , θ ₂ ) If it is at the position of (0,0), the satellite 10 is in a correct attitude. On the other hand, if the center positions of the earths E1 and E3 in the images 203 and 303 deviate from (θ ₁ , θ ₂ ) = (0, 0), it is understood that there is a posture error and the posture is not correct.

 When determining that the position of the earth is not correct, the attitude control module 73 operates the actuator 80 in step S44 to change the attitude of the satellite around the roll axis and / or the pitch axis so as to take the correct attitude. . As a result, an appropriate posture can be obtained in which the z-axis matches the direction toward a specific target position on the earth (for example, the position of a ground antenna).

For example, when the target position is Tokyo, Japan, the position of Tokyo is searched for in the images 203 and 303, and the posture is set so that the coordinates of the searched position become (θ ₁ , θ ₂ ) = (0, 0). Is controlled. Note that the visible light whole handball image 203 is more suitable for the search of the target position than the infrared whole spherical image 303.

 Whether or not the z-axis is correctly pointed at a target position to be pointed (for example, the position of a ground antenna) may be determined based on the images 203 and 303. This determination is made, for example, by comparing the reference spherical images 205 and 305 with the images 203 and 303. The reference images 205 and 305 are stored in the memory 72 in advance. The reference images 205 and 305 are, for example, images at the time of control when the z-axis is correctly pointing to the target position. By performing attitude control such that the image of the earth in the image 203 matches the image of the earth in the reference image 205, a correct attitude can be obtained. It is preferable to use the visible light image 203 also when using the reference image 205.

 In step S45, the attitude control module 73b determines whether the images of the earth in the images 203 and 303 are rotating. When the satellite 10 is spinning around the z-axis, even if the position of the earth does not change and remains stationary in the images 203 and 303, the earth rotates in a stationary state. The presence or absence of rotation of the image of the earth is determined by the presence or absence of a change in the surface pattern of the earth. It is preferable to use the visible light image 203 to determine whether or not the surface pattern has changed.

 Even if the satellite 10 is spinning only around the z-axis, there is no problem if the communication antenna 30 is a circularly polarized antenna, but if spinning around the z-axis becomes a problem, the attitude control module 73b proceeds to step S46. , The actuator 80 is operated to suppress spin around the z-axis (yaw axis). The control amount for spin suppression is determined based on the angular velocity and direction of rotation of the earth.

 By the above-described three-axis attitude control, the satellite 10 can be stabilized in an attitude in which the earth directing surface 11a points to the target position of the earth. However, the attitude control module 73b also performs the attitude control in step S47 to increase the solar power generation efficiency. In the attitude control in step S47, only the attitude around the z axis (yaw axis) is controlled.

 Since the photovoltaic power generation panel 40 has the highest power generation efficiency when facing the sun, it is preferable that the photovoltaic power generation panel 40 face the sun as much as possible. Therefore, in step S47, the attitude control module 73b directs the surface 12c on which the photovoltaic power generation panel 40 is provided toward the sun as much as possible based on the position of the sun (the second celestial body) in the images 203 and 303. The attitude of the satellite 10 is changed around the z-axis as described above. By this attitude control, the direction of the photovoltaic power generation panel 40 can be changed according to the position of the sun. In the attitude control in step S47, only the attitude around the z-axis (yaw axis) is controlled, and the attitude around the x-axis and y-axis does not change. Will be maintained.

 In the present embodiment, since the satellite 10 includes the omnidirectional photographing device 50, two astronomical objects whose positional relationship between the earth and the sun can change are always simultaneously photographed regardless of the attitude of the satellite 10. can do.

 [3. Deformation]

 The present invention is not limited to the above embodiment, and various modifications are possible.

[4. Appendix]
The earth sensor of Patent Literature 1 is provided only on the earth-facing surface of an artificial satellite. When the attitude of the satellite is stable with the earth-facing surface generally pointing at the earth, even if the earth sensor is provided only on the earth-facing surface, the earth is always scanned and the satellite's attitude error is corrected. Can be detected.

 However, the attitude of the satellite may become unstable, and an earth sensor that should point the earth may not point the earth. If the earth sensor is not pointing at the earth, the earth cannot be scanned, the attitude of the satellite cannot be grasped, and attitude control becomes difficult. Attitude instability is particularly likely to occur on relatively small satellites, for example, microsatellites.

 The attitude becomes unstable, for example, when an artificial satellite is put into orbit. Due to the principle of the satellite release mechanism for putting an artificial satellite into orbit, it is often impossible to make the artificial satellite spinless at the time of launching the satellite. When the satellite spins, the earth sensor cannot always point at the earth. In addition, when an abnormality occurs, the attitude of the artificial satellite becomes unstable, and the artificial satellite may spin or the earth-facing surface of the artificial satellite may not point at the earth.

 As described above, since it is difficult to perform attitude control using only the earth sensor, it is necessary to separately provide a mechanism for roughly stabilizing the attitude of the satellite in addition to the earth sensor. However, if a separate attitude stabilizing mechanism is required, the size and cost of the satellite will increase. Moreover, in the case of a relatively small satellite such as a microsatellite, it may be very difficult to provide such a mechanism due to size restrictions.

 Therefore, even if the attitude of a spacecraft such as an artificial satellite becomes unstable, it is desired that the attitude can be controlled with reference to a reference celestial body such as the earth.

 In one embodiment of the present invention, the attitude control of a spacecraft is performed based on one or a plurality of reference celestial objects in an image captured by the omnidirectional imaging device. Thereby, even if the attitude of the spacecraft becomes unstable, the attitude can be controlled with reference to the reference celestial body.

 The celestial sphere photographing device may be one that performs photographing by sensing visible light, or one that performs photographing by sensing infrared light. Here, the infrared light may be far infrared light or near infrared light.

(1) The spacecraft according to the embodiment includes a controller that controls the attitude of the spacecraft. The controller of the embodiment controls the attitude of the spacecraft based on the reference celestial object in the image captured by the omnidirectional imaging device. Since the omnidirectional imaging device can capture images in all directions viewed from an artificial satellite, a blind spot does not occur even when the attitude of the artificial satellite changes. Therefore, even when the attitude of the satellite changes due to the spin of the satellite, the reference celestial object can be reliably photographed. As a result, even if the attitude of the artificial satellite changes significantly, the controller can perform attitude control based on the reference celestial object without losing sight of the reference celestial object.

 The attitude control may include despin control for suppressing the spin of the satellite, or pointing control for pointing the satellite in a desired direction. In order to surely perform the despin control, the pointing control, and the like, the attitude control is preferably three-axis attitude control. The three-axis attitude control is to control the attitude of the artificial satellite using three axes of a roll axis, a pitch axis, and a yaw axis.

 Here, the image shot by the omnidirectional imaging device is an image of the omnidirectional image. Hereinafter, an image obtained by photographing a spherical image is referred to as a spherical image. The celestial sphere image may be composed of one image data, or may be composed of a plurality of image data. When the celestial sphere is shot by sharing with a plurality of cameras, a plurality of image data is obtained. Although the plurality of image data may be handled as a celestial sphere image, it is preferable that one image data obtained by combining the plurality of image data is treated as a celestial sphere image. Since one image data represents the whole celestial sphere, processing such as image analysis becomes easy.

 The reference celestial body is a celestial body that serves as a reference for the attitude of the satellite. A celestial body is an object that exists in outer space. The celestial body is, for example, the earth or other planet, the moon or other satellite, the comet, the sun or other star, a cluster, a nebula, or a galaxy. The celestial body may be another space vehicle or other artifact. One or more celestial objects may be used as reference objects in the spherical image. For example, the reference celestial body may be the earth alone, the earth and the sun, the earth and the moon, or the earth, the sun, and the moon. Since the omnidirectional photographing apparatus can photograph all directions viewed from an artificial satellite, it can easily photograph a plurality of celestial bodies.

 (2) The attitude control performed by the controller of the embodiment may include suppressing spin occurring in the spacecraft and directing the spacecraft to at least one reference celestial body. A stable attitude can be obtained by suppressing spin and pointing the spacecraft toward the reference celestial body. Here, “suppressing the spin” may be to completely stop the spin, or may be to suppress the spin without completely stopping the spin. "Pointing a spacecraft toward at least one reference celestial body" refers to directing a spacecraft toward a reference celestial body. Means pointing to a reference object.

 (3) The attitude control performed by the controller of the embodiment preferably includes attitude control based on the surface pattern of the reference celestial object in the image. The surface pattern of the reference celestial object is the appearance of the photographed reference celestial object. The surface pattern of the earth is determined, for example, by the shape of a continent or sea. When the surface pattern of the reference celestial object is used for attitude control, the spacecraft can be accurately directed to a specific position on the reference celestial object.

 (4) Preferably, the one or more reference objects include a first object and a second object different from the first object. The number of reference objects may be three or more. The attitude control performed by the controller of the embodiment is such that, based on the first celestial object in the image, the first direction based on the spacecraft is directed to the first celestial object, and based on the second celestial object in the image, The method may include adjusting a posture around an axis along a direction along the first direction based on a position of the second celestial object in the image. In this case, the spacecraft can take an appropriate posture according to the positional relationship between the plurality of celestial bodies.

 (5) The first celestial body is, for example, the earth. The first celestial body may be, for example, a celestial body or another celestial body as a navigation target. The second celestial body is, for example, the sun. The second celestial body may be another celestial body.

 (6) The omnidirectional imaging device of the embodiment may be configured to obtain a visible light image of the omnidirectional and an infrared image of the omnidirectional. The controller according to the embodiment can select any one of the visible light image and the infrared image, and can perform the posture control based on one or a plurality of reference celestial objects in the selected image.

 (7) The controller of the embodiment can control the attitude based on one or more reference objects in the visible light image and one or more reference objects in the infrared image.

 (8) In the embodiment, the spacecraft is preferably a microsatellite.

 (9) In the embodiment, the controller can control the attitude of the spacecraft based on one or a plurality of reference objects in the celestial sphere image.

 (10) In the embodiment, the method of controlling the attitude of the spacecraft is based on one or more reference objects in the spherical image.

 (11) In the embodiment, the computer program causes the computer to execute processing including controlling the attitude of the spacecraft based on one or a plurality of reference objects in the celestial sphere image. The computer program is stored on a computer-readable storage medium. The computer program stored in the storage medium is executed by a processor.

Reference Signs List 10 artificial satellite 11a earth directing surface 11b opposite surface 12a first surface 12b second surface 12c third surface 12d fourth surface 21 first fisheye lens 22 second fisheye lens 30 antenna 40 solar power generation panel 50 spherical imaging device 60 Processor 70 Controller 71 Processor 72 Memory 73 Computer program 73a Attitude analysis 73b Attitude control 73c Communication processing 74 Image storage area 75 Interface 76 Interface 77 Interface 80 Actuator 90 Battery 100 Wireless communication device

Claims (3)

Space vehicle provided with the space omnidirectional imaging equipment capable of capturing a plurality of surfaces arranged in navigation body to capture the omnidirectional image around the space vehicle. A first hemispherical camera provided on the spacecraft so as to photograph one hemisphere of the whole celestial sphere centered on the spacecraft, and the universe so as to photograph the other hemisphere of the whole celestial sphere. A spacecraft including a spherical imaging device including: a second semispherical camera provided on a side opposite to a position where the first semispherical camera is provided in the navigational body. The spacecraft according to claim 1 or 2, which is a microsatellite.