Satellite device and method for imaging space objects

Abstract

The invention relates to a satellite device (100, 200) for imaging space objects (116, 116'), wherein the satellite device (100, 200) is movable along an orbit (102) with a position-dependent orbit coordinate system (104) which comprises an orbit axis (106), a gravitational axis (108) and a pitch axis (109), the satellite device (100, 200) comprising a telescope device (212) having a field of view (112, 112'), a telescope axis (110, 110', 218) and an imaging telescope sensor (210), which is arranged and designed to generate images (132) of space objects (116, 116') in front of a starry background. and a control device (204), which is designed to control the satellite device (100, 200) in such a way that, during operation as intended, a predetermined pitch angle (114) is set between the telescope axis (110, 110', 218) and the orbit axis (106), and to control the telescope sensor (210) in such a way that continuously lined images (132, 134) of space objects (116, 116') and stars are generated, in order to obtain a plurality of lined images (132, 134) for generating a space object overview.

Description

[0001] Satellite device and method for imaging space objects

[0002] The invention relates to a satellite device and a method for imaging space objects, in particular in near-Earth space, for generating a space object position image.

[0003] The imaging, observation, and cataloging of space objects is generally well known. Space objects, particularly space debris and satellites, are observed using Earth-based telescopes and radar stations. Space objects, particularly space junk, are an undesirable byproduct of space travel because they can hinder space travel and cause damage to the Earth's surface. More than 55,000 recorded and cataloged space objects orbit the Earth in an orbit with a diameter of more than 10 cm. Based on statistical models, ESA estimates that there are more than 1 million objects larger than 1 cm in near-Earth space. Such space objects can collide with active satellites or space shuttles and, due to their high speeds, usually cause considerable damage.While the parts of Earth's orbit captured and catalogued by Earth-based telescopes and radar stations lead to a better understanding of space objects in Earth's orbit, they are not sufficient for commercial space travel, as even smaller parts must be captured and, in particular, higher temporal resolution is required. Furthermore, the spatial resolution of this approach is generally insufficient, as no or only limited observation is possible, particularly at high latitudes.

[0004] One approach to observing space objects using telescopes is called staring. Staring involves maintaining a fixed orientation relative to the starry background during the image exposure. As a result, the stars appear point-like in the image, while less distant objects, such as space objects in Earth's orbit, generate a line-like signal in the image due to their relative motion, the length and shape of which depend on the image exposure time.

[0005] Another approach is so-called tracking. In tracking, the space object of interest is tracked along the optical axis of the telescope, thus minimizing object movement in the image. The space object of interest generates a point-shaped signal in a first approximation, while the starry background is imaged with line-shaped image elements. A disadvantage of tracking is that only a single object can be observed during an observation interval. Furthermore, the field of view must be moved to another object between two observation intervals, which is why a low throughput of observed objects is a further disadvantage of tracking. Furthermore, the orbit of an object to be observed should be known approximately a priori.

[0006] Due to the need for regular tracking movements, angular accelerations during staring and tracking during image integration lead to non-constant signal movements in the image, meaning that accurate measurements, especially astrometric and / or photometric measurements, cannot be derived from the image data. Thus, observation time is effectively lost due to correction movements, among other things. In general, staring and tracking lead to complex operation of the observation system or satellite, which is primarily due to attitude control and regulation, for example, for tracking, as well as the alignment of the antennas to the ground station and / or the solar panels to the sun.

[0007] When observing space objects using a telescope on a satellite, previous approaches typically involve optimizing the observation situation relative to an object to be observed, for example, by maintaining a minimum solar phase angle. This is usually accompanied by a suboptimal number of objects to be observed.

[0008] The publication by Krag, H., et al., "Space-based optical observation of small debris objects." Space Debris, Vol. 473, 2001, discloses a satellite-based observation of space debris using a telescope. A disadvantage of this approach is that few or no observations can be detected, at least in certain regions of the orbit itself and in certain orbital regimes of the objects of interest.

[0009] CN105910583A discloses a method for detecting space debris.

[0010] It is therefore an object of the invention to provide a satellite device and a method for imaging space objects that reduce or eliminate one or more of the aforementioned disadvantages. In particular, it is an object of the invention to provide a solution that enables a high detection frequency of a large number of space objects in Earth's orbits. Furthermore, it is an object of the invention to provide a solution that enables the detection of particularly small space objects in Earth's orbits.

[0011] This object is achieved with a satellite device and a method according to the features of the independent patent claims. Further advantageous embodiments of these aspects are specified in the respective dependent patent claims. The features disclosed in the patent claims, the description, and the drawings can be combined individually in any technologically expedient manner, with further embodiments of the invention being shown.

[0012] According to a first aspect, the object mentioned at the outset is achieved by a satellite device for imaging space objects, in particular radiation-emitting space objects, preferably in near-Earth space, to generate a space object position image, wherein the satellite device is movable along an orbit with a position-dependent orbit coordinate system having an orbit axis, a gravity axis, and a pitch axis, the satellite device comprising a telescope device with a field of view, a telescope axis, and an imaging telescope sensor arranged and configured to generate images of space objects against the star background, and a control device configured to control the satellite device such that, during normal operation, a predetermined pitch angle is established between the telescope axis and the orbit axis, and to control the telescope sensor such thatthat line-shaped images of space objects and stars are continuously generated in order to obtain a plurality of line-shaped images for generating a space object position image.,

[0013] In a preferred embodiment, the control device is configured to control the satellite device such that the pitch angle is constant. In particular, the pitch angle is constant within an observation interval.

[0014] Alternatively or additionally, it is preferred that the control device is configured to control the satellite device such that the pitch angle is set within a pitch angle range. The pitch angle range can extend, for example, between +20° and -20°, in particular between +4° and -12°. An advantage of this embodiment is that the orbit heights to be observed can be focused.

[0015] Alternatively or additionally, it is preferred that the control device is configured to control the satellite device such that the telescope axis moves relative to the orbit axis in the pitch direction and / or the telescope axis oscillates relative to the orbit axis at a predefined angular velocity in the pitch direction. An advantage of this embodiment is that a multitude of orbital planes and a multitude of different particle sizes can be observed. The angular velocity during the oscillating movement can, for example, be between 27 min and 67 min.

[0016] The invention is based on the finding that space objects can be advantageously detected with a satellite-based telescope if the telescope axis is aligned in a defined manner relative to the Earth's horizon, for example, always the same or with a predetermined oscillation, so that the telescope is guided essentially without acceleration to produce optimal images. The guidance of the telescope is essentially without acceleration, since, for example, in the case of a predetermined oscillation, a rapid reversal of movement at the reversal points is required.

[0017] This results in the space objects themselves, as well as the stars in the background, being imaged in a line-like manner. Such line-like images can be advantageously evaluated and, in particular, the space objects can be identified. This results in a high detection frequency of a large number of space objects in all orbits. As a result, a comprehensive space situation picture can be provided that can be used for the safe and automated operation of additional satellites. Furthermore, the line-like images and the selection of an optimal pitch angle allow a signal-to-noise ratio to be set to meet requirements.

[0018] The invention is further based on the finding that it represents a compromise between various optimization goals for viewing as many objects as possible as clearly as possible. Among other things, suboptimal, particularly larger, sun phase angles can be considered in order to align the field of view to regions with high object density that are not in the Earth's shadow through a uniform positional movement.

[0019] The invention is further based on the finding that the predetermined pitch angle allows the field of view to be directed to regions of high object density while simultaneously enabling a favorable sun phase angle and / or contrast, thus optimizing the detectable field of view transitions. The uniformity of the movement allows for advantageous exposure during this time, and accurate measurement values ​​can be extracted.

[0020] The satellite device is designed to image space objects. This involves, in particular, optical imaging of the space objects using an optical telescope sensor. The imaging of the space objects occurs, in particular, through radiation emitted by the space objects, for example, through reflection of solar radiation. The satellite device is, in particular, arranged and designed to monitor an orbit in near-Earth space, for example, the Low Earth Orbit (LEO). Furthermore, the satellite device can also detect space objects in higher orbital planes.

[0021] The satellite device is movable along an orbit, specifically around the Earth. At each point along the orbit, the orbital coordinate system is uniquely defined. The orbital coordinate system is oriented to the current trajectory. The orbital coordinate system is also referred to as the local reference system. The orbital coordinate system is spanned by the orbital axis, the gravity axis, and the pitch axis.

[0022] The orbit axis describes the direction of the orbit at any point on the orbit and is therefore aligned in the tangent direction. The gravity axis is the axis at any point on the orbit that leads to the center of the Earth. The gravity axis is essentially parallel to a position vector of the satellite device. The pitch axis is aligned orthogonal to the orbit axis and the gravity axis. The pitch angle and a corresponding pitch movement occur in particular in a plane spanned by the orbit axis and the gravity axis with a pitch direction. The yaw angle and the corresponding yaw movement, explained in more detail below, occur in particular in a plane spanned by the orbit axis and the pitch axis. The satellite device comprises the telescope device with the field of view. The field of view can be conical and / or pyramid-shaped around the telescope axis.The telescope device further comprises the imaging telescope sensor, which can be, for example, a CCD sensor or a CMOS sensor. During normal operation of the satellite device, the telescope axis is preferably aligned, among other things, with a section located between the orbit and the Earth. The telescope axis is thus regularly formed as a secant with respect to the orbit, and the pitch angle is negative. Furthermore, a positive pitch angle can also be set.

[0023] The satellite device further comprises the control device, which is configured to control the satellite device such that, during normal operation, a constant pitch angle is established between the telescope axis and the orbit axis. Due to the constant pitch angle, the satellite device generally does not move in the orbital coordinate system.

[0024] The control device is preferably arranged and configured to provide a correction command, in particular to an attitude control unit described below, so that the telescope axis and the orbit axis maintain the constant pitch angle. In particular, the correction command is configured such that it causes the attitude control unit to influence the satellite device such that the constant pitch angle is maintained and / or adjusted.

[0025] With respect to the orbital coordinate system, no pitch movement occurs at a constant pitch angle, since the constant pitch angle between the telescope axis and the orbit axis produces images of stars and space objects that are particularly easy to evaluate. In the constant pitch angle variant, a pitch movement in the orbital coordinate system generally only occurs for corrections, since deviations from the pitch angle can occur due to disturbances. In the inertial system, on the other hand, a continuous pitch movement is carried out so that the telescope axis remains consistently aligned with the Earth's horizon. From the perspective of the satellite device, the pitch movement represents a change in the field of view, either upwards or downwards.In the variant with adjustable pitch angle within the pitch angle range, the pitch movement occurs at defined times and / or positions along the orbit or continuously. This allows, for example, the focus to be directed to space objects at defined orbital altitudes and / or space objects of other sizes and / or brightness classes.

[0026] The constant pitch angle between the telescope axis and the orbit axis maintains a consistent viewing direction relative to the Earth's horizon. The satellite system is therefore controlled in such a way that, during normal operation, a constant pitch angle is also maintained between the orbit and the telescope axis. In other words, during normal operation, the telescope axis forms a constant angle with the orbit.

[0027] Intended operation means in particular that the satellite device is in orbit and orbits the Earth.

[0028] The control device is further configured to control the telescope sensor so that continuous line-shaped images of space objects and stars are generated. Due to the movement of the satellite device on the curved orbit and the constant pitch angle between the telescope axis and the orbit axis, space objects and stars are imaged in line-shaped patterns with a suitably selected orbit, since there is always a relative motion between the telescope axis and the space objects or stars.

[0029] The continuous generation of line-like images of space objects and stars means, in particular, that exposures are performed at short intervals. The invention is also based on the finding that lines in images are easier to recognize than point-like images of stars or space objects. Particularly due to the large number of space objects and stars, a line-like image is easier to evaluate than point-like images.

[0030] A satellite device controlled in this way eliminates the previous need for regular corrections or focusing during operation, so that a harmonious image can be generated on the basis of which space objects can be detected with a higher probability.

[0031] The satellite device preferably comprises a solar cell unit arranged and configured to convert sunlight into electrical energy. The solar cell unit is further preferably arranged and configured to provide the electrical energy.

[0032] A preferred embodiment of the satellite device provides that the control device is configured to control the satellite device such that the pitch angle is set between +20° and -20°.

[0033] A negative pitch angle means that the telescope axis initially passes through a section located between the Earth and the orbit. A pitch angle of 0° means that the telescope axis is aligned parallel to the orbit. A positive pitch angle means that the telescope axis is aligned away from the Earth. Choosing the optimal pitch angle is always a compromise between an optimized field of view within a certain orbit altitude range, for example, at a pitch angle between 0° and -5°, and a high noise component in the signal, for example, at a pitch angle of -15° to -20°, because atmospheric influences become greater the further the telescope is aligned towards Earth, i.e. the larger the pitch angle. In particular, it is preferred that the pitch angle be between -12° and +4°.

[0034] In a preferred embodiment of the satellite device, the control device is configured to control the satellite device such that the telescope axis executes a yaw movement around the gravity axis, so that the field of view can be aligned to at least one predetermined orbital regime. From the perspective of the satellite device, the yaw movement of the telescope axis represents a change in the field of view to the right or left. Thus, the field of view can be aligned to orbital regimes in which a high density of space objects is expected, for example, over the Earth's poles.

[0035] A further preferred embodiment of the satellite device is characterized in that the control device is configured to control the satellite device in such a way that a constant yaw angle is established between the telescope axis and the orbit axis in order to align the field of view to at least one predefined orbital regime.

[0036] In a further preferred embodiment of the satellite device, it is provided that the control device is configured to control the satellite device in such a way that the telescope axis oscillates, in particular oscillates discontinuously, around the gravity axis by means of the yaw movement in a predefined angular range, wherein this yaw movement is carried out at a first angular velocity in order to observe at least two predefined orbital regimes.

[0037] Particularly for orbits that do not directly pass over the Earth's poles, oscillation around the gravity axis can be used to align the telescope axis to the region above the North Pole and the region above the South Pole. Furthermore, the yaw motion is preferably selected to minimize the solar phase angle, allowing particularly small space objects to be observed. Oscillation is preferably not continuous, but rather is performed at a rapid angular velocity from a first orientation to a second orientation to minimize disturbances during image acquisition.

[0038] A further preferred embodiment of the satellite device is characterized in that the control device is configured to control the satellite device in such a way that the telescope axis can be pivoted by 180° between a first orientation and a second orientation by means of the yaw movement as a function of a solar phase angle, so that the field of view can be aligned as a function of a solar phase angle.

[0039] Although the imaging of space objects according to the invention does not necessarily require the telescope axis to be aligned away from the sun, it is nevertheless disadvantageous to look directly near the sun, as space objects reflect little or no radiation at a small angle of incidence. Therefore, a yaw movement of 180° between the first alignment and the second alignment can accommodate this condition, allowing, for example, a panning movement on a corresponding side of the Earth facing the sun.

[0040] A further preferred embodiment of the satellite device is characterized in that the control device is configured to control the telescope sensor such that an exposure time is between 0.1 seconds and 2 seconds, in particular between 0.25 seconds and 1 second, preferably between 0.1 seconds and 0.5 seconds, in order to obtain evaluable line-shaped images of space objects and stars.

[0041] It is particularly preferred that the control device is configured to determine an exposure duration or the exposure duration such that a line-shaped image of a space object with 15 to 315 pixels, in particular 30 to 200 pixels, of the telescope sensor can be imaged, and to control the telescope sensor with the exposure duration.

[0042] The exposure time can, for example, be between 0.1 and 0.5 seconds, as described above. An image of a space object with 30 to 200 pixels has proven to be advantageous for evaluation.

[0043] In a further preferred embodiment of the satellite device, it is provided that it comprises an attitude control unit which is signal-coupled to the control device and which is arranged and designed to change an orientation of the satellite device with respect to the orbit coordinate system, so that a pitch movement and / or the yaw movement can be effected by controlling the attitude control unit.

[0044] To execute the pitch movement, the attitude control unit is particularly designed to provide the satellite device with a one-time pulse, so that the satellite device rotates continuously relative to the inertial system due to the essentially nonexistent friction in space, thus establishing a constant pitch angle between the orbit axis and the telescope axis. Furthermore, the attitude control unit is preferably designed to keep the pitch angle constant, for example, by receiving the correction signal. The control device is preferably configured to detect a deviation in the pitch angle and generate the correction signal. Specific pulses from the attitude control unit may be required to implement the yaw movement.

[0045] Alternatively or in addition to the attitude control unit, the satellite device may comprise an alignment device for the telescope, so that it is not the satellite device as such that moves relative to the orbit coordinate system, but the telescope.

[0046] In a further preferred embodiment of the satellite device, it is provided that it comprises an evaluation unit which is arranged and designed to evaluate the line-shaped images based on a star catalog in order to recognize space objects and at least one property of the space objects, and to generate a first data set representing the recognized space objects and the property, and a transmitting unit which is arranged and designed to transmit the first data set to a receiving unit located on Earth.

[0047] The property of the space object can be, for example, a position in the image, a position in space, an orbit, or a size of the space object. Furthermore, the property can be an apparent brightness of the space object. Furthermore, the property can be a rotation state. Furthermore, the property can be a variation of the properties mentioned above. Furthermore, the property can be a size, a shape, and / or a surface property of the space object.

[0048] The transmitting unit can, for example, be designed as or comprise one, two or more antennas.

[0049] In a further preferred embodiment of the satellite device, it is provided that it comprises a compression unit which is arranged and designed to generate a second data set representing the line-shaped images in a compressed manner, wherein the second compressed data set can be transmitted by means of a or the transmitting unit to a receiving unit located on Earth.

[0050] The evaluation unit has the advantage that the images can be evaluated directly at the satellite device, and if necessary, only text files, for example image coordinates in a specific format, preferably as encrypted binary data, need be transmitted to Earth or the receiving unit. The data volumes are generally small. If evaluation at the satellite device is not appropriate, it may be advisable to compress the data in such a way that it can be transmitted securely to the receiving unit. In low-Earth orbit, for example, data can be transmitted to a single receiving unit within a time window of 10 to 15 minutes, so the second data set should be large enough to be transmitted to the receiving unit within this time.

[0051] According to a further aspect, the object mentioned at the outset is achieved by a method for imaging space objects, comprising the steps of: moving a satellite device along an orbit with a position-dependent orbit coordinate system which has an orbit axis, a gravity axis and a pitch axis, the satellite device comprising a telescope device with a field of view, a telescope axis and an imaging telescope sensor for generating images of space objects against the star background, setting a predetermined pitch angle between the telescope axis and the orbit axis and continuously generating line-shaped images of space objects and stars in order to obtain a plurality of line-shaped images for generating a space object position image.

[0052] It is preferred that the pitch angle be set constant. Furthermore, the pitch angle is preferably set within a pitch angle range. Furthermore, it may be preferred that the telescope axis moves relative to the path axis in the pitch direction and / or that the telescope axis oscillates relative to the path axis at a predefined angular velocity in the pitch direction.

[0053] In a preferred embodiment of the method, it is provided that it comprises the step of setting a yaw angle, for example by performing a yaw movement, of the telescope axis around the gravity axis, so that the field of view can be aligned to at least one predetermined orbital regime. In a further preferred embodiment of the method, it is provided that the setting of the pitch angle and / or the execution of the yaw movement is effected by a change in the position of the satellite device.

[0054] It is preferred that the satellite device is controlled such that the pitch angle is between +20° and -20°, in particular between +4° and -12°.

[0055] It is further preferred that the method comprises the step of setting a constant yaw angle between the telescope axis and the orbital axis. Furthermore, the method may comprise the step of adjusting the telescope axis by means of the yaw movement within a predefined angular range around the gravity axis, wherein this yaw movement is performed at a first angular velocity in order to observe at least two predefined orbital regimes.

[0056] In a further preferred embodiment of the method, it is provided that it comprises the step of pivoting the telescope axis as a function of a solar phase angle by means of the yaw movement by 180° between a first orientation and a second orientation, so that the field of view is aligned as a function of a solar phase angle, in particular with respect to space objects in the field of view.

[0057] In a further preferred embodiment of the method, it is provided that it comprises the step of controlling the telescope sensor such that an exposure time is between 0.1 seconds and 2 seconds in order to obtain evaluable line-shaped images of space objects and stars.

[0058] In a further preferred embodiment of the method, it is provided that it comprises the step of determining an exposure time such that a line-shaped image of a space object is imaged with 10 to 80 pixels of the telescope sensor and controlling the telescope sensor with the exposure time.

[0059] In a further preferred embodiment of the method, this comprises the step of evaluating the line-shaped images based on a star map to detect space objects and at least one property of the space objects, and generating a first data set representing the detected space objects and the property. Furthermore, the method can comprise the step of transmitting the first data set to a receiving unit located on Earth.

[0060] In a further preferred embodiment of the method, it is provided that it comprises the step of generating a compressed second data set representing the line-shaped images, wherein the second data set is transmitted by means of a or the transmitting unit to a receiving unit located on Earth.

[0061] In a further preferred embodiment of the method, it is provided that the satellite device is moved in a sun-synchronous orbit with an altitude of 350 to 600 kilometers.

[0062] It is further preferred that the telescope axis be aligned such that a 90° angle is established between the telescope axis and a direction toward the sun. Furthermore, it is preferred that the angle between the telescope axis and the direction toward the sun is between 0° and 90°.

[0063] It is preferred that the telescope axis alternates between the angles 0° and 90°, particularly by means of the yaw motion. This enables a pointing mode in which a constant pitch movement with a yaw angle of 0° is performed during part of the orbit, thus maintaining a view in the orbital plane. During the remaining part of the orbit, the solar phase angle is minimized via the yaw angle, for example, a yaw angle of 90° in a dawn-dusk sun-synchronous orbit.

[0064] For further advantages, design variants and details of the individual aspects and their possible further training, please refer to the description of the other aspects, the corresponding features and further training.

[0065] Preferred embodiments are explained using the accompanying figures. They show:

[0066] Figure 1 : a schematic, two-dimensional view of a

[0067] Satellite device in low Earth orbit; Figure 2: a schematic, two-dimensional view of a

[0068] satellite device in low Earth orbit;

[0069] Figure 3: a schematic, two-dimensional view of a

[0070] satellite device in low Earth orbit;

[0071] Figure 4: a schematic, three-dimensional view of an exemplary

[0072] Embodiment of a satellite device in low Earth orbit;

[0073] Figure 5: a schematic, three-dimensional view of an exemplary

[0074] Embodiment of a satellite device in low Earth orbit;

[0075] Figure 6: a schematic, three-dimensional view of an exemplary

[0076] Embodiment of a satellite device in low Earth orbit;

[0077] Figure 7: a schematic, two-dimensional view of a

[0078] illustration representation;

[0079] Figure 8: schematic, two-dimensional representations of

[0080] Image representations using the tracking and staring techniques;

[0081] Figure 9: a schematic, two-dimensional view of an exemplary

[0082] Embodiment of a satellite device; and

[0083] Figure 10: a schematic representation of a process.

[0084] In the figures, identical or essentially functionally identical or similar elements are designated by the same reference numerals.

[0085] The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual, independently considered features of the invention, which also further develop the invention independently of one another and are also to be considered as components of the invention, either individually or in a combination other than that shown. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.

[0086] Figures 1 and 2 show views in which the pitch axis is perpendicular to the image plane, so that only the orbit axis 106 and the gravity axis 108 of the orbit coordinate system 104 of the orbit 102 are shown. Figures 1 and 2 show that the origin of the orbit coordinate system 104 is located at the satellite device 100. The satellite device 100 comprises a telescope device with a telescope axis 110, which in Figure 1 has a pitch angle of 0° and is thus aligned parallel to the orbit axis 106. The telescope further defines a field of view 112.

[0087] A second exemplary telescope axis 110' is also shown, which is aligned directly with the Earth's horizon. The pitch angle 114 is set between the telescope axis 110' and the orbit axis 106.

[0088] When the satellite device 100 orbits Earth 1 clockwise, it becomes clear that the satellite device 100 continuously rotates in the image plane to maintain a constant pitch angle 114 between the telescope axis 110, 110' and the orbit axis 106, since the orbit axis 106 continuously moves. In Figure 1, the telescope is oriented opposite to the direction of flight, so-called backward pointing is set. Alternatively, forward pointing can be set. Furthermore, the field of view is oriented toward the north pole 2, since there is generally a higher object density above the north pole 2.

[0089] Figure 2 also shows two space objects 116, 116', wherein it can be seen that a downwardly inclined field of view, with the telescope axis 110', is larger than a field of view with a small pitch angle, here 0°, of the telescope axis 110, since the field of view 112' covers a larger area of ​​the near-Earth orbit.

[0090] Figure 3 shows the position of the satellite device 100 illustrated in Figures 1 and 2 from a different perspective, as shown along the individual axes of the orbital coordinate system 104. In particular, the pitch axis 109, oriented orthogonally to the orbital axis 106 and orthogonally to the gravity axis 108, is shown. Furthermore, the direction of the sun 118 is shown here, further showing that the field of view 112 is oriented away from the sun. Alternatively, the telescope axis 110, 110' can form an angle of 90° with the direction of the sun 118. In Figures 1 and 2, the direction 118 of the sun is in the image plane.

[0091] Figures 4 and 5 show that the telescope axis 110 can be adjusted in a plane spanned by the path axis 106 and the pitch axis 109 by a yaw movement. In particular, a yaw angle between the path axis 106 and the telescope axis 110 can be adjusted in the aforementioned plane. Thus, the field of view can be aligned to the right and left, so that, for example, the object density ranges above the poles can be focused.

[0092] Figure 6 shows that two rotation points 128 can be defined at which the yaw movement pivots the telescope axis 110 by 180° depending on the sun's phase angle. To avoid aligning the telescope axis 110 directly toward the sun, the telescope axis 110 is pivoted by 180° at the rotation points 128. A slight deviation from 180° is also possible. The rotation points 128 can, for example, be located above or adjacent to the equator.

[0093] Alternatively or additionally, more than two rotation points 128 can be defined, at which the telescope axis 110 is pivoted by a predetermined rotation angle. The rotation angle can be 180° or less and / or greater than 180°. The advantage of more than two rotation points 128 can be that an increased focus can be placed on areas with high object density. For example, the telescope can be moved toward the north pole 2 with forward pointing in order to obtain images of the area of ​​high object density above the north pole 2. At the north pole 2, the telescope can be pivoted by 180° in order to continue obtaining images of the area of ​​high object density above the north pole 2.

[0094] Figure 7 shows an image representation 130 of line-shaped images of space objects 132 and stars 134, which was created using the satellite device 100 described above with the corresponding control. Due to the constant pitch angle 114, the space object 132 and the stars 134 are represented equally in line form.

[0095] To illustrate the difference compared to the known methods, Figure 8 shows the image representations of a tracking method (left) and a staring method (right). During tracking, the space object 132' is tracked along the telescope axis, resulting in a point-shaped image and the stars 134' in line-like form. During staring, the telescope axis is aligned with the stars 134", resulting in a space object 132" in line-like form.

[0096] Figure 9 shows a satellite device 200. The satellite device 200 can be configured analogously to the satellite device 100. The satellite device 200 includes an attitude control unit 202, which is arranged and configured to change an orientation of the satellite device 200 with respect to the orbit coordinate system 104, so that the pitch movement 124 and the yaw movement 122 can be effected by controlling the attitude control unit.

[0097] Furthermore, the satellite device 200 comprises the control device 204, which is configured to control the satellite device 200 such that, during normal operation, a constant pitch angle 114 is established between the telescope axis 218 and the orbit axis 106 and to control the telescope sensor 210 such that line-shaped images 132, 134 of space objects and stars are continuously generated in order to generate a plurality of line-shaped images 132, 134 for generating a

[0098] to obtain a space object situational image.

[0099] The satellite device 200 further comprises an evaluation unit 205, which is arranged and designed to evaluate the line-shaped images 132, 134 based on a star map in order to recognize space objects and at least one property of the space objects, and to generate a first data set representing the recognized space objects and the property.

[0100] Furthermore, the satellite device 200 comprises two solar panels 206, 208 for generating electrical energy to supply the individual energy-consuming units of the satellite device 200. Furthermore, the satellite device 200 comprises antennas 214 arranged and configured to communicate with a receiving station on Earth. Furthermore, the satellite device 200 comprises the telescope 212, which includes the telescope sensor 210 and a telescope aperture 216, in particular a stray light aperture.

[0101] Figure 10 shows a method for imaging space objects 116, 116'. In step 300, the satellite device 100, 200 is moved along the orbit 102 using a position-dependent orbit coordinate system 104 having a path axis 106, a gravity axis 108, and a pitch axis 109.

[0102] In step 302, a constant pitch angle is set between the telescope axis 110, 218 and the track axis 106.

[0103] In step 304, line-shaped images 132, 134 of space objects and stars are continuously generated to obtain a plurality of line-shaped images for generating a space object position image. Steps 300, 302, and 304 are executed entirely or substantially in parallel.

[0104] With the satellite device 100, 200 described above and the corresponding method, it is now possible to obtain an image representation 130 in which stars 134 and space objects 132 are represented in a line-shaped manner, so that this can be advantageously evaluated.

[0105] In particular, by skillfully controlling the satellite devices 100, 200, any desired orbits 102 can be selected, so that with a suitable constellation, the number of required satellite devices 100, 200 is reduced. This is made possible, among other things, by the fact that the telescope axis 110, 110', 218 does not necessarily have to be oriented away from the sun. REFERENCE SYMBOL

[0106] 1 Earth

[0107] 2 North Pole

[0108] 100 satellite devices

[0109] 102 orbit

[0110] 104 Orbital coordinate system

[0111] 106 Railway axis

[0112] 108 Gravity axis

[0113] 109 Pitch axis

[0114] 110, 110' telescopic axle

[0115] 112, 112' field of view

[0116] 114 pitch angle

[0117] 116, 116' space object

[0118] 118 Direction of the Sun

[0119] 120 yaw angle

[0120] 122 Yaw movement

[0121] 124 Pitch movement

[0122] 126 Earth's axis

[0123] 128 Rotation point

[0124] 130, 130', 130" Image display

[0125] 132, 132', 132" space object

[0126] 134, 134', 134" star

[0127] 200 satellite device

[0128] 202 Position control unit 204 Control device

[0129] 205 Evaluation unit

[0130] 206 solar panels

[0131] 208 Solar panel 210 Telescopic sensor

[0132] 212 Telescope

[0133] 214 antennas

[0134] 216 Telescopic aperture

[0135] 218 Telescopic axle

Claims

CLAIMS 1. Satellite device (100, 200) for imaging space objects (116, 116'), wherein the satellite device (100, 200) is movable along an orbit (102) with a position-dependent orbit coordinate system (104) having an orbit axis (106), a gravity axis (108) and a pitch axis (109), the satellite device (100, 200) comprising a telescope device (212) with a field of view (112, 112'), a telescope axis (110, 110', 218) and an imaging telescope sensor (210) arranged and designed to generate images (132) of space objects (116, 116') against the star background, and a control device (204) configured to control the satellite device (100, 200) such that during normal operation, a predetermined pitch angle (114) is established between the telescope axis (110, 110', 218) and the path axis (106), and o to control the telescope sensor (210) in such a way,that continuously line-shaped images (132, 134) of space objects (116, 116') and stars are generated in order to obtain a plurality of line-shaped images (132, 134) for generating a space object position image., 2. Satellite device (100, 200) according to claim 1, wherein the control device (204) is arranged to control the satellite device (100, 200) such that the pitch angle is constant.

3. Satellite device (100, 200) according to one of the preceding claims, wherein the control device (204) is configured to control the satellite device (100, 200) such that the pitch angle is set within a pitch angle range.

4. Satellite device (100, 200) according to one of the preceding claims, wherein the control device (204) is configured to control the satellite device (100, 200) such that the telescope axis moves relative to the orbit axis in the pitch direction and / or the telescope axis oscillates relative to the orbit axis at a predefined angular velocity in the pitch direction.

5. Satellite device (100, 200) according to one of the preceding claims, wherein the control device (204) is configured to control the satellite device (100, 200) such that the pitch angle (114) is set between +20° and -20°.

6. Satellite device (100, 200) according to one of the preceding claims, wherein the control device (204) is configured to control the satellite device (100, 200) such that the telescope axis (110, 110', 218) performs a yaw movement about the gravity axis (108) so that the field of view can be aligned to at least one predetermined orbital regime.

7. Satellite device (100, 200) according to one of the preceding claims, wherein the control device (204) is configured to control the satellite device (100, 200) such that a constant yaw angle (120) is established between the telescope axis (110, 110', 218) and the orbit axis (106) in order to align the field of view to at least one predefined orbital regime.

8. Satellite device (100, 200) according to one of the preceding claims, wherein the control device (204) is configured to control the satellite device (100, 200) such that the telescope axis (110, 110', 218) oscillates around the gravity axis (108) by means of the yaw movement in a predefined angular range, wherein this yaw movement is carried out at a first angular velocity in order to observe at least two predefined orbital regimes.

9. Satellite device (100, 200) according to one of the preceding claims, wherein the control device (204) is arranged to control the satellite device (100, 200) such that the telescope axis (110, 110', 218) is adjusted in dependence on a The yaw movement can be rotated 180° between a first orientation and a second orientation depending on the sun phase angle, so that the field of view can be aligned depending on the sun phase angle.

10. Satellite device (100, 200) according to one of the preceding claims, wherein the control device (204) is configured to control the telescope sensor (210) such that an exposure time is between 0.1 seconds and 2 seconds, in particular between 0.25 seconds and 1 second, in order to obtain evaluable line-shaped images (132, 134) of space objects (116, 116') and stars.

11. Satellite device (100, 200) according to one of the preceding claims, wherein the control device (204) is configured to determine one or the exposure duration such that a line-shaped image (132) of a space object (116, 116') can be imaged with 10 to 80 pixels of the telescope sensor (210), in particular with 15 to 70 pixels, and to control the telescope sensor (210) with the exposure time.

12. Satellite device (100, 200) according to one of the preceding claims, comprising an attitude control unit (202) which is signal-coupled to the control device (204) and which is arranged and designed to change an orientation of the satellite device (100, 200) with respect to the orbit coordinate system (104) so that a pitch movement and / or the yaw movement can be effected by controlling the attitude control unit (202).

13. Satellite device (100, 200) according to one of the preceding claims, comprising an evaluation unit (205) which is arranged and designed to evaluate the line-shaped images (132, 134) based on a star catalog in order to recognize space objects (116, 116') and in each case at least one property of the space objects (116, 116'), and to generate a first data set representing the recognized space objects (116, 116') and the property, and a transmitting unit which is arranged and designed to transmit the first data set to a receiving unit located on Earth.

14. Satellite device (100, 200) according to one of the preceding claims, comprising a compression unit which is arranged and designed to generate a second data set representing the line-shaped images (132, 134) in a compressed manner, wherein the second compressed data set can be transmitted by means of a or the transmitting unit to a receiving unit located on Earth.

15. A method for imaging space objects (116, 116'), comprising the steps of: Moving a satellite device (100, 200) along an orbit (102) with a position-dependent orbit coordinate system (104) having a path axis (106), a gravity axis (108) and a pitch axis (109), the satellite device (100, 200) comprising a telescope device (212) with a field of view, a telescope axis (110, 110', 218) and an imaging telescope sensor (210) for generating images (132) of space objects (116, 116') against the star background, Setting a predetermined pitch angle (114) between the telescope axis (110, 110', 218) and the orbit axis (106), and continuously generating line-shaped images (132, 134) of space objects (116, 116') and stars in order to obtain a plurality of line-shaped images (132, 134) for generating a space object position image.

16. Method according to the preceding claim, comprising the step of: adjusting a yaw angle of the telescope axis (110, 110', 218) about the gravity axis (108) so that the field of view can be aligned to at least one predetermined orbital regime.

17. Method according to the preceding claim, wherein the setting of the pitch angle (114) and / or the execution of the yaw movement is effected by a change in position of the satellite device (100, 200).

Images