Spacecraft, propulsion device and method for propelling a spacecraft

Abstract

The invention relates to a spacecraft (200) having a propulsion device (100) which comprises at least one propulsion module (10) having at least one laser system (12) for emitting a laser beam (50), and an apparatus (40), in particular a scanning apparatus, for receiving and guiding the laser beam (50) onto a region (60), in particular on an outer side (202), of the spacecraft (200), which region is designed or provided as a material source for removing material on the spacecraft (200) by means of the laser beam (50). The invention also relates to a propulsion device (100) for a spacecraft (200), and to a method for propelling a spacecraft (200).

Description

[0001] Description

[0002] title

[0003] Spacecraft, propulsion device and method for propelling a spacecraft

[0004] State of the art

[0005] The invention relates to a spacecraft with a propulsion device, a propulsion device for a spacecraft, and a method for propelling a spacecraft with a propulsion device.

[0006] A number of propulsion systems are known for generating thrust on spacecraft. Currently, chemical propulsion, cold gas propulsion, electric propulsion, ion propulsion, Hall effect propulsion, field effect propulsion (ion propulsion), and light sails are used, for example. Laser propulsion, electric propulsion, plasma propulsion, and pulsed plasma thrusters (PPTs) are also being investigated as propulsion systems for spacecraft within the framework of research projects.

[0007] Many of the existing technologies require a fuel tank and fuel to provide thrust.

[0008] Due to physical limitations, chemical propulsion systems achieve a maximum specific impulse of approximately 450 s, which means they require a relatively large amount of fuel compared to, for example, electric propulsion systems. The specific impulse l sp In seconds, the change in momentum in N s per ejected propellant mass in kg divided by the acceleration due to gravity in m / s² 2 The specific impulse can be viewed as fuel efficiency.

[0009] Chemical propulsion systems also have a limited thrust range in which they can be used, thus limiting the accuracy of thrust control. Current, purely chemical propulsion systems allow for a controlled reentry of the spacecraft, for example, in the event of a crash landing in the ocean. This may be necessary for large spacecraft when there is a significant risk that the object will not burn up completely upon reentry into the atmosphere.

[0010] DLR-4287 WO

[0011] Cold gas propulsion systems achieve a low specific impulse of typically 80 s, requiring a large amount of propellant to power a spacecraft. Ion drives, Hall effect drives, field effect drives, and plasma drives require high voltages, magnetic fields, radio frequency fields, and propellant tanks for liquid or gaseous fuels.

[0012] Light sails only work in sunlight and not in the Earth's shadow, are complicated to set up and have low thrust as well as poor thrust vector control 11 e .

[0013] Conventional laser drives require multiple systems to enable thrust vector control.

[0014] In PPT drives, the electrodes degrade extremely quickly and are therefore not durable enough for practical application.

[0015] WO 2022 / 089979 describes a method for planning a satellite maneuver, in particular for planning a change in a satellite's orbit after the completion of a mission, wherein the satellite has a propulsion unit with a ground-based power supply. The method comprises the steps of configuring at least one ground-based laser system for generating a laser beam, in particular laser pulses; configuring at least one laser ground station including the at least one laser system; and designing an optical transmission link for transmitting the laser pulses from the at least one ground station to the satellite.

[0016] Furthermore, the procedure includes the steps of configuring the satellite-based propulsion unit, in particular an ablation drive, in which mass is removed from the propulsion unit using laser pulses; and determining a trajectory achievable with the propulsion unit. These steps are repeated iteratively until the desired trajectory change is achieved.

[0017] Disclosure of the invention

[0018] DLR-4287 WO

[0019] 2024-09-24 The object of the invention is to create an improved spacecraft with a propulsion device.

[0020] Another objective of the invention is to create an improved propulsion device for a spacecraft.

[0021] Another object of the invention is to provide an improved method for propelling a spacecraft with a propulsion device.

[0022] The problems are solved by the features of the independent claims. Favorable embodiments and advantages of the invention become apparent from the further claims, the description, and the drawings.

[0023] According to one aspect of the invention, a spacecraft is proposed with a propulsion device comprising at least a propulsion module with at least one laser system for emitting a laser beam, and a scanning device for receiving and directing the laser beam to an area of ​​the spacecraft which is designed or provided as a material source for removing material from the spacecraft by the laser beam.

[0024] In this case, at least the scanning device can be located outside a thermally insulated central volume (if present) of the spacecraft.

[0025] The area of ​​the spacecraft designed or intended to serve as a material source for material removal by the laser beam is an area accessible to the laser beam and from which the ablated material can escape. This area can be located on the exterior of the spacecraft. Alternatively or additionally, the area can also be accessible to the laser beam through an opening in the spacecraft.

[0026] The proposed spacecraft features a laser-ablative propulsion system, allowing the use of a solid propellant and eliminating the need for a fuel tank. This is an advantage over all propulsion technologies that require liquid or gaseous fuel, such as cold gas propulsion, chemical propulsion (except for solid-propellant rocket engines), and ion thrusters.

[0027] DLR-4287 WO

[0028] 2024-09-24 Furthermore, laser-ablative drives can demonstrably achieve a high specific impulse, greater than 1000 s, and therefore require relatively little fuel or mass.

[0029] Laser-ablative propulsion systems typically do not require (besides laser radiation) additional electromagnetic fields, as is the case with most electric propulsion systems, i.e., high voltage, strong magnetic field, RF frequencies, which must be shielded to avoid interfering with the rest of the spacecraft's electronics.

[0030] Laser-ablative drives can be electrically operated and are therefore not directly dependent on, for example, solar radiation, as is the case for light sails, thanks to energy storage.

[0031] Laser-ablative drives enable very fine thrust adjustment due to the extremely low selectability of pulse bits (nN s) and the near-continuous variation of the laser pulse repetition rate. By transferring the laser scanning system of the scanning device outside the spacecraft, the known properties of laser-ablative drives can be further improved.

[0032] The proposed propulsion device is capable of addressing multiple areas of the spacecraft as fuel reservoirs (exposed solids) with a laser system, thereby enabling the implementation of highly effective thrust vector control.

[0033] Because a single propulsion unit can already address multiple fuel reservoirs, adding a second unit easily provides redundancy for overall thrust generation. This means that one propulsion unit could fail completely without jeopardizing the mission. In this case, only the maximum thrust is reduced by half. The total addressable impulse and attitude control remain virtually unaffected.

[0034] DLR-4287 WO

[0035] 2024-09-24 The simultaneous operation of two propulsion devices also allows the thrust vector to be placed almost ideally through the center of gravity of the spacecraft, so that it experiences no torque during acceleration maneuvers.

[0036] Relocating the laser scan head of the scanning system outside the spacecraft now allows, in addition to thrust generation, the application of laser radiation and laser-based measurement techniques to a large portion of the spacecraft's exterior or other areas accessible to the laser beam. This enables, for example, laser material processing of the spacecraft's outer skin for separating, cutting, welding, roughening, heat-treating, or drilling the surface or components. Optionally, optical components can also be regenerated, for example, using laser sputtering.

[0037] With suitable laser parameters, a slight pressure can be exerted on components at specific points as photon pressure.

[0038] Measurement methods such as LIPS (laser induced plasma spectroscopy) for material characterization, LIDAR (Light Detection And Ranging) for surface characterization and polarimetry can be added by adding detectors to the drive device.

[0039] In addition to dedicated propellant mass in the form of an ablator, the laser system can also detach support mass that was required due to mission parameters such as the rocket launch with its acceleration, but is no longer relevant for the subsequent course of the mission, or even use it directly as propellant.

[0040] This allows the mass of the spacecraft to be further reduced to save fuel, and at the same time the same mass can be used as fuel to further reduce the required amount of dedicated fuel and thus save even more mass.

[0041] DLR-4287 WO

[0042] September 24, 2024: After the mission ends, it is usually necessary to lower a satellite into a reentry orbit. If the satellite has components that could survive reentry, a controlled reentry, for example over ocean areas away from shipping lanes, would be required. This precise lowering, requiring a comparatively high thrust over a short period, is not possible with current electric propulsion systems, so a chemical propulsion system with a relatively large amount of propellant and mass is usually required.

[0043] In this scenario, the proposed propulsion system offers the possibility of preparing the spacecraft's robust components for reentry through methods such as laser material processing—for example, perforating, machining, or cutting—to enable the satellite to potentially burn up completely. Demonstrating this functionality could further reduce the requirements for the reentry propulsion system, as it would then allow for an uncontrolled reentry, requiring only orbital descent and thus permitting extended thrust phases, for which the proposed propulsion system is also suitable.

[0044] For example, an off-axis imaging technique can be advantageously used for a laser-ablative drive to direct the scanned laser beam at an angle relative to the normal of the ablation area, thus eliminating the need for refocusing. Such an arrangement can also be employed in the drive device proposed here to provide a focal plane that is essentially parallel to the satellite surface and / or the ablation area.

[0045] Since relatively large distances are required, typically 0.5 to 4 times the edge length of the spacecraft, and the scanning optics cannot be arbitrarily large, the laser focus can advantageously have a relatively large Rayleigh length, i.e., the distance along the optical axis that a laser beam needs until its cross-sectional area doubles, starting from the beam waist or focus. Thus, a tilted or even flat focus surface for the laser beam is not necessary.

[0046] DLR-4287 WO

[0047] 2024-09-24 The simplest way to focus the beam onto the ablation surface is to weakly focus it, preferably with a variable focusing unit, and then scan it across the surface of the material to be ablated using one or more, typically one or two, fast deflecting mirrors. It can also be advantageous to combine a fast scanner with a slow aligning mirror to address the largest possible area for ablation.

[0048] Typical parameters for efficient thrust generation with aluminum ablation are a pulse energy area density (fluence) of 3 to 5 J / cm². 2With a pulse duration of 5 ns and a wavelength of 1 pm, this translates to a pulse energy of approximately 0.3 to 0.5 mJ and a Rayleigh length of nearly 300 mm for a focus diameter of 0.1 mm. Therefore, relatively large focus shifts during the scanning process can be neglected. The divergence angle of the laser beam is approximately 7 mrad, resulting in a scanning optic having an aperture of 7 mm at a distance of 1 m and 14 mm at a distance of 2 m.

[0049] Higher pulse energies allow even larger ablation areas to be addressed with smaller optics.

[0050] With a favorable spacecraft design, the scanning device can be mounted on a boom. This allows for efficient laser ablation of various areas, particularly on the outer surface of the spacecraft. The scanning device's optics can, for example, be mounted on a boom, which positions it effectively relative to the spacecraft.

[0051] With a favorable spacecraft design, the propulsion module can be mounted on the spacecraft. This allows the propulsion module and laser system to be efficiently powered from within the spacecraft and provides a stable and / or protected mounting location.

[0052] DLR-4287 WO

[0053] September 24, 2024: With a favorable spacecraft design, the propulsion module can be mounted on the boom. Alternatively, it is also possible for at least the laser system of the propulsion module and the necessary electronics to be mounted on the boom, with only control signals and power supply provided by the spacecraft. The propulsion module and scanning unit can advantageously be attached together to the boom in a compact design.

[0054] The laser system of the drive module can be attached to the end of the boom, but can also send the laser radiation in the form of a laser beam to the scanning device through or alongside the boom.

[0055] With a favorable design of the spacecraft, an ablator for removing material using the laser beam can be arranged on the boom.

[0056] By adding an ablator or propellant to the boom, thrust can be generated at a relatively large distance from the spacecraft's center of gravity. This creates a long lever arm, which can very effectively generate torque. This allows the spacecraft's rotation rate and orientation to be changed, but also enables the desaturation of reaction wheels, also known as gyroscopic wheels, which transfer angular momentum to the spacecraft through their own rotation and are used for orientation and stabilization. Desaturation in this case means a reduction in rotational speed.

[0057] With a favorable design of the spacecraft, the boom can be adjustable, at least in its length and / or position relative to the target area. In particular, the boom can be designed as at least one of the following: a telescopic device, a printable hose, or a stabilized cable system. This allows the boom to flexibly position the scanning device in order to direct the laser beam appropriately onto the area of ​​the spacecraft where material is being ablated.

[0058] DLR-4287 WO

[0059] 2024-09-24 The boom is usually extended, unfolded, or positioned using a similar mechanism only after launch into space. The term "boom" should not be interpreted restrictively here. For example, it could also be a printable tube that was previously flexible, or a clever cable construction that is stabilized by flight dynamics, such as rotation.

[0060] According to a favorable design of the spacecraft, the propulsion module can include a beam splitter and a measuring system, wherein the beam splitter can be designed to direct a portion of a returning laser radiation into the measuring system.

[0061] This allows the reflected laser beam to be continuously analyzed, thus optimizing the outgoing laser beam to meet the thrust generation requirements. Analyzing the laser beam reflected from the area of ​​the spacecraft containing the material to be ablated prevents mismatches between the laser beam and the material of the ablation zone. Additionally, the spacecraft's addressable surface can optionally be examined if required for the mission.

[0062] With a favorable design of the spacecraft, the propulsion module can include at least two mirrors for deflecting and / or moving the laser beam to scan the material source and / or for stabilizing the laser beam relative to the scanning device. This allows the propulsion module to take over at least some of the functions of the scanning device, which can facilitate a compact design of the propulsion unit.

[0063] With a favorable design of the spacecraft, the boom can incorporate relay optics. In particular, the relay optics can include multiple optical lenses for at least a 4f imaging of the laser beam. A scanned laser beam can also be guided along the boom via relay optics. The relay optics allow the laser beam to be appropriately shaped and transmitted with minimal loss.

[0064] DLR-4287 WO

[0065] 2024-09-24 According to a favorable design of the spacecraft, the scanning device can include at least one mirror and / or deflector for moving the laser beam and / or at least one optical unit for focusing the laser beam onto the area of ​​the spacecraft that is designed or intended to serve as a material source. This advantageously provides the possibility of material ablation at the focus of the laser beam.

[0066] According to a favorable embodiment of the spacecraft, the scanning device can have at least two mirrors and / or deflectors, wherein a focusing lens, in particular a variable one, can be arranged between or in front of the at least two mirrors and / or deflectors to focus the laser beam on the area of ​​the spacecraft which is designed or intended as a material source.

[0067] The mirror and / or deflector positioned in the beam path after the focusing lens can be designed to scan the material source with the laser beam. This advantageously provides the possibility of material ablation at the focus of the laser beam.

[0068] In a favorable configuration, the spacecraft can include an additional propulsion module, in particular an ion drive and / or a Hall drive. Specifically, after its operational phase, the additional propulsion module can be designed or intended to serve as a material source for material removal by the laser beam.

[0069] Since laser propulsion is limited in its average power output with current technology, it can be advantageous to use alternative propulsion concepts for certain mission phases. One possible mission phase is raising the orbit, for example to geostationary positions, or lowering the spacecraft's orbit. A very efficient way to change this is through the use of electric propulsion systems, such as an ion drive or a Hall effect drive. These drives typically ionize a noble gas, such as argon or xenon, to accelerate the resulting ions in electrostatic fields, and in the case of a Hall effect drive, also in conjunction with magnetic fields.

[0070] DLR-4287 WO

[0071] 2024-09-24 Such an ion drive has an ion accelerator module which is connected to a noble gas pressurized gas tank.

[0072] Typically, these propulsion systems continue to be used even after the primary mission is completed by carrying more fuel (noble gas). However, the extravehicular laser propulsion system can also use any material as fuel for extended periods. For example, the propulsion unit or even the fuel tank can be used as a fuel source for the laser propulsion system, saving the need to accelerate components for the entire mission. Often, the laser propulsion system's power is sufficient to cover the majority of the mission.

[0073] For example, the laser system can be used for laser communication and, if necessary, also for attitude control and orbit adjustment of the spacecraft.

[0074] With a favorable spacecraft design, in addition to dedicated propellant mass in the form of an ablator, components that are no longer needed after a certain mission point can be detached and / or used directly as propellant as material sources for material removal by the laser beam. This can include, for example, propellant mass required due to mission parameters such as the rocket launch and its acceleration, but also propulsion systems whose propellant has been consumed.

[0075] According to a further aspect of the invention, a propulsion device for a spacecraft is proposed, comprising at least a propulsion module with at least one laser system for emitting a laser beam, and a scanning device for receiving and directing the laser beam onto an area of ​​the spacecraft which is designed or intended as a material source for material removal from the spacecraft by the laser beam. At least the scanning device is arranged outside the spacecraft.

[0076] DLR-4287 WO

[0077] 2024-09-24 The proposed propulsion device features a laser-ablative drive; therefore, a solid propellant can be used, eliminating the need for a fuel tank. This is an advantage over all propulsion technologies that require liquid or gaseous propellant. This includes, for example, cold gas propulsion, chemical propulsion (except solid-propellant rocket engines), and ion thrusters.

[0078] The area of ​​the spacecraft designed or intended to serve as a material source for material removal by the laser beam is an area accessible to the laser beam and from which the ablated material can escape. This area can be located on the exterior of the spacecraft. Alternatively or additionally, the area can also be accessible to the laser beam through an opening in the spacecraft.

[0079] Furthermore, laser-ablative drives can demonstrably achieve a high specific impulse, greater than 1000 s, and therefore require relatively little fuel or mass.

[0080] Laser-ablative drives enable very fine thrust adjustments due to the extremely low selectability of pulse bits (nN s) via the almost stepless variation of the laser pulse repetition rate. By transferring the laser scanning system of the scanning device outside the spacecraft, the known properties of laser-ablative drives can be further improved.

[0081] The proposed propulsion device is capable of using multiple areas of the spacecraft as fuel reservoirs (exposed solids) with a laser system, thereby enabling the implementation of very effective thrust vector control.

[0082] Relocating the laser scan head of the scanning system outside the spacecraft now allows, in addition to generating thrust, laser radiation and laser-based measurement techniques to be applied to a large portion of the spacecraft's exterior or other areas of the spacecraft accessible to the laser beam.

[0083] DLR-4287 WO

[0084] September 24, 2024. This allows, for example, laser material processing of the spacecraft's outer skin for separating, cutting, welding, roughening, heat-treating, or drilling the surface or components. Optionally, optical components can also be regenerated, for example, using laser sputtering.

[0085] According to a further aspect of the invention, a method for propelling a spacecraft by means of laser ablation with a propulsion device is proposed, wherein at least one propulsion module of the propulsion device emits a laser beam, and a scanning device receives the laser beam and focuses it on an area of ​​the spacecraft which serves at least temporarily as a material source for removing material from the spacecraft by the laser beam.

[0086] Material removal can advantageously generate thrust for the spacecraft.

[0087] The proposed method is based on laser-ablative propulsion, therefore a solid propellant can be used, eliminating the need for a fuel tank. This is an advantage over all propulsion technologies that require liquid or gaseous propellant. This includes, for example, cold gas propulsion, chemical propulsion (except solid-propellant rocket engines), and ion thrusters.

[0088] Furthermore, laser-ablative drives can demonstrably achieve a high specific impulse, greater than 1000 s, and therefore require relatively little fuel or mass.

[0089] Laser-ablative drives enable very fine thrust adjustment due to the extremely low selectable pulse bits (nN s) via the almost stepless variation of the laser pulse repetition rate.

[0090] In a favorable embodiment of the method, the scanning device and / or the drive module can be arranged on a boom of the spacecraft, which can be extended or retracted as required.

[0091] DLR-4287 WO

[0092] 2024-09-24 By transferring the laser scanning system of the scanning device and / or the propulsion module outside the spacecraft, the known properties of laser-ablative propulsion systems can be further improved.

[0093] The proposed propulsion device is capable of using multiple areas of the spacecraft as fuel reservoirs (exposed solids) with a laser system, thereby enabling the implementation of very effective thrust vector control.

[0094] Relocating the laser scan head of the scanning system outside the spacecraft now allows, in addition to generating thrust, laser radiation and laser-based measurement techniques to be applied to a large portion of the spacecraft's exterior or other areas accessible to the laser beam. This enables, for example, laser material processing of the spacecraft's outer skin for separating, cutting, welding, roughening, heat-treating, or drilling the surface or components. Optionally, optical components can also be regenerated, for example, using laser sputtering.

[0095] With a favorable design of the method, a portion of the laser radiation from the propulsion module can be directed into a measurement system via a beam splitter. This allows the reflected laser beam to be continuously analyzed, enabling the outgoing laser beam to be optimized for thrust generation requirements. By analyzing the laser beam reflected from the area of ​​the spacecraft containing the material to be ablated, mismatches between the laser beam and the material of the ablation zone can be avoided. Additionally, the addressable surface of the spacecraft can be examined if required for the mission.

[0096] In a favorable embodiment of the method, the laser beam can be deflected and / or moved by at least one, and in particular at least two, mirrors of the drive module. This allows the drive module to take over at least some of the functions of the scanning device, which can facilitate a more compact design of the drive unit.

[0097] DLR-4287 WO

[0098] 2024-09-24 According to a favorable embodiment of the method, the laser beam can be focused onto the scanning device via a relay optic arranged in the boom, whereby the laser beam can be focused by means of 4f imaging via a plurality of optical lenses of the relay optic. The relay optic allows the laser beam to be suitably shaped and transmitted with minimal loss.

[0099] In a favorable embodiment of the method, the laser beam can be moved by at least one mirror and / or deflector of the scanning device and / or focused by at least one optical unit onto the area of ​​the spacecraft that can be ablated as a material source. This advantageously provides the possibility of material ablation at the focus of the laser beam.

[0100] In a favorable embodiment of the method, the laser beam can be focused onto the area of ​​the spacecraft serving as the material source by means of a focusing lens, particularly a variable one, which is arranged between or in front of at least two mirrors and / or deflectors. The laser beam can be moved along with the mirror and / or deflector arranged in the beam path downstream of the focusing lens. Thus, the mirror and / or deflector arranged in the beam path downstream of the focusing lens can be configured to scan the material source with the laser beam. This advantageously provides the possibility of material ablation at the focus of the laser beam.

[0101] In a favorable embodiment of the method, the laser beam can be directed at an ablator mounted on the boom, which serves as a material source for removing material from the spacecraft using the laser beam. By adding an ablator or propellant to the boom, thrust can be generated at a relatively large distance from the spacecraft's center of gravity. This creates a large lever arm, enabling the very effective generation of torque. This, in turn, allows for changes to the spacecraft's rotation rate and orientation.

[0102] DLR-4287 WO

[0103] September 24, 2024: With a favorable embodiment of the method, the rotational speed of reaction wheels on the spacecraft can be reduced by means of a torque generated by the ablator removing material. Advantageously, this allows reaction wheels, which transfer angular momentum to the spacecraft through their own rotation and are used for orientation and stabilization, to be desaturated. In this case, desaturation means a reduction in rotational speed.

[0104] In a favorable embodiment of the method, the laser beam can be focused, at least temporarily, onto the window of a laser beam exiting the scanning device to regenerate it. This allows material deposited on the window by the ablation process to be removed again by the laser beam.

[0105] In a favorable embodiment of the process, a vacuum-based thin-film production method can be used, at least temporarily, to regenerate a mirror of the drive device using the laser beam, whereby the mirror can be coated. Optionally, optical components can also be regenerated, for example, by means of laser sputtering.

[0106] There are two ways to regenerate the beam exit point. One option is to position a window at the beam exit point, which can be regenerated using various methods, including focusing the laser beam onto the window or changing the window itself, should material from the ablation process accumulate on it.

[0107] Alternatively, the deflecting mirrors can be regenerated, for example by thermal vapor deposition. Any method that produces reflective surfaces in a vacuum is conceivable here.

[0108] In a favorable embodiment of the method, material can be introduced during a spacecraft mission into the area, particularly on the exterior, of the spacecraft, which serves at least temporarily as a material source for material removal from the spacecraft by the laser beam. In particular, the material can be of natural or artificial origin.

[0109] DLR-4287 WO

[0110] September 24, 2024: For example, during missions to another celestial body, material from that body can be attached to the exterior of the spacecraft and used as fuel for the laser-ablative propulsion system. This allows the spacecraft's fuel reserves to be replenished advantageously during the mission, potentially extending its duration. The material source can be of natural origin, i.e., material from the celestial body itself, or of artificial origin, such as material produced on the celestial body. The material can be attached to the exterior of the spacecraft in the designated area manually or automatically.

[0111] In a favorable embodiment of the method, the spacecraft can be propelled by means of an additional propulsion module, in particular an ion drive and / or a Hall drive. A Hall drive accelerates the propellant using an electric field and is frequently used in satellites in low Earth orbit. In particular, after its operational phase, the additional propulsion module can be used as a material source for material removal by the laser beam.

[0112] Since laser propulsion is limited in its average power output with current technology, it can be advantageous to use other propulsion concepts for certain mission phases. One possible mission phase is raising or lowering the spacecraft's orbit. A very efficient way to change this is through the use of electric drives, such as an ion drive or a Hall drive. These drives typically ionize a noble gas, such as argon or xenon, to accelerate the resulting ions in electrostatic fields, and in the case of a Hall drive, also in conjunction with magnetic fields.

[0113] Typically, these propulsion systems continue to be used even after their primary mission is complete, by carrying more fuel (noble gas). However, the extravehicular laser propulsion system can also use any material as fuel for extended periods.

[0114] DLR-4287 WO

[0115] 2024-09-24 For example, the drive unit and the fuel tank can be used as material sources for the laser propulsion system, saving the need to accelerate components for the entire mission. Often, the laser propulsion system's power is sufficient to cover the majority of the mission.

[0116] For example, the laser system can be used for laser communication and, if necessary, also for attitude control and orbit adjustment of the spacecraft.

[0117] With a favorable implementation of the process, in addition to dedicated propellant mass in the form of an ablator, components that are no longer needed after a certain mission point can be separated and / or used directly as propellant as a material source for material removal by the laser beam. This can include, for example, propellant mass required due to mission parameters such as the rocket launch and its acceleration, but also propulsion systems whose propellant has been consumed.

[0118] drawing

[0119] Further advantages become apparent from the following description of the drawings. The drawings illustrate exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations.

[0120] They show, for example:

[0121] Fig. 1 is a schematic representation of a spacecraft with a

[0122] Drive device according to an embodiment of the invention;

[0123] Fig. 2 shows a schematic representation of a drive module of the

[0124] Propulsion device of the spacecraft for emitting a laser beam according to an embodiment of the invention;

[0125] Fig. 3 shows a schematic representation of a relay optic arranged in an arm of the spacecraft according to an embodiment of the invention;

[0126] DLR-4287 WO

[0127] 2024-09-24 Fig. 4 a schematic representation of a scanning device for receiving and guiding the laser beam according to an embodiment of the invention;

[0128] Fig. 5 shows a schematic representation of a scanning device for receiving and guiding the laser beam according to a further embodiment of the invention;

[0129] Fig. 6 shows a schematic representation of a spacecraft with a propulsion device according to a further embodiment of the invention;

[0130] Fig. 7 is a schematic representation of a spacecraft with a propulsion device according to a further embodiment of the invention; and

[0131] Fig. 8. A schematic representation of a spacecraft with a propulsion device according to a further embodiment of the invention.

[0132] Embodiments of the invention

[0133] In the figures, similar or equivalent components are numbered with the same reference symbols. The figures merely show examples and are not to be understood as limiting.

[0134] Before the invention is described in detail, it should be noted that it is not limited to the respective components of the device or the respective process steps, as these components and processes may vary. The terms used here are intended solely to describe particular embodiments and are not used restrictively. Furthermore, where the singular or indefinite articles are used in the description or in the claims, this also refers to the plural of these elements, unless the overall context clearly indicates otherwise.

[0135] DLR-4287 WO

[0136] September 24, 2024. The directional terminology used below, including terms such as "left," "right," "above," "below," "in front," "behind," "after," and the like, serves only to improve the understanding of the figures and is in no way intended to limit their generality. The components and elements depicted, their interpretation, and their use may vary according to the considerations of a person skilled in the art and be adapted to the respective applications.

[0137] Figure 1 shows a schematic representation of a spacecraft 200 with a propulsion device 100 according to an embodiment of the invention.

[0138] The spacecraft 200 comprises a propulsion device 100 with a propulsion module 10 having at least one laser system 12 (see Figure 2) and with a scanning device 40. The scanning device 40 can be arranged outside a thermally insulated central volume of the spacecraft 200.

[0139] The drive module 10 of the drive device 100 emits a laser beam 50. The scanning device 40 receives the laser beam 50 and focuses it on an area 60 of the spacecraft 200, which serves at least temporarily as a material source for removing material from the spacecraft 200 by the laser beam 50.

[0140] The area 60 of the spacecraft 200, which is designed or intended as a material source for the removal of material from the spacecraft 200 by the laser beam 50, is an area 60 that is accessible to the laser beam 50 and from which the removed material can escape. This area 60 can be located on an outer surface 202 of the spacecraft 200. Alternatively or additionally, the area 60 can also be accessible to the laser beam 50 through an opening in the spacecraft 200.

[0141] The scanning device 40 is located outside the spacecraft 200. The material beam 70 with the ablated material is shown schematically pointing away from the spacecraft 200.

[0142] The propulsion module 10 is located on the spacecraft 200.

[0143] DLR-4287 WO

[0144] 2024-09-24 The scanning device 40 is arranged on a boom 30 of the spacecraft 200, through which the laser beam 50 is guided. Optionally, the boom 30 can have a relay optic 32 as shown in Figure 3. The relay optic 32 can, for example, have a plurality of optical lenses 34 for at least one 4f image 36 of the laser beam 50.

[0145] The boom 30 is adjustable at least in its length and / or position relative to area 60. In particular, the boom 30 can be, for example, a telescopic device, a printable hose, or a stabilizable cable device. The boom can be extended or retracted as needed. In particular, the boom can be folded in during the launch of the spacecraft and only extended in space.

[0146] In the illustrated embodiment, the spacecraft 200 has a laser-ablative propulsion module 10, which is connected to the scanning device 40 via a boom 30. The laser beam 50 is generated in the propulsion module 10 and sent to the scanning device 40 via the boom 30.

[0147] The scanning device 40 serves to focus the laser beam 50 onto the spacecraft 200 and thus ablate material from it. The ablation beam 70 then generates a recoil. To vary the thrust vector, other positions on the spacecraft are also suitable for generating ablative thrust.

[0148] Figure 2 shows a schematic representation of the drive module 10 of the drive device 100 of the spacecraft 200 for emitting a laser beam 50 according to an embodiment of the invention.

[0149] The drive module 10 includes a laser system 12 which generates a laser beam 50. Furthermore, the drive module 10 includes two mirrors 18, 20 for deflecting and / or moving the laser beam 50 for scanning the material source and / or for stabilizing the laser beam 50 relative to the scanning device 40. The laser beam 50 is deflected and / or moved by the two mirrors 18, 20 of the drive module 10.

[0150] DLR-4287 WO

[0151] September 24, 2024. Furthermore, the propulsion module 10 features an optional beam splitter 16 and a measuring system 14. The beam splitter 16 is located in the beam path upstream of the first mirror 18. This directs the reflected laser radiation 52 into a measuring system 14. This allows the reflected laser beam 52 to be continuously analyzed, thus optimizing the outgoing laser beam 50 for thrust generation requirements. By analyzing the laser beam 52 reflected from the area 60 of the spacecraft 200 containing the material to be ablated, mismatches between the laser beam 50 and the material of the ablation area can be avoided. Additionally, the addressable surface of the spacecraft can be examined if required for the mission.

[0152] Optionally, to regenerate a mirror 18, 20 of the drive device 10 by means of the laser beam 50, a method of vacuum-based thin-film production can be applied at least temporarily, whereby the mirror 18, 20 is coated.

[0153] Figure 3 shows an optional relay optic arranged in the boom 30 of the spacecraft according to an embodiment of the invention. The laser beam 50 is focused onto the scanning device 40 via the relay optic 32 arranged in the boom 30. This conventional structure for a relay optic 32 is based on a series of 4f images 36 with lenses 34 and can transmit both the laser radiation 50 and its exit angle. Thus, it is possible to provide a passive scanning optic at the end of the boom 30.

[0154] Figure 4 shows a schematic representation of a scanning device 40 for receiving and guiding the laser beam 50 according to an embodiment of the invention.

[0155] The scanning device 40 has two mirrors 44, 46 and / or deflectors 44, 46 for moving the laser beam 50 and an optical unit 42 for focusing the laser beam 50 onto the area 60 of the spacecraft 200, which is designed or intended to be a material source.

[0156] DLR-4287 WO

[0157] 2024-09-24 Optionally, to regenerate a mirror 44, 46 of the scanning device 40 by means of the laser beam 50, a method of vacuum-based thin-film production can be applied at least temporarily, whereby the mirror 44, 46 is coated.

[0158] The scanning device 40 constitutes an active scanning optic. The laser beam 50 enters the scanning device 40 and is guided and scanned via one or more mirrors 44, 46 or deflectors 44, 46. Finally, the laser beam 50 is focused by one of the optical units 42 to provide the possibility of ablating the material at the focus 54 of the laser beam 50.

[0159] To regenerate a window 43 of a beam exit of the laser beam 50 from the scanning device 40, the laser beam 50 can be focused at least temporarily on the window 43 in order to remove material deposited on it by ablation.

[0160] Figure 5 shows a schematic representation of a scanning device 40 for receiving and guiding the laser beam 50 according to a further embodiment of the invention.

[0161] The scanning device 40 also includes two mirrors 44, 46 and / or deflectors 44, 46. A focusing lens 48, in particular a variable lens, is arranged between the mirrors 44, 46 and / or deflectors 44, 46 for focusing the laser beam 50 onto the area 60 of the spacecraft 200, which is designed or intended to serve as a material source. The mirror and / or deflector 44, 46 arranged in the beam path downstream of the focusing lens 48 is designed to scan the material source with the laser beam 50.

[0162] The scanning device 40 represents a further embodiment of an active scanning optic. The laser beam 50 enters the scanning device 40 and is guided and scanned via one or more mirrors 44, 46 or deflectors 44, 46. Before passing through the actual scanning mirrors 44, 46, the laser beam 50 is focused by the optionally variable focusing lens 48. This allows for ablation at the focus 54 of the laser beam 50.

[0163] DLR-4287 WO

[0164] 2024-09-24 Figure 6 shows a schematic representation of a spacecraft 200 with a propulsion device 100 according to a further embodiment of the invention.

[0165] In this further variant, the drive module 10 and also relevant electronics are moved to the outside, so that laser system 12, electronics and scanning device 40 are arranged on the boom 30 outside the spacecraft 200 and only control signals and power supply are still provided by the spacecraft 200.

[0166] With the extendable boom 30, a compact module, similar to a conventional drive of the spacecraft 200, can also be offered in this embodiment, which is installed similarly to a conventional drive of the spacecraft 200, which is only unfolded in space and then provides full functionality.

[0167] Figure 7 shows a schematic representation of a spacecraft 200 with a propulsion device 100 according to a further embodiment of the invention.

[0168] Immediately adjacent to the area 60, where material is removed by the laser beam 50, is another drive module 80, which is connected to a fuel tank 82. This additional drive module 80 can, for example, be configured as an ion drive and / or a Hall drive. Ion drives typically ionize a noble gas, such as argon or xenon, to accelerate the ions thus generated in electrostatic fields, and in the case of a Hall drive, also in conjunction with magnetic fields.

[0169] Such an ion drive 80 has an ion accelerator module which is connected to a noble gas pressurized gas tank as a fuel tank 82.

[0170] Typically, these drives continue to be used even after the primary mission is complete, by carrying more fuel (noble gas) in fuel tank 82. The extravehicular laser drive can use any material as fuel for extended periods.

[0171] DLR-4287 WO

[0172] 2024-09-24 For example, the ion drive module 80, as well as the fuel tank 82, can be used as a material source for the laser drive, which would otherwise have to be accelerated for the entire mission. Often, the power of the laser drive is sufficient to cover the main part of the mission.

[0173] The additional drive module 80 can thus also be advantageously used as a material source for material removal by the laser beam 50 after completion of its operational phase. In this way, the laser system can be used, for example, for laser communication and then, if required, also for attitude control and orbit adjustment of the spacecraft 200.

[0174] Figure 8 shows a schematic representation of a spacecraft 200 with a propulsion device 100 according to a further embodiment of the invention. An ablator 84 or additional propellant is arranged on the boom 30, specifically at the output of the scanning device 40.

[0175] Material is also removed from the Ablator 84 by the laser beam 50. Because the Ablator 84 is mounted on the boom 30, thrust can be generated at a relatively large distance from the center of gravity of the spacecraft 200. This corresponds to a large lever arm, which allows for the very effective generation of torque. This makes it possible to effectively change the rotation rate and orientation of the spacecraft 200.

[0176] The torque generated in this way can be used, for example, to desaturate reaction wheels 90, which transfer angular momentum to the spacecraft 200 through their own rotation and are used for the orientation and stabilization of the spacecraft 200. In this case, desaturation means that the rotational speed of the reaction wheels 90 is reduced.

[0177] In addition to dedicated propellant mass in the form of the Ablator 84, the Laser System 12 can also detach components that are no longer needed at a given point in the mission or even use them directly as propellant. This can include propellant mass required by mission parameters such as the rocket launch and its acceleration, but also propulsion systems such as the additional propulsion module 80 in Figure 7, whose propellant has been consumed.

[0178] DLR-4287 WO

[0179] 2024-09-24 Reference number

[0180] 10 Drive module

[0181] 12 laser systems

[0182] 14 Measuring system

[0183] 16 beam splitters

[0184] 18 mirrors

[0185] 20 mirrors

[0186] 30 booms

[0187] 32 relay optics

[0188] 34 lens

[0189] 36 4f figure

[0190] 40 Scanning setup

[0191] 42 optical unit

[0192] 43 windows

[0193] 44 mirrors

[0194] 46 mirrors

[0195] 48 Focusing lens

[0196] 50 laser beam

[0197] 52 Returning laser beam

[0198] 54 Focus of the laser beam

[0199] 60 area

[0200] 70 Ablation beam

[0201] 80 Drive module

[0202] 82 Fuel tank

[0203] 84 Ablator

[0204] 90 reaction wheels

[0205] 100 drive device

[0206] 200 spacecraft

[0207] 202 Outside

[0208] DLR-4287 WO

[0209] 2024-09-24

Claims

1. Claims 1. Spacecraft (200) with a propulsion device (100) comprising at least a propulsion module (10) with at least one laser system (12) for emitting a laser beam (50), a scanning device (40) for receiving and directing the laser beam (50) to an area (60) of the spacecraft (200) which is designed or provided as a material source for removing material from the spacecraft (200) by the laser beam (50).

2. Spacecraft according to claim 1, wherein the scanning device (40) is arranged on a boom (30) of the spacecraft (200).

3. Spacecraft according to claim 1 or 2, wherein the propulsion module (10) is arranged on the spacecraft (200).

4. Spacecraft according to claim 2 or 3, wherein the propulsion module (10) is arranged on the boom (30).

5. Spacecraft according to one of claims 2 to 4, wherein an ablator (84) for removing material by means of the laser beam (50) is arranged on the boom (30).

6. Spacecraft according to one of claims 2 to 5, wherein the boom (30) is designed to be adjustable at least in its length and / or position relative to the area (60), in particular wherein the boom (30) is designed at least as one of a telescopic device, printable hose, or stabilizeable rope device.

7. Spacecraft according to one of the preceding claims, wherein the propulsion module (10) has a beam splitter (16) and a measuring system (14), wherein the beam splitter (16) is configured to direct a portion of a reflected laser radiation (52) into the measuring system (14). DLR-4287 WO 2024-09-24 8. Spacecraft according to one of the preceding claims, wherein the propulsion module (10) has at least one, in particular at least two mirrors (18, 20) for deflecting and / or moving the laser beam (50) for scanning the material source and / or for stabilizing the laser beam (50) relative to the scanning device (40).

9. Spacecraft according to any one of claims 2 to 7, wherein the boom (30) has a relay optic (32), in particular wherein the relay optic (32) has a plurality of optical lenses (34) for at least one 4f imaging (36) of the laser beam (50).

10. Spacecraft according to one of the preceding claims, wherein the scanning device (40) comprises at least one mirror (44, 46) and / or deflector (44, 46) for moving the laser beam (50) and / or at least one optical unit (42) for focusing the laser beam (50) onto the area (60) of the spacecraft (200) which is designed or provided as a material source.

11. Spacecraft according to one of the preceding claims, wherein the scanning device (40) has at least two mirrors (44, 46) and / or deflectors (44, 46), wherein a focusing lens (48), in particular variable, is arranged between or in front of the at least two mirrors (44, 46) and / or deflectors (44, 46) for focusing the laser beam (50) onto the area (60) of the spacecraft (200) which is designed or provided as a material source, wherein the mirror and / or deflector (44, 46) arranged in the beam path after the focusing lens (48) is designed for scanning the material source with the laser beam (50).

12. Spacecraft according to one of the preceding claims, comprising a further drive module (80), in particular an ion drive and / or a Hall drive, in particular wherein the further drive module (80) is designed or provided as a material source for material removal by the laser beam (50) after completion of its operational phase. DLR-4287 WO 2024-09-24 13. Spacecraft according to one of the preceding claims, wherein, in addition to dedicated propellant mass in the form of an ablator (84), components that are no longer needed from a given mission time onwards are detachable and / or directly usable as propellant as a material source for material removal by the laser beam (50).

14. Propulsion device (100) for a spacecraft (200) according to one of the preceding claims, comprising at least a propulsion module (10) with at least one laser system (12) for emitting a laser beam (50), a scanning device (40) for receiving and directing the laser beam (50) onto an area (60) of the spacecraft (200) which is designed or provided as a material source for removing material from the spacecraft (200) by the laser beam (50), wherein at least the scanning device (40) is arranged outside the spacecraft (200).

15. Method for propelling a spacecraft (200) according to any one of claims 1 to 13 with a propulsion device (100) according to claim 13, wherein at least one propulsion module (10) of the propulsion device (100) emits a laser beam (50), and a scanning device (40) receives the laser beam (50) and focuses it on an area (60) of the spacecraft (200) which serves at least temporarily as a material source for removing material from the spacecraft (200) by the laser beam (50).

16. Method according to claim 15, wherein the scanning device (40) and / or the drive module (10) are arranged on a boom (30) of the spacecraft (200), which is extended or retracted as required.

17. Method according to claim 15 or 16, wherein a portion of a reflected laser radiation (52) from the drive module (10) is directed into a measuring system (14) via a beam splitter (16).

18. Method according to one of claims 15 to 17, wherein the laser beam (50) is deflected and / or moved by at least one, in particular at least two mirrors (18, 20) of the drive module (10). DLR-4287 WO 2024-09-24 19. Method according to one of claims 15 to 18, wherein the laser beam (50) is imaged onto the scanning device (40) via a relay optics (32) arranged in the boom (30), wherein the laser beam (50) is imaged via a plurality of optical lenses (34) of the relay optics (32) by means of 4f imaging (36).

20. Method according to one of claims 15 to 19, wherein the laser beam (50) is moved with at least one mirror (44, 46) and / or deflector (44, 46) of the scanning device (40) and / or is focused with at least one optical unit (42) onto the area (60) of the spacecraft (200) which is ablated as a material source.

21. Method according to one of claims 15 to 20, wherein the laser beam (50) is focused by a focusing lens (48), in particular a variable lens, which is arranged between or in front of the at least two mirrors (44, 46) and / or deflectors (44, 46), onto the area (60) of the spacecraft (200) which serves as a material source, wherein the laser beam (50) is moved with the mirror and / or deflector (44, 46) arranged in the beam path after the focusing lens (48).

22. Method according to one of claims 15 to 21, wherein the laser beam (50) is directed towards an ablator (84) which is arranged on the boom (30) and serves as a material source for removing material from the spacecraft (200) by the laser beam (50).

23. Method according to claim 22, wherein a rotational speed of reaction wheels (90) of the spacecraft (200) is reduced by means of a torque generated by removing the material from the ablator (84).

24. Method according to one of claims 15 to 23, wherein, in order to regenerate a window (43) of a beam exit of the laser beam (50) from the scanning device (40), the laser beam (50) is focused at least temporarily on the window (43). DLR-4287 WO 2024-09-24 25. Method according to one of claims 15 to 24, wherein a method of vacuum-based thin-film production is applied at least temporarily to regenerate a mirror (18, 20, 44, 46) of the drive device (10) and / or the scanning device (40) by means of the laser beam (50), wherein the mirror (18, 20, 44, 46) is coated.

26. Method according to one of claims 15 to 25, wherein during a mission of the spacecraft (200) material is brought into the area (60) in particular on the outside (202) of the spacecraft (200), which serves at least temporarily as a material source for removing material from the spacecraft (200) by the laser beam (50), in particular wherein the material is of natural or artificial origin.

27. Method according to one of claims 15 to 26, wherein the spacecraft (200) is driven by means of a further drive module (80), in particular an ion drive and / or Hall drive, in particular wherein the further drive module (80) is used as a material source for material removal by the laser beam (50) after completion of its operational phase.

28. Method according to one of claims 15 to 27, wherein, in addition to dedicated propellant mass in the form of an ablator (84), components that are no longer needed from a given mission time onwards are separated and / or used directly as propellant as a material source for material removal by the laser beam (50). DLR-4287 WO 2024-09-24

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