Abstract:
Systems and methods are described for emulating proximity operations of a spacecraft. In one embodiment, a method includes: projecting an image of a first spacecraft on a surface and initiating a proximity operation between the first spacecraft and a second spacecraft. The method further includes evaluating sensor feedback from the second spacecraft based on the proximity operation.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure generally relates to spacecraft proximity operations, and more particularly relates to methods and systems for emulating spacecraft proximity operations in a laboratory. 
       BACKGROUND 
       [0002]    Laboratories have been developed that enable hardware-in-the-loop simulations of proximity operations performed by spacecraft. For example, the laboratories include a test bed that includes a chaser spacecraft and a target spacecraft simulator that float via air pads on a flat floor. Sensors and actuators of the chaser spacecraft may be tested relative to the target spacecraft. Such a laboratory requires a large space to operate and is expensive to implement. 
         [0003]    As a result, it is desirable to provide improved methods and systems for emulating spacecraft proximity operations in a laboratory. Other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention. 
       BRIEF SUMMARY 
       [0004]    According to various exemplary embodiments, systems and methods are described for emulating spacecraft proximity operations. In one embodiment, a method includes: projecting an image of a first spacecraft on a surface and initiating a proximity operation between the first spacecraft and a second spacecraft. The method further includes evaluating sensor feedback from the second spacecraft based on the proximity operation. 
         [0005]    In another exemplary embodiment, a system includes a projection device that projects an image of a first spacecraft on a surface. The system further includes a hardware prototype of a second spacecraft. The system further includes a test module that initiates a proximity operation between the first spacecraft and the second spacecraft. 
         [0006]    Other embodiments, features and details are set forth in additional detail below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The present invention will hereinafter be described in conjunction with the following figures, wherein like numerals denote like elements, and 
           [0008]      FIG. 1  is a functional block diagram illustrating a spacecraft emulation system in accordance with exemplary embodiments; and 
           [0009]      FIG. 2  is a flowchart illustrating a spacecraft proximity emulation method in accordance with exemplary embodiments. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    The following detailed description of the invention is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. As used herein, the term “module” refers to any hardware, software, firmware, electronic control component, processing logic, and/or processor device, individually or in any combination, including, without limitation: an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. 
         [0011]    Turning now to the figures and with initial reference to  FIG. 1 , an exemplary laboratory  10  is shown to include an emulation system shown generally at  12  in accordance with exemplary embodiments. The emulation system  12  emulates and tests proximity operations of spacecraft. The proximity operations can include, but are not limited to, approach, rendevous and docking operations and close maneuvering. Although the figures shown herein depict an example with certain arrangements of elements, additional intervening elements, devices, features, or components may be present in actual embodiments. It should also be understood that  FIG. 1  is merely illustrative and may not be drawn to scale. 
         [0012]    The exemplary emulation system  12  is shown to include at least two spacecraft  14 ,  16 . The first spacecraft  14  is a projected image of all or part of hardware components of a space vehicle. As can be appreciated, the space vehicle may be any vehicle that is designed to fly in space for example, for the purpose of, communications, earth observation, meteorology, navigation, planetary exploration, and transportation. 
         [0013]    In various embodiments, a projector  18  is located in some relation to a surface  20  of the laboratory  10 . The projector  18  projects the image of the first spacecraft  14  on the surface  20 . The projector  18  includes a projector module  22  that includes or communicates with software such as Satellite Tool Kit (STK) or other software to project the image on the surface  20 . The software projects the first spacecraft  14  such that the first spacecraft may be rotated and translated to perform proximity operations. 
         [0014]    The second spacecraft  16  is a hardware prototype of a space vehicle. As can be appreciated, the space vehicle may be a hardware prototype of any vehicle that is designed to fly in space, for example, for the purpose of communications, earth observation, meteorology, navigation, planetary exploration, and transportation. 
         [0015]    In various embodiments, the second spacecraft  16  is a surrogate spacecraft, or testbed, which can maneuver in three rotational degrees of freedom in the laboratory. As shown, the testbed is supported by a spherical airbearing  24  that may be mounted on a cement or other type of block  26 . The testbed is rotatable about xyz axes via the airbearing  24 . 
         [0016]    The testbed includes any or all of the subsystems that are typically associated with a spacecraft, including but not limited to, attitude control (ACS), a momentum control system (MCS) to torque the vehicle, power, thermal, telemetry and command, structure, and a payload. In general, the testbed includes one or more actuators A 1 -An, and one or more sensors S 1 -Sn for managing spacecraft momentum and torque needs for attitude control. The testbed further includes one or more control modules  28  that control the operations of the spacecraft  16  and report a system state. The control module  28  includes embedded software for processing external commands, implementation of control/steering laws and implementation of internal housekeeping, and fault management functions. 
         [0017]    The emulation system  12  utilizes the two spacecraft  14 ,  16  to emulate and test proximity operations, such as, but not limited to docking of the two spacecraft  14 ,  16 . To emulate and test the spacecraft  14 ,  16 , the emulation system  12  includes one or more test modules  30 . The test module  30  communicates with the projector module  22 , and/or the control module  28 . The test module  30  can be located on the second spacecraft  16  (as shown), can be located remote from the second spacecraft  16  (e.g., in another room (not shown) separate from the laboratory  10 ), or located in part on the second spacecraft  16  and located in part remote from the second spacecraft  16  (e.g., as two or more modules that communicate). 
         [0018]    The test module  30  issues commands to the projector  18  and the second spacecraft  16 , and evaluates feedback from the second spacecraft  16 . The test module  30  emulates and tests the various proximity operations by setting the origin of the second spacecraft  16  as an unmoving reference and evaluating the first spacecraft  14  as it translates and rotates with respect to the second spacecraft  16 . By evaluating the two spacecraft  14 , and  16  in this manner, the sensors S 1 -Sn of the second spacecraft  16  are able to sense the same images as in actual proximity operations with an actual first spacecraft. 
         [0019]    Referring now to  FIG. 2 , and with continued reference to  FIG. 1 , a flowchart illustrates an emulation method that can be performed by the emulation system  12  of  FIG. 1  in accordance with the present disclosure. As can be appreciated in light of the disclosure, the order of operation within the method is not limited to the sequential execution as illustrated in  FIG. 2 , but may be performed in one or more varying orders as applicable and in accordance with the present disclosure. 
         [0020]    The method may begin at  100 . The first spacecraft  14  is projected on the surface  20  of the laboratory  10  at  110 . A test of a proximity operation is initiated by the test module  16  at  120 . Based on the proximity operation, one or more commands are generated by the test module  30  to the control module  28  of second spacecraft  16  and to the projector module  22  of the projector  18  at  130 . The actuators A 1 -An and/or the sensors S 1 -Sn of the second spacecraft  16  are controlled by the control module  28  based on the commands at  140 . Substantially simultaneously or thereafter, projection of the first spacecraft  14  is controlled by the projector module  22  based on the commands at  150 . The test module  30  collects and evaluates feedback from the control module  28  and/or the sensors S 1 -Sn based on the proximity operation at  160 . Test results are then generated based on the evaluation at  170 . Thereafter, the method may be repeated and/or may end at  180 . 
         [0021]    As can be appreciated, one or more aspects of the present disclosure can be included in an article of manufacture (e.g., one or more computer program products) having, for instance, computer usable media. The media has embodied therein, for instance, computer readable program code means for providing and facilitating the capabilities of the present disclosure. The article of manufacture can be included as a part of a computer system or provided separately. 
         [0022]    Additionally, at least one program storage device readable by a machine, tangibly embodying at least one program of instructions executable by the machine to perform the capabilities of the present disclosure can be provided. 
         [0023]    While at least one example embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of equivalent variations exist. It should also be appreciated that the embodiments described above are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing various examples of the invention. It should be understood that various changes may be made in the function and arrangement of elements described in an example embodiment without departing from the scope of the invention as set forth in the appended claims and their legal equivalents.