WO2005110847A1

WO2005110847A1 - Spacecraft capturing apparatus

Info

Publication number: WO2005110847A1
Application number: PCT/CA2005/000718
Authority: WO
Inventors: Jocelyn Boily
Original assignee: Astrokeys Inc.
Priority date: 2004-05-13
Filing date: 2005-05-12
Publication date: 2005-11-24

Abstract

An apparatus for capturing a spacecraft includes a shaft for connection to the nose end of a spacecraft; a sleeve on the shaft; a latch on the sleeve; a plate on the sleeve for engaging a spacecraft motor exhaust nozzle to stop the sleeve in the nozzle; articulated fingers on the free end of the shaft; and flexible tendons interconnecting the stop plate and tendons, whereby, upon entering the nozzle, the sleeve stops and the shaft continues to move causing flexing of the tendons to bend the fingers to positions in which the nozzle is captured by the fingers, tendons and stop plate.

Description

SPACECRAFT CAPTURING APPARATUS This invention relates to an apparatus for capturing a satellite or other spacecraft. There are hundreds of satellites in earth orbit. Because of, inter alia, orbital decay there is often a need to change the orbit or the orientation of a satellite or other spacecraft by towing or pushing it using another spacecraft. Because most satellites are built without structural features intended for connection to a tug, there is a need for an apparatus for capturing and towing such satellites. The object of the present invention is to meet such need by providing a relatively simple apparatus for mounting on a spacecraft permitting docking of the spacecraft with or capturing of a satellite with a view to manipulating the satellite in orbit. Accordingly, the present invention relates to an apparatus for capturing a satellite, which includes a rocket motor or structural feature of similar geometry comprising: a shaft having a first end for connection to a nose end of spacecraft, and a second free end; a first sleeve slidably receiving said shaft; a latch on one end of said first sleeve permitting movement of the shaft toward an outer, free end of the first sleeve; a stop plate on said first sleeve for engaging a satellite exhaust nozzle, whereby movement of the first sleeve into the nozzle is restricted; a plurality of articulated fingers extending out of said free end of said shaft, , said fingers having outer free ends; and flexible tendons extending between said stop plate and said free ends of the fingers, whereby when the shaft and free end of the first sleeve are driven into an exhaust nozzle of a satellite engine, the stop plate engages the outer end of the nozzle, stopping movement of the first sleeve into the nozzle, the shaft continues movement through the neck of the nozzle causing the tendons to engage the neck, and continued movement of the shaft into the nozzle, bends the tendons and fingers, so that the fingers, the stop plate and the tendons latch the apparatus to the nozzle. The invention is described below in greater detail with reference to the accompanying drawings, wherein: Figure 1 is a schematic, isometric view of the satellite capturing apparatus in accordance with the present invention; Figure 2 is a front view of the apparatus of Fig. 1 ; Figure 3 is a schematic front view of a drive and latch assembly; Figure 4 is a schematic side view of the assembly of Fig. 3; Figures 5 to 7 are schematic, longitudinal sectional views of a satellite exhaust nozzle and the front or outer end of the apparatus of Figs. 1 and 2; Figure 8 is a schematic, isometric view of a second embodiment of the satellite capturing apparatus of the present invention; Figure 9 is a side view of the outer end of the apparatus of Fig. 8; Figure 10 is a front view of the apparatus of Figs. 8 and 9; Figure 11 is a schematic longitudinal sectional view of the front or outer end of the apparatus of Figs. 8 to 10 grasping a pipe, and Figure 12 is a side view of a finger used in the apparatus of Figs. 8 to 10. Referring to Figs. 1 and 2 of the drawings, the basic elements of the present invention include a shaft 1 , which is connected to the front end or nose of a spacecraft 2, a sleeve 3 carrying a stop plate 4, three articulated fingers 5 and tendons 6 extending between the stop plate 4 and, outer free ends of the fingers 5. Bushings or bearings 7 (Figs. 3 to 7) are provided between the shaft 1 and the sleeve 3 permitting sliding of the shaft in the sleeve. The inner or rear end of the sleeve 3 carries a housing 8 containing a drive and latch assembly for moving the sleeve longitudinally of the rear end of the shaft 1 so that the position of the sleeve on the shaft can be altered. An example of a drive and latch system is shown in Figs. 3 and 4. The system includes a rack 9 mounted in a recess 10 in the shaft 1 and a pinion 11 extending through a slot 12 in the bottom of the sleeve 3 into engagement with the rack 9. The pinion 11 is rotated by a small motor 13 connected to the pinion by a one-way clutch 14 and a shaft 15. The clutch 14 permits movement of the sleeve 3 in one direction only. The motor 13 includes a brake (not shown). It is preferable to be able to change the position of the sleeve 3 on the shaft 1 and the length of the tendons 6 to accommodate different engine exhaust nozzles 16 (Figs. 5 and 7) on satellites, i.e. because the dimensions of engine exhaust nozzles 16 differ, a universal satellite capturing apparatus should be adjustable. In its simplest form, the apparatus could be designed for capturing only satellites having similar exhaust nozzles, in which case the length of the tendons 6 would be fixed, i.e. not adjustable. Moreover, in such simplest form of the apparatus, the drive could be omitted. A simple latch mechanism (not shown) such as a pawl rotatably mounted in the sleeve 3 and a row of longitudinally extending sawtooth grooves and teeth in the shaft 1 could be used to permit movement of the shaft 1 relative to the sleeve in one direction only, i.e. outwardly. Such an assembly could not be released from a captured satellite. In the first embodiment of the invention, by actuating the drive system in the housing 8, the position of the sleeve 3 on the shaft 1 is adjusted to accommodate engine exhaust nozzles 16 of different dimensions. Once the sleeve 3 is at the desired location on the shaft 1 , the shaft 1 is free to move in the sleeve 3 towards the outer free end 10 thereof, but movement of the shaft in the opposite direction in the sleeve 3 is prevented by the one-way clutch 14. At the same time as the position of the sleeve 3 on the shaft 1 is being adjusted, the length of the tendons 6 must be adjusted. For such purposes, the inner ends of the tendons 6 are mounted on reels (not shown) in housings 18 on the stop plate 4 (Figs, land 3 to 7). Movement of the shaft 1 relative to the sleeve 3 in a direction out of the free end 19 of the sleeve is guided by one or more splines 21 in the free end of the sleeve extending into longitudinally extending grooves 22 (one shown) in the free end 23 of the shaft 1. The splines 21 and grooves 22 permit longitudinal movement while preventing rotation of the shaft 1 in the sleeve 3. With reference to Figs. 2 and 5 to 7, the three articulated fingers 5 are at 120° to each other for balanced gripping of the interior of a satellite engine exhaust nozzle 16. Of course, two or more fingers 5 could be used, three being preferred. The fingers 5 are mounted in the free end 23 of the shaft 1 and in the rest position extend slightly out of the free end 19 of the sleeve 3. Each finger 5 includes three sections 25, 26 and 27, pivotally interconnected by resilient hinges 28. In use, with the length of the tendons 6 fixed and movement of the shaft 1 in the sleeve 3 being permitted in one direction only, i.e. outwardly, the spacecraft 2 carrying the capturing apparatus is maneuvered into a position in which the free end of the apparatus enters the nozzle 16 (Fig. 3). As the apparatus enters the nozzle 16, the fingers 5 enter the throat 30 of the nozzle (Fig. 4). When the stop plate 4 engages the interior of the nozzle 16, further movement of the sleeve 3 into the nozzle is prevented. The shaft 1 continues to move, pushing the fingers 5 through the throat 30 and the fixed length tendons 6 flex around the throat_, forcing the fingers 5 to bend outwardly until the radial distance (Fig. 7) from the tips of the fingers 5 to the centerline 31 of the nozzle 16 exceeds the radius r₂ (Fig. 5) of the throat. Forward motion of the shaft 1 stops when the tips of the fingers 5 engage the inner end 33 of the nozzle 16, or when the finger section 27 engages the stop defined by the leading end of the section 26. Further movement of the apparatus into the nozzle 16 is prevented by the stop plate 4 and outward movement of the apparatus is prevented by the fingers 5 and the tendons 6, which are prevented from releasing by the latch defined by the one-way clutch 14 and the motor brake, i.e. the apparatus is locked to the nozzle 16 of the now captured satellite. The orbit and/or orientation of the satellite can be changed by appropriate firing of the engine and/or thrusters of the spacecraft carrying the apparatus of the present invention. The apparatus can be unlocked and the satellite released from the spacecraft by releasing the motor brake and actuating the drive system in the housing 8 to move the shaft 1 in the sleeve 3 away from the outer free end 19 if the sleeve. By actuating the motor 13, the pinion 11 is rotated to move the shaft 1 further into the nozzle 16, removing the tension on the tendons 6. The resilient hinges 28 return the fingers 5 to the straight position, and the apparatus can be disengaged from the nozzle 16. It will be appreciated that use of a plurality of finger sections 25, 26 and 27, permits use of the apparatus with a variety of exhaust nozzles 16. With some nozzles 16, the shaft 1 will move farther out of the sleeve 3 and the intermediate and outer sections 26 and 27 will bend more than in nozzles of the size and shape shown in Figs. 5 to 7; In the following description of a second embodiment of the invention, wherever possible the same reference numerals have been used to identify elements the same as or similar to elements in the apparatus of Figs. 1 to 5. Referring to figs. 6 to 9, in a second embodiment of the invention, a second sleeve 35 is mounted coaxially on the sleeve 3. The rear ends of the tendons 6 are connected to the front end of the sleeve 35. A housing 36 at the rear end of the sleeve 35 contains a drive and latch assembly (not shown) similar to the assembly of Figs. 3 and 4 for moving the second, outer sleeve 35 longitudinally of the inner sleeve 3, whereby the apparent length of the tendons 6 can be changed. The stop plate 4 of the first embodiment is replaced by a sleeve 38 with a cylindrical side wall 39 and an annular rear wall 40. The tendons 6 extend from the outer free ends of the fingers 6 through slots 42 in the rear wall 40 to the front end of the sleeve 35. During use, the free front end 43 of the sleeve 38 contacts the nozzle 16 of a satellite. Rectangular notches 44 in the front end 38 of the sleeve 33 are adapted to receive a pipe 45 (Fig. 11), thin plates or cables which can be grasped by a finger 5 when the fingers bend. The number of notches 44 is equal to the number of fingers 5. The notches 44 are so arranged that their centers are halfway between the fingers 5. Another unique feature of the second embodiment of the invention is a triangular extension or nose 46 on the front or outer end of the shaft 1 which provides support for the articulated fingers 5. By providing interlocking, longitudinally extending splines and grooves (not shown) in the nose 46 and the fingers 5, proper alignment of the fingers can be maintained during launching, pre-docking maneuvering and releasing of a captured satellite. As best shown in Figs. 11 and 12, in the second embodiment of the invention, each finger 5 includes two finger sections 48 and 49. The inner section 48 is pivotally connected to the shaft 3 by a resilient hinge 50, and the outer section 49 is pivotally connected to the inner section 48 by a hinge 51. Preferably the hinges 50 and 51 are offset with respect to each other, i.e. the distance of the axis of the rotation 53 of the inner hinge 50 from the longitudinal axis of the shaft 1 is greater than the distance of the axis of rotation 54 of the hinge 51 from such longitudinal axis. With this arrangement, the tension on the tendons 6 will automatically cause the outer finger sections 49 to bend outwardly before the inner sections 48. Thus, the fingers 5 automatically adjust to the interior dimensions of the nozzle 16. When three finger sections are used (as in the first embodiment of the invention), the nose 46 stabilizes the fingers 6 and keeps the apparatus aligned in the nozzle 16 by preventing movement of the middle finger sections from moving toward the longitudinal axis of the shaft 3, providing high rigidity to the apparatus in the latched condition. It will be appreciated that various modifications can be made to the apparatus without affecting the basic principles underlying the invention. For example, two tendons 6 can be used with each finger 5, each tendon of a pair of tendons extending from spaced apart locations on the stop plate 4 or the sleeve 35 to the outer free end of a finger 5. Moreover, shock absorbers can be provided on the stop plate 4 to cushion contact forces between the apparatus and a satellite at the moment of the capture.

Claims

CLAIMS: 1. An apparatus for capturing a satellite, which includes a rocket motor or structural feature of similar geometry comprising: a shaft having a first end for connection to a nose end of spacecraft, and a second free end; a first sleeve slidably receiving said shaft; a latch on one end of said first sleeve permitting movement of the shaft toward an outer, free end of the first sleeve; a stop plate on said first sleeve for engaging a satellite exhaust nozzle, whereby movement of the first sleeve into the nozzle is restricted; a plurality of articulated fingers extending out of said free end of said shaft, said fingers having outer free ends; and flexible tendons extending between said stop plate and said free ends of the fingers, whereby when the shaft and free end of the first sleeve are driven into an exhaust nozzle of a satellite engine, the stop plate engages the outer end of the nozzle, stopping movement of the first sleeve into the nozzle, the shaft continues movement through the neck of the nozzle causing the tendons to engage the neck, and continued movement of the shaft into the nozzle, bends the tendons and consequently the fingers, so that the fingers, the stop plate and the tendons latch the apparatus to the nozzle.

2. The apparatus of claim 1 , including a first drive on said first sleeve for moving said shaft longitudinally of said first sleeve, whereby the shaft can be moved further into a satellite nozzle beyond the latched position to return the tendons from and fingers from bent to straight conditions, permitting removal of the apparatus from the nozzle.

3. The apparatus of claim 2, wherein each said finger includes a plurality of sections; and resilient hinges interconnecting said sections permitting bending of the fingers and return of the fingers to a straight condition.

4. The apparatus of claim 3 including reels on said stop plate for changing the effective length of said tendons, whereby the apparatus can be adapted to different exhaust nozzles.

5. The apparatus of claim 3, wherein said stop plate includes an annular rear wall; a cylindrical side wall having a free front end for engaging a satellite nozzle; and notches in said front end for receiving a structural element in the exhaust nozzle of a satellite, whereby the structural element can be retained by the fingers when the fingers are bent.

6. The apparatus of claim 5 including a second sleeve slidably mounted on said first sleeve for receiving one end of each said tendon; and a second drive for moving said second sleeve relative to said first sleeve to change the effective length of said tendons.