A satellite retrieval system with first and second pairs of coacting parallel bars are separately mounted in spaced parallel planes on the front of a spacecraft. The bars of one pair are at right angles to bars of the other pair, and together the two pairs of bars effect a variable aperture adapted to close around a rod extending from a second spacecraft to effect the capture of the latter

Loughead, T. E.

Pruett, E. C.

Robertson, K. B.

English

NASA Technical Reports Server

United States Patent P I 1  4,391,423 
Pruett et al. [451 Jul. 5,1983 
[54] SATELLITE RETRIEVAL SYSTEM 
[75] Inventors: Wwin C. Pruett; Kern B. Robertson; 
Tomas E. Loughead, all of Huntsville, 
Ala. 
represented by the Administrator of 
the National Aeronautics and Space 
Administration, Washington, D.C. 
[73] Assignee: The United States of America as 
[21] Appl. No.: 248,745 
[22] Filed: Mar. 30,1981 
[51] Int. Cl.3  ................................................ B64G 1/64 
[52] U.S. Cl. .................................... 244/161; 244/115; 
269/152; 269/242; 269/244; 294/86 R 
[58] Field of Search ..................... 244/137 R, 115, 116, 
244/161; 294/86 R, 67 BB; 269/152, 155,244, 
242, 111, 115 
1561 References Cited 
U.S. PATENT DOCUMENTS 
3,552,688 1/1971 Baekken .............................. 244/115 
3,790,121 2/1974 Sels et ai. ............................ 269/115 
3,868,139 2/1975 Drelicharz ...................... 294/67 BB 
4,105,241 8/1978 Mee ..................................... 244/161 
4,123,020 10/1978 Korsak ................................ 244/116 
4,173,324 11/1979 Rudmann ............................ 244/161 
4,177,964 12/1979 Hujsak ................................ 244/161 
FOREIGN PATENT DOCUMENTS 
127955 of 1950 Sweden ............................... 269/111 
409590 of 1934 United Kingdom ................ 269/114 
Primary Examiner-Galen L. Barefoot 
Attorney, Agent, or Firm-J. H. Beumer; J. R. Manning; 
L. D. Wofford, Jr. 
[571 ABSTRACT 
A satellite retrieval system (10) wherein first and second 
pairs of coacting parallel bars (M), and (94) are sepa- 
rately mounted in spaced parallel planes on the front of 
a spacecraft (14). The bars of one pair are at right angles 
to bars of the other pair, and together the two pairs of 
bars effect a variable aperture adapted to close around a 
rod (26) extending from a second spacecraft (22) to 
thereby effect the capture of the latter. 
5 Claims, 5 Drawing Figures 
22 
https://ntrs.nasa.gov/search.jsp?R=19830021032 2020-03-22T00:48:42+00:00Z
. Patent Jui. 5 ,  1983 Sheet 1 of 2 4,396,423 
L 
U.S. Patent Jui. 5 ,  1983 Sheet 2 of 2 4,396,423 
4,39 1,423 
1 2 
FIGS. 2-4 are diagrammatic illustrations of the re- 
trieval system and illustrating certain additional ele- 
ments of it. 
SATELLITE RETRIEVAL SYSTEM 
ORIGIN OF THE INVENTION 
5 The invention described herein was made in the per- 
formance of work under a NASA contract and is sub- 
ject to the provisions of Section 305 of the National 
Aeronautics and Space Act of 1958, public law 85-568 
(74 STAT 453; 42 U.S.C. 2457). 
TECHNICAL FIELD 
This invention relates generally to devices and sys- 
tems for coupling space vehicles, and particularly to a 
grappling system borne by one spacecraft for securing it 15 
to another. 
10 
BACKGROUNDART 
With the advent of the space age, and with increased 
numbers of space vehicles operating, it is only logical 20 
that there be occasions when it is desirable to effect 
docking between them. A variety of devices and sys- 
tems have been proposed for this purpose, and reference 
is particularly made to U.S. Pat. Nos. 3,254,863; 
3,508,723; 3,910,533; 4,018,409; and 4,117,964. 
These patents illustrate a variety of techniques and in 
general employ variously configured mating units car- 
ried by the vehicles to be joined. These appear to re- 
quire fairly close dimensioned contact, and this in turn 
requires a fairly precise maneuver by one or both of the 30 
vehicles. This can present a problem inasmuch as if 
there is an initial non-aligned contact which does not 
result in a joinder, this contact may result in an impact 
transmitted by one vehicle to another which can pro- 
duce an undesired rotation, possibly tumbling, of one of 35 
25 
the vehicles. This must then be corrected before dock- 
ing can be finally accomplished, which, of course, adds 
to the complexity and time required for docking. 
It is the object of this invention to provide an im- 
proved docking or retrieval system wherein docking 
components of the vehicle effecting retrieval surround 
the docking component of the vehicle to be retrieved by 
a significant clearance prior to any mechanical contact, 
and thereby a contacting maneuver is relatively assured 
which will result in successful capture. 
DISCLOSURE OF THE INVENTION 
In accordance with this invention, a vehicle which is 
to be retrieved would be equipped with a simple rectan- 
gular rod which has at an outer end an enlarged region 
or knob. The retrieving vehicle has mounted on it a 
retrieval fixture which consists of two pairs of orthogo- 
nally arranged grappling bars, a front pair and a rear 
pair. With the retrieving vehicle maneuvered wherein 
the two pairs of bars surround, but do not touch, the 
rectangular retrieval rod on the vehicle to be retrieved, 
the front bars are operated to close on the rod to a loose 
fit. Then, the orthogonally arranged rear bars are oper- 
ated to close to make a rigid or hard contact with the 
rod. This forces the two vehicles into axial alignment, 
and thereafter the vehicles are drawn to a position 
where interengaging latches operate to finally and 
firmly couple the vehicles. 
BRIEF DESCRIPTION OF THE DRAWINGS 
FIG. 1 is an exploded pictorial view illustrative of the 
principal elements of the system of this invention. 
40 
45 
50 
55 
60 
65 
FIG. 5 is a pictorial illustration of a detail of the latch 
mechanisms finally connecting the retrieving vehicle 
with the retrieved vehicle. 
BEST MODE FOR CARRYING OUT THE 
INVENTION 
Referring to FIG. 1, a satellite retrieval assembly 10 is 
mounted to the front end 12 of a space vehicle 14 which 
is to function as a retrieval vehicle. Assembly 10 is 
supported on vehicle 14 via an aft support plate 24 by 
conventional attachment means (not shown). 
A vehicle to be retrieved or captured, as illustrated 
by vehicle 22, would include a relatively simple dock- 
ing interface 29 consisting of rod fixture 26 and catches 
28 on guide member 30, supported on satellite vehicle 
22 by supports 25. Rod fixture 26 consists of a rectangu- 
lar rod 27 having an enlarged rectangular knob 31 at its 
outer end. 
Satellite retrieval assembly 10 on space vehicle 14 
provides three basic elements: forward guide member 
32, which mounts solenoid operated receptacle latch 33, 
which mates with coordinately shaped catches 28 on 
guide 30 of vehicle 22; a forward capture bar assembly 
34, and aft capture bar assembly 36. In addition to 
mounting receptacle 33, forward guide member 32 is 
conveniently observable by TV cameras 97 and 99 
(FIGS. 2-4), and when viewed with respect to guide 30 
of target vehicle 22, the maneuvering of vehicle 14 into 
a docking posture with target vehicle 22 is facilitated. 
Capture is effected by a combination of forward capture 
bar assembly 34 and aft capture bar assembly 36 posi- 
tioned in this order behind guide member 32. 
Forward capture bar assembly 34 employs a pair of 
parallel horizontal capture bars 40, and these are driven 
toward and away from each other by threadable en- 
gagement with drive screws 42 and 44. Their orienta- 
tion is assisted by spaced guide shafts 46 and 48 which 
extending through openings 50 of the capture bars. A 
motor 52 is mounted on front mounting plate 54 (in turn 
mounted on frame members 56 and 58) by brackets 60 
and 62. A sprocket 64 on motor 52 drives a chain 65, 
which in turn drives sprocket 66 attached to shaft 68 
supported on plate 54 by bearings 72, 74, and 76. The 
sprocket and drive chain are diagrammatically illus- 
trated. Bevel gear 78 on shaft 68 drives bevel gear 80 
mounted to drive screw 42, and bevel gear 82 on shaft 
68 drives bevel gear 84 mounted to drive screw 44. 
Drive screws 42 and 44 are supported by bearings 86 
and 88, which in turn are conventionally mounted to 
plate 54 (by means not shown). The screw threads on 
drive screws 42 and 44 and corresponding internal 
threads on capture bars 40 are selected so that the two 
capture bars move in the opposite direction as drive 
screws 42 and 44 are rotated by motor 52. 
Aft capture bar assembly 36 is positioned behind 
forward capture bar assembly 34 and is arranged with 
its parallel capture bars 94 are right angles to those of 
forward capture bar assembly 34. Capture bars 94 are 
mounted and driven by oppositely positioned screw 
drives 96 and 101, with the screw drives supported by 
guides 98 and 100 mounted in the same manner as 
guides 46 and 48 of front capture bar assembly 34. Drive 
screws 96 and 101 and guide shafts 98 and 100 of aft 
capture bar assembly 36 are movably supported on a 
guide frame 102, and it is slidably supported on guides 
4.391,423 
3 
104 which maintain the plane of plate 102 vertical and 
thus normal to the axis of vehicle 14 while it is movable 
along this axis to effect a retraction or extension of aft 
capture bar assembly 36 with respect to vehicle 22. 
Guides 104 are rigidly supported on support plate 24. A 
motor 111 is attached with brackets (not shown) to 
frame 102, and it drives a sprocket 113 and chain 115, 
which in turn drive sprocket 117 connected to shaft 119. 
Bevel gear 121 on shaft 119 drives bevel gear 123 con- 
nected to drive screw 96. Retraction and extension is 
powered by motor 106 mounted by bracket 108 on 
frame 102. A sprocket 112 of motor 106 drives a 
sprocket 114 on shaft 116 by means of a chain 118, the 
sprocket and chain being diagrammatically illustrated. 
Drive shaft 116 is supported by brackets 120 and 122 on 
frame 102, and pinions 124 (one shown) mounted on 
shaft 116 mesh with racks 128 and 130, which are fixed 
mounted to frame 56, in turn attached'to vehicle 14. 
Depending upon the direction of operation effected by 
motor 106, pinion gears 124 drive frame 102 and thus aft 
capture bar assembly 36 in a retract (left) or extend 
(right) direction. 
Limit switches may be employed with all of the drive 
systems described to turn off a given motor when cap- 
ture bars or frame members 102 have reached a selected 
limit. 
FIG. 5 illustrates in detail the latch-catch combina- 
tion employed to effect a final hard dock between chase 
vehicle 14 and target vehicle 22. Two identical latch 
cam members 200 and 202 are mounted in a body mem- 
ber 204 of a latch 206 supported on frame 208. Each 
latch cam member is pivotally mounted on shaft 210, 
and each is biased in the position shown by a spring (not 
shown). In this latch position, catch 212 is firmly held in 
place by the cam members. Release of catch 212 is 
accomplished by means of rotary solenoid 214 coupled 
to each of the latch cam members, and when energized, 
the rotary solenoid rotates a latch cam member in a 
direction which would raise the cam members out of 
engagement with catch 212. 
To examine operation of the retrieval system, assume 
that capture bar assemblies 34 and 36 are operated to 
their maximum extended position (FIG. 2), and thus the 
aperture of the retrieval system is at a maximum. As- 
sume further that the retraction frame 102 is operated to 
cause frame 102 to move to its maximum extended posi- 
tion wherein frame 102 would be at its maximum posi- 
tion to the right (as illustrated in FIG. 1). Target vehicle 
22 would then be observed via television cameras 97 
and 99, and vehicle 14 would be maneuvered toward 
target vehicle 22 and along a course which enables rod 
fmtue 26 of target vehicle 22 to be encompassed by 
retrieval assembly 10 as, for example, diagrammatically 
illustrated in FIG. 2. It will thus be seen in FIG. 2 that 
there need not be close axial alignment between the 
vehicles. With rod future 26 as shown in FIG. 2, for- 
ward capture bars 40 are operated together to centrally 
capture rod fmture 26, essentially along a vertical plane 
passing through the longitudinal axis of vehicle 22. 
Typically, this operation would be such as to effect a 
relatively loose contact between capture bars 40 and 
rod fmture 26. 
Next, and this is illustrated in FIG. 3, aft capture bars 
94 are operated via motor 111 to be drawn toward rod 
fmture 26, and in this instance, bars 94 press tightly 
against rod fmture 26, and by virtue of the planar nature 
of the rectangular surfaces of rod 26 and bars 94, this 
causes vehicle 22 to be moved to the axial alignment 
4 
position of the vehicle shown in FIG. 3. Thus, at this 
point, the vehicles are brought to axial alignment 
wherein receptacle latch 33 and catches 28 are direc- 
tionally aligned. Next, and finally, motor 106 is oper- 
5 ated to effect a retraction of frame 102, and thus aft 
capture bars 94 are moved to a position as shown in 
FIG. 4, and wherein latch catches 28 on vehicle 22 are 
drawn into and locked to a position by and within re- 
ceptacle latch 33 to thus complete the docking, and 
10 wherein there is a firm hard dock connection between 
the vehicles. 
From the foregoing, it will be appreciated that a 
basically simple but very effective docking system is 
realized. Relatively standard mechanisms are employed 
15 in the retrieval assembly on the chase vehicle, and like- 
wise for the target vehicle. The initial proximity maneu- 
ver between vehicles need not be in terms of axial align- 
ment of the vehicle, and considerable latitude of the 
approach is possible. Once the docking rod of the target 
20 vehicle is within the retrieval assembly, and thus en- 
compassed by the capture bars, capture by the bars is 
certain, and thus the problem of non-aligned initial 
contact contributing to a tumbling maneuver on the 
part of one of the vehicles with respect to the other is 
25 eliminated. 
We claim: 
1. A satellite retrieval system for employment with a 
a cubical first frame adapted to be fixedly attached to 
a rectangular second frame positioned around said 
cubical first frame and including support means for 
movably supporting said second frame on said 
cubical first frame; 
a first pair of parallel bars movably mounted on said 
cubical first frame for balanced relative movement 
with respect to a center line through said cubical 
first frame and normal to a plane of said second 
frame, being movable across said first frame; 
a second pair of parallel bars, orthogonal to said first 
pair of parallel bars, movably mounted on said 
second frame for balanced relative movement with 
respect to said center line, and positioned within 
said cubical first frame; 
first operating means for selectively moving bars of 
said first pair of parallel bars toward and away 
from each other; 
second operating means for selectively moving bars 
of said second pair of parallel bars toward and 
away from each other; and 
retracting means including drive means coupled be- 
tween said cubical first frame and said second 
frame for selectively moving said second frame 
along said center line and between extended and 
2. A retrieval system as set forth in claim 1 including 
a first pair of spaced threaded rods mounted on said 
cubical frame, in turn threadably supporting said first 
pair of parallel bars, and said first operating means com- 
60 prises means for rotating said threaded rods and rela- 
tively moving said last-named parallel bars. 
3. A retrieval system as set forth in claim 2 including 
a second pair of spaced threaded rods rotatably sup- 
ported on said second frame and threadably supporting 
65 said second pair of parallel bars, and said second operat- 
ing means includes means for rotating said second pair 
of threaded rods and effecting the relative movement of 
said second pair of parallel bars. 
spacecraft comprising: 
30 a spacecraft; 
35 
40 
45 
50 
55 retracted positions. 
4,39 1,423 
5 6 
4. A retrieval system as set forth in claim 3 including: 
a rod attachable on one end to a satellite to be re- 
trieved, said rod having an enlarged region at an 
end opposite to said one end, whereby with said 
retraction means on said spacecraft in an extended 
position, and said bars of said pairs of bars rela- 
tivelY spaced apart, the spacecraft would be ma- 
neuvered until a portion of said rod and said en- 
larged end region of said rod extend through said 10 
parallel bars; 
said first operating means is operated to cause said 
first parallel bars to approach each other to loosely 
grip said rod, and thereby effecting an initial, soft, 15 
attachment between the spacecraft and satellite; 
then said second operating means would be operated 
to cause said second pair of parallel bars to move 
between said spacecraft and said rod, and thereby 
the satellite; and finally 
said retraction means would be operated to a retract 
position and thereby draw in said second frame and 
satellite to a selected docking position. 
5. A retrieval system as set forth in claim further 
a third frame mounted on and spaced parallel with 
a fourth frame supportable on said satellite and gener- 
latch 
5 
comprising: 
said cubical frame; 
ally conforming to said third frame; and 
first latch elements supported by said third frame, 
comprising: 
and 
on =id fourth 
frame and adapted to mate with said first latch 
element for finally making a firm latch connec- 
tion between a said space vehicle and satellite. 
second latch elements 
toward each other and effect a firm engagement * * * * *  
20 
25 
30 
35 
45 
50 
55 
60 
65 


Satellite retrieval system

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