Attitude control system for spacecraft based on conversion of incident solar radiation on movable control surfaces into mechanical torque

Acord, J. D.

Lonborg, J. O.

Nicklas, J. C.

Randall, J. C.

English

NASA Technical Reports Server

REPLY TO 
ATTN OF: 
FROM: 
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 
WASIIINGTON, D.C. 20546 
October 15, 1970 
~ ~ ~ / ~ c i e n t i f i c  & Technical Information Divis ion 
At tent ion:  M i s s  Winnie M. Morgan 
~ ~ / 0 f f i c e  of A s s i s t a n t  General 
Counsel f o r  Pa ten t  Matters  
SUBJECT: Announcement of NASA-Owned 
U.S. Pa ten t s  i n  STAR 
I n  accordance wi th  t h e  procedures cont,ained i n  t h e  Code GP 
t o  Code US1 memorandum on t h i s  s u b j e c t ,  da ted  June 8,  1970, 
t h e  a t t a c h e d  NASA-owned U.S. p a t e n t  i s  being forwarded f o r  
a b s t r a c t i n g  and announcement i n  NASA STAR. 
The fol lowing information i s  provided: 
U.S. Pa ten t  No. 
Corporate Source 
Supplementary 
Corporate Source 
: Cal i f .  I n s t i t u t e  of Technology 
NASA Pa ten t  Case No.: XNP-02982 
P lease  note  t h a t  t h i s  p a t e n t  covers an invent ion  made by an 
employee of a  NASA con t rac to r .  Pursuant t o  Sect ion  305(a) of 
t h e  ~ a t i o n a l  Aeronautics and Space Act, t h e  name of t h e  
Administrator  of NASA appears  on t h e  f i r s t  page of t h e  p a t e n t ;  
however, t h e  name of t h e  a c t u a l  inventor  (au thor)  appears a t  
t h e  heading of Column No. 1 of t h e  S p e c i f i c a t i o n ,  following t h e  
words ' I .  . . wi th  r e s p e c t  t o  an  invent ion  of .  . . ." 
Gayle Parker  
Enclosure : 
Copy of Pa ten t  
I 
' e l  
8 
1 9  (PAGES) , (CODE) 
z - /
(NASA CR OR TMX OR AD NUMBER) 
3/ 
(CATEGORY) 
9 
https://ntrs.nasa.gov/search.jsp?R=19700032539 2020-03-17T02:11:35+00:00Z
Feb. 14, 1967 HUGH L. DRYDEN DEPUTY 3,304,028 
ADMINISTRATOR O F  T H E  NATIONAL AERONAUTICS 
A N D  SPACE ADMINISTRATION 
ATTITUDE CONTROL FOR SPACECRAFT 
Filed Aug. 11, 1964 2 Sheets-Sheet 1 
SUN 
L INE 
SOLAR 
RADIATION 
IS. I 
Feb. 94, '8967 HUGH L. DRYDEN DEPUTY 3,304,028 
ADMINISTRATOR O F  T H E  NATIONAL AERONAUTICS 
A N D  SPACE ADMINISTRATION 
ATTITUDE CONTROL FOR SPACECRAFT 
Filed Aug. 11, 1964 2 Sheets-Sheet 2 
United States Patent Ofice Patented Feb. 3,304,028 14, 1967 
panel and supporting a positioning motor 5 .  The posi- 
3,304,028 tioning motor includes a shaft 6 (FIGURE 5 )  to  which 
ATTITUDE CONTROL FOR SPACECRAFT is secured a radial mounting arm 7. 
H ~ $ a ~ ~ , " , " ~ d D ~ ~ ~ ~  f ~ ~ i ~ ~ ~ ~ ~ n $ i ~ ~ r ~ p " ~ ~ ~ ~  Secured to the extremity of the moontin: arm is a bi- inavenaiow ~~h~ 67. ~ i ~ k l ~ ~ ,  D. 5 metallic element 8 comprising two strips of dissimilar 
.Barnes 0. Eonnborg, and James C. Ranndre2iP metals bonded together. Each bimetallic element warps 
Filed Aue. 11. 1964. Ses. No. 388,966 in proportion to its temperature. The bimetallic elcnients 
6 elaik~s. (61. 244-1) ' are disposed so that when the axis of the antenna mast 3 
is aligned with the sun, they are essential!y normal to the 
The invention described hcrein was made in the Per- 10 sun's axis and with the sun, the bimeta1Iic elements are 
formance of work under a National Aeronautics and Space equally exposed to the radiant energy therefrom. 
Administration contract subject to the provisions of Sec- Also secured to the extremity of the inounting arm 7 
tion 305 of the Nation8al Aeronautics and Space Act of  and underlying the bimetallic eleinent 8 is a yieldable 
1958, public Law 85-568 (72 Stat. 435; 42 U.S.C. 2457). frame 9 (FIGURES 5 and 7 )  capable of warping as the 
This invention relates to attitude contro!~ for space- 15 extremity of the bin~etallic element deflects. The frame 9 
craft and included in the objects of this invention are: in turn pivotally supports, at  its secured end adjacent the 
First, to provide an attitude control for spacecraft which arm 7, a lever unit 16) by means of a f~iicrum pin 88.  
utilizes ~novable control surfaces exposed to solar pres- The lever unit 10 extends under and beyond the frame 9 
sure so arranged that by adjustment of these surfaces the and is provided near its extended end with a slop engag- 
incident solar radiatic,n is converted inlo mechanical 20 ing pin 12 adapted to engage a stop pad 13 provided at  
torques about the center of mass of the spacecraft. the extremity of the frame. The lever u i~i t  $0 may corn- 
Second, to provide an attitude control for spacecraft prise two similar and parallel strips lion, 88th (FIGURE 
which incorporates temperature responsive elements which, 6 )  joined together b y  the fulcrum pin 11 and stop engag- 
on exposurc to the radiant ecergji from the sun, alters ing pin 12. 
the position of the controi suriraces and which utilizes 25 Wrapped about the f u l c r ~ ~ m  pin 11 is a biasing spring 
shutter means which vary exposure oF the lenlperat~rre 14 (FIGURE 6 )  which serves to hold the pin 112 in yield- 
respansive eienient:; so as to cause the coiltrol surfaces to able engagement with the stop pad 113. Attached to tlie 
lnaintain the spacecraft in a predetermined attitude rela- extremity of the strips 10a, l ob ,  of the control lever unit 
tive to the sun. 10 is a control vane. panel or surface 15 iFSGURE 5)  
Third, to provide an attitude co~:trol for spacecraft 30 which is preferably provided with a scrcw adjustment 16 
which does not need the use of any consu~nable energy so that the angular relalion of the control surface 13ay 
source, or the use of any solar cells needed for generatiag be pradjusted with respect to the lever unit PO. The 
electrical energy required for operation of the equipment control panels like the radiating arms 2, may be solar 
carried by the spacecraft, in order to maintain the attitude panels, and when the angular positions of the control 
of the spacecraft. b~xtwhic'n is instead self-sufficient for 35 panels are varied, the effective area of ex:~cscre thereof 
its operation. to the sun is varied accordingly. In this mar,ner, a con- 
Fourth. to provide an attitnde control for spacecraft trollable solar pressure control effect may be obtained. 
which, allhough capable of coinpie:e attitude control of Each bracket 4 supports a lower and an upper control 
the spacecraft. may be utilized as a vernier altitude con- shutter 17 and 18, respectively, vihich overlie the bi- 
trcl which is bro~lght into operation after jets. or  other 4C inetaliic element 8. The shutters 17 and 18 are plates 
control means, have brought the spacecraft into the ap- in which are provided a series of slits 19 so arranged that 
proximately desired attitude. for predetermined changes in attitude the expo'sure of the 
With the above and other objects in view. as may ap- bimetallic element to the sun will vary in a predictable 
pear hereinafter, reference is directcd t o  the accompany- manner. As shown in FIGURES 2 and 3, the slits 39 in 
ing drawings in which: 45 the shutter 17 are offset slightly with respect to the slits 
FIGURE 1 is a tjipica! spacecraft showing attitude con- 19 in the shutter 18. 
trols at  the extremities thereof; Operation of the attitude control is as follows: 
FFGURE 2  is a diagrain~nalical view illustrating the With reference to FIG. 2, the solar panels or a r n ~ s  2 
niodc of operation of the attitude cor~trol; arc, in front of the center of mass 20 of the spacecraft, 
FIGURE 3 is a diagramn~atical view showing the man- 50 that is, toward the sun with respect to the center of mass. 
ncr in which the conlroi surfaces arc varied in order to Thus, the spacecraft would be basically unstable were i t  
effect change in the siabilized attiiude of the spacecraft; not for the control surfaces 15. An angular error in- 
FIGURE 4 is a fragn~entory top view 0'5 one 01 the dicated by 21 (FIGURE 2 )  will catise an unbalanced 
attitude control units: torque which will tend to increase this angle. In theory 
FIGURE 5 is a fragmentary sectional view thereof 55 it is quite simple to design a passively stable spacecraft. 
through 5-5 of FIG. 4; It is necessary only to make certain that the centroid of 
FTGURE 6 is a fragmenlary vicw laken through 6-6 solar pressure on the craft is "down sun" from the center 
of FIG. 5 ;  of mass 20. This is analagous to the action of a sea an- 
FIGURE 7 is an enlarged fragmentary sectional view chor that holds the bow of a vessel into the wind during 
taken within circle 7 of FIG. 5. 60 a storm. However, it has been found that such a con- 
A typical spacecraft may involve a central body or mass figuration is not sufficie~lt for the control of the space- 
1 having radiating arms 2 which may be solar panels. craft. 
As is well known. solar panels respond to energy from As shown in FIGURE 1, the center of pressure of the 
the sun which is intcrceptedby the panels so as to develop spacecraft witho,ut the vanes 15 attached lies between the 
solar pressure froces. These solar pressures are used in 65 center 20 of the mass and the sun. As previously dis- 
the practice of the invention to control the attitude of the cussed, this results in a statically unstable system, unless 
spacecraft. Mounted at the center of the spacecraft is a some means is provided to take care of the situation. 
low gain antenna mast 3. Thus the purpose of attaching the vanes 15 is threefold: 
At the exiren~ily of each panel or  arm 2 is a bracket (1) to make the spacecraft system statically stable; (2 )  
4 (FIGURES 4 and 5) extcnding at  right angles to the 70 to align the stable position of the spacecraft with the 
3,304,028 
3 4 
null oE the primary attitude control system; and (3)  to  surfaces to  vary the angular positions of said control 
supply retarciing forces to damp out any oscillations that surfaces thereby to vary the exposure of said control 
may occur. surfaces to the sun: 
The control snrfaces 15 define positive angles designated (c)  and shutters interposed between said bimetallic 
22 with respect to the solar panels (FIGURE 2) .  By 5 elements and the S L I ~  for varying the exposure of 
choice of ar'eas and lengths and positive angles of the each of said control surfaces to the sun in directions 
control surfaces, the spacecraft may be rendered stable. tending to move said spacecraft toward a preselcctcd 
Under this stable condition, an  angular error 21 will then attitude relative to  the sun. 
cause an unbalanced torque which will tend to decrease 3. An attitude control for spacecraft having a central 
this angle. That is, should the attitude of the spacecraft 10 mass ancl radiating arms, said control comprising: 
change so ar; to change the angle 21, for exampie, the ( a )  control surfaces at  the extremities of said arms, 
sh~ltters 17 and 18 change the amount of radiant energy said control surfaces being movable to vary their 
incident on the respective bimetallic elements 8 in FIG- respective effective areas exposed to solar pressure; 
URE 2, so as to change correspondingly the angles 22 de- (b )  biil~etallic elemcnts enpageable wiih said control 
fined by the vanes. If the spacecraft is given an impulse, 15 surfaces to  vary their effective areas of exposure; 
it would tend to oscillate about the center of mass 20 (c)  and means interposed between said bimetallic ele- 
unless dampening means were used. lllents and the sun for varying the exposure thereof 
The arrangement of the control panels and shutters 17 to the sun on changes in altitude of the spacecraft 
and 118 and their effect on the bimetallic elements 8 may from a preselected attitude, thereby to cause a cor- 
be predeterinined so that the desired dampening effect may 20 rective change in the effective exposures of said con- 
be readily attainable. That is, if the spacecraft is in an  trol surfaces tending lo restore said spacecraft to its 
oscillatory mode, the shutters may be designed to differen- preselected attitude. 
tially expose the bimetallic elements to counteract or  4. A n  attitude contro.1 for spacecraft having a central 
dampen oscillation. This is aided by utilizing the thermal mass and radiating arms, said control coiliprising: 
inertia o l  the binxtallic elements. That is, the vanes 15 25 ( a )  control surfaces at  the extremities of said arms, 
are moved in a manner such that the torque of the vanes said control s~lrfaces being movable to vary their 
lags the spacecraft position. respective effective areas exposed to solar pressure; 
While the attitude control has been described as the sole ( b )  bimetallic elements engageable with said control 
attitude coritrol for the spacecraft and may in many cases surfaces to vary their effective areas of exposure; 
consiitute the sole control, it may be operated in conjunc- 30 (c)  and shutters interposed between said bimetallic ele- 
lion with other controls and function to accomplish fine or ments and the sun for varying the exposure of each 
vernier adjustment of the spacecraft. of said control surfaces to the sun in directions tend- 
111 such case, the positioning motors 5 may be con- ing to move said spacecraft toward a preselected at- 
trolled by sensing means, not shown, so as to vary the titude relaiive to the sun. 
gross angular positions of the arm 7 and frame 9 and thus 35 5.  The combination of claim 2 wherein said shutters 
of the control paneis 15. The motors 5 may be of the well include: 
known stepping type, so that each motor is stepped from ( a )  at least a pair of parallel plates each having a pair 
one particular angular position to the next upon the re- of oppositely disposed faces with at least one face 
ceipt of energizing current, and each motor remains thereof directed toward the sun; 
locked in the stepped position when in a de-energized 40 (b )  means defining in each plate of said pair of plates 
condition. Still further, attitude control jets 23 such as a plurality of slits extending between the oppositely 
shown in a copending application of Batsch et al., Serial disposed faces thereof; and 
No. 182,696, filed April 4, 1962, now Patent No. 3,178,- (c)  means securing said pair of plates to a given one of 
883, may be utilized with suitable sensory means to effect the arms of the spacecraft in a mann*er such that said 
gross adjustment of the attitude of the spacecraft. 45 plates are arranged in face-to-face, mutually displaced 
The attitude control herein disclosed is capable of main- relationship overlying given birneiallic elements. 
tainiag a spacecraft within a small fraction of a degree of 6.  In  combination with a spacecraft having at  least one 
thc desired attitude. displaceable control surface for dictating attitude for the 
While a particular embodiment of this invention has spacecraft relative to the sun in response to an impinge- 
been shown and described, it is not intended to 4imit the 50 ment of solar Pressure thereon, a solar energy responsive 
same to the exact details of the construction set forth, and actuator adapted for effecting displacement of the control 
it embraces such changes, modifications, and equivalents surface comprisin~: 
of the parts and their formation and arrangement as come ( a )  a lever pivotally connected between the spacecraft 
within the purview of the appended clain~s. and the control surface adapted to be actuated for 
What is claimed is: 55 effecting displacenient of the control surface; 
1. An attitude control for spacecraft having a central ( b )  a bimetallic strip adaptecl to deform in the presence 
mass and radiating arms, said control comprising: of solar energy secured at  one end to the spacecraft 
( a )  angularly movable control surfaces at  the extremi- and having a free end engageable with said lever 
lies of said arms responsive to solar pressure; adapted to engage said lever and effect a variable 
( b )  bimetallic elements engageable with said control 60 actuation of said lever as a varying quantity of radiant 
surfaces to vary the angular positions of said control energy is caused to impinge thereon; 
surfaces thereby to vary the exposure of said control (c)  at  least a pair of parallel plates each having a pair 
surfaces to  the sun; of opposed faces wiih one face thereof being directed 
(c)  and means interposed between each of said bi- toward the sun; 
metallic elements and the sun for varying the ex- 65 (d )  means defining in each plate a plurality of openings 
posure thereof to the sun on change in attitude of the extending between the faces; 
spacecraft thereby to cause said responsive means to ( e )  means securing said pair of plates to the spacecraft 
vary the angular positions of said control surfaces in in a manner such that said plates are disposed in a 
clirections tending to move said spacecraft toward a face-to-face, m ~ ~ t ~ ~ a l l y  disp aced relationship with the 
preselected attitude relative to the sun. 70 openings thereof being arranged in a predetermined 
2.  An attitude control for spacecraft having a central alignment between the sun and the bimetallic strip 
mass and radiating arms, said control comprising: for passing solar energy to said strip in a varying 
( L I )  :~ngi!larly nlovable control s~~r faces  at  the exlremi- quantity as the a t t i t~~t ie  of the spacecraft is caused to 
ties of said arms responsive to solar pressure; ~indergo a change. 
(b )  bimetallic elements engageable with said control 75 (References on fo8Uowiang page) 
3,304,028 
5 6 
References Cited by the Examiner Villers et al., "A Solar Sail Attitude Stabilizer, Satellites 
UNITED STATES PATENTS and Interplanetary Probes," ARS Space Flight Report 
to the Nation, New York Coliseum, Oct. 9-15, 1961. 3,173,626 3/1965 Sohn ----------------- 244-1 
3,206,141 9/1965 Dryden --------------- 244-1 McElvain, "Effects of Solar Radiation Pressure Upon 
3,239,165 3/1966 Sohn-----------------244-1 6 Satellite Attitude Control," ARS Guidance, Control, and Navigational Conference, Aug. 7-9, 1961. 
References Cited by the Applicant Roberson, "Attitude Control of Satellites and Space 
UNITED STATES PATENTS Vehicles," Advances in Space Science, 1960. 
3,145,948 8/1964 Kershner. Astounding Science ~ ic i ion ,  May 195 1, pages 136-143. lo Jet Propulsion, March 1958, pages 188-190. 
OTHER REFERENCES Solar Sailing, by Theodore P. Cotter, OTS Department 
Sohn, "Attitude Stabilization by Means of Solar Radia- of Commerce publication SCR-78, datcd April 1959. 
tion Pressure," ARS Journal, pp. 371-373, May 1959. 
Tsu, "Interplanetary Travel by Solar Sail," ARS 4our- 15 FERGUS S. MHDDLETON, Prin~ary Exan~iner. 
nal, pp. 422-427, June 1959. 


Attitude control for spacecraft Patent

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server