# Copyright: Public domain. # Filename: PLANETARY_INERTIAL_ORIENTATION.agc # Purpose: Part of the source code for Luminary 1A build 099. # It is part of the source code for the Lunar Module's (LM) # Apollo Guidance Computer (AGC), for Apollo 11. # # Assembler: yaYUL # Contact: Jim Lawton # Website: www.ibiblio.org/apollo. # Pages: 1140-1148 # Mod history: 2009-05-28 JVL Updated from page images. # # This source code has been transcribed or otherwise adapted from digitized # images of a hardcopy from the MIT Museum. The digitization was performed # by Paul Fjeld, and arranged for by Deborah Douglas of the Museum. Many # thanks to both. The images (with suitable reduction in storage size and # consequent reduction in image quality as well) are available online at # www.ibiblio.org/apollo. If for some reason you find that the images are # illegible, contact me at info@sandroid.org about getting access to the # (much) higher-quality images which Paul actually created. # # Notations on the hardcopy document read, in part: # # Assemble revision 001 of AGC program LMY99 by NASA 2021112-061 # 16:27 JULY 14, 1969 # Page 1140 # ***** RP-TO-R SUBROUTINE ***** # SUBROUTINE TO CONVERT RP (VECTOR IN PLANETARY COORDINATE SYSTEM, EITHER # EARTH-FIXED OR MOON-FIXED) TO R (SAME VECTOR IN THE BASIC REF. SYSTEM) # # R = MT(T) * (RP + LP X RP) MT = M MATRIX TRANSPOSE # # CALLING SEQUENCE # L CALL # L+1 RP-TO-R # # SUBROUTINES USED # EARTHMX, MOONMX, EARTHL # # ITEMS AVAILABLE FROM LAUNCH DATA # 504LM = THE LIBRATION VECTOR L OF THE MOON AT TIME TIMSUBL, EXPRESSED # IN THE MOON-FIXED COORD. SYSTEM RADIANS B0 # # ITEMS NECESSARY FOR SUBR. USED (SEE DESCRIPTION OF SUBR.) # # INPUT # MPAC = 0 FOR EARTH, NON-ZERO FOR MOON # 0-5D = RP VECTOR # 6-7D = TIME # # OUTPUT # MPAC = R VECTOR METERS B-29 FOR EARTH, B-27 FOR MOON SETLOC PLANTIN1 BANK COUNT* $$/LUROT RP-TO-R STQ BHIZ RPREXIT RPTORA CALL # COMPUTE M MATRIX FOR MOON MOONMX # LP=LM FOR MOON RADIANS B0 VLOAD 504LM RPTORB VXV VAD 504RPR 504RPR VXM GOTO MMATRIX # MPAC=R=MT(T)*(RP+LPXRP) RPRPXXXX # RESET PUSHLOC TO 0 BEFORE EXITING RPTORA CALL # EARTH COMPUTATIONS EARTHMX # M MATRIX B-1 CALL EARTHL # L VECTOR RADIANS B0 MXV VSL1 # LP=M(T)*L RAD B-0 MMATRIX # Page 1141 GOTO RPTORB SETLOC PLANTIN BANK COUNT* $$/LUROT # Page 1142 # ***** R-TO-RP SUBROUTINE ***** # SUBROUTINE TO CONVERT R (VECTOR IN REFERENCE COORD. SYSTEM) TO RP # (VECTOR IN PLANETARY COORD SYSTEM) EITHER EARTH-FIXED OR MOON-FIXED # # RP = M(T) * (R - L X R) # # CALLING SEQUENCE # L CALL # L+1 R-TO-RP # # SUBROUTINES USED # EARTHMX, MOONMX, EARTHL # # INPUT # MPAC = 0 FOR EARTH, NON-ZERO FOR MOON # 0-5D = R VECTOR # 6-7D = TIME # # ITEMS AVAILABLE FROM LAUNCH DATA # 504LM = THE LIBRATION VECTOR L OF THE MOON AT TIME TIMSUBL, EXPRESSED # IN THE MOON-FIXED COORD. SYSTEM RADIANS B0 # # ITEMS NECESSARY FOR SUBROUTINES USED (SEE DESCRIPTION OF SUBR.) # # OUTPUT # MPAC = RP VECTOR METERS B-29 FOR EARTH, B-27 FOR MOON R-TO-RP STQ BHIZ RPREXIT RTORPA CALL MOONMX VLOAD VXM 504LM # LP=LM MMATRIX VSL1 # L = MT(T)*LP RADIANS B0 RTORPB VXV BVSU 504RPR 504RPR MXV # M(T)*(R-LXR) B-2 MMATRIX RPRPXXXX VSL1 SETPD 0D GOTO RPREXIT RTORPA CALL # EARTH COMPUTATIONS EARTHMX CALL EARTHL GOTO # MPAC=L=(-AX,-AY,0) RAD B-0 RTORPB # Page 1143 # ***** MOONMX SUBROUTINE ***** # SUBROUTINE TO COMPUTE THE TRANSFORMATION MATRIX M FOR THE MOON # # CALLING SEQUENCE # L CALL # L+1 MOONMX # # SUBROUTINES USED # NEWANGLE # # INPUT # 6-7D = TIME # # ITEMS AVAILABLE FROM LAUNCH DATA # BSUBO, BDOT # TIMSUBO, NODIO, NODDOT, FSUBO, FDOT # COSI = COS(I) B-1 # SINI = SIN(I) B-1 # I IS THE ANGLE BETWEEN THE MEAN LUNAR EQUATORIAL PLANE AND THE # PLANE OF THE ECLIPTIC (1 DEGREE 32.1 MINUTES) # # OUTPUT # MMATRIX = 3X3 M MATRIX B-1 (STORED IN VAC AREA) MOONMX STQ SETPD EARTHMXX 8D AXT,1 # B REQUIRES SL 0, SL 5 IN NEWANGLE 5 DLOAD PDDL # PD 10D 8-9D=BSUBO BSUBO # 10-11D=BDOT BDOT PUSH CALL # PD 12D NEWANGLE # EXIT WITH PD 8D AND MPAC= B REVS B0 PUSH COS # PD 10D STODL COB # PD 8D COS(B) B-1 SIN # SIN(B) B-1 STODL SOB # SETUP INPUT FOR NEWANGLE FSUBO # 8-9D=FSUBO PDDL PUSH # PD 10D THEN 12D 10-11D=FDOT FDOT AXT,1 CALL # F REQUIRES SL 1, SL 6 IN NEWANGLE. 4 NEWANGLE # EXIT WITH PD 8D AND MPAC= F REVS B0 STODL AVECTR +2 # SAVE F TEMP NODIO # 8-9D=NODIO PDDL PUSH # PD 10D THEN 12D 10-11D=NODDOT NODDOT # MPAC=T AXT,1 CALL # NODE REQUIRES SL 0, SL 5 IN NEWANGLE 5 NEWANGLE # EXIT WITH PD 8D AND MPAC= NODI REVS B0 # Page 1144 PUSH COS # PD 10D 8-9D= NODI REVS B0 PUSH # PD 12D 10-11D= COS(NODI) B-1 STORE AVECTR DMP SL1R COB # COS(NODI) B-1 STODL BVECTR +2 # PD 10D 20-25D=AVECTR= COB*SIN(NODI) DMP SL1R # SOB*SIN(NODI) SOB STODL BVECTR +4 # PD 8D SIN PUSH # PD 10D -SIN(NODI) B-1 DCOMP # 26-31D=BVECTR= COB*COS(NODI) STODL BVECTR # PD 8D SOB*COS(NODI) AVECTR +2 # MOVE F FROM TEMP LOC. TO 504F STODL 504F DMP SL1R COB GOTO MOONMXA BANK 25 SETLOC PLANTIN3 BANK COUNT* $$/LUROT MOONMXA STODL AVECTR +2 SINNODI # 8-9D=SIN(NODI) B-1 DMP SL1R SOB STODL AVECTR +4 # 0 HI6ZEROS # 8-13D= CVECTR= -SOB B-1 PDDL DCOMP # PD 10D COB SOB PDDL PDVL # PD 12D THEN PD 14D COB BVECTR VXSC PDVL # PD 20D BVECTR*SINI B-2 SINI CVECTR VXSC VAD # PD 14D CVECTR*COSI B-2 COSI VSL1 STOVL MMATRIX +12D # PD 8D M2=BVECTR*SINI+CVECTR*COSI B-1 VXSC PDVL # PD 14D SINI # CVECTR*SINI B-2 BVECTR VXSC VSU # PD 8D BVECTR*COSI B-2 COSI VSL1 PDDL # PD 14D 504F # 8-13D=DVECTR=BVECTR*COSI-CVECTR*SINI B-1 COS VXSC # Page 1145 DVECTR PDDL SIN # PD 20D 14-19D= DVECTR*COSF B-2 504F VXSC VSU # PD 14D AVECTR*SINF B-2 AVECTR VSL1 STODL MMATRIX +6 # M1= AVECTR*SINF-DVECTR*COSF B-1 504F SIN VXSC # PD 8D PDDL COS # PD 14D 8-13D=DVECTR*SINF B-2 504F VXSC VAD # PD 8D AVECTR*COSF B-2 AVECTR VSL1 VCOMP STCALL MMATRIX # M0= -(AVECTR*COSF+DVECTR*SINF) B-1 EARTHMXX # COMPUTE X=X0+(XDOT)(T+T0) # 8-9D= X0 (REVS B-0), PUSHLOC SET AT 12D # 10-11D=XDOT (REVS/CSEC) SCALED B+23 FOR WEARTH,B+28 FOR NODDOT AND BDOT # AND B+27 FOR FDOT # X1=DIFFERENCE IN 23 AND SCALING OF XDOT, =0 FOR WEARTH, 5 FOR NDDOT AND # BDOT AND 4 FOR FDOT # 6-7D=T (CSEC B-28), TIMSUBO= (CSEC B-42 TRIPLE PREC.) NEWANGLE DLOAD SR # ENTER PD 12D 6D 14D TAD TLOAD # CHANGE MODE TO TP TIMSUBO MPAC STODL TIMSUBM # T+T0 CSEC B-42 TIMSUBM +1 DMP # PD 10D MULT BY XDOT IN 10-11D SL* DAD # PD 8D ADD X0 IN 8-9D AFTER SHIFTING 5,1 # SUCH THAT SCALING IS B-0 PUSH SLOAD # PD 10D SAVE PARTIAL (X0+XDOT*T) IN 8-9D TIMSUBM SL DMP 9D 10D # XDOT SL* DAD # PD 8D SHIFT SUCH THAT THIS PART OF X 10D,1 # IS SCALED REVS/CSEC B-0 BOV # TURN OFF OVERFLOW IF SET BY SHIFT +1 # INSTRUCTION BEFORE EXITING. RVQ # MPAC=X= X0+(XDOT)(T+T0) REVS B0 # Page 1146 # ***** EARTHMX SUBROUTINE ***** # SUBROUTINE TO COMPUTE THE TRANSFORMATION MATRIX M FOR THE EARTH # # CALLING SEQUENCE # L CALL # L+1 EARTHMX # # SUBROUTINE USED # NEWANGLE # # INPUT # INPUT AVAILABLE FROM LAUNCH DATA AZO REVS B-0 # TEPHEM CSEC B-42 # 6-7D= TIME CSEC B-28 # # OUTPUT # MMATRIX= 3X3 M MATRIX B-1 (STORED IN VAC AREA) BANK 26 SETLOC PLANTIN1 BANK COUNT* $$/LUROT EARTHMX STQ SETPD # SET 8-9D=AZO EARTHMXX 8D # 10-11D=WEARTH AXT,1 # FOR SL 5, AND SL 10 IN NEWANGLE 0 DLOAD PDDL # LEAVING PD SET AT 12D FOR NEWANGLE AZO WEARTH PUSH CALL NEWANGLE SETPD PUSH # 18-19D=504AZ 18D # COS(AZ) SIN(AZ) 0 COS PDDL # 20-37D= MMATRIX= -SIN(AZ) COS(AZ) 0 B-1 504AZ # 0 0 1 SIN PDDL HI6ZEROS PDDL SIN 504AZ DCOMP PDDL 504AZ COS PDVL HI6ZEROS PDDL PUSH HIDPHALF GOTO EARTHMXX # Page 1147 # ***** EARTHL SUBROUTINE ***** # SUBROUTINE TO COMPUTE L VECTOR FOR EARTH # # CALLING SEQUENCE # L CALL # L+1 EARTHL # # INPUT # AXO,AYO SET AT LAUNCH TIME WITH AYO IMMEDIATELY FOLLOWING AXO IN CORE # # OUTPUT # -AX # MPAC= -AY RADIANS B-0 # 0 BANK 06 SETLOC EARTHLOC BANK COUNT* $$/LUROT EARTHL DLOAD DCOMP AXO STODL 504LPL -AYO STODL 504LPL +2 LO6ZEROS STOVL 504LPL +4 504LPL RVQ # Page 1148 # CONSTANTS AND ERASABLE ASSIGNMENTS 1B1 = DP1/2 # 1 SCALED B-1 RPREXIT = S1 # R-TO-RP AND RP-TO-R SUBR EXIT EARTHMXX = S2 # EARTHMX, MOONMX SUBR. EXITS 504RPR = 0D # 6 REGS R OR RP VECTOR SINNODI = 8D # 2 SIN(NODI) DVECTR = 8D # 6 D VECTOR MOON CVECTR = 8D # 6 C VECTR MOON 504AZ = 18D # 2 AZ TIMSUBM = 14D # 3 TIME SUB M (MOON) T+T0 IN GETAZ 504LPL = 14D # 6 L OR LP VECTOR AVECTR = 20D # 6 A VECTOR (MOON) BVECTR = 26D # 6 B VECTOR (MOON) MMATRIX = 20D # 18 M MATRIX COB = 32D # 2 COS(B) B-1 SOB = 34D # 2 SIN(B) B-1 504F = 6D # 2 F(MOON)