I

179-73225

BELLCOMM, INC. 955 L'ENFANT PLAZA NORTH, S.W. WASHINGTON, D. C. 20024

SUBJECT: Distribution of t h e Final Report .DATE: October 7, 1968 a of the Apol lo Guidance Software

Task Force - Case 310 FROM: W. G. Heffron

IJIEMOHANDUM FOR FILE

This memorandum has been prepared to distribute

the Final Report of the Apollo Guidance Software Task

Force.

The Final Report has been reviewed by Task Force

members and signed by t h e Task Force's chairman, Dr. G. E.

Mueller--Associate Administrator for Manned Space Flight.

2014-WGH-bjh

Attachment

F I N A L R E P O R T

A P O L L O G U I D A N C E S O F T W A R E T A S K F O R C E

September 23, 1968

A P P R O V E D

/ C h a i r m a n

FINAL REPORT

APOLLO GUIDANCE SOFTWARE TASK FORCE

1. I n t r o d u c t i o n

T h i s i s t h e f i n a l r e p o r t o f t h e Apol lo Guidance

S o f t w a r e Task F o r c e , which was e s t a b l i s h e d by D r . G . E .

M u e l l e r , A s s o c i a t e A d m i n i s t r a t o r f o r Manned Space F l i g h t ,

NASA, a t t h e r e q u e s t o f L t . Gene ra l S. C . P h i l l i p s , USAF,

Apol lo Program D i r e c t o r .

The pu rpose o f t h e Task Force was s t a t e d i n a

l e t t e r d a t e d December 1 8 , 1967 from Dr. Muel l e r t o D r . R . R .

G i l r u t h , D i r e c t o r , Manned S p a c e c r a f t C e n t e r , as " t o d e t e r -

mine whe the r t h e r e are any a d d i t i o n a l a c t i o n s which cou ld be

t a k e n to improve t h e s o f t w a r e development and v e r i f i c a t i o n

p r o c e s s and o u r v i s i b i l i t y and c o n t r o l of i t . "

The Task Force was c h a i r e d by D r . Mue l l e r : member-

s h i p i s g i v e n i n E n c l o s u r e 1. F o u r t e e n mee t ings were h e l d

a t l o c a t i o n s and dates g iven i n E n c l o s u r e 2 . Minutes o f

t h e mee t ings were p u b l i s h e d and a c t i o n i tems were a s s i g n e d

and accompl ished . A l l are a v a i l a b l e from t h e s e c r e t a r i e s

o f t h e T a s k F o r c e ( g i v e n i n E n c l o s u r e 1).

T h i s f i n a l r e p o r t p r e s e n t s , b r i e f l y , t h e major

t o p i c s of d i s c u s s i o n , t h e Task F o r c e ' s recommendations f o r

f u r t h e r Apol lo Program a c t i o n and f o r t r e a t m e n t o f s o f t w a r e

i n advanced programs, and t h e c o n c l u s i o n s drawn b y t h e Task

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F o r c e as a r e s u l t of t h e p r e s e n t a t i o n s made t o i t by t h e

o r g a n i z a t i o n s i n v o l v e d . The minu tes and a c t i o n i tems s e r v e

as a f u l l r e p o r t on t h e Task F o r c e ' s a c t i v i t i e s .

2 . Major T o p i c s o f D i s c u s s i o n

Although t h e T a s k Force rev iewed a l l a s p e c t s of

s o f t w a r e development from i n i t i a l e s t a b l i s h m e n t o f r e q u i r e -

ments t o p o s t f l i g h t a n a l y s i s , t h e major t o p i c s o f d i s c u s s i o n

were as f o l l o w s :

1. The a s s i g n m e n t s o f r e s p o n s i b i l i t y and p a r t i c i p a t i o n

by t h e numerous o r g a n i z a t i o n s i n v o l v e d i n o r a f f e c t i n g

s o f t w a r e .

2 . C o o r d i n a t i o n and c o n t r o l , i n f o r m a l l y and th rough

documents and s p e c i f i c a t i o n s , as t h e y a f f e c t i n t e r f a c e s between

s o f t w a r e and hardware, s o f t w a r e and crew p r o c e d u r e s , r e q u i r e -

ments f o r s o f t w a r e , d e s i g n data r e q u i r e d f o r s o f t w a r e d e v e l -

opment and v e r i f i c a t i o n , and c o m p a t a b i l i t y between t h e

Pr imary Guidance Computer and t h e Abort Guidance System i n

t h e Lunar Module.

3. S o f t w a r e cod ing t e c h n i q u e s , p r o c e d u r e s and

management.

4 . S o f t w a r e s c h e d u l e per formance and v i s i b i l i t y .

5. S o f t w a r e t e s t i n g r e q u i r e m e n t s and ph i losophy .

6 . A p p l i c a t i o n of t r a i n e r s and h y b r i d s i m u l a t o r s t o

s o f t w a r e v e r i f i c a t i o n .

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3. Recommendations f o r t h e Apol lo Program

S e v e r a l recommendations o f t h e Task Force have

a l r e a d y been a c t e d upon. The f o l l o w i n g a d d i t i o n a l recom-

mendat i o n s a re made.

I. The d i f f i c u l t i e s i n s o f t w a r e development

r e f l e c t t h e c o m p l e x i t i e s o f t h e Apol lo m i s s i o n s and w i l l

c o n t i n u e t o r e q u i r e t o p l e v e l management a t t e n t i o n a t MSC

and MSFC. Management p r o c e d u r e s and working ar rangements

as p r e s e n t e d appear s a t i s f a c t o r y . S i n c e s o many o r g a n i z a -

t i o n s are i n v o l v e d , it i s recommended t h a t MSC and MSFC

p r o v i d e f o r m a l d e f i n i t i o n of t h e o r g a n i z a t i o n i n t e r f a c e s

and r e s p o n s i b i l i t i e s between MSC and MSFC, and i n t e r n a l l y t o

t h o s e c e n t e r s .

11. C o n t r o l o f c o n s t a n t s , c o o r d i n a t e s y s t e m s , ope ra -

t i o n a l data, d e f i n i t i o n o f s o f t w a r e v a r i a b l e s , was i d e n t i f i e d

as a c o n t i n u i n g problem i n s o f t w a r e development . The com-

p l e x i t y o f t h e Apol lo Sof tware i n t e n s i f i e s t h e Task F o r c e ' s

conce rn . The Task Force makes t h e f o l l o w i n g recommendations:

1. M S C , MSFC and K S C management s h o u l d s u p p o r t u s e o f Apo l lo Program S t a n d a r d s f o r P h y s i c a l C o n s t a n t s , Env i ronmen ta l Data and C o o r d i n a t e Axes, amending and e x t e n d i n g them as becomes n e c e s s a r y .

2 . The MSC Apol lo S p a c e c r a f t Program O f f i c e O p e r a t i o n a l Data C o n t r o l a c t i v i t y s h o u l d r e c e i v e c o n t i n u i n g management a t t e n t i o n and s u p p o r t . MSFC and K S C s h o u l d r ev iew t h i s e f f o r t i n a n a c t i v e e f f o r t t o improve t h e i r c u r r e n t data c o n t r o l methods.

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3. Working w i t h i n t h e p r e s e n t s i t u a t i o n , MSC and MSFC s h o u l d encourage s t a n d a r d i z a t i o n o f t h e symbols and names o f s o f t w a r e v a r i a b l e s , and promote unde r s t and- i n g o f t h e s e q u a n t i t i e s by r e q u i r i n g a p p r o p r i a t e t a b l e s of nomenc la tu re , d i c t i o n a r y - l i k e l i s t i n g s , e t c .

111. I n d e v e l o p i n g s o f t w a r e , MSC and MSFC shou ld

r e q u i r e c l e a r i d e n t i f i c a t i o n of a l l c o n d i t i o n s which c a u s e

s o f t w a r e program i n t e r l o c k s , e r r o r i n t e r r u p t s , r e d l i n e r e s t r i c -

t i o n s , e t c . , p r e f e r a b l y b y t h e s o f t w a r e programmer. These

s h o u l d b e rev iewed f o r a p p l i c a b i l i t y by o p e r a t i o n a l sys tem

g r o u p s .

I V . The Task Force e n d o r s e s t h e p l a n s f o r i n c r e a s e d

u s e o f h y b r i d s i m u l a t o r s and t r a i n e r s i n ha rdware / so f tware /

crew i n t e r f a c e v e r i f i c a t i o n and recommends Apol lo Program

O f f i c e c o n t i n u e d s u p p o r t o f t h i s a c t i v i t y .

V. The Task Force f e e l s t h a t s o f t w a r e t e s t i n g a t

K S C s h o u l d emphasize v e r i f i c a t i o n of i n t e r f a c e s , and o f t h e

i n t e g r i t y of t h e program. KSC s c h e d u l e s shou ld pe rmi t d e l i v -

e r y o f f l i g h t programs f o r b o t h t h e l aunch v e h i c l e and t h e

s p a c e c r a f t as l a t e as t h e Countdown Demonst ra t ion T e s t or t h e

F l i g h t Readiness T e s t , whichever i s e a r l i e r .

4 . Recommendations f o r Advanced Programs

F o r Space programs such as Apol lo A p p l i c a t i o n s ,

P l a n e t a r y Miss ions , e t c . , t h e Task Force draws t h e f o l l o w i n g

recommendations from Apol lo Program e x p e r i e n c e .

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1. Exper i enced p e r s o n n e l shou ld be a s s i g n e d t o t h e

advanced program as q u i c k l y as p o s s i b l e , r a the r t h a n u s e t h e

e a r l y s t a g e s of a n advanced program t o t r a i n i n e x p e r i e n c e d

p e o p l e .

2 . T e c h n i c a l o r g a n i z a t i o n s s h o u l d spend some 1 0 % o f

t h e i r t i m e on advanced programs, s o as t o promote t h e c a r r y

o v e r o f e x p e r i e n c e .

3. A t h o r o u g h , e a r l y , e f f o r t a t s y s t e m s e n g i n e e r i n g

i s as i m p o r t a n t f o r t h e crew/computer/spacecraft s y s t e m as

i t i s for hardware . The e f f o r t shou ld produce :

a. A d e t a i l e d System S p e c i f i c a t i o n , s u i t a b l e as a basis f o r s o f t w a r e and hardware development . Design r e q u i r e m e n t s s h o u l d b e d e t a i l e d and s p e c i f i c , accu racy and per formance r e q u i r e m e n t s s h o u l d be g i v e n , and i n t e r f a c e s p e c i f i c a t i o n s s h o u l d be tho rough and comple te .

b . An O p e r a t i o n s Handbook f o r t h e crew.

c . A d e t a i l e d m i s s i o n t i m e l i n e .

To i n s u r e these are r e a l i s t i c , t h e y shou ld be based

on m i s s i o n development and rehearsa l work i n a s u i t a b l e f u l l

s c a l e t r a i n e r , as w e l l as on a n a l y s i s .

4. There shou ld be a de l ibera te p o l i c y o f maximum

c a r r y o v e r of g u i d a n c e t e c h n i q u e s from e a r l i e r programs.

5. There s h o u l d be a s i m i l a r l y d e l i b e r a t e e f f o r t t o

promote s i m p l i c i t y .

6 . I n choos ing a computer , p a r t i c u l a r l y i n d e t e r m i n i n g

t h e q u a n t i t y of and t h e r a t i o between erasable and non-e rasab le

memory, t h e d i f f i c u l t i e s i n s o f t w a r e development shou ld weigh 0

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as heavily as the more traditional hardware aspects. While

a computer and its software do lend an element of flexibility,

experience teaches that software is more difficult to develop

than hardware, that, verification of software, in particular,

is a time consuming task.

7. In designing software, particular effort should be

placed on avoiding or mitigating redline restrictions, error

interrupts, program interlocks, etc. Those that remain should

be clearly identified.

8 . Present standardization of physical constants, envi-

ronmental data and coordinate axes should be extended to

include symbolic names and mathematical symbols for software

variables.

9 . Organizational structure and assignments should

stress accountability for performance as well as scope of

authority and responsibility. Panels, committees, e t c . ,

should be used to promote coordination and to formalize

agreements, but not as replacements for line organizations.

6. Conclusions

The Task Force draws the following conclusions:

1. It is in basic agreement with the present software

situation.

2. No major improvements remain to be made.

3. Software complexity requires a high level of com-

munication and participation by the many organizations

involved.

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4 . There i s a d e q u a t e s o f t w a r e s c h e d u l e c o n t r o l and

v i s i b i l i t y a t p r e s e n t , a l t h o u g h s c h e d u l e s and f l i g h t d a t e s

w i l l make s o f t w a r e a s u b j e c t o f c o n t i n u a l concern .

5. I n d e v e l o p i n g c o n f i d e n c e i n s o f t w a r e , f u l l advan tage

s h o u l d be t a k e n o f t h e s e v e r a l h y b r i d s i m u l a t o r s and t r a i n e r s .

C o o r d i n a t i o n o f a c t i v i t y and fo rma l f a i l u r e and d i s c r e p a n c y

r e p o r t i n g s y s t e m s must be c o n t i n u e d .

And, as a g e n e r a l c o n c l u s i o n , t h e Task F o r c e f e e l s

i t i s i m p o r t a n t t o r e c o g n i z e t h a t s o f t w a r e r e q u i r e m e n t s w i l l

a lways be dynamic. A s s u c h , s p e c i f i c a t i o n s and r e q u i r e m e n t s

w i l l n e v e r b e a v a i l a b l e i n a comfor t ab ly e a r l y t i m e frame.

T h i s w i l l a lways c a u s e a c c e l e r a t e d development s c h e d u l e s .

Apo l lo Program management must r e c o g n i z e , t h e r e f o r e , t h a t

s o f t w a r e w i l l r e q u i r e c o n t i n u a l a t t e n t i o n and e f f o r t t o

i n s u r e t i m e l i n e s s and s t a b i l i t y . And Advanced Programs s h o u l d

a t t e m p t , as e a r l y as p o s s i b l e , t o d e f i n e these r e q u i r e m e n t s

and s p e c i f i c a t i o n s s o as t o m i t i g a t e these problems.

7. Acknowledgment

The Task F o r c e f e e l s t h a t i t has been f u r n i s h e d f u l l

c o o p e r a t i o n and cand id t e s t i m o n y . The s i n c e r i t y and d e d i c a t i o n

of a l l members of t h e NASA team was a p p a r e n t . The i r de te rmi-

n a t i o n t o meet t h e c h a l l e n g e o f t h e Apol lo Program i s recog-

n i z e d , a p p r e c i a t e d , and commended.

BELLCOMM, INC.

ENCLOSURE 1

APOLLO GUIDANCE SOFTWARE TASK FORCE MEMBERSHIP

APOLLO GUIDANCE SOFTWARE TASK FORCE

CHAIRMAN:

Dr. George E. Mueller Associate Administrator for Manned Space Flight National Aeronautics and Space Administration 600 Independence Avenue, S. W. Washington, D. C. 20546

MEMBERS :

Mr. Kenneth F. Steffan Head, Guidance Dynamics Department Building A3-2093 Aerospace Corporation P. 0. Box 95085 Los Angeles, California 90049

Dr. D. R. Hagner Director, Apollo Applications Division Bellcomm, Inc. 955 L'Enfant Plaza North, S.W. Washington, D. C. 20024

(213) 648-6117

0

(202) 484-7654

Mr. James S. Martin, Jr Head, Advanced Space Projects Office (Unmanned) Langley Research Center (Mail Stop 159) National Aeronautics and Space Administration Langley Station Hampton, Virginia 23365 (703) 722-7961 - Ext. 3265 Mr. John P. Mayer Chief, Mission Planning and Analysis Division (FM) Manned Spacecraft Center National Aeronautics and Space Administration Houston, Texas 77058 (713) 483-3301

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(Members Cont'd.)

Mr. Ludie G. Richard Director, Technical Systems Office (R-TO-DIR) George C. Marshall Space Flight Center National Aeronautics and Space Administration Huntsville, Alabama 35812 (204) 877-3760

Mr. A. P. Boysen, Jr. Director, Mission Assignments Division Bellcomm, Inc. 955 L'Enfant Plaza North, S. W. Washington, D. C. 20024 (202) 484-7894

Mr. Leon R. Bush Director, Flight Operations, MOL Project Building 100-2061 Aerospace Corporation P. 0. Box 95085 Los Angeles, California 90049 (213) 648-5936

SUPPORTING MEMBERS:

Dr. Richard H. Battin Associate Director Instrumentation Laboratory Massachusetts Institute of Technology 75 Cambridge Parkway (MS73) Cambridge, Massachusetts 02142 (617) 864-6900 - EXt. 1295

Mr. Richard B. Hanrahan RTCC Project Manager International Business Machine Corporation 1322 Space Park Drive Houston, Texas 77058 (713) 591-3300 Mr. Clarence W. Pittman Manager, Mission Trajectory Control Program TRW Systems Group (Hl-2009) Space Park Drive Houston, Texas 77058 (713) 488-3530 - Ext. 2411

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SECRETARIES:

M r . Rober t V . Spe r ry Head, Guidance and C o n t r o l Department Bellcomm, I n c . 955 L 'Enfan t P l a z a North, S. W . Washington, D . C . 20024 ( 2 0 2 ) 484-7968

M r . W . Gordon Hef f ron Head, Guidance Program Ana lys i s Department Bellcomm, I n c . 955 L 'Enfant P l a z a North, S . W . Washington, D . C . 20024 ( 2 0 2 0 484-7970

ENCLOSURE 2

PLACES AND DATES OF TASK FORCE MEETINGS

APOLLO G U I D A N C E SOFTWARE TASK FORCE MEETINGS

Meet ing P l a c e Date

1 Manned S p a c e c r a f t C e n t e r , Houston, Texas Dec. 2 0 , 1967

2 . C h a r t e r h o u s e H o t e l , Cambridge, Mass. J a n . 4 , 1968

3 . M a s s a c h u s e t t s I n s t i t u t e o f Technology, J a n . 5 , 1 9 6 8

4 . NASA H e a d q u a r t e r s , Washington, D . C . J a n . 1 6 , 1968

5. TRW Sys tems, Redondo Beach, C a l i f . J a n . 2 4 , 1368

6 . North American Rockwell C o r p o r a t i o n , J a n . 2 5 , 1 9 6 8

Cambridge, Mass.

Downey, C a l i f o r n i a

7 . Grumman A i r c r a f t E n g i n e e r i n g C o r p o r a t i o n , Feb. 3, 1 9 6 8 Bethpage , N . Y .

8 . NASA H e a d q u a r t e r s , Washington, D . C . Feb. 9 , 1 9 6 8

9. J . F. Kennedy Space C e n t e r , Cape Kennedy, F l o r i d a

Feb. 1 8 , 1968

1 0 . G . C . M a r s h a l l Space F l i g h t C e n t e r , Feb. 2 3 , 1 9 6 8 H u n t s v i l l e , Alabama

11. Hol iday I n n , Nassau B a y , Texas March 1, 1968

1 2 . Manned S p a c e c r a f t C e n t e r , Houston, Texas March 2&3, 1968

1 3 Manned S p a c e c r a f t C e n t e r , Houston, Texas May 2 0 , 1968

1 4 . Manned S p a c e c r a f t C e n t e r , Houston, Texas J u l y 1 2 , 1968

BELLCOMM, INC. SUBJECT: Distribution of the Final Report FROM: W. G. Heffron

of the Apollo Guidance Software Task Force - Case 310

DISTRIBUTION

Task Force Members Messrs. R. H.

NASA

MSC -

MSFC

KSC -

A. P. L. R. D. R. R. B. J. P. J. S. G. E. c. w. L. G. R. V. K. F.

R. 0. L. D. J. K. T. A. J. R. H. T. s. c. J. B. G. C.

R. G. c. c. L. c. R. A. T. F. R. R. G. M. J. C.

Battin - MIT Boysen, Jr. - Bellcomm Bush - Aerospace Corporation Hagner - Bellcomm/MLS Hanrahan - IBM Mayer - MSC/FM Martin - NASA/Langley Station Mueller - NASA/M Pittman - TRW Richard - MSFC/R-TO-DIR Sperry - Bellcomm/MAS Steff'an - Aerospace Corporation

Aller/MAO Day/MAT Holcomb/MAO K e e gan/MA Kuba t /MP Luskin/ML Phillips/MA Skaggs/MAP White, Jr./MAR

Chilton/EG Kraf t/FA Dunseith/FS Gardiner/EG Gibson/FS5 Gilruth/AA Low/PA Stokes/FS5

E. O'Cennor/I-DIR L. B. James/I-V-MGR F. A. Speer/I-140-MGR W. von Braun

K. H. Dehcs H. F. Gruene/LV R. 0. Middleton/AP R. A. Petrone/LO J. Williams/LS

BELLCOMM, INC.

D i s t r i b u t i o n c o n t i n u e d

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Bellcomm, I n c . Messrs. D. A . Chisholm

D. A . DeGraaf I . M . Ross J . W . Timko R. L . Wagner

C e n t r a l Files 4 CODY TO

Department 1 0 2 4 F i l e L i b r a r y