NASA Technical Memorandum 102297 

Photovoltaic Module On-Orbit Assembly 

for Space Station Freedom 

T. Sours 

Lewis Research Center 

Cleveland, Ohio 

R. Lovely and D. Clark 

Rockwell International 

Rocketdyne Division 

Canoga Park, California 

Prepared for the 

24th Intersociety Energy Conversion Engineering Conference 

cosponsored by the IEEE, AIAA, ANS, ASME, SAE, ACS, and AIChE 

Washington, D. C . , August 6- 1 1, 1989 

[NASA-TH- 102297) PHOTOVOLTAIC MODULE N09-26887 

ON-ORBIT ASSEHBLY FOR SPACE STATION FREEDOH 

(MAS$. Lev& Research Center) 10 pCSCL 228 Unclas 

63/10 . .1)224221 
PHOTOVOLTAIC MODULE ON-ORBIT ASSEMBLY 

FOR SPACE STATION FREEDOM 

T. Sours 

NASA Lewis Research Center 

Cleveland, OH 44135 

and 

R. Lovely and D. Clark 

Rocketdyne Division, Rockwell International 

Canoga Park, CA 

ABSTRACT 

One of tlie elements of tlie Space Station 

F re ed o in pu\\. e r s y s t e ni i s tlie Ph ot o\,u I t ;i i c 

(PV) module. These nioclitles \vi11 be 

assembled on-orbit cluring the assembl!. 

phase of tlic program. These nioclules will 

be risseniblecl either from the shirttle orbiter 

or from the Mobile Servicing Center (,MSC). 

This paper clescribes the different types of 

assenibl). operations that \vi11 be used to 

assemble PV Modules. 

1. Introduction 

Freedom \\,ill be constructed on-orbit 

beginning in the mid 1990's. The 

construction of Freecloni will reclitirc- abnctt 

t\ve ti ty N a t iona I Space Tra ti spur ta I ion 

System (NSTS) missions over a period of 

three years. The on-orbit configuration and 

assembly sequence are in the process of 

being optimizeel to satisfy program and 

NSTS requirements that must be qatisfiecl. 

In orcler to ensure that the station can be 

a sse ni blj, opera tio tis recp i re me ti t s in us t be 

considered early in the design phase of tlie 

f 1 i g h t ha rclwa re. Tlie c 11 rre n t base I i ne 

configiiration \vith four PV Modules is sh0Lj.n 

in Figure 1. 

successfu I ly assemblecl on-orbi t. the 

1.1 Assembly Reclitil-enients 

During the baseline phase. Freedom \\.ill be 

po~~erecl by phot o\ o I t a i c in ucl it I e s . h 1 C) IT 

po\\~ I- ge tierat ion capLibi I i 1) nil I bc aclclccl 

\\, i t h e i 1 he r phot in c) I ta i c in ucl it I e s or \\,it 11 

solar cl).namic mocliilcs clitring \lie ?I-()\\ 111 

phase. 

Each assenibl), mission in the assembly 

sequence will lea1.e on-orbit a full!. 

functional and sur\.i\able spacecraft. The 

effect of failed ecluiimient on-orbit and the 

sit bsequeti t reclir i red ma i ti tena lice a tic1 

logistics during the assenibl). phase iiiiist 

also be considered. Tlie asseriihly seclltence 

ti1 us t a I so si1 ppori co ti t i nge ncy and a boi- t 

operations 01' the NSI'S. 1 lie launch 

manifest for each mission must meet all of 

the orbiter constraints on volunie, mass, 

center-of-mass, phj.sica1 clearances, saietj.. 

stritctitral ititegrit!, and otlier NSTS 

recl it i re in e tits . Tlie o ti -CI r b i t ope ratio ti s ni it 5 t 

not esceecl tlie a\ ailable EVA. lV,4. po\\er. 

poi ti ti ng capa hi I i t!, ancl other resources 

a \.a i I ab I e cl it r i ng t lie ;.I s se in b I y plia se . 

One of the objectij es of the assembly 

sequence is to prevent the need for "tIiro\v 

awaj." hard\\.are that \+ill only be used to 

temporarily support Freedom during its 

~- 

1 
assembly phase. The goal is to build 

Freedom in such a way that each piece of 

equipnient is installed in its operating 

location without the need to remove or 

relocate it at a later point in the assembly 

sequence. i 

1.2 On-Orbit Assembly Operations 

Since the Space Station Freedom Program is 

still in a definition phase, the concepts for 

the various systems are in a state of flus. 

This work is part of ongoing activities in the 

area of on-orbit assembly planninp. As the 

design pi-ocess progresses this work will be 

refined to ensure the successful integration 

between systems on the station. Extensive 

ccmpitter simulation \vi11 be used during this 

j)rocess. This will be complemented by 

neutral buoyancy testing of selected 

ha rclwa re. S hii t t le fl ig h t demonstrations wi I I 

be used prior to the start of the space station 

assembly process to verify the performance 

of the telerobotic systems. 

2. Electric Power System 

'I'he NASA Lewis Research Center has the 

responsibility to produce the electric power 

system (EPS) for Space Station Freedom. 

The Rocketdyne division of Rockwell 

International Corporation in Canoga Park, 

California is the prime contractor for this 

effort. This includes the design, 

&\.e lo pine n t . ma nu f ac t ur i ng . as se in bl y 

p I ann i n g an cl ni a in te n a nce p 1 a n ti i ng for the 

e n d - t o -e n cl s )rs t e in a r c Ii i t e c t u re. 

The tu.0 main parts of the power system are 

the Solar Power Modules for power 

generation and energy storage and tlie Po\\.er 

Management and Distribution System which 

\vi11 manage and deliver power to the user 

systems. 131 

I 

-. I he space station will be powered l>js i\\o 

solar power modules. These solar power 

modules will be built up from a combination 

of solar photovoltaic (PV) modules ancl 

solar dynamic (SD) modules. The port ancl 

starboard solar power modules on the station 

will be intercliangeable. 

The solar power modules are located on 

either end of the transverse boom. The\. are 

separated from the rest of tlie station b). 

alpha gimbals. The purpose of this ginihril is 

to provide siin tracking of the solar pu\\-ttimodules. The alpha gimbals niiist mahe one 

complete i-e\.olution for each orbit of the 

Earth. The station \vi11 be in a circular orbit. 

220 nautical miles above the Earth surface 

with a 28.5 degree inclination to the ecliiator. 

In this orbit a satellite \sill take ninetj. 

minutes to circle the globe. 

2.1 PV Module Description 

The PV module consists of three large 

components that \vi11 to be installed onto tlie 

space station truss. These are the Integrated 

Eclitipnient Assenibly (IEA) and tuto Beta 

Gimbal/Solar Arm). (BG/SA) assemblies. 

The I n tegra t ecl Eq ii i pine 11 t Assenibl}. ( 1 EA) 

will be pre-integratecl on the ground during 

u ground processing. It will contain the battery 

and PMAD Orbital Replacement Units 

(ORU) for one PV module. On-orbit the 

IEA will be attached to the truss, tlie 

e I ec t r i ca I con n ec t i ci ti s in ate cl a ncl the 

cleplol.able pumped loop radiator \\,ill be 

deplojwl. The thernial cooling loop tiill not 

reqiiire an). fluid connections to be macle 

on -orbit . 

The beta gimbal and the solar array \\rill also 

be preintegratecl on tlie ground. On-orbit 

they will be instailed in the truss ancl their 

I 2 
I” 

respective electrical connections mated. No 

active cooling of these devices is required. 

The inboard PV moclule will include two 

bays of space station truss, cable trays, EVA 

System hardware as well as the components 

mentioned above. The outboard PV 

Modules will be the same as the inboard 

modules with tlie addition of two truss bays 

to provide clearance from the inboard 

in odu les . 

The PV module launch package consists of 

the Integratecl Equipment Assembly, two 

Beta Gimbal / Solar Array Assemblies, Truss 

and Utilities. The launch cradle to support 

these items during the launch phase of the 

NSTS mission is built into tlie structure of 

tlie IEA. 

3. On-orbit Assembly Operations 

Careful planning is being done to ensure that 

the station can be assembled on-orbit. Crew 

time, equipment, data, power and other 

resoiirces all must be utilized to perform the 

on-orbit assembly. One goal of assembly 

planning is to minimize the EVA time that is 

required to assemble the station. This will 

be accomplished bq designing tlie flight 

hardware such that it is easily assembled 

on-orbit and through the use of telerobotic 

devices to aid the astronauts in their tasks. 

As Freecloni grows the assembly operations 

will be supported increasingly by station 

based resources. The Mobile Transporter 

(MT) will be powered by the NSTS on the 

first missions and from the station EPS. on 

later flights. The EVA and IVA astronauts 

\\,ill be supplied b) either system. As tlie 

station grows it will become less dependent 

on a visiting orbiter for assembly resources. 

When Freedom reaches its’ Permanently 

Maimed Capability (PMC) assembly 

activities can be conducted \vithoiit tlie 

presence of an orbiter. 

EVA astronauts will perfoi-m the majority of 

the assembly tasks on the station. The IVA 

crew will be able to manipulate the 

Astronaut Positioning Systems ( APS’s) to 

position tlie EVA astronauts for assemble 

operations. [SI 

Translation of crew and equipment is one of 

tlie most time consuming tasks of station 

assembly. Though the use of remotel!- 

operated nia ii i pu I a tors and as t rona 11 t

positioning aids a portion of the assembly 

\vork load will be shifted from the EVA ere\\. 

to tlie IVA crew. The function of ecluipnient 

retrieval and ci-e\\. positioning \\:ill be 

perfornied by IVA astronauts operating the 

robotic systems on the station and shuttle. 

The EVA astronauts \vi11 be able to more 

effecti\-ely use their time to perforni those 

tasks that require the desterous capabilit!-. 

The Flight Telerobotic Sen icer (FTS) \\ill be 

a\ailable to support Mobile Sen icing Center 

(MSC) based assembly ot the PV module5 

161 It may be niounted onto the Space 

Station Remote Manipulator System 

(SSRMS) to assist in PV module assembl~. 

The SSRMS will be used to release the PV 

module components from tlie launch cradle. 

It \\ill also sense as an alignment and 

stabilization aid for the EVA a4tronaiits as 

the! install the tran\ition qtructures bet\ieen 

the PV coniponent\ and tlie space station 

t I-US s . 

Fo r t 11 me EPS e I e ni e n ts req 11 iring a 11 tom a ted 

cle p I o y me n t the 

deployment sequence will be controlled by 

( so I a r a r raq bl a ii ke t s) 

3 
IVA ere". A Iwckup deployment method \,ia 

EVA must be available for each automated 

de p I ojme n t seq it ence . 

4. NSTS Based Assembly 

Operations 

The current assembly sequence [ 1 I nianifests 

a PV Module on the first assembly mission. 

This first element launch (FEL) will be 

constructecl out of the cargo bay of an 

orbiter \eliicle. The orbiter will serve as a 

base of operations for this activity. The MT 

will include the AI’S. This tle\.ice will 

transport and position EVA ast~*onauts so 

that the). can effectively assemble and later 

niai ntai ti Freedom. 

On the FEL, the equipment that will provicle 

tlie needed assembly capabilitj. must be 

includecl as \vel1 as all of the systems that 

constitute a function on the station. The 

Asseiiibl). Work Platform (AWP) \\.ill be the 

first item to be assembled on-orbit. This 

cle\.ice pro\licles a stand-off from the cargo 

baj. and a stable frame to assemble the truss 

in. The MT is mounted on the out\i:arcl encl 

of the AWP. This de\,ice u.ill securely hold 

the nocles of the truss as it is asseniblecl and 

the proper equipment installed. The MT \\fill 

be used to translate bays of the truss away 

From the orbiter as they are completed. 

During the assembly of the first two PV 

modules there will be a limit of two six hour 

long EVA periocls that can be utilized to 

perform the necessary EVA asseriihly 

opera t io tis. 

4.1 NSTS Based Assembly Scenario 

The assemblj- of the PV Module \vi11 begin 

after the AWP and MT have been erected in 

the orbiter cargo bay and checked out. The 

first bay of truss will then be erected. 121 

This hay will contain 11ie I3eta Gimbals aid 

the i r respective tra ii s i t ion structures . ~ I’he 

AWP, MT aid this first asseniblecl ba! of 

truss is illustrated in Figure 2. 

The SRMS will retrie\.e the first beta 

gimbal/solar array fro111 the cargo bay and 

position it into the face of the truss so that 

the EVA astronauts can attach it to tlie beta 

transition structures. The MT will rotate the 

asseiiibljr 180 degrees to allniv for the 

installation 01’ the second heta pinibal/ solar 

array. This it. sho\\n in Figure 3. 

The MT will rotate 00 clegr-ees am1 the EVA 

crew \\,ill install the utilitj. tra1.s onto the beta 

gimbals and begin assembly of tlie second 

bay of ti-uss. The SRMS \\ill retrie\.e ancl 

position the IEA inlo the center of this ir~tsy 

baj, as it is hiiilt. Figiire 4 sho\\.s an EVA 

a st ro n aut i tis t a I I i ng t ti e t rn ii s it i c) ti s t 1-11 c t u re 

that secures tlie IEA in place. 

The next step is for the E\’,4 ere\\. to unlatch 

ancl deploy the radiator. The PV Moclule at 

the conclusioii of the EVA acti\.ities is sIio\\m 

in Figure 5. 

The first PV Module \vi11 be one item on tlie 

launch manifest for this assembly mission. 

After its‘ assernbl>. the crew will assemble 

the remaining equipment to produce the 

configuration illustrated in Figure 6. 

5. MSC Based Assembly 

0 p e ra ti o 11s 

The MSC \\ill be used as the base 01 

operations fo I- a sse iii b I j ;I c t i 1.i t i es that must 

be conductecl a\\’a), from the dochecl orbiter. 

The MSC \\.ill be transported on tlie truss b!. 

the MT. The MSC.‘ \\rill pro\.ide for the 

temporary stowage of equipment on its base 

structure as well as a manipulator arm 

similar to those on the orbiter fleet. The 

4 
SSRMS will provide equipment retrieval and 

positioning capability to support on-orbit 

operations. 141 

The second PV module delivered to orbit will 

be assembled using the MSC. In this second 

PV module assembly mission the launch 

packaged PV module must be removed from 

the cargo bay and attached to the MSC for 

transportation to the assembly operations 

site. 

IVA astronauts usill be used during assembly 

operations to control the various telerobotic 

equipment that will support tlie assembly 

activities being concluctecl external to tlie 

1) res s 11 r i z ecl en v i ro n ni e n t of the station. 

Tlie S h i I t t I e Re mote Man i pu 1 a tor S y s t e ni 

(SRMS) will be used to remove equipment 

from the cargo bay of tlie orbiter. The 

equipment will then be handed off to the 

SSRMS and sto\vecl on the MSC. 

The SSRMS is [lie station version of the 

c;liiittle arm. 1.11 It will be used to retrieLfe 

and position EVA cre\v and equipment. The 

SSRMS \\*ill be capable of being operated 

from within the pressurized living 

eriviroiiiiieiit of the station, from 

or from an EVA control station. 

No EVA crew will be needed 

items from the cargo bay and 

onto the MSC. The Truss 

packages and the transition 

an orbiter. 

to remove 

stow them 

struthode 

Striictii re 

packages \\ill be teniporariI~ stowed onto tlie 

MSC for transportation to tlie assembly 

operations site. 

5.1 MSC Based Assembly Scenario 

After the orbiter has docked to the station 

the PV modules will be transferred to the 

Mobile Servicing Center. To do this the 

orbiter SRMS will grasp a grapple fi\tiire 

located on the PV module cradle. The 

SRMS will then remoire the PV niocliile 

launch package from the cargo bay and 

position it so that tlie station’s SSRMS can 

grasp a second grapple fixture. After this is 

accomplished the SRMS will release its 

grapple fixture so that the SSRMS will be 

free to position tlie PV Launch Package onto 

the MSC base unit. The PV launch package 

is secured onto the MSC by a third grapple 

fixture on the launcli cradle \\it11 3 

corresponding capture mechanisni located on 

the body of tlie MSC. 

The t 1-11 ss s t riic t 11 re 1x1 c ha ?e, the t 1-a n \ it i c) n 

structure package and tlie cirilitl tl-a! 

package \\/ill siiiiilarl) be renio\wl from the 

cargo baj and sto\\ecl onto the h1SC. 

This process of removing the PV ninclirle 

from tlie cargo bal and sto\zing it onto tlie 

MSC will be c01itro11ecl bj. tlie IVA ere\\ 

without the aid of FVA astronauts. 

When all of the items recliiired to birilcl one 

PV module have been reriio\ ecl ti-om the 

orbiter and stowed for transport. the Mobile 

Transporter \\ill then besin its \lo\\ joiirne) 

to the work location. 

The station IVA crew will coniniancl the 

alpha gimbal to stop and align itself so that 

the MT can make the alpha gimbal crossing. 

The MT nil1 tra\el to the \\orb site am1 \top. 

As\eriiblj of the outboard PV nioclule begins 

\\ rth the a-ri\al of (lie El 4 ci-e\\ 171. Tlie 

EVA cre\v I\ ill be tran\portecl trum the 

airloch to tlie assenibly operations site b) the 

Crew and Eqirii~nient Translation Aid 

(CETA). 

5 
Tlie EVA crew will ingress the APS foot 

restraints and prepare the utility deployment 

device. 

The will then index forward one truss 

bay. As it indexes the utility deployer will 

deploy five nieters of utility tray. The EVA 

astronauts will secure the deployed utility 

trays to the truss structure. The APS will 

IJosition the EVA astronauts so that they can 

remaining bays will be constructed in a 

similar fashion. The last bay of truss \\.ill 

not have cliagoiials on tlie upper aiicl lower 

faces in orcler to allow the beta gimbals to be 

placed in tlie center of those truss faces. 

Figure 7 illustrates truss asseiiibly. 

After the truss structure has been assembled. 

the PV nioclule components \\.ill be installed. 

The SSRMS \$fill grapple tlie upper beta 

giiiibal/solar arraj. package and reposition it 

into the center of the truss face to be 

iiistallecl. Tlie EVA crew \\ill attach tlie 

transition struts to the corners of the truss 

face. The lo\\~r beta ginibal/solar arra}' \?rill 

be installed in a similar fashion. Alter the 

he t a g i in ba I /so I a r sec u re I y 

fastened to the triiss structure. The EVA 

crew will retrieve the transition utility tray 

and install them onto the beta gimbals. This 

is illustratecl in Figure 8. 

A diagonal truss strut will be renio\'ed from 

the adjacent truss ba). to allow for IEA 

installatioii. The SSRMS \f.ill grapple the 

(EA and reposition it into the center of the 

truss bajr. The SSRMS c\pill be used to align 

ma ke t lie needed co ti tie c t i o ti s . 'r 11 

a rra y s a re 

and stabilize the large IEA so that the EVA 

crew can install the transition structure tliat 

secures it to the truss. The installed IEA is 

illustrated in Figure 9. Tlie EVA astronauts 

will complete their tasks by deploying the 

piimpecl lool, radiator aticl installins the 

transition utility tray. The assembled PV 

Module is illustratecl in Figure 10. 

VII. References 

1 .20/13 Assembly Sequence: Space Station 

Freecloni Progrnni 

2. Watson. Iirclith I. : et. al.: Mubilc 

hii s porter Test Res 11 I I s - An As sc ti1 b I! 

Concept tor Space Stat ion atid Large Spicc 

Structures, NASA TM 100661, August 19SS. 

3. Rockwell I ti te I- na t i o tia I . Roclie trl!.ne 

Division : Po\ver S1,stein Desci-iptiuii 

Document, RIiRD 8S433. 2s October 19SS 

4. SPAR Aerospace. Preseiita t io ti tu 

representatic.es of tlie NASA Leivis Reseal-ch 

Ce ti te r , Meet i ng in Tor oii t 0. Ca iiacla , .I 11 I l,, 

1988. 

5. McDunneI Douglas Aeronautics ancl 

As t 1-011 a it t i c s Co I- poi-a t i on. Pr e se ti t a t i on to t h e 

EVA System Worliing GI-oup. Meeting at 

(7. NASA G oclcl a rcl S 1x1 ce F I ig 11 t Ce ti te r . Presentation at the FTS Implenientation 

Meeting, Meeting at Cleveland, OH. 

November, 1988. 

7. Sours, Thomas J. ; A Definition Study of 

the On-orbit ,Assembl>. Operations for tlie 

Out boa rcl Plio t o\'o I t a i c Po\\.er M oclu le s for 

Space Station Freeclotii. N,4S.4 Thl 102006. 

hlarc11 1c)sc). 

Iioustoll.T'\, IlIl\~. 198s. 

6 
\ \ \ \ -RcslmouLT 

w \ - us.uJ3.HIByQxILEs - LffiIs~suor)uE 

Figure 1 Space Station Freedom Configuration 

Figure 2 Assemble First Truss Bay 

Figure 4 Install IEA 

Figure 3 Install Beta Gimbal / Solar Array 

Figure 5 Assembled PV Module 

7 
S-Band Antennal 

Stbd, Inboard 

PV Power Module -+ 

Figure 7 Assemble Truss Bays Figure 8 Install Beta Gimbal/Solar Arrays 

Figure 9 Install IEA 

ORIGSKAL PAGE IS 

OF POOR QUALITY 8 
National Aeronautics and 

1. Report No. 2. Government Accession No. 

NASA TM-102297 

Report Documentation Page 

3. Recipient's Catalog No. 

4. Title and Subtitle 5. Report Date 

Photovoltaic Module On-Orbit Assembly for Space Station Freedom I 

7. Author@) 

I 6. Performing Organization Code 

8. Performing Organization Report No. 

9. Performing Organization Name and Address 

National Aeronautics and Space Administration 

Lewis Research Center 

Cleveland, Ohio 44135-3191 

12. Sponsoring Agency Name and Address 

National Aeronautics and Space Administration 

Washington, D.C. 20546-0001 

T. Sours, R. Lovely, and D. Clark 

10. Work Unit No. 

474- 18- 10 

11. Contract or Grant No. 

13. Type of Report and Period Covered 

Technical Memorandum 

14. Sponsoring Agency Code 

I E-4973 

19. Security Classif. (of this report) 20. Security Classif. (of this page) 

Unclassified Unclassified 

21. No of pages 22. Price' 

10 A02 

16. Abstract 

One of the elements of the Space Station Freedom power system is the Photovoltaic (PV) module. These modules 

will be assembled on-orbit during the assembly phase of the program. These modules will be assembled either 

from the shuttle orbiter or from the Mobile Servicing Center (MSC). This paper describes the different types of 

assembly operations that will be used to assemble PV Modules. 

17. Key Words (Suggested by Author(s)) 

Space Station 

EVA 

Assembly 

PV module 

18. Distribution Statement 

Unclassified - Unlimited 

Subject Category 18