BR-144

October 1999

Directorate of Manned Spaceflight and MicrogravityDirection des Vols Habités et de la Microgravité

Columbus: Europe’sLaboratory on the International Space Station

Columbus:Europe’sLaboratory on theInternationalSpace Station

BR-144October 1999

Directorate of Manned Spaceflight and MicrogravityDirection des Vols Habités et de la Microgravité

Contents

In the Beginning... 4

Columbus Characteristics 8Payload Accommodation and Resources 8Physical Characteristics 10Functional Architecture 11

Industrial Consortium 24

Columbus Development 26Overall Principles 26‘Model’ Philosophy and Commonality 26Software Development 28Development Status 29

System Level 29Software Level 31Subsystem/Equipment Level 31

Project Difficulties and Their Resolutions 32

Utilisation and Facility Development 33

Ground Segment and Training 36

Columbus Launch and ISS Assembly Sequence 38

Conclusions 39

Acronyms & Abbreviations 40

Further information on ESA and its participation in the International SpaceStation can be found at http://www.estec.esa.nl/spaceflight/

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Fig. 1a. The InternationalSpace Station as it will

appear after completionin 2004. (ESA/D. Ducros)

Fig. 1a. ESA’s Columbus module is ageneral-purpose laboratory.(ESA/D. Ducros)

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In the Beginning...

In October 1995, at their meeting inToulouse, the ESA Council met atMinisterial level and approved theprogramme ‘European Participation inthe International Space Station Alpha’ –some 10 years after the authorisation ofstudies and Phase B work by theMinisterial Council at Den Haag in 1985.During that 10-year period, a variety offlight elements and associated groundinfrastructure was studied and developedin parallel with coherent work on theAriane-5 and Hermes programmes, whichall led to integrated European scenariosthat were clearly unaffordable. Therefore,in late 1994, a series of dramaticprogrammatic cutbacks was introduced,which underwent frequent iterationswith ESA Member States and the SpaceStation Partners, in particular the US. Theprocess culminated in a package worthsome EUR2.6 billion being approved inToulouse.

This approved programme consisted of:

• the Columbus laboratory developmentand launch (at that time called theColumbus Orbital Facility, or COF, butnow simply Columbus, Fig. 1a), amodule permanently attached to theInternational Space Station (Fig. 1b) forconducting scientific experiments,research and development;

• the Automated Transfer Vehicle (ATV),a logistics vehicle launched by Ariane-5for uploading research and systemequipment, gases and propellant, andthe destructive downloading of Stationtrash;

• Station utilisation preparation andastronaut-related activities;

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• studies of a European Crew TransportVehicle (CTV), leading to involvementin the X-38 demonstrator and possibleparticipation in the Crew ReturnVehicle (CRV);

• exploitation of the results of theAtmospheric Reentry Demonstrator(developed under the Hermesprogramme) for ATV and CTV.

The ISS consists of pressurised andunpressurised elements, including:

• laboratory modules from the US, ESA,Japan and Russia;

• a robotic manipulator system from theCanadian Space Agency;

• interconnecting Nodes and crewhabitation quarters;

• a service module, a control module,docking modules and an airlock;

• crew transfer and crew rescue vehicles;

• truss structures supporting solargenerators, radiators and exposedpayload platforms.

After initial assembly, the Station will bepermanently manned by up to sevencrew members drawn from all five of thePartners. Assembly began at the end of1998 and is planned for completion in 2004.

Europe and the International Space Station

European involvement in manned spaceflight stretches back to 1969, when NASA issued aninvitation to participate in the post-Apollo programme. Europe opted in 1972 to develop themodular Spacelab as an integral element of the Space Shuttle. Spacelab’s 22 missions betweenNovember 1983 and April 1998 made outstanding contributions to astronomy, life sciences,atmospheric physics, Earth observation and materials science.

Participation in the International Space Station now takes Europe to the front rank of mannedspace flight. For the first time, more than 40 years after the dawn of the Space Age, scientists andengineers will maintain a permanent international presence in space. While orbiting at an averagealtitude of 400 km, they will continuously perform scientific and technological tests usinglaboratories comparable with the best on Earth. The Station will be a research base like those builtin the Antarctic, but it uniquely involves five international Partners (USA, Europe, Japan, Russiaand Canada) and embraces most fields of science and technology.

Physicists, engineers, physicians and biologists will work together pursuing fundamental researchand seeking commercially-oriented applications. Research will extend far beyond fundamentalgoals such as puzzling over the mysteries of life: the Station will be a test centre for developinginnovative technologies and processes, speeding their introduction into all areas of our lives.

Fully assembled after 5 years, the International Space Station will total about 420 t in orbit andoffer 1300 m3 of habitable volume. With a length of 108 m, span of 74 m and vast solar panels, itwill shelter a permanent crew of three astronauts during the assembly phase and 6-7 once itbecomes fully operational in 2004. There will be six laboratories. The US will provide one plus ahabitation module; there will be European, Japanese and Russian research modules, allmaintained with Earth-like atmospheres. Additional research facilities will be available in theconnecting Nodes. The central 90 m Truss connecting the modules and the main solar powerarrays will also carry Canada’s 17 m-long Remote Manipulator System robot arm on a mobile baseto perform assembly and maintenance work. An emergency crew return vehicle – initially aRussian Soyuz and later a Crew Return Vehicle (with ESA involvement) – will always be dockedonce permanent habitation begins in early 2000.

ESA’s major contribution to the Station is the Columbus laboratory. Columbus will provide Europewith experience of continuous exploitation of an orbital facility, operated from its own groundcontrol facility in Oberpfaffenhofen, Germany. In this pressurised laboratory, European astronautsand their international counterparts can work in a comfortable shirtsleeve environment. This state-of-the-art workplace, launched in early 2004, will support the most sophisticated research inweightlessness for at least 10 years. Columbus is designed as a general-purpose laboratory,accommodating astronauts and experiments studying life sciences, materials processes, technologydevelopment, fluid sciences, fundamental physics and other disciplines.

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The Columbus laboratory is thecornerstone of Europe’s participation inthis enormous international undertaking.It will be positioned on the starboard sideof the Station’s leading edge.

Following quickly after the ToulouseMinisterial conference, a contract wassigned between ESA and its PrimeContractor, Daimler Benz Aerospace (nowDaimlerChrysler Aerospace), DASA, inMarch 1996, at a fixed price ofEUR658 million, the largest singlecontract ever awarded by the Agency atthat time. DASA heads a consortium ofcontractors reflecting the cream ofEurope’s industrial expertise in mannedspace, developed as a result of theSpacelab programme, and which will bedescribed in more detail later in thisbrochure.

ESA’s Exploitation Programme for 2000-2013 was presented at the MinisterialCouncil meeting in Brussels in May 1999,where the overall programme approach

and the initial phase of activities wereapproved. The programme will be carriedout in 5-year phases, each with a 3-yearfirm commitment and a 2-year provisionalcommitment. The programme covers theSystem Operations costs in Europe, theESA share of the overall Station CommonOperations costs and the EuropeanUtilisation-related costs. The averageyearly cost over the whole period will beabout EUR280 million, in 1998 economicconditions.

This brochure describes the characteristicsof the Columbus laboratory, itsdevelopment philosophy and status, theutilisation plans, the industrialdevelopment team, ground segmentdevelopment and astronaut training, thestatus of overall Station assembly and theimmediate future for Columbus.

Fig. 2. Europe’s contribution to the International SpaceStation. The main elements – Columbus, ATV and the

microgravity facilities – are in dark blue. (ESA)

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Payload Accommodation and ResourcesColumbus, in common with the rest ofthe International Space Station, providesan environment for pursuing researchand applications development in manyfields. It offers unique fundamentalcharacteristics:

• payload complement flexibility,provided by a modular design servicedby a regular logistics, maintenance andupgrade capability;

• permanent crew presence, forservicing payload-support systems andinteracting with the payloads;

• continuous availability of a groundinfrastructure for monitoring andcontrolling onboard activities, with thedecentralised approach allowingexperimenters to interact with theirpayloads.

Columbus provides internal payloadaccommodation for multidisciplinaryresearch into material science, fluidphysics and life sciences – all requiringminimum microgravity disturbances. Inaddition, the External Payload Facility(EPF) hosts space science and Earthobservation payloads. Although it is theStation’s smallest laboratory module,Columbus offers the same payloadvolume, power, data retrieval,vacuum/venting services, etc as theothers. This is achieved by carefulutilisation of the available volume and bysometimes compromising crew accessand maintainability in favour of payloadaccommodation.

All of the Columbus payload accommo-

dation locations provide a multitude ofresources (see Table 1) so that a widespectrum of payloads can be handled forthe many years of operations to come.

System functions such as Emergency,Warning & Caution detection andannunciation, voice communicationto/from the ground and internalmonitoring by two video cameras haveinterface provisions for payloads. Ingeneral, the payload interfaces aredesigned so that failures cannotpropagate from the payload hardware tothe Columbus system, and vice versa. Forexample, if the system water pump fails,the DMS automatically reconfigures tothe backup pump, so that the payloadracks are not left without cooling.

The International Standard Payload Racks(ISPRs) carry standardised interfaces thatallow integration and operation in anynon-Russian ISS module, includingColumbus. European payloads areconnected to dedicated data busses,enabling data to be routed, via the ISSdata transfer system, directly to theEuropean Control Centre and thence tothe individual users, in a secureenvironment. For payloads in NASAracks, interfaces to the NASA DataManagement System are provided.

Columbus will be launched with aninternal payload of up to 2500 kg in fiveracks, which will be completed and/orreconfigured on-orbit by later launches ofadditional ISPRs. The external payloadswill be installed on-orbit using the SpaceStation Remote Manipulator System(SSRMS) as standardised packagesinterfacing with the External PayloadFacility.

Columbus Characteristics

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Table 1. Columbus Payload Resources.

Total Resources Internal External Remarks

Location •10 active ISPRs •4 interface planes pointing 8 lateral rack positions support •3 stowage ISPRs to zenith, nadir & flight Active Rack Isolation System (ARIS).•centre aisle direction Functional resources from

Standard Utility Panels.

Mass•2500 kg at launch •2500 kg at launch •0 kg at launch•10160 kg on-orbit •9000 kg on-orbit •4x290 kg on-orbit

Electrical Power•13.5 kW total •5x6 kW ISPRs •2x1.25 kW per interface Overall total during mission•120 Vdc 5x3 kW ISPRs plane depends on power availability

3x1.2 kW Standard Utility from ISS.Panels Additional 1.2 kW Auxiliary Power

also available for each rack.

Cooling •1 water cooling loop per •passive coolingactive ISPR

Data Management•1 dedicated payload computer

(SPARC)•Crew interfaces by laptop•Columbus payload bus •1 cold redundant per •1 cold redundant per Telemetry & telecommand links to/

(MIL Std 1553) active ISPR interface plane for from ground via ISS S-band systems Columbus or US bus

•US payload bus (MIL Std 1553) •1 cold redundant per •1 cold redundant per active ISPR interface plane for

Columbus or US LAN•Columbus LAN (ETHERNET) •1 cold redundant per •Analog/discrete inputs/ For monitoring and control of

active ISPR outputs of external payloads.•US LAN (ETHERNET) •1 cold redundant per

active ISPR

Video•Video distribution (NTSC), •2 interfaces per active ISPR •N/A Fibre optics interface either for

compression (MPEG) and video or high-rate data transmission.transmission to ground

•Video recording

High-Rate Data•Multiplexing and downlink •2 interfaces per active ISPR •2 cold redundant per Fibre optics interface at ISPR,

(up to 43 Mbit/s via SSMB (1 kbit/s up to 32 Mbit/s) interface plane electrical at EPFand/or JEM) (1 kbit/s up to 32 Mbit/s)

Vacuum Line •1 per lateral ISPR (8x) •N/A <0.19x10-6 bar

Venting Line •1 per active ISPR (10x) •N/A

Nitrogen Supply •1 per active ISPR (10x) •N/A

N/A: not applicable

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Columbus Physical CharacteristicsThe Columbus laboratory – 9.9 t withoutresearch equipment – has a 4.5 m-diameter cylindrical section closed withwelded endcones, forming a pressurised,habitable volume about 8 m long intotal. The total volume is about 75 m3,,reducing to about 50m3 with a full rackload. The 2219-aluminium alloy cylinderis 4 mm thick, increasing to 7 mm for theendcones. The module’s passive CommonBerthing Mechanism (CBM) will attach itto the active CBM of the ESA-providedinterconnecting Node-2.

Columbus will be delivered to the ISS bythe Space Shuttle Orbiter, carried in thespaceplane’s cargo bay via its trunnionsand keel fitting. A Station-commongrapple fixture will allow the SSRMS to liftit out of the Orbiter and transport it to itsfinal destination on Node-2.

Inside Columbus, the ISPR laboratory racksare arranged around the circumference ofthe cylindrical section, in a 1 g

configuration, to provide the workingenvironment for up to three astronauts. Atotal of 16 racks can be carried in foursegments of four racks each.

The central area of the starboard cone is

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700 kg on-orbit in 1.5 m3) and threeprovide passive stowageaccommodation.

The cabin is ventilated by a continuousairflow entering via adjustable airdiffusers on the upper stand-offs, suckedin from the Station by a fan centredbelow the hatch in the port cone. Theinternal layout is shown in Figs.3-6.

Each active payload rack location iscompatible with ISPR requirements.Externally, four payload supportstructures provide the same mechanicaland functional interfaces as NASA’sstandardised Express Pallets for externalpayloads on the ISS Truss.

Functional ArchitectureAs with any spacecraft, the functionalarchitecture of Columbus is complicated.Although Columbus is not autonomous –so, for example, it has no powergeneration or attitude control systems – itis a manned laboratory and therefore hasan Environmental Control and LifeSupport Subsystem (ECLSS) as well asman-machine interface provisions. Theoverall architecture is shown in Fig. 7,together with the principal interfaces tothe rest of the Station and to thepayloads.

The various systems and functionality ofthe module are detailed in the following:

Fig. 8: the Emergency, Warning &Caution (EW&C) block diagram showsthat all safety-related parameters –whether of the system or of thepayloads – are monitored and broughttogether on a dedicated redundant setof computers (the Vital TelemetryComputers, VTCs), which alerts theStation in the event of a problemaboard Columbus. Audio and visualwarnings are given to the crew, andlaptop interfaces allow the astronauts

Fig. 3. Mock-up of the Columbus interior.

configured for system equipment thatrequires undisturbed crew viewing andhandling access, such as video monitorsand cameras, switching panels, audioterminals and fire extinguishers. Theremainder of the system equipment ishoused in the rest of the endcone areasand three of the deck (floor) racks. Thatleaves 13 racks available for payloads, ofwhich 10 are fully outfitted withresources for payloads (each can house

Fig. 4. Cutaway view ofColumbus.

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to ‘safe’ the module from any locationin the Station via the ISS Command &Control (C&C) bus.

Fig. 9: the end-to-end communicationsinfrastructure is such that all datacollected aboard Columbus – be theysystem housekeeping, low- or high-rate payload data, or video data – aremultiplexed and then passed throughthe Station to either the NASA Tracking& Data Relay Satellite System (TDRSS)or the Japanese/ESA Data Relay & TestSatellite (DRTS)/Artemis systems andthence to the control centres, foronward transmission to the users.(Uplink command data from theground is via only TDRSS.)

Fig. 10: shows the correspondingColumbus onboard block diagram forcommunications.

Fig. 11: Station power is generatedcentrally by huge solar wings. This120 Vdc system routes power to allStation users. Inside Columbus, thepower goes through the central PowerDistribution Unit (PDU) and from there,as 120 Vdc or 28 Vdc, to all payloadracks, external platform locations,centre aisle standard utility panels andsubsystems.

Fig. 12: the internal Columbus DataManagement System (DMS) is shown.General data are separated fromsafety-related data as explained above.MIL bus and Ethernet local areanetwork media are accessible to allpayload locations, and a series ofcomputers services all user needs.Crew interfacing is available vialaptops, which can be plugged intothe system at any location.

Fig. 13: in a similar manner to the DMS,the software architecture is segregatedsuch that safety-related packages,system monitoring and payload

packages are defined and distributedto serve the end users most efficiently.This figure shows the types of servicesand their locations on the variouscomputers.

Fig. 14: Columbus active thermal controlis via a water loop serving all payloadrack locations. It is connected to theISS centralised heat rejection system viainterloop heat exchangers. In addition,there is an air/water heat exchanger toremove condensation from the cabinair.

Fig. 15: the module is wrapped ingoldised Kapton Multi Layer Insulationto minimise overall heat leaks. Asystem of electrical heaters combatsthe extreme cold possible at someStation attitudes. These heaters will beactivated during both the launch andthe transfer from the Shuttle cargo bayto Node-2, drawing on the SSRMSpower supply.

Fig. 16: as with many other ISS systems,the life support system is centralised.Columbus air circulation is driven byfans taking fresh air from Node-2,passing the air through diffusers intothe cabin for crew ventilation, andthen back to the Node for fresheningand carbon dioxide removal. The crewcan control temperature and humidity,and air content is monitored forcontamination from the systems orpayloads. Pressure control and reliefare also available.

The systems resources briefly describedabove are distributed to the payloads viastandard connections. Fig. 17 (payloadracks), Fig. 18 (centre aisle) and Fig. 19(EPF) show these connections. Inaddition, a venting and vacuumcapability is provided at each of the 10active ISPR locations for the payloads, asshown in Fig. 20.

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Fig. 6. One of the threefloor subsystem racks.This is rack D1, whichcarries life supportelements.

Fig. 5. The principle elements of Columbus.There are 10 active ISPR locations (blue).

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Fig. 7. Columbus system functional architecture.

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Fig. 8. Emergency, Warning and Caution: all safety-related parameters arebrought together on the VTCs.

Fig. 9. The end-to-end communicationsinfrastructure for Columbus. (ESA)

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Fig. 10. Columbus onboard communicationsinfrastructure.

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Fig. 11. Columbus power distribution. • designed for up to18 kW total power tosubsystems andpayload, maximum13.5 kW to payload

• 120 Vdc and 28 Vdcsupply for Columbusequipment; 120 Vdcsupply for payload

• all 120 Vdc outputsprotected/switched bySolid-State PowerControllers (SSPCs)

• Standard Utility Panelpower outletsprotected with GroundFault Interruptor (GFI)to ensure groundsafety even withgrounding failure inportable equipment

• 2x1.25 kW availableper ExPM location,total 2.5 kW externalpayload power

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Fig. 12. The Columbus Data Management System.

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Fig. 13. The software architecture for Columbus.

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Fig. 14. The Columbus active thermal control system.

Fig. 15. Columbus passive thermal control and heaters.

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Fig. 16. The Columbus environmental control system.

Fig. 17. System resources available via the ISPR Utility Interface Panel.

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Fig. 19. Resources available to payloads on the ExternalPayload Facility. Functional interfaces: power 120 Vdc,

1.25 kW per Feeder, 2.5 kW total; 32 MBytes/s; datamanagement Columbus payload bus + LAN, alternative US

payload bus + US LAN.

Fig. 18. Resources available to payloads in the centre aisle.

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Fig. 20. Vacuum and venting is available forpayloads in each of the 10 active ISPRs.

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An industrial consortium led by DaimlerChrysler AerospaceAG (DASA) is undertaking the Columbus laboratory develop-ment under a Fixed Price Contract to ESA. Thedistribution of work within the consortium aims at:

• allocating the appropriate tasks to com-panies with the greatest capability andexperience in the relevant fields;

• achieving the most cost-effective development, tak-ing into account thestringent ceiling pricetarget set by the Agen-cy. To this end,maximum use isbeing made of com-mon European andISS items. CommonE u r o p e a nd e v e l o p m e n t sinclude the pri-mary structure andlife support itemsfrom the Multi-Purpose LogisticsModule (based onan ESA/ASI inter-agency arrangement),and Data ManagementSystem items from theRussian Service Module (the ESA DMS-R contract).Common ISS items include thehatch and Common BerthingMechanism. Maximum use isbeing made of off-the-shelf itemssuch as video cameras/recorders andlaptop computers;

• minimising expenditure outside of participatingstates, so long as equivalent items could be developed inEurope at a comparable price;

Industrial Consortium

D DASA-RI

Columbus Prime

F Matra MarconiSpace

DMS

B SpacebelInformatique

USS/SWW

I Alenia AerospazioDivisione Spazio

HUB

NL HollandseSignaal AG

MSD

D DASA-RI

HRM

US McDonnell DouglasAerospace

MAL Panel

US SCI Inc.

BCS (ICS)

B Alcatel BellSpace & Defense

EGSE

F AlcatelSpace Industries

PDU

F AlcatelSpace Industries

VDPU

D Kayser-Threde

VCR/VM

I Officine Galileo

Camera

NL ORIGIN B.V.

CPLI/MCD

I Space SoftwareItalia, S.p.A.

COAP

DK Rovsing

FWDU

N CAP GEMINI

TSCV

B SpacebelInformatique

Test & Data Base Services

F/D MMS/Bosch Telecom

EEE Agents

I Alenia AerospazioDivisione Spazio

LAPAP

CH CIR

PPSB

D OHBDK RovsingDK Terma

System Support

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• using equipment-level competition as a mechanism toachieve low prices.

The resulting industrial consortium is shown inFig. 21. The organigramme has the following

specific aspects:

• a very important role is allocatedto Alenia Aerospazio. Building

on the reuse of significantMPLM elements (structure,

thermal control and ECLSequipment), Alenia Aero-

spazio is responsible forthe overall physicalc o n f i g u r a t i o n ,thermo-mechanicalsystem design andC o l u m b u spre-integration.

• only two classicalsubsystem contractshave been placed:the Data Manage-ment System with

Matra Marconi Spaceand the Environmen-

tal Control and LifeSupport Subsystem with

Dornier. All other units aresubcontracted at the equip-

ment/assembly level, thuseliminating a management

layer in part of the programme.

The selected companies representsome of the most skilled and experienced

European aerospace contractors, many ofthem with manned space experience through the

Spacelab and Eureca projects.

Fig. 21. The Columbusindustrial consortium.

I Alenia AerospazioDivisione Spazio

PICA

US Boeing

ISS Common Items

I Microtecnica

WPA

E SENERIngeniera Y Sistemas

Racks/Floors/EPF-Str.

F Aerospatiale

MDPS/NDI

D OHB System GmbH

Harness

D DASA-RI

ECLS

F Soterem

Fan, CWSA

F Secan

CHX

D Draeger Aerospace

Sensors

D Kayser-Threde

Ducting

US Suppliers

Valves

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housings for Columbus. Theirqualification is within the off-the-shelfphilosophy, which requires morestringent environmental criteria tocompensate for the uncertainties of thereduced design and manufacturingtransparency.

The overall Columbus system functionalarchitecture (including all onboard

Overall PrinciplesColumbus development revolves aroundthe classical project review system ofPreliminary Design Review (PDR), CriticalDesign Review (CDR), QualificationReview (QR) and Acceptance. Suchreviews are conducted at the primecontractor/systems level by ESA, and arebased on corresponding lower levelreviews conducted by the prime andlower level contractors. Phase C/D beganin January 1996. The launch date is afunction of the overall ISS assemblyschedule, which has suffered significantdelays in its early stages, but theavailability of the Columbus flight unit isnot on a critical path. However, becausethe module will be launched with some2500 kg of payloads, their developmentmust be harmonised so that, before finalacceptance, they are integrated into thelaboratory and checked out to ensurecompatible interfaces.

The System PDR was successfullyconcluded in late 1997, and the CDR isforeseen for mid-2000. Launch isexpected to be early 2004.

‘Model’ Philosophy and CommonalityThe model philosophy at the unit levelranges from dedicated Qualification Unitsto the Protoflight approach, dependingon the complexity of the items. Severalunits common to other projects are beingadopted (Fig. 22 and Table 2) withoutfurther qualification, after proof that theiroriginal requirements meet or exceedthose of Columbus.

In order to minimise programme costs,commercial video equipment is beingadapted by adding interface circuitry and

Table 2. Columbus Units Sourced from Other Projects.

Source: International Space Station

Power Data Grapple Fixture (PDGF)Smoke SensorPortable Fire Extinguisher (PFEX)Portable Breathing Apparatus (PBA)Audio Terminal Unit (with cold plate)Audio AntennaCommon Berthing Mechanism (passive half)HatchLaptopMaster Alarm PanelPayload Ethernet HUB/Gateway (PEHG)Flight Release Attachment Mechanism for EPF I/FModule Lighting UnitEmergency Lighting Unit

Source: Multi-Purpose Logistics Module

Primary Structure Cabin Air DiffuserCabin Depressurisation AssemblyLine Shut-off ValvePositive/Negative Pressure Relief Assembly

Source: DMS-R

Computer itemsMass Memory Unit item

Source: Off-The Shelf (OTS)

Video MonitorVideo RecorderVideo Camera

Columbus Development

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software) will be proved on an ElectricalTest Model (ETM) at DASA’s Bremenfacilities. The ETM includes the completepower distribution and datamanagement system; all other functionalonboard units will be represented by atleast one Engineering Model (EM) perunit type for interface compatibilitytesting. The EM units will be identical tothe Flight Models in physical andfunctional design (only differences indetailed manufacturing processes andparts quality are acceptable). The ETMwill be functionally attached to GroundSupport Equipment, which simulates theISS and payload interfaces in order toensure end-to-end testing. The ETM willnot contain representative primary orsecondary structures, but will have a fullyrepresentative set of power and dataharnesses.

All other items of the Columbus systemare simulated such that all systemfunctions can be exercised during theETM test campaign and, later, be used fortrouble-shooting in parallel to the FlightModel assembly, integration and testphase.

After ETM testing has been completed,

the model will be extended to becomethe Rack Level Test Facility (RLTF) byadding flight-identical mechanical andthermal interfaces to support payloadinterface verification. The payloads willthus be tested in a high-fidelity Columbussimulator. For those payloads that will belaunched within Columbus, this testingwill be done before their integration intothe Columbus flight configuration. Thiswill validate the RLTF’s fidelity so thatpayloads to be added after Columbus hasheaded into orbit can be verified on thesimulator with high confidence.

All remaining functional qualificationactivities that rely on an identical systemconfiguration but which cannot beprovided by the ETM (e.g.electromagnetic susceptibility, internalnoise, microgravity disturbance andoverall contamination levels) will becarried out on the Columbus ProtoflightModel (PFM). Before the functional unitsare integrated within it, the Columbusflight model mechanical configurationwill be subjected to dynamic modalsurvey tests to verify the launch andon-orbit mathematical models. Cabinventilation was verified in February 1999on a mock-up of the Columbus interior at

Fig. 22. Examples of elements from otherprojects adopted for

Columbus.

MPLM Structure

SSPC MPLM-ECLS

DMS-R Control Post

CGS

Columbus

➙➙

➙

➙

➙

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Dornier, using the fans and ductinghardware, and fire suppressiondemonstrations began in March 1999 onmechanical mock-ups of the relevantareas.

A mechanical mock-up is used at Aleniain Turin to demonstrate and qualifyon-orbit maintenance procedures –replacement of functional units and localrepairs to, for example, the structure andharness. The test campaign at 1 g hasbeen completed, as has the first ‘zero-gravity’ verification, which wasperformed in a water tank at Alenia. This

simulated internal operations and wasperformed with ESA and NASAastronauts. Final zero gravity verificationof external operations will be done atNASA Johnson.

The mock-up and ETM/RLTF will bothsupport operational evaluation andtroubleshooting analyses during theentire life of the Columbus laboratory.

Software DevelopmentThe Columbus programme involves alarge number of different software items

Fig. 23. Columbus system and software

inter-relationships.

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All flight software developed bysubcontractors will be delivered forintegration with the flight applicationand DMS software, and for testing on theSoftware Integration and TestEnvironment (SITE) before use on theETM. The final qualification of flightsoftware will be performed as part of theoverall end-to-end functional Columbusqualification.

Several thousand housekeeping data enditems have to be acquired and processedby software in order to minimise crewand ground involvement in operation ofthe complex Columbus system, inaddition to supporting failure detectionand isolation during maintenance. All ofthis information is collected in a ground-based Mission Data Base, which is alsothe foundation for the later utilisation ofColumbus when setting up the completeonboard software, including the payloadand its related ground station operationalprocedures.

There is special emphasis on softwareinvolved in critical functions. In general,the involvement of software in safety-critical functions is minimised.

The end product is a highly complicatedset of software with many interfaces andfunctions. A measure of the complexitycan be seen in Fig. 23, which shows theelements of the software packages andhow they will be integrated into theoverall system package.

Development Status

System LevelFollowing the successful Columbus PDRin December 1997, the system designhas been established, as scheduled in theColumbus Design and Development Plan.A number of significant safety-relatedmodifications arising from the PDR havebeen implemented:

• modification of the configuration toimprove fire suppression;

(onboard and in GSE) that are beingdeveloped, integrated and usedconcurrently by several contractors. Thismeans that common standards must beenforced for design, documentation,review and release procedures anddetailed software module interfacedefinitions. Therefore a standardised setof development tools and facilities hasbeen imposed. Equally, it is necessary tomaintain adequate margins for computerperformances and memory sizes, whichare progressively released only at definedevents (‘margin management’).

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• a reworking of the Emergency,Warning and Caution concept, andthe addition of Caution channels.

In addition, at that stage of the project,the External Payload Facility was addedto Columbus. The EPF was not in theoriginal baseline because ESA had hopedto use other Station capabilities – eitherNASA’s Express Pallets or Japan’s ExposedFacility. However, the utilisation cost ofthe NASA real estate proved to beprohibitive, and the NASDA facility iscompletely booked for the foreseeablefuture. It was therefore decided to extendthe Columbus capability.

The combination of the safety-relatedchanges and EPF’s introduction led to a

Configuration Review of the Columbusmechanical system design in order toevaluate the implementation of thesepost-PDR differences. This reviewsuccessfully concluded in September1998.

The project is now in a phase thatfeatures:

• functional system testing on theElectrical Test Model;

• equipment and subsystem CriticalDesign Reviews;

• building up a Qualification databaseon the equipment-level test results, theoverall system analyses and those

Fig. 24. The Columbus Electrical Test Model.

The ETM racks are thedark cabinets in the

background of the mainphotograph, seen in full

in the small insetpicture. The lighter

cabinets are the EGSEracks.

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requirements expectedto be closed by asimple ‘Review ofDesign’.

For the ETM tests, theElectrical GroundSupport Equipment(EGSE) has been installedand connected to theETM. An initial version ofthe system software hasbeen integrated and theETM testing began inMay 1999. Fig. 24 showsthe ETM in its testconfiguration.

Conduct of the unit- andsubsystem-level CDRs is well under way.The campaign is ensuring overall designintegrity and compatability with thelower level interfaces. Permission forequipment qualification/flightmanufacturing is being released as theseCDRs are completed. For mechanicalsystem items (structure, thermal, harness,ECLSS, etc), CDR results are beingintegrated to generate the Pre-IntegratedColumbus Assembly (PICA, at Alenia). ThePICA-level CDR is planned for late in1999. In the meantime, the Flight Unit’sprimary structure – a derivative of MPLM’sprimary structure and thus qualified by‘similarity’ – is under construction.Welding on the cylinders and endconesbegan in May 1999. Fig. 25 shows partof the flight hardware.

The final/complete system Columbus CDRis planned for mid-2000, after the mostcritical ETM test results have beenobtained and the lower level CDRs havebeen closed out.

Software LevelThe Columbus onboard software is basedon the Data Management System (DMS)software extended by other modules –such as laptop applications and flight

automated procedures –to provide the end-to-end system functions.

By mid-1999, the DMSsoftware was in a verycritical phase: thebaselined architecturewas shown to beincompatible with theimplemented dataprocessing memory andspeed. Whereas the

computer memory shortage has beensolved by memory upgrades, thelimitation in central processing unitperformance has necessitated extensivesoftware changes. A review by externalexperts began in March 1999 to producea solution with minimum programmaticimpacts. The architecture has beenchanged and coded has restarted;qualified DMS software will be deliveredin the spring of 2000.

Nevertheless, initial testing on the ETMcan go ahead because the first tests coveronly the most basic Columbus functions.The completion of ETM testing relies onthe complete suite of software beingavailable. Since the DMS softwareinterfaces strongly with the other softwaremodules, these may also be influenced,depending on the changes. This area ofproject development has priority.

Subsystem/Equipment LevelDifferent equipment has reached varyingdegrees of design maturity, ranging from‘PDR close-out’ for the Payload PowerSwitching Box (a late arrival due to EPF’saddition) up to ‘CDR close-out’ for manyunits, such as HUB and the HeaterControl Unit.

Fig. 25. Columbus Flight Model hardwareunder construction atAlenia Aerospazio in

Turin. (Alenia)

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Several unit pre-qualification tests havebeen successful, providing highconfidence that the formal qualificationtests on Qualification Models orProtoflight Models will be successful. Thecabin ventilation qualification test wassuccessful in February 1999, and the firstof the fire suppression demonstrationswas carried out in March 1999. Theclosed-loop performance of the module’swhole water loop was tested in late 1998.

The Environmental Control and LifeSupport Subsystem (ECLSS) CDR began inJanuary 1999. This review is in two parts.The first reviewed the subsystem-level testand analyses results, using data from theequipment developers. The second willbe performed when the correspondingequipment-level CDRs are completed.Two of the units have had problems (inone case a contractor had to bereplaced), so finalisation of the subsystemCDR will be achieved only after these areresolved.

The DMS CDR has had to be delayedbecause of the software incompatibilityproblems discussed above.

Project Difficulties and their ResolutionsAs Columbus is but one element of theStation, there are many technical andoperational inter-dependencies that areevolving concurrently with ESA’s module.The interface design and verificationtherefore needs constant attention andthorough planning. An InterfaceCoordination Working Group (ICWG),co-chaired by NASA and ESA, routinelymeets to define and refine the evolvinginterface definition, and to agree on theverification of the interface decisions.Incompatabilities arise no matter howclosely this is tracked, and thus designchanges and/or test changes have to beincorporated into the programme. Anumber recently occurred in the datamanagement interface domain and in

the testing of software transfertechniques. Such problems are anintegral part of an internationalundertaking as vast as the ISS.

In some areas, the Columbus programmeis at the cutting edge of technology. Forexample, in the design and verification ofthe Meteoroid and Debris ProtectionSystem (MDPS), the module’s outer layerfor shielding the crew and payloads fromthe hostile environment of low Earthorbit. The mathematics of damageprediction is not an exact science, andtests shooting particles at more than10 km/s yield widely scattered results.The combined talents of European,American, Japanese and Russians expertsin this field have yet to come up with asolution other than extremeconservatism. Columbus currently carriesabout 2 t of protection around itspressure shell.

In other areas, the programme has beenused to trigger the ‘Europeanisation’ oftechnologies, rather than continuing torely on other (generally American)sources. This has led to certain maturityproblems. An example is thecondensating heat exchanger, intendedto control cabin humidity and based onthe difficult technology of hydrophiliccoating. The manufacturing processes –new for European industry – are verysensitive to contamination and a long-term solution has not yet been qualified.Another example is the cabin fan, whichhad acoustic noise and microgravitydisturbance problems.

Moreover, the ‘normal’ project problemshave also hit Columbus development –excess mass and insufficient computermemory capability, for example. Severalchanges ranging from material change todesign modifications have had to beimplemented to regain an adequate massmargin. The computer memory has beenupgraded by adding RAM.

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Columbus accommodates 10 internal International Standard PayloadRacks and four External Payload Facility platforms. These are all sharedequally by ESA and NASA for the whole duration of the ISS programme.Eight of the ISPRs are housed along the laboratory’s sidewalls, with theremaining two in the ceiling area. (The rest of the rack locations aretaken up with Columbus subsystem equipment or overall Stationstowage space, for which three racks are allocated.) Each ISPR and EPFlocation is provided with power, data, video and cooling. Nitrogenpurging and vacuum resources are available to the payload racks. Theresources available at any one time are limited by the overall ISScapability, so resource timelining has to be developed, planned andexecuted.

The multi-purpose Columbus laboratory is designed to provideopportunities for all possible branches of space research, technologyand exploitation, including:

◊ space biology,◊ human physiology,◊ material science,◊ fluid science,

Utilisation and Facility Development

Fig. 26. Biolab willsupport biologicalresearch. (ESA)

Fig. 27. EPM will support physiological

research. (ESA)

◊ space science,◊ Earth observation,◊ general physics,◊ technology development.

The payload complement operating atany one time will be selected as afunction of many variables, including: the type of payloads (suchas pure research on the one hand,potential commercial applications onthe other), the level and duration ofresources required (crew time, power, data, etc), and their origin (are they from a Participating State?). Also taken into account will be the general merit of thepayloads in scientific and/orapplication terms, and how they canbe packaged as a compatiblecomplement.

Numerous payload facilities are beingdeveloped in parallel with theColumbus laboratory development, for

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use both inside and outside the module.These include:

• Biolab (Fig. 26): a rack supportingbiological experiments onmicroorganisms, animal cells, tissuecultures, small plants and smallinvertebrates in zero gravity. This is anextension – as for so many otherpayloads – of pioneeringwork conducted on theSpacelab missions;

• European PhysiologyModules (Fig. 27): a rackdedicated to studyingbody functions in zerogravity, such as boneloss, circulation,respiration, organ andimmune systembehaviour, and theircomparison with 1 gperformance todetermine how the

results can be applied toEarth-bound atrophy andage-related problems;

• Material ScienceLaboratory (Fig. 28): a rackfor research in solidificationphysics, crystal growthwith semiconductors,measurement ofthermophysical propertiesand the physics of liquidstates. For example, crystalgrowth processes aimed atimproving ground-based

production methods can be studied. Inmetal physics, the influences ofmagnetic fields on microstructure canbe determined. Microstructure control during solidification could leadto new materials with industrialapplications;

• Fluid Science Laboratory (Fig. 29): arack for studying the complexbehaviour in instabilities and flows inmultiphase systems, their kinetics as afunction of gravitational variation, andthe coupling between heat and masstransfer in fluids, along with researchinto combustion phenomena thatshould lead to improvements in energyproduction, propulsion efficiency andenvironmental issues;

• Numerous external facilities, such as:Atomic Clock Ensemble in Space

(ACES), providing an ultra-accurateglobal time-scale, thereby

Fig. 28 (top): the Material Science Laboratory willinvestigate solidification physics, crystal growth withsemiconductors, thermophysical properties and thephysics of liquid states. (ESA)

Fig. 29 (centre): The Fluid Science Laboratory willstudy fluid behaviour in the absence of gravitationaleffects. (ESA/Ducros)

Fig. 30 (bottom): The European Drawer Rackprovides a modular capability for sub-rack payloads.(ESA)

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supporting precise evaluations ofrelativity;

Expose, mounted on the CoarsePointing Device (CPD), to supportthe long-term studies of microbesin artificial meteorites and differentecosystems;

FOCUS, an infrared detection systemto discover and track vegetationfires and volcanoes;

Solar Monitoring Observatory (alsomounted on the CPD), to measure

the Sun’s total and spectralirradiance;

Technology Exposure Facility (TEF), aninfrastructure providing for a widerange of on-orbit technologyinvestigations.

To provide user information andeventually to support experimentdevelopment and operations, theErasmus User Centre (EUC) wasinaugurated at ESTEC in June 1999.

Fig. 31. Columbus also offers fourExternal Payload Facility platforms.

(ESA/Ducros)

Fig. 32. ESA’s Erasmus User Centreprovides support to potential andactive Space Station users. (ESA)

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In the same way that Columbus is anintegral part of a total ISS system, itsground segment is part of a biggerwhole. The core of the ESA groundsegment is the Columbus Control Centre,a facility at DLR’s German SpaceOperations Centre (GSOC) inOberpfaffenhofen. This centre will be thedirect link to the on-orbit infrastructure; itwill handle the Columbus module’scommand and control, and participate inplanning and timelining Columbus orbitalactivities. It will be the interface to thede-centralised User Centres, which willhave direct access to the payloads undertheir responsibility. It will also be theinterface to the overall Space StationControl Center (SSCC) at NASA Johnsonin Houston, Texas and the PayloadOperations Integration Center (POIC) atNASA Marshall in Huntsville, Alabama,ensuring compatibility betweenColumbus and the rest of theinfrastructure, as well as with the manysimultaneous payload investigations.

The Columbus Control Centre willoperate under the supervision of amanagement team, and will provide thereal time operational decisions. It willhave engineering and logistics supportand the support of the EuropeanAstronauts Centre (EAC). The EACorganises and conducts crew training forColumbus operations, operates themedical facilities in support of crewhealth and oversees the general well-being of ESA crews and their families.

Training mock-ups representing thefunctional characteristics (and thephysical interior) of the Columbus

laboratory are being developed – acomplete and high-fidelity mock-up forEAC and a simpler one for the SpaceStation Training Facility (SSTF) at NASAJohnson. The architecture for this crewtrainer is shown in Fig. 33.

The initial payloads will be launched withColumbus, having been checked outwith the module before leaving theground. As time passes, new racks will beadded and these will also need to beverified as compatible with the Columbussystem. For this, the Rack Level TestFacility is being developed to simulatethe on-orbit and ground segments, aswell as the characteristics of the otherpayloads housed within the module, sothat the new rack can be thoroughlytested. To maximise the cost-effectivenessof this RLTF, and to ensure the fidelity ofits simulation, the check-out equipmentwill re-use the Electrical Test Model onwhich Columbus itself will have beenverified. Fig. 34 shows a schematic of theRLTF.

During the Station’s operational phase, allthe ground segment and the on-orbitinfrastructure will be connected by amulti-national communications system (asimplified block diagram is shown inFig. 10). Command of the laboratory andits payloads will be via the ColumbusControl Centre and the InterconnectionGround Subnet (IGS) central nodethrough NASA’s Tracking and Data RelaySatellite System to the ISS receivers. Allsafety-related command and control willgo through the Space Station ControlCenter in Houston to ensure thecentralised control of safety actions.

Ground Segmentand Training

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Downlinks will be available via TDRSSand the ESA Artemis / Japanese DataRelay and Test Satellite system, which willform a constellation early next century.

The Station’s composite data streamrouted via TDRSS will be sent to the

Payload Data Service System (PDSS) atNASA Marshall for demultiplexing into‘Element’ virtual channels. The ESA relayat Marshall will separate out theColumbus data and make it available tothe Columbus Control Centre and theUser Centres via the IGS central node.

Fig. 33. The architecturefor the Columbus crewtrainer as part of theSpace Station TrainingFacility at NASA Johnson.(ESA)

Fig. 34. The Rack LevelTest Facility (RLTF). (ESA)

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During Phase B, it had been planned tolaunch the Columbus module on anAriane-5. However, before programmeapproval, the Design-to-Cost requirementdictated that the module should bedownsized to a 4-rack-long configurationso that its primary structure could bederived from ASI’s MPLM. (This avoidedthe design and qualification cost of adedicated new structure, saving tens ofmillions of Euros.) The MPLM, though,was designed and qualified for launch onNASA’s Space Shuttle, which thereforebecame the baseline for Columbus. Bythe time Columbus was approved, at theToulouse Ministerial Council in 1995, theoverall ISS Assembly Sequence wasalready established, so the Columbuslaunch was set at the end of thesequence. It has since been advancedsomewhat in the sequence, but itremains the last of the non-Russianlaboratory modules to be attached.

There have been problems in beginning

the Assembly Sequence, owing to varioustechnical and financial problems of someof the other Partners. The first launch, ofthe US-financed Russian ‘Zarya’ module,finally took place in November 1998,closely followed by NASA’s ‘Unity’ Node-1a month later. A logistics flight wasperformed in May 1999, but the nextelement to be attached is Russia’s‘Zvezda’ Service Module, planned forearly 2000, some 9 months later thanexpected.

The first permanent crew will enter theStation in early 2000 and by mid-2000the first dedicated payload module – theUS Laboratory ‘Destiny’ – will belaunched, closely followed by an MPLMwith its payload racks, thereby enablingthe first utilisation activities to begin inthe second half of 2000.The effects ofthe initial delay, and the further delay inthe Service Module’s appearance, hasmeant that the launch of Columbus isnow planned for early 2004.

Columbus Launch andISS Assembly Sequence

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It took a long time for the InternationalPartners, including Europe, to formalisetheir participation in the construction andoperations of the International SpaceStation, and many years of paper studies,iterations and unfulfilled programmestarts were expended. However, since theend of 1995, the implementation ofEuropean involvement has gatheredsignificant momentum, and Columbus,the cornerstone of the participation, is atthe vanguard of this progress.

The module is now well into thehardware phase: flight model items areunder construction, qualification tests are

underway and the design is baselined.Columbus has accumulated the normalnumber of development problemsexpected of any complicated spacecraft,but none is insurmountable. Itscompletion schedule is well ahead of theplanned launch date.

The ground segment is also underimplementation, utilisation plans are inplace and the first experiments are beingdeveloped. The entire European mannedspace community is looking forwardeagerly to starting its new, on-orbit,adventure.

Conclusions