Europe's programme for participation in the International Space Station was initiated at the Council Meeting at Ministerial Level in The Hague (Netherlands) in 1987. There the European Ministers in charge of space affairs decided to participate in the International Space Station with the Columbus Programme, and to build up a European capability in manned space transportation. With that decision, Europe responded positively to the President of the United States invitation of 1984, to participate as a partner in the design, development, operation and utilisation of a permanently manned civil space station. Many countries welcomed this invitation and in 1988, the Governments of the United States, Belgium, Denmark, France, Germany, Italy, The Netherlands, Norway, Spain, United Kingdom, Japan, and Canada signed the necessary Intergovernmental Agreement (IGA). The European governments specifically laid down in this Agreement that they acted collectively as a single partner, in their role as ESA Member States.
In the IGA, the USA, the European Participating States, Japan and Canada agreed on the objectives, technical capabilities, and rules of operation and utilisation of the International Space Station, and committed themselves to providing elements for the Station.
At that time, Europe proposed to participate with three elements in the orbital infrastructure - the Attached Pressurised Module (APM), the Man-Tended Free Flyer (MTFF), and the Polar Platform (PPF) - and to use the Ariane-5 launcher and the Hermes spaceplane for logistic flights to the Station.
Both the Columbus and the Hermes programmes were organised in two phases. Phase 1 covered the study and pre-development activities, ending with a checkpoint where the results of this phase were to be assessed with a view to adjusting, if necessary, the technical content, the financial envelope and the commitments of the Participating States for Phase 2. The latter would then lead to the final development, manufacture, launch and initial operations of the APM, MTFF, PPF and Hermes.
The end of Phase 1 of the Columbus and Hermes programmes, initially scheduled for the end of 1990, was actually reached in late 1991 at the time of the next Ministerial Council in Munich. The technical assessment was positive and the maturity of both programmes good enough to embark on Phase 2, even though the initial cost estimates had been exceeded.
However, in the light of the profound geopolitical changes that had occurred since 1989, the question was raised as to whether it was politically wise to fully embark on Phase 2 without examining possible new perspectives for a broader international cooperation, in particular with the Russian Federation. A one-year reflection period was therefore proposed by the Munich Ministerial Council, and Phase 1 was formally completed at the end of 1992.
In the light of the new political situation and the resulting financial problems for certain ESA Member States, the Ministerial Council of November 1992 in Granada adopted a stepped approach for the European long-term space policy. This stepped approach had a strong impact on the continuation of the Columbus and Hermes programmes. The Granada Council approved the complete development of the Attached Pressurised Module (APM) and the Polar Platform (PPF) for Columbus, but the Man-Tended Free-Flyer (MTFF) was abandoned. The Ministers also agreed on a Spacelab E-1 and a Eureca 2 flight as part of the Columbus Precursor Flight Programme.
After the Granada Council, the Hermes programme was reoriented into the Manned Space Transportation Programme (MSTP), and a three-year period extending from 1993 to 1995 was agreed on in order to define a future manned space transportation system in cooperation with Russia.
Agreement was also reached on a three-year phase to study the possible joint development of an in-orbit infrastructure with Russia as a successor to the present Russian Mir space station. In order to gain a better knowledge of the Russian manned spaceflight capabilities, two missions of European astronauts on the Mir station were approved within the Columbus Precursor Flight Programme: Euromir 94 and Euromir 95.
The Granada decisions were, however, to a large extent overtaken by external events.
The envisaged cooperation with Russia on a common winged space transportation vehicle derived from the Hermes spaceplane became unrealistic when it emerged that Russia was not in a position to embark on the development of a new crew vehicle. The European plans were therefore oriented to system studies and technological activities for a European capsule-type vehicle - called the Crew Transport Vehicle (CTV) - to be used either in cooperation with the USA or Russia, or in an autonomous European scenario. For the transport of cargo, a separate vehicle was studied - the Automated Transfer Vehicle (ATV) - which would also provide the propulsion and avionics for the CTV.
After having lost their initial purpose with Hermes reorientation into the CTV and ATV projects, the development of the European space suit for Extra-Vehicular Activities (EVA) and the European Robotic Arm (ERA) was continued together with Russia, with a view of using them on the then planned Russian space station Mir 2.
In December 1993, Russia accepted the invitation by the then four participants in the International Space Station to become a full partner in this cooperation programme. As a consequence, the Russian plans for the future Mir 2 space station were abandoned, and the Russian elements already under development were reoriented to become the Russian segment of the International Space Station. The European/Russian cooperation on the European Robotic Arm followed this reorientation and so the ERA became an element of the International Space Station. Since the ERA would already be required early during the assembly sequence of the Russian station elements, the Russian partner urged ESA to agree to the full development and delivery of the European Robotic Arm, independently from the other elements of the European Manned Space Transportation Programme (MSTP). ESA agreed and the ERA became a separately-financed project as part of the so-called Early Delivery Elements.
To Russia's dissatisfaction, ESA Member States did not agree to a similar procedure for the EVA, and the project was abandoned.
However, during the negotiations on ERA and EVA, it emerged that Russia needed, as a result of its participation in the International Space Station, an advanced Data Management System (DMS) for its Servicing Module on the Station. A more detailed investigation of the Russian requirements showed that the European Data Management System under development within the Columbus Programme suited Russian needs, and it was agreed that Europe would deliver a DMS to Russia as a further Early Delivery Item.
Shortly after the Granada Council, well before the decision that Russia would join the programme, the International Space Station underwent a profound redesign by NASA. The uncertainty on the future of the Station stopped the initiation of the complete development programme for the Columbus Attached Pressurised Module (APM), agreed at the Granada Council. The Polar Platform (PPF) development, not affected by the redesign process, was transferred to the Earth Observation Programme. For the remaining APM, a bridging phase was started in April 1993 with the aim of supporting NASA's redesign activities and, at the same time, performing studies on technical simplifications and making financial savings of the European element in the International Space Station. The bridging phase ended late in 1993 with the definition of a new reference baseline for the APM, now called the Columbus Orbital Facility (COF).
After Russia joined the International Space Station programme, the studies on a possible future European/Russian space station, which had been approved in Granada, were stopped. In addition, the Spacelab E-1 and Eureca 2 precursor flight missions had to be put on hold due to insufficient financial commitment by the ESA Member States. Only the two Euromir missions, and the storage of Eureca after its successful first flight, could be financed.
Europe's political will to be present on the International Space Station, already demon-strated with the decision to finance the European ERA and DMS contributions to the Russian segment of the Station, was further stressed with the decision to also provide Early Delivery Items to the USA, such as laboratory support equipment (a microgravity research glovebox), four freezers for biological samples, an instrument-pointing system called Hexapod, and a mission database software package. In exchange for the provision of the Early Delivery Items to NASA and to the Russian Space Agency (RKA), Europe obtained as compensation hardware elements needed for the ATV development, and the right to conduct scientific and operational activities on board the Station already during the assembly phase, before the arrival of Europe's own laboratory - the COF.
The end of the Space Station's redesign exercise, and Russia's entry into the programme, resulted in the political, programmatical and technical restabilisation of the programme and, in February 1994, the ESA Member States approved the Manned Space Transportation Programme and the Columbus Programme for the period 1993-1995 by an Act in Council . They also agreed on the necessary steps to merge the two programmes into one coherent Manned Spaceflight Programme, to be submitted to the Ministerial Council in 1995 for approval.
The implementation of the February 1994 Act in Council led to the setting up of a single Manned Spaceflight Programme Board at Delegate level, the establishment of a Directorate for Manned Spaceflight and Microgravity within ESA concentrating all the efforts related to manned spaceflight, and the immediate start of joint Columbus/MSTP system activities within ESA and industry. One major result of these activities is the submission of the Programme Proposal on the European Participation in the International Space Station Alpha (ISSA).
International Space Station
European Robotic Arm (ERA)
It goes without saying that the large multidisciplinary utilisation potential of the International Space Station for scientific research and applications is Europe's primary motivation for participating in the design, development, operation and utilisation of the Station.
The physical advantages of the Station's position in space are the low-gravity environment in orbit, the near-perfect vacuum of space, and the potential of the Station as a suitable base for observing the Earth and the Universe.
One of the most prominent properties of the Station's environment is the state of near- weightlessness, also called microgravity, resulting from the Station's unpropelled flight around Earth, with the Earth's gravity force being continuously compensated by the centrifugal force due to the curved form of the trajectory. This attribute is particularly interesting for life sciences and physical sciences. Gravity influences many biological, chemical and physical phenomena, relations and processes. On Earth, its effect is so predominant that it masks the effects of other forces, or even prevents these other forces from playing a role.
The main effects due to Earth's gravity are convection, sedimentation and the pressure resulting from a body's own weight. The elimination of these effects in the microgravity environment of the ISSA makes it possible to study experimentally the influence of the second-order forces normally hidden by gravity effects. Knowledge of the influence of these forces allows us to improve the existing theoretical and numerical models on Earth which describe the biological, chemical or physical process as a whole, not only under low-gravity conditions in space, but also under normal gravity conditions. At the same time, the microgravity environment on board ISSA makes it possible to conduct biological, chemical or physical processes in ways not possible on Earth. This opens new perspectives for the production of composite materials, large crystals like complex proteins and other products difficult to produce on Earth.
The International Space Station will also be an appropriate base for intensive studies in the life sciences disciplines on the influence on the space environment on biological systems and on human physiology. The studies in space of the influence of gravity on all forms of life, ranging from cellular and molecular levels to whole organisms, have already revealed a substantial number of surprises and put certain theories of underlying fundamental biological mechanisms and processes into question.
In addition to microgravity, the environment on board the International Space Station is characterised by vacuum, space radiation and the extreme heat and cold in space. The study of the influence of these environmental factors is not only of interest for scientific research, but also for more application-oriented domains like engineering sciences and industrial activities.
Space has become the workplace of numerous commercial satellites and other unmanned space systems. Manufacture, launch and operation of these systems cost several billion ECUs per year. Any malfunction represents a severe economic loss. ISSA's utilisation as a testbed for new technologies will provide new opportunities to try out, adapt and optimise new materials, technologies and critical equipment in their real working environment, and thereby reduce the development risk for new space systems both unmanned and manned.
The study of weightlessness, space radiation and other physical effects of the space environment on board the International Space Station, as well as the observation possibilities offered by the distortion-free and absorption-free vacuum of space outside the Earth's atmosphere, are of interest for space science disciplines such as astronomy, astrophysics, radiation physics, magnetospheric physics and the science of the Sun and the Solar System.
ISSA's suitability as a base for the observation of the Earth and its environment is due to its orbital parameters and the resources available in terms of electrical power, data handling and accommodation. The disciplines that can benefit from the ISSA include meteorology and climate research, environment protection, geodesy, geology and agriculture.
Utilisation is, however, not the only reason which motivates Europe to participate in the International Space Station. Political conside-rations and international cooperation have to be borne in mind, as well as the preparation of future space missions and industrial aspects, and a long-term investment in the economic foundations for the benefit of future generations.
With Russia's entry into the programme, the ISSA has become one of the most important cooperative programmes between East and West. At a fraction of the cost of the arms race in the Cold War era, the International Space Station will contribute to tearing down political and cultural barriers and to building mutual confidence between former adversaries. For the Western nations, it opens a door to Russia's immense experience in manned spaceflight.
All major spacefaring nations are concentrating their efforts in manned spaceflight on the International Space Station, and no other space station is likely to be built in the near or medium- term future. Through its participation in the ISSA programme, Europe will acquire the technical, operational, scientific and industrial capabilities in the key areas required for any future manned exploration and exploitation of space at a fraction of the cost it would incur if it had to build the complete in-orbit and ground infrastructure alone. The International Space Station will be a stepping stone for future manned space programmes.
Europe is today mastering the development, manufacture, launch and operations of unmanned space systems. Participation in the International Space Station will allow Europe to broaden its industrial base and to open up new applications for European space systems. This is particularly true for the new European launcher Ariane-5, due to go into operation in 1996. Furthermore, after several years marked by continuous budget reductions and programme uncertainties, the European aerospace industry, already severely affected by the reductions in the defence and air transport sectors, urgently needs the stability of a long-term programme such as the European participation in the International Space Station in order to maintain its teams of highly qualified engineers and scientists at a reasonable level, and to remain present in one of the key areas for the future.
The International Space Station is an important step towards the continuous manned exploitation of space. Although providing substantial benefits for the progress of science and technology, it will probably not be financially profitable in the short- or medium-term. European participation in ISSA must rather be looked upon as a long-term investment, necessary to build the foundations for the economic prosperity of future generations.
The International Space Station will be a truly global scientific research institute in space, a platform for the observation of the Earth and other celestial bodies, and a testbed for new technologies. In order to meet these objectives, it will consist of seven pressurised modules in which a permanent, international crew will live and work. The ISSA will be occupied by three astronauts in the early utilisation phase, and by six astronauts once it is completed. In addition to the pressurised research and crew living facilities, the Station will have external attachment sites for the accommodation of scientific and technological payloads which need to be directly exposed to space. Fully assembled, the 108 mby 74 m Station will have a total mass of more than 400 tonnes. Assembly will start in November 1997 with the launch of the Russian-built Functional Cargo Block (FGB) and will be completed in June 2002.
The Station will fly at an altitude ranging from 335 km during assembly to 460 km during routine operations. At this altitude, the Station will orbit the Earth in less than 90 minutes, travelling at approximately 29 000 km/h. Its orbit will cross the Earth's Equator at an angle of 51.6 degrees, resulting in a sine-wave-shaped flight path from which 85% of the Earth's surface can be observed, where 95% of the population live.
The proposed programme for Europe's ISSA participation consists of three main elements:
The COF is the core element of the proposed European participation. It is a cylindrical module with an overall length of 6.7 m and an external diameter of 4.5 m. The estimated launch mass of the module is 9500 kg, plus the mass of the initial payload. The module will be attached to node 2 of the Station, through which it will receive power and other resources. The COF will be controlled from the COF Control Centre.
The COF is a multi-disciplinary laboratory for scientific, technological and industrial investiga-tions under space conditions. In order to remain versatile and to meet the utilisation needs over its projected ten years of life, the COF can be reconfigured in orbit, being based on the concept of so-called International Standard Payload Racks (ISPR). These racks offer a modular, standardised environment for the accommodation of scientific and functional equipment. The COF can accommodate ten ISPR-type racks for scientific experiments and three racks for stowage of Station and crew items. Each ISPR-type rack has a payload volume of about 1.5 m 3 and can support up to 700 kg.
In addition to the European module, the Station will be outfitted for research purposes with one American and one Japanese laboratory module, and three Russian research modules. The first laboratory module, the US laboratory, will arrive in orbit in 1998; The others will gradually be added from 1998 until completion of the Station in 2002. According to current plans, the European COF will be the last research element to arrive in 2002. Since the European, American and Japanese laboratory modules all employ the ISPR concept the experiments will be interchangeable between these laboratories.
Beyond its practical value for scientific and technological research, the COF constitutes Europe's essential contribution to the International Space Station partnership, since the Intergovernmental Agreement (IGA) stipulates the provision of an orbital element to the Station by each partner. The United States, carrying the major financial burden of the Station's construction and operation, insist on this condition being fulfilled, since they have been assured of utilisation rights for five of the ten ISPRs in the COF as compensation for the infrastructure elements they are providing for the benefit of all partners. This corresponds to more than a third of NASA's own capability of 13 ISPRs in the US Laboratory, and the loss of such an important utilisation capability would severely affect American utilisation plans for the Station as a whole.
Columbus Orbital Facility (COF)
The second element of the proposed programme for European participation in the International Space Station is a transfer vehicle for Ariane-5, called the Automated Transfer Vehicle (ATV). In combination with Ariane-5 it will provide Europe with a payload transportation capability to the Station.
The so-called mixed fleet scenario gives each partner the right to visit the Station, and to resupply its own Station elements with its own space transportation systems. Independent access to the ISSA by each partner is not only an important political and operational aspect, but also a financial issue with regard to each partner's contribution to operations costs. ISSA operations will be divided into two categories: firstly, partner-specific operations necessary for the partner-owned elements and, secondly, common operations necessary for the Station as a whole.
The idea of this sharing of common operations is that, rather than paying cash into a pooled account, each partner provides services in kind up to the value of its share in the common operations. Since space transportation is one of the major operational cost factors, Europe is all the more interested in using its own space transportation systems not only for the resupply of the COF, but also as a means of contributing to its share of common operations cost.
The European launch vehicle most suitable for these tasks is the new Ariane-5 launcher. However, primarily designed as a satellite launcher, Ariane-5 is not equipped to perform rendezvous and docking manoeuvres with a space station. For this purpose, a separate transfer vehicle with the necessary avionics and propulsion capability is needed to perform these manoeuvres and to carry payloads to the Station. The proposed Automated Transfer Vehicle (ATV) is such a vehicle.
The ATV will look like a 2.5 m long section of the central stage of Ariane-5. It is composed of a propulsion module and an avionics module. Equipped at the rear with eight small reactive engines, the ATV will be attached to a payload-carrying structure and will push it through space in much the same way as a push-tug boat pushes a barge on a river.
The payload-carrying structures would be a function of the two categories of payload to be transported by the ATV: unpressurised cargo which can be directly exposed to the space environment, and pressurised cargo which needs to be transported under controlled atmospheric conditions.
The first category of payload is mainly functional equipment and scientific experiments to be mounted outside the International Space Station. The open transport of these payloads by the ATV permits their direct transfer by the Station's remote manipulator system to their final destination on the outside, without the need to pass through pressurised modules and airlocks. For the second category of payload, the ATV would be fitted with a pressurised container, which could be derived from the Italian Mini Pressurised Logistics Module (MPLM), on which the COF's mechanical structure is also based. It is also possible for the ATV to carry a mixture of both cargo types.
Depending on the type of payload carrier or payload module, the ATV could transport up to 6.7 t of pressurised or up to 9 t of unpressurised payload. The ATV could also provide Europe with the capability to carry the COF to the Station.
For its launch, the ATV, together with its payload and its payload carrier, will be mounted on top of Ariane-5 like a normal satellite, protected by the Ariane fairing. After injection into an elliptical orbit approximately ten minutes after launch, the ATV will separate from Ariane and push its cargo under its own power into ISSA's circular orbit and then automatically perform the necessary rendezvous manoeuvres with the Station. This will take approximately two days. Depending on the type of mission, the ATV will then either directly dock at one of the docking ports, or fly to a holding point where it will be seized by the Station's remote manipulator system.
In its mixed cargo configuration, the ATV would be able to push the whole Station into a higher orbit. This re-boost manoeuvre is necessary at regular intervals of several months to compensate for the Station's altitude loss due to atmospheric drag.
Having spent up to six months attached to the Station, during which the payload carrier could be used for the storage of experiments and functional equipment, it would be loaded with waste material from the Station for the destructive return flight into the Earth's atmosphere.
Beyond its value to Europe's participation in the International Space Station, the ATV also constitutes a strategic step in Europe's development of future space transportation systems. It complements Ariane-5 with a capability to perform orbital transfer and rendezvous missions, and represents Europe's first step towards controlled re-entry technology.
Automated Transfer Vehicle (ATV)
The third element of the proposed programme for European participation in the International Space Station concerns utilisation preparation.
The ISSA is, in many respects, a new way of pursuing the scientific and technological exploitation of space. It involves many partners and makes use of a large orbital and terrestrial infrastructure. In terms of system development and operation costs, it demands a substantial financial commitment from all programme participants. It is therefore vital to ensure the efficient and rewarding scientific and technical use of the Station. These efforts not only concern the planned scientific research activities on board the Station, but must also include the support of application projects which might lead to commercial exploitation at a later stage.
The Utilisation Preparation Programme element responds to these objectives, covering three main aspects:
The proposed programme includes the activities necessary to maintain a European astronauts corps and to develop basic facilities for astronaut training.
Gravity is one of the Universe's fundamental forces. It generates the attraction or pull without physical contact which gives us on Earth the sensation of weight. The pull of gravity on a spacecraft 250 to 300 km above the Earth is only slightly less than on the surface of our planet. However, the fact that the spacecraft is orbiting around the Earth in free-fall conditions gives rise to a virtually weightless state, called 'microgravity'.
Experiments have shown that in microgravity, crystals with improved chemical properties and a greater degree of structural perfection can be obtained. In particular, the growth of some protein crystals is enhanced, allowing these important biological substances to be analysed by X-ray diffraction, and as a result their structure and biological functions can be determined. The biological function of proteins plays an important role in research into new drugs.
In the area of cell biology evidence has emerged, especially as a result of the flights of the ESA Biorack, that some biological cells and unicellular organisms function differently in microgravity conditions than they do on Earth. This may help our understanding of how evolution works at the cellular level, since all life on Earth evolved in the presence of gravity.
Space experiments in human physiology have given new and significant insight into the working of the human balance system as well as the functioning of the human heart/blood and fluid distribution systems. These results will help our understanding of how astronauts adapt to weightless conditions in space, and may also have a considerable impact on the future treatment of patients on the ground.
Researchers in the fluid sciences have found that a fluid at the critical point , as well as surface- tension driven flows, can be more easily investigated in a microgravity environment. This research is already leading to a better understanding of industrial processes on the ground.
Some specific examples are:
ESA's Microgravity Programme started formally in 1982. It is now known as the EMIR-1 Programme. Facilities were flown on the SL-1, D-1, D-2, IML-1, IML-2 and USML-1 Spacelab missions, as well as on the Eureca platform, sounding rockets, Russian retrievable carriers, Mir and Spacehab.
The major objectives of ESA's Microgravity Programme are to:
343 experiments have been performed to date - 50% of them in the last three years - in the framework of ESA's Microgravity Programme, 183 of them (=53%) on manned missions (Shuttle/Spacelab, and Mir). The other 160 experiments have been performed on sounding rockets and unmanned retrievable satellites (Bion, Foton, Eureca).
In June 1992, the Microgravity Programme Board adopted a Resolution on the future structure of the Microgravity Programme which was approved by Council in July 1992, and by the Council at Ministerial Level on 9/10 November 1992 at Granada. This Resolution decreed that the Agency's microgravity activities would in future be split into two distinct financially independent elements:
APCF Flight model
Spacelab IML-2 launch
The proposed EMIR-2 programme (1996 2001) is essentially a research programme, whereas the MFC programme (1997 2002) covers the development of the large multi-user facilities to be accommodated in the Columbus Orbital Facility (COF). Since the schedule for the delivery of payloads for early Space Station utilisation (e.g. US-Laboratory) is more critical, early payloads are included in the EMIR-2 programme.
The EMIR-2 programme has three elements:
The MFC programme is dedicated to the development of three multi-user laboratories to be used in the ESA outfitting of the pressurised module of the Columbus Orbital Facility, and two furnace facilities. The programme covers the main development phase (phase-C/D) costs of these facilities as well as the costs associated with the development of cartridges and test containers. All other costs associated with the exploitation or utilisation of these facilities are assumed to be covered by other programme phases. It is also assumed that, as part of the overall package to be approved at the Council Meeting at Ministerial Level in 1995, the MFC programme can start in mid-1996 (commitments only), and run until the year 2002.
The facilities to be developed within the MFC are:
All these facilities will be accommodated on, and launched with, the Columbus Orbital Facility, with the exception of one furnace which will be accommodated somewhat earlier (2000) in the US Lab, on the basis of a cooperative agreement with NASA.
Maxus sounding rocket