Exploration system technology aspects in the exploration programme of the European Space Agency

Acta Astronautica 59 (2006) 3 – 12 www.elsevier.com/locate/actaastro

Exploration system technology aspects in the exploration programme of the European Space Agency Richard Fisackerly∗ , Claus-Juergen Reimers, Alain Pradier ESTEC, Noordwijk, The Netherlands Available online 19 April 2006

Abstract Within its exploration programme Aurora, the European Space Agency is preparing activities for human exploration of the solar system to be implemented in the next 5–10 years. These activities will be based on a long-term plan for exploration with a horizon of 30 years. As ESA is convinced that exploration can only be done via international collaboration, this long-term plan will be harmonised with the intentions of other potential international partners. Consequently, the Agency will concentrate in the near future mainly on activities which it wishes to introduce into an international partnership for exploration. The near term programme will contain robotic activities towards Mars i.e. the implementation of one mission and the preparation of subsequent missions. This will be accompanied by technology developments to support future missions. Concerning human exploration activities ESA is preparing a role for the return to the Moon, which it sees as a way-station on the route to Mars. Potential contributions will leverage on past investments. Capabilities considered in this context are habitation, life support and assembly in orbit. © 2006 Elsevier Ltd. All rights reserved.

1. Introduction Exploration of our solar system has long been a core activity for the world’s space faring nations, returning scientific discovery, technological innovation and providing inspiration for future generations. Indeed Europe has played a key role in this effort up to now, with probes studying the Sun itself, our own Moon and Mars, moons of the outer planets and with spacecraft already en-route to study the nature of comets, to name only a few. Recent events have however sparked off a further reinvigoration of interest in space exploration, to build on past successes and aim for even more ambitious investigation of our solar system, while pushing further ∗ Corresponding author. Fax: +31 715 658 305.

E-mail addresses: [email protected] (R. Fisackerly), [email protected] (C.-J. Reimers), [email protected] (A. Pradier). 0094-5765/$ - see front matter © 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.actaastro.2006.02.017

the boundaries of human spaceflight in preparation for our own, first hand, exploration of our solar neighbourhood. Indeed Europe placed itself at the fore-front of this next generation of space exploration by embarking upon the Aurora Preparatory Programme in 2001. The first years of this programme have given Europe, through the European Space Agency (ESA), European industry and academia, the opportunity to consider a long-term strategy for exploration, based on step-wise scientific and technological progress leading, in the case of Aurora, to the ultimate human exploration of Mars. In addition to this long-term view of possible paths to take, Aurora has gone further in laying down more concrete plans for the near-term exploration of Mars. Detailed systems studies into Mars robotic missions (i.e. ExoMars and Mars sample return (MSR)) have allowed Europe to identify which technologies and capabilities might be key in the future, and a wide range of focussed technology

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development activities have already been initiated in order to begin maturing these technologies. Throughout this first, preparatory, phase of the Aurora programme however, the international context surrounding exploration has been developing rapidly in particular with the emergence of a new US initiative to return to the Moon, the decisions being taken on the future of the ISS and the developing exploration programmes of other nations such as Russia, Japan, China and India. This paper describes how the ESA is addressing the future challenges of space exploration, within this new international context, and also within the framework of the newly created ESA directorate of Human spaceflight, microgravity and exploration (HME). This approach is based on the existing heritage gained from both past Aurora activities and the strong experience obtained within Europe’s human spaceflight activity to date. In particular, this paper will outline the technology development and the approach to this development being pursued, which will form an important part of the program proposal for exploration to be considered at the next ESA Ministerial Council in December 2005. Within the overall programme of exploration being prepared for the council, one important element, among others, is of course to continue the European exploration of the Mars surface, the first steps of which will be achieved through the ExoMars rover mission, described in the next section. 2. ExoMars 2.1. Past heritage The ExoMars mission represents a major step in advancing the exploration of Mars, particularly from a European perspective. To be launched in 2011, the mission will search for traces of past and present life, characterise Martian geochemistry and water distribution at various locations, improve the knowledge of the Mars environment and geophysics, and identify possible hazards before landing other spacecraft or, in the longer term, humans. Having defined these objectives, various systems studies carried out both internally and by industry have developed mission concepts for ExoMars broadly consisting of a descent module delivering a mobile rover platform and payload to the Mars surface (Fig. 1). These studies have investigated in detail the critical aspects of such a mission, both from an operational and a technological point of view. Indeed the consideration of technological requirements is of key importance in overall program planning since the experience and

Fig. 1. ExoMars rover concept.

heritage gained within ExoMars, including the capabilities developed, will provide a large part of the foundation on which future European missions, and European contributions to international collaborations, is based. Returning again to the ExoMars systems studies, which have recently completed the phase A stage, the work done both within ESA and by European industry highlighted technology requirements and related gaps in European capabilities. Having identified these capabilities, a range of activities were initiated within the Aurora preparatory program in order to begin development of key technologies for ExoMars. These activities aimed at maturing critical technologies to the point were they could be distilled into the ExoMars project development. The critical capabilities identified included landing on Mars, mobility on the surface and the exploitation of solar power on the surface, among others. Considering the case of entry, descent and landing, an activity was initiated to consider alternative descent and landing technologies (ADLT), specifically vented airbags. In addition to performing a preliminary systems design of an atmospheric descent and landing system, the activity also includes the hardware testing of a vented airbag concept, as shown below (Fig. 2). As well as indicating the potential of this specific airbag technology, the wider scope of this activity has highlighted critical areas in the descent and landing system and allowed the definition of an end-to-end testing strategy for such a system, to be discussed in more detail later. In terms of surface mobility a specific activity was initiated under the Aurora preparatory programme aiming at developing a set of tools, commonly known

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Fig. 2. Vented airbag concept (courtesy of Vorticity Ltd.).

as the Rover chassis evaluation tool (RCET). These tools will allow the accurate and reliable modelling and prediction of locomotion system and sub-system components including wheels, chassis, etc. In addition to these software-based tools, the activity will also develop testbeds for both single wheels and entire chassis in order to validate results of models. With this activity Europe will have the tools and facilities needed to accurately test the locomotion concepts developed for ExoMars. For the specific case of solar power generation on Mars, it is important to study and understand the effects of the Mars surface environment on solar cells. To achieve this two activities were initiated in order to both understand the behaviour of different cell designs, e.g. dual and triple junction, in Martian spectral and temperature conditions, and also to investigate the impact of and possible mitigation techniques for dust deposition on solar cells. These activities, drawing to a close now, are helping inform and guide the further Mars surface mission specific technology development for solar cells. The above mentioned activities, along with other experience, are the foundation on which many of the future planned activities are being built. The framework within which this planned activity is being initiated is discussed in the next section. 2.2. Planned activity With the completion of the ExoMars phase A study work, the system level insight obtained into many of the critical technology issues through this work, and with many of the initial Aurora technology development activities producing results and reaching their end goals, there is a current need to ensure continuity of

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development while also focussing on areas highlighted within systems studies. This continuation is provided by a series of technology development activities which have two major goals: first to bridge the gap between the preliminary development undertaken in the early stages of the Aurora program and the mission specific development to be carried out in the ExoMars phase B1 work, and second to continue building technological experience in key areas of relevance to future exploration missions such as Mars sample return. Examples of these activities, which are now approved and many of which are in their initial stages, cover several different fields. Firstly in order to meet the foreseen scientific objectives of the ExoMars mission it is necessary to focus specific development in order to mature potential instrument technologies. Such instruments include for example an Ultra-violet spectrometer and a dust and water instrument suite in order to study in more detail the Mars environment, its effects on the Mars surface and possible risks to future missions. In addition to this several instrument technologies such as gas chromatograph/mass spectrometry, Raman/laser induced breakdown spectrometry, X-ray diffractometry and a life marker chip (LMC) are being developed as potential methods for both characterising the mineralogy of acquired samples, and also to indirectly detect signs of life. These activities will mature these technologies in order that suitable instruments are ready for inclusion in future ExoMars development. Other important activities, which are of direct relevance to ExoMars but which will benefit future Mars missions in general, include specific work on understanding and modelling the Mars environment, i.e. the improvement of the current European Martian circulation model and climate database as well as the modelling of the Mars radiation environment. Also of relevance to Mars surface missions, including ExoMars, is the improvement and optimisation of solar cell and solar array design for specific Mars surface conditions. Building upon the experience described in the previous section, several follow-on activities will be performed to continue the actual cell development process (based on recommendations from past work), to develop test facilities in order to test the electrical performance of cells in Mars representative conditions, and also to develop facilities which can simulate more specifically the Mars dust conditions (to begin testing dust mitigation techniques developed in previous work). The example activities described above form part of a package of work aimed primarily at maturing

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technologies for applications in the ExoMars project, but also to address more long-term Mars mission requirements. These “planned” activities are approved and are being initiated under the relevant technology development programs. In addition to these specific technology development activities, another major area of current activity is the phase B1 stage of systems work on the ExoMars mission itself. Still in its initial stages, this work involves several major aspects; firstly, the review of high-level requirements and constraints specifically with respect to revised launch date plans (now for 2011) and other factors such as launcher, mission architecture, etc.; secondly, the designs and choices developed and made in the phase A work must be revisited in light of new mission requirements and the constraints they impose e.g. reduced rover mass; and thirdly, critical areas of technology development will be considered within the ExoMars project itself e.g. drilling, breadboarding of rover chassis, and breadboarding and testing of EDL systems. All of these areas will build upon the heritage gained through the Aurora activities described earlier, and will incorporate the results of ongoing work. Through this phase B1 activity, technologies critical to the mission development will be passed from the dedicated technology development effort, to the ExoMars project itself ensuring coherence and integrity. The future of ExoMars, including its further development stages right up to the launch itself, currently represent one of the major components of the Exploration programme proposal being prepared for the Ministerial Council in December. Should this be approved, Europe will have the chance to implement many of the technologies currently being developed, and to create a foundation of capabilities on which future missions can be built. One such mission, which may be greatly affected by the outcomes of the ExoMars development, is Mars sample return. 3. Mars sample return 3.1. The mission Since the beginning of the exploration of the planet Mars, it has been a long-term aim to return a sample from the surface back to Earth, and with the increasing number of successful Mars surface missions, the technological advances driven by these and the wealth of scientific data returned, the possibility of a MSR mission has moved from a long-term aim to being firmly on the medium term horizon (Fig. 3). Returning such

Fig. 3. Mars sample return mission concept.

a sample, or indeed several distinct samples, would allow us to use the wealth of Earth based laboratories and facilities to take the study of Mars and the search for potential life there to a new level. NASA recently responded to this prospect by indicating that, having begun considering an MSR mission, a potential launch date could be as early as 2016. Within Europe, and specifically within the Aurora program, the MSR mission has already received substantial attention, in part because it represents a milestone between smaller scale science missions and the large-scale lander missions, which may include human missions. Having been picked out as a key scientific and technological milestone in the progressive exploration of Mars, as envisaged within Aurora, the MSR mission was studied both within ESA and by European industry. This phase A1 level work defined what is known as a “ground-breaking” architecture, i.e. a stationary lander taking a sample from its immediate surroundings. In addition to this, the architecture included a dual launch mission, with an Earth return capsule being placed into Mars orbit separately from the lander and Mars ascent vehicle (MAV) combination. As well as gaining an initial understanding of the overall considerations in such a mission, the phase A1 study work also highlighted the critical mission phases and capabilities involved in such a mission. These include the soft-precision landing on the surface of Mars, the ascent back to orbit and the rendezvous of spacecraft in Mars orbit, to name but a few. This study work helped drive several technology development activities aimed at beginning to address some of the key technical issues and performing the required trade-offs between various options. These activities, performed in parallel to the early technology development work for ExoMars, form much

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of the past European heritage with respect to the MSR mission. 3.2. Past and planned activity Performed in close cooperation with the phase A1 system work, the technology development activities related to MSR included work in the following main areas. Landing on the surface of Mars, particularly for such a large and specialised payload as the MSR lander, represents a significant challenge. In order to begin addressing the requirements of such a soft, precise landing, work was performed to begin study and development of the required sub-systems for such a landing, e.g. navigation system and sensors. The technologies associated with this are also relevant for a possible rendezvous system, the requirements of which were also considered in this activity. Ascent from the Mars surface, in particular the chemical propulsion system required and the GNC design needed, was also addressed within several activities aimed at both down-selecting potential propulsion systems and also addressing many of the GNC challenges posed. With the baseline mission architecture pointing towards a rendezvous in Mars orbit, an activity was performed in order to consider this rendezvous and what methods could be employed to transfer a sample container between two spacecraft in space. This choice between the docking of two spacecraft or the capture of a small container by a single spacecraft remains open, however the first phase of technology development in this area has given a clearer idea of the differences involved and has matured the different options to such a state where a good assessment can be made as to advantages and disadvantages. In order to satisfy the stringent planetary protection requirements associated with the return of a Mars sample to Earth, one key technology is that of sealing and monitoring. Specifically this refers to the sealing of a container (or several nested containers) and the monitoring of this seal’s closure and its status throughout mission operations (e.g. Mars–Earth return transfer). To begin addressing this, past technology activities have studied possible options and have begun considering breadboard designs to identify critical technical issues. The above examples formed part of a package of initial MSR-related technology development activities carried out in the early phase of the Aurora program. These activities, and the phase A1 study work, represent the

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back-drop to a new set of activities aimed at further maturing key technologies and focussing on the preliminary development of hardware and testable concepts. These activities also focus in the areas of landing sensor technology, breadboarding of capture/docking systems, development of facilities for the testing of GNC for both landing and rendezvous, and the further development of sealing and monitoring concepts, among other areas. These activities have also been approved and are currently in their initial stages. In addition to this past heritage and current work, the advancement of the MSR mission from a systems perspective is also an important element of development. However, this systems work, at phase A2 level, is so affected by changing international factors and the more long-term European perspective, that it can be better understood in the context of the future European approach to MSR development. 3.3. Future European approach As past studies have shown, the scale of any future MSR mission is such that it will most likely be performed through an international cooperative effort led by NASA. Considering this it is important that Europe adopt an approach which both builds on past activity and heritage, while also preparing to take a strong and important role in a future MSR mission. The most immediate work relating to MSR is the phase A2 system level activity. The MSR phase A2 work, like the ExoMars phase B1, is influenced by several major factors; first, mission analysis considerations must be reviewed to take into account a 2016 or later launch date; second, the outcomes of the phase A1 study work and the preliminary technology development will focus attention on mission critical areas and particular design challenges; third, with the recent success of the Mars exploration rovers, it will be important to study the impact on the overall mission of including a mobile element in the MSR architecture; and fourth, with the prospect of an international cooperation, it is important for Europe to begin considering in more detail potential European contributions to an MSR mission. The MSR phase A2 work, approved and already in its preliminary stages, represents a very important step in European MSR-related activity, however substantial future system level work and technology development is required to prepare Europe for a role in a future MSR mission. Such a package of system work and technology development activity is at an advanced stage of preparation and is to be proposed at the Ministerial

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Council in December as part of the exploration program proposal. 3.4. Proposed system activity With the prospect of international cooperation it is important to begin coordinating the development effort between potential partners. While the MSR phase A2 work will begin this task, and may involve some interaction with NASA in certain fields, it is proposed that the next logical step of system level work would be a joint system study into an MSR concept with NASA. Building on the past heritage of both Europe and the US, as well as other potential partners, such a study would narrow down potential options and help outline a common architecture. Developing such an architecture, as well as a shared understanding of the major challenges involved would help in discussions on possible roles and responsibilities, and thus potential European contributions. For ESA to initiate such a study, along with the past heritage gained through the preparations for ExoMars and the development related to MSR, in addition to the proposed MSR technology development outlined in the next section of this paper, would place Europe in a good position to begin determining its own priorities and areas of interest. With the MSR phase A2 system level work due to begin very soon, and with a follow on joint system study at the proposal stage, Europe is in a good position to improve further the understanding of the system design aspects of the MSR mission. In addition to this the system level work has already, and will in the future, act as a major input to the technology development work being undertaken. The interaction between the system level work planned and proposed, with the technology development heritage and proposed future work, represents an important part of the European approach to MSR. 3.5. Activity interaction In the proposed European MSR development package, in addition to the proposed joint system study described in the previous section, several specific areas of MSR-related technology development are proposed. Before describing these individual fields and the scope of the activities proposed, it is important to take a wider view of the system and technology development work; past, present and future. One of the outcomes of the initial MSR phase A1 work was the identification of several critical capability areas which were key to an MSR mission. This helped

drive much of the early technology development work conducted in Europe, as described earlier in the paper. This study heritage, the experience gained through technology activities and the new perspectives gained to the MSR mission through the success of mobile Mars missions have helped formulate an updated set of key enabling capabilities for MSR (Fig. 4). These are: • deep drilling, sample acquisition, processing and transfer, • surface mobility, • biological containment system, • rendezvous and capture/docking, • soft/precision landing, • planetary ascent. A logical set of development activities has been proposed for each of these areas, to be described briefly shortly, however it is important to note that despite identifying the criticality of these areas, Europe does not intend to pursue each technology to the point of implementation in an MSR mission. Instead the proposed approach is to perform some technology development, in addition to the ongoing and proposed system studies, as part of a technology down-selection process. Gradually, through the interaction between system work and technology development, individual areas will be identified as strong possible European contributions to an international MSR mission. This continuous focussing of European effort and resources aims to enable Europe to play a meaningful and strategically important role in an MSR mission. The down-selection process, and its interaction with systems studies, is illustrated below (Fig. 5). Despite the intention to down-select specific areas for more focussed development in the future, it is important that a coherent development effort is formulated for each of the identified capabilities. As part of the preparation for the exploration program proposal to the Ministerial Council, such strategies have already been developed, and plans of activity proposed. In many cases these activities include smaller scale systems studies into specific areas e.g. a MAV. Such smaller scale studies will interact strongly with the proposed MSR system studies, and will also help guide the technology development work. These packages of work, for each identified capability, are described briefly in the next section. More detailed descriptions of these activities, as well as the other exploration technology development work, can be found on the ESA exploration technology development website, accessible through the main Aurora web page: www.esa.int/SPECIALS/Aurora/index.html.

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Fig. 4. Enabling capabilities relating to MSR.

Fig. 5. Technology down-selection process.

3.6. Proposed technology development activity Deep drilling, sample acquisition, processing and transfer (DDSAPT): These technologies represent crit-

ical capabilities for any MSR mission, since they provide the first link in the sample collection and transfer chain. Building on the past heritage of other European lander missions, the proposed development approach

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for DDSAPT technologies consists of identifying what kind of delta development is required of the drill developed for ExoMars, while also considering new, more innovative approaches to specific areas of drilling. Further activities will concentrate on the most reliable sample transfer mechanisms in order to ensure this critical and challenging phase is addressed properly. Europe’s strong heritage in robotics gives this area good potential for future activity, which will be boosted greatly by the development and operation of the ExoMars drill assembly. Surface mobility: With the advantages of mobility starkly highlighted by the recent successes of the Mars exploration rovers, the capability to move on the surface during sample collection is seen as very important in an MSR architecture. To address this, a package of activities is proposed to begin to develop a sample fetching rover (SFR). Such a development would build very much on the experience gained through the development of the ExoMars rover and, similarly to the drilling case, a substantial amount of effort will be directed to identifying the delta development needed from the system developed for ExoMars. To help guide this process, a rover system study is proposed which will interact strongly with the wider MSR mission study, and which will help determine the specific requirements of such a mobile vehicle. Already identified as requiring attention are the areas of locomotion and navigation for which the heritage of ExoMars might not fully meet the requirements of an SFR. Biological containment system: With the stringent planetary protection requirements imposed by an MSR mission, as well as the need to ensure the prevention of sample contamination, it is deemed critical to develop a biological containment system to protect both the Earth’s biosphere, and the Mars sample, from crosscontamination. To begin to address this challenge, it is proposed to initiate a biological containment system design activity. This would bring together many of the activities already performed by ESA which includes the assessment of sealing and monitoring technologies, the design of a sample container and the integration of the container design with the technologies selected. The new proposed activity would bring the results of these together with those from activities in other fields such as the development of sample transfer technologies in Mars orbit (i.e. capture or docking) and the drilling, sample acquisition, processing and transfer development described earlier. Rendezvous and capture/docking: Given the indication of the need for sample transfer in Mars orbit, and the preliminary technology development already carried

out in Europe in this area, it is proposed to continue this through a set of dedicated activities intended to, first, assist in making the trade-off between the options of capture and docking, and second, to further develop the down-selected concept. To this end a set of activities will take both the hardware testing, and the GNC system development to the point at which a decision can be made, likely dependent very much on the outcome of ongoing MSR system studies. It is then proposed to mature both the hardware mechanism, and GNC design through the use of integrated test facilities, in order to prepare the chosen concept for possible flight demonstration. Of course, how far down this development path Europe chooses to go depends very much on the downselection of capabilities it performs. Soft-precision landing: As is the case for the ExoMars mission, landing on the Mars surface is one of the most difficult and challenging phases of the MSR mission. However, substantial differences exist in the approaches required for these two missions. The MSR mission requirements are substantially more stringent than those of ExoMars, and the landing system required to meet these must be capable to ensuring a soft, precise landing. Such a capability involves both advanced propulsion systems to perform the descent, and specialised GNC systems to control the lander during this phase. A great deal of development heritage already exists in the frame of navigation techniques and sensor technologies based on visual navigation systems and on laser-based sensors. This has been coupled with studies into soft landing demonstration concepts and the preliminary definition of test facilities. Proposed activity in this field would continue to mature GNC and sensor technologies, implementing more advanced features such as hazard avoidance etc. while also preparing to integrate these technologies into developing lander testbeds. Planetary ascent: One of the many reasons the MSR mission represents such a milestone in Mars exploration is the fact it will be the first time a mission has gone through the complete operations of travelling to, and returning from the Mars surface, a critical step on the path to possible future human missions. An important phase of this is the ascent from the Mars surface, requiring both advanced propulsion systems and specialised ascent GNC systems. ESA has already begun addressing the challenges of planetary ascent through activities aimed at both considering the GNC for a MAV and identifying potential engine options for such a vehicle. The proposed activity will continue to build on this through the maturation of GNC system design, the adaptation and optimisation of the baseline engine, and the devel-

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opment of an ascent vehicle demonstrator for systems tests. The six specific areas identified above relate specifically to MSR, and as has been explained, these development strategies, although intended to take the technology from its current status to a readiness for flight demonstration, will be subject to a down-selection in order that Europe can best focus its resources. In addition to these MSR specific activities however, three other areas are addressed in the program proposal, intended to be of direct benefit to all future Mars missions, but which have specific relevance to ExoMars in the short term. These areas are: Entry, descent and landing technologies: Building on the work performed on the vented airbag concept, further activity is proposed to conduct an end-to-end test campaign of a full landing system, from the high altitude deployment of parachutes to the final, safe touchdown of the airbag. This development will include the further breadboarding of airbag designs (either vented or unvented depending on the results of the ongoing assessment), and of specific components. The end-to-end test is composed of three distinct phases, aimed at testing parachute deployment, the active velocity control system and the airbags themselves. Thus the test will in fact involve three overlapping tests. This campaign, is intended to be integrated into the further ExoMars project development. Radioisotope heat units: With the increasing sizes of Mars missions, and the thermal requirements imposed on them, solar power generation may be reaching its limits in terms of its ability to keep critical components such as payload electronics warm. An alternative to using solar power for thermal control is to employ small radioactive devices which produce heat, radioisotope heat units (RHUs). Such devices have been used on all successful Mars surface missions to date, and have already been used on two European missions, with the help of the US. If such devices are to be used onboard a mission such as ExoMars, it is important Europe begins addressing the issues involved. Having made the decision not to develop the RHUs themselves within Europe, instead procuring them e.g. from Russia, a set of activities is proposed to build on previous work and develop the required procedures and safeguards needed for working with and using RHUs aboard space missions. This includes testing, space craft integration and launch. Planetary protection: The requirement to protect the Mars surface from contamination from Earth is one of the most challenging requirements to meet. This legal

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obligation is also of critical importance in ensuring the reliability of any scientific measurements made during a mission. Planetary protection itself covers a wide range of areas, all of which require attention, and which are dealt with to some degree in the proposed package of activities. These include: the assessment of materials which are incompatible with sterilisation procedures, and the identification of alternative materials; the development of assembly, integration and verification (AIV) procedures which ensure planetary protection requirements are adhered to; the development of a low-temperature sterilisation process for particularly sensitive components and finally the preliminary consideration of the requirements for a Mars sample receiving facility. These activities should address the functional requirements of ExoMars while beginning to understand the additional planetary protection requirements of an MSR mission. This entire package of development, largely aimed at preparing for a MSR mission, builds on past technology developments and study heritage, integrating the results of work currently ongoing and preparing for the future with follow-on developments and new activities, both to further mature technologies and develop the understanding of the MSR mission within Europe. Much of this MSR activity has close links with the ongoing development of the ExoMars project, and together the activities give a comprehensive coverage of the developments needed for Europe to take part in the progressive exploration of Mars, both independently and in an international cooperation. The robotic exploration of Mars is however only one part of the European activity in the frame of exploration. As was the long-term vision of Aurora, one of the goals of the near term exploration effort is to pave the way for expanding and extending the human presence in space, beyond its current confines in low Earth orbit, to the Moon and eventually to Mars. Indeed in this area too Europe has been active in a wide range of fields and over several different contexts, from its practical experience in the ISS program to preparations for human exploration made within Aurora and other programs. 4. Human exploration While many of the goals of exploration can be achieved through robotic missions, having a human element to the exploration effort has been identified as being of key importance for the long term. Not only can humans benefit greatly the scientific investigation of other planets and the search for evidence of life on

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the likes of Mars, but also the technical challenges and social significance of extending human activity to other worlds can be of immeasurable benefit to society as a whole. However, even with the experience gained through past human missions to the Moon, the technological difficulties associated with such a mission, or indeed future human missions to Mars, represent a great challenge to be addressed. As envisaged within Aurora, the missions and activities discussed earlier in this paper not only serve to make scientific discoveries or advance the technologies associated with robotic missions, but also represent some of the first steps in development required on the path to future human exploration. This includes the fields of entry, descent and landing, planetary ascent, GNC, advanced autonomy, etc. While these capabilities would be advanced by future robotic missions, there are areas for which dedicated development is needed in order to address many of the human specific challenges. The recent reinvigoration in interest in human exploration has been borne in part out of the new NASA effort to return to the Moon with a human mission before the end of the next decade. This intends to be a first step to a sustainable human presence on the Moon, and to developing experience and capabilities with a view to future Mars missions. Europe has already begun to consider how it might play a role in this future effort, which will likely involve a large degree of international cooperation. This has been performed through the initiation of several study activities within ESA first to understand the current requirements of a human mission to the Moon, as well as possible precursor requirements, and in addition to possible role of the ISS in such a program. Europe’s heritage within the ISS program plays a strong part in preparations for future human exploration and possible participation in a return to the moon. Experience ranges from the development of robotics systems, to advanced life support units, to the construction of entire modules. In addition to this, study and technology development heritage exists over a wide range of fields including inflatable technologies, re-entry vehicles, rendezvous and docking, etc. Europe’s future approach to development in the field of human exploration consists of continuing studies into future human lunar exploration scenarios in an effort to begin identifying potential areas where Europe might be able to contribute. Such a contribution need not however be limited to Europe’s current experience since

technology development, and demonstration, is planned in several areas including rendezvous and docking (with the International Berthing and Docking Module, IBDM) and advanced life support systems. Independent European access to space for humans is also being considered through cooperation with Russia on the Clipper program. Clipper is a vehicle which should deliver six crew to the ISS and return them to the Earth, however its roles and capabilities could be foreseen to expand in a future international exploration scenario. Through engaging in preliminary studies with Russia in the area, Europe will be able to assess the feasibility and advantages of such a project. While Europe’s strategy to human exploration will be very much dependent on the plans other, larger, international partners, the approach being followed is intended to give Europe the widest possible options to become involved in near-medium term international human exploration. This would then enable the gathering of capabilities and experience to take an important role in longer term activity. 5. Conclusion The technology development activities presented here, including past European heritage, ongoing activity and the work currently being planned by ESA, concentrate largely on robotic missions to Mars. Aligning the technological objectives of these activities with the progressive development of both ExoMars and Mars sample return, at a system level, is ensuring key enabling capabilities are in place when required. Development related more specifically to MSR is preparing Europe to play a strong and meaningful role in a future international cooperation effort, while system level work will involve Europe in this evolving understanding of the mission. A strong synergy between ExoMars and MSR development will ensure the efficient and targeted use of European resources. In addition to this, the changing international landscape with respect to future human exploration, possibly to the Moon, is being addressed through building on Europe’s past human spaceflight heritage and engaging in a range of future activities. This technology development approach represents one of the core elements of the programme proposal for exploration which will be presented to the ESA Ministerial Council for approval in December 2005, and which aims to pave the way for a bright European future in space exploration.