Earth observation from space has demonstrated its growing scientific, social, economic and political importance by contributing to a better understanding and regular monitoring of the Earth and its environment, by supporting a wide range of applications and by providing essential data for geopolitical purposes.
We live on a planet recognised more and more as having both limited resources and a fragile ecosystem. The Earth's environment and climate are determined not only by complex interactions between the various components - the atmosphere, the oceans, the ice regions and the land - interactions as yet still imprecisely understood, but also by the ever-increasing ability of mankind to impact on them. Our well-being on Earth therefore depends on the careful management of our resources and on an improved understanding of the complex interactions determining our ecosystem. Only in this way can we identify the true effect of anthropogenic impacts, and thereby determine the extent to which they have to be moderated.
Over the last two decades, Earth Observation from space has been playing an ever-increasing role by providing data that contribute more and more to such ends. To a large extent, this reflects the growing importance of Earth Observation:
It is therefore not surprising that, over the years, it has been increasingly recognised that many key aspects of monitoring and managing our planet can only be adequately addressed by Earth Observation from space. Indeed, there is an ever-growing community of users from different sectors (public or private, research or applications) with more and more varied requirements.
In this regard, ESA has been playing an ever-increasing role in Earth Observation in the World.
The first Meteosat was launched in 1977 and since that time the Meteosat series of satellites has provided data for both weather prediction and scientific research. The success of the Agency's Pre-operational Meteosat Programme led to the formation of the European Meteorological Satellite Organisation, Eumetsat, on whose behalf ESA has constructed, launched and operates three further spacecraft for the Meteosat Operational Programme. With a fourth such satellite under construction and due to be launched in 1997, the operational service will be able to continue until early into the next century, by which time the Second-Generation Meteosat, itself now under development, will become available.
Launched in the middle of 1991, ESA's first remote-sensing satellite ERS-1 has been faultlessly gathering and providing data from its unique all-weather microwave instruments for over four years, by far exceeding the initial objectives that were laid down for it and revolutionising many areas of the Earth sciences and their practical applications. It routinely provides global maps of sea-surface winds as inputs to numerical weather forecasting. It monitors sea ice and open ocean conditions globally, aiding in ship routing, exploration and ocean sciences. It has led to the development of new areas in the monitoring of key aspects of Europe from space (e.g. resources, land use, coastal processes, disaster monitoring, to name but a few). It also provides a wealth of data of importance to environmental monitoring, climate research and operational users.
Whilst ERS-1 is seen as a major step forward, its full potential both for research and for operational applications can only be fully realised if the longer-term continuity of its important and unique data can be assured. Many of the processes relevant to climatic studies have time scales that exceed the duration of a single mission.
Meteosat-3 and 4: 16 May 1993
The follow-on satellite ERS-2 was launched in April 1995. Besides providing essential continuity of data through to the next generation satellite Envisat, it adds an important new capability, that of a Global Ozone Monitoring Experiment (GOME), to address an area of growing concern, namely atmospheric chemistry, and in particular to be able to generate global ozone maps every three days.
The second generation polar-orbiting Earth Observation satellite Envisat-1 is under development for launch in 1999. The most challenging Earth Observation satellite ever undertaken by ESA, it will not only provide continuity of ERS observations, but will add important new capabilities for gathering valuable information to contribute to the understanding and monitoring of the Earth's environment, particularly in the areas of atmospheric chemistry and ocean biological processes.
By the year 2000, the Meteosat geostationary satellite series will have been routinely acquiring data for more than 28 years. In 1994 the Meteosat Second Generation programme, jointly funded by the ESA Member States and Eumetsat, commenced. It provides for the development of a new satellite series, with considerably enhanced performance, to replace the present Meteosat s, with a first launch in the year 2000.
The third new satellite area embarked upon recently is that of Metop, a polar-orbiting satellite aimed at not only continuing and improving meteorological observations from a 'morning' polar orbit for operational services, but also endowing Europe with an enhanced capability for routine climate monitoring. This will be achieved through a cooperation between ESA and Eumetsat, with a first satellite launch foreseen in 2001 (and which will complement the USA polar-orbiting satellites). The ESA Metop Preparatory Programme has been underway for more than 2 years, and the Phase-C/D implementation programme has been proposed for decision in the second half of 1995.
With the advent of remote-sensing satellites, the potential role and importance of observation of the Earth's land masses, oceans, ice and atmosphere from space has become increasingly recognised. To ensure that European users have access to these important new data sets, ESA started the Earthnet Programme at its establishment in Italy (ESRIN) in 1977.
The Earthnet Programme is responsible for acquiring, pre-processing, cataloguing, archiving and distributing data from Earth Observation satellites. As well as handling data from the ERS satellites, and from a variety of other satellites such as the Landsat series, MOS-1, JERS-1, Spot and the NOAA Tiros-N series, Earthnet will be responsible for handling payload data for future missions, in particular Envisat.
It is of great importance that the wide range of data essential for monitoring, protecting, and controlling our Planet, its environment and its resources be both obtained and made available to those who must make the crucial decisions, and the Agency's plans are made with this in mind. The ESA Programme is seen as an important contribution to the overall international cooperative effort to monitor and understand the Earth's environmental system.
With an eye to the future, the Earth Observation Preparatory Programme (EOPP) was started in 1986 in order to prepare a sound basis for new programmes over the coming years. This Programme has already been extended to run until 1996 and has been proposed to be extended for a further 5 years, into the early part of the next century. The EOPP conducted the study and preparatory activities that led to the approval of the Envisat and Meteosat Second Generation programmes and the Metop Preparatory Programme.
ERS-1/ERS-2 multitemporal image: Italy
The future ESA Earth Observation Programmes focusses on five fundamental objectives:
The realisation of these objectives forms the basis of ESA's Earth Observation Programme. They are based on the increasing recognition that there are major problems, many of which are only recently recognised, associated with the well-being of humans on an Earth with limited resources and with ever-increasing demands on those resources. These can only be addressed effectively if the complexities of the global Earth system are understood to a much greater degree than at present. Better observations are fundamental to this requirement.
Given that these issues are of concern to all of the World's nations, they call for well-coordinated international cooperation. No one nation can afford to develop and operate the complex space systems and ground infrastructures necessary to realise the objectives. ESA's Earth Observation Programme recognises this by seeking collaboration and taking full account of other Earth- observation programmes that are either in progress or are currently being planned.
A significant contribution is made to these objectives by the Earth Observation satellites already developed and in-orbit, together with their ground segments, and will be made by the further ESA satellite systems currently under development.
The realisation of the Agency's Earth Observation strategy depends on an integrated future programme building on the current satellite systems in-orbit and under development, together with their ground segments, and focussing on the following broad objectives:
The elaboration of how to realise the objectives is conducted, inter alia, through on-going dialogue and consultation with the wide user community - most recently through a major three-day User Consultation Meeting held in October 1994.
The concept of two different classes of mission to realise the objectives has emerged and been endorsed. This Dual Mission Strategy consists of:
Earth Explorer Missions: these are research demonstration missions with the emphasis on advancing understanding of the different Earth system processes. Each mission would focus on a particular research field or re-group a limited number of research fields. The demonstration of specific new observing techniques could also fall under this category. Earth Explorer Missions will be entirely funded by ESA, with mission durations tailored to the specific mission requirements.
Earth Watch Missions: these are pre-operational missions addressing the requirements of specific Earth Observation application areas. After the development/pre-operational phase to be funded by ESA, the responsibility for this type of mission would eventually be transferred to (European) entities providing operational services. To ensure such a scenario, data continuity over a period of at least ten years would be required.
Already a number of candidate missions for each of the two categories have been identified by the user community. For the first Earth Explorer mission some nine candidates have been identified which, following further review, are expected to be narrowed down to a subset of three or four for assessment and detailed feasibility study and from which the first Earth Explorer mission would be selected. For the first Earth Watch mission some five candidate themes have been identified, including monitoring of coastal zones, open ocean, ice, land and atmospheric chemistry; they are currently being further explored.
As regards those aspects concerned with the provision of data, with the evolution of the ground segment to improve access and availability of data and products, and with improvement of awareness and utilisation of Earth Observation data products, a number of complementary thrusts are to be pursued.
Within the satellite system programmes themselves, the user data ground segment will play an important role in ensuring, to the maximum extent possible, that all user needs are fully addressed.
This is proposed to be complemented by the establishment of a Data User Programme (DUP) concerned with promoting improved access to, and availability of multi-mission Earth Observation data and their wide distribution, as well as deepening the involvement of user entities. In addition, the DUP will be a mechanism facilitating enhanced cooperation between ESA Member States, the European Commission (EC) and ESA in the use of Earth Observation data from space. The DUP will also enable the transfer of technology from emerging R&D to pre-competitive applications. The DUP is planned to be approved in the second half of 1995.
The third thrust is through increased cooperation, both within Europe in particular with Eumetsat, with the European Commission, with Member States and with the User Community - and with other space-faring nations in the World, such as the USA and Japan, especially in the area of Earth Observation data, products and services.
ERS-1 & ERS-2 : United Kingdom