"I can see the Earth. It is so beautiful." These were the first words ever spoken in space, by the Russian cosmonaut Yuri Gagarin in 1961, and they were visionary in every sense. It is only really since we have been able to look at our Earth from the outside – from space – that we have begun to understand the physical processes that govern its behaviour, to apprehend its fragilities, and to gain the first insights into our responsibilities in terms of how we use its resources. Earth observation from space has truly revolutionised how we view our home planet.
Watching over our planet
With their unique global perspective, satellite systems offer incomparable advantages to help us better understand, manage and protect the Earth’s precious environment. They provide an instantaneous view of vast areas of the Earth’s surface – a single image taken by a geostationary meteorological satellite, with coverage of up to 200 million square kilometres, can show nearly half the planet. They can observe every corner of the Earth, for both global assessments as well as detailed views of specific locations. With their rapid, frequent revisit capability, they can monitor phenomena as they evolve, be they natural or man-made.
Surveying the globe and its atmosphere in ever more minute detail, space-based observation systems are continually enhancing our factual knowledge of the Earth’s eco-system, shedding light on factors such as global warming, the greenhouse effect and the depletion of the ozone layer, assessing the health of our planet. They are indispensable for keeping a close and constant watch on topographical changes, such as variations in the thickness of the ice-sheets, coastal erosion, desertification and deforestation. They track the world’s weather patterns, giving increasingly long-range forecasting capability, and warn of climatic events such as hurricanes and windstorms which could give rise to floods. Satellite pictures transmitted in the immediate aftermath of the 26 December 2004 Indian Ocean tsunami were vital, enabling urgent evaluation of the areas most affected and intervention decisions to be made. Earthquakes, volcanic eruptions, landslides and forest fires are also often visible from space, and satellites provide us with a tool, if not for prevention, at least for rapid response.
Monitoring and maximising the Earth’s resources
Largely thanks to satellite data, today we are only too aware of the impact of human activity on the Earth, the potential damage, and the legacy we are leaving to our children. Gas emissions and pollution affecting the environment are the object of intense scrutiny by sensitive satellite instruments; satellite imagery records land use change and demographic pressures. Space-based Earth observation data are a key support for sound environmental management practices, promoting sustainable development and for controlling compliance with established protocol, such as the Kyoto agreement.