Window on the World
Everyday the fine balance of our planet’s natural ecological system is gradually being altered by many of the normal activities associated with modern daily life that we all take for granted.

Today, therefore, we have an urgent need to monitor and understand both man-made and natural changes to our atmosphere, land and the oceans in every part of the world.

In many cases satellites are the only way to obtain suitable data. Satellites orbiting the Earth can gather comprehensive information. But visual systems that rely on daylight and clear conditions to ‘see’ the surface have a distinct disadvantage – they cease to function when it is cloudy or at night.

So European engineers, under the direction of ESA, developed a special instrument called a Synthetic Aperture Radar (SAR). As one of the key instruments on the ERS-1 and -2 satellites the SAR is a high-resolution, wide-swath imaging radar producing high quality images of the oceans, coastal zones, polar ice and land regions, irrespective of weather conditions and cloud coverage or whether it is day or night.

It works by bouncing microwaves off the Earth’s surface and measuring the reflected radiation. A SAR also has five different modes of operation, allowing a variety of image types and giving us a new and permanently open window on the world.

What is ERS?
The first SAR was launched into space by Europe’s Ariane-4 rocket in July 1991 as one of three main instruments on ESA’s ERS-1 spacecraft. It was followed by a second on ERS-2 in 1995.

At the time the two ERS satellites were the most sophisticated Earth observation spacecraft ever developed and launched in Europe.

ERS-1 completed its operation in 1999, overlapping with the new ERS-2 launched in 1995. These highly successful ESA satellites have collected a wealth of valuable data on the Earth’s land surfaces, oceans, and polar caps.

They have been called upon to monitor natural disasters such as severe flooding or earthquakes in remote parts of the world.

On a global scale they have expanded our understanding of the interaction between the oceans and atmosphere, ocean currents and changes in the Arctic and Antarctic ice, giving climatologists more confidence in assessing climate trends.

The ERS satellites have also kept a close eye on agricultural areas, forests, coastlines and marine pollution.

By detecting land-use changes, such as the destruction of tropical rain forests, ERS data has helped governments around the world police a broad range of local and global environmental problems.

For the good of Europe
As the most comprehensive modern day source of satellite environmental data, the ERS spacecraft have brought significant benefits to Europe and the rest of the world.

These benefits have ranged from improved public services, such as weather forecasting and crop monitoring, to the creation and sharing of commercial and industrial enterprises, and helping European scientists to excel in key areas of environmental research.

Who uses the data
Today, several hundred research groups worldwide, involving at least 2000 scientists, use ERS data to further their studies.

Much of this research has paved the way for the formation of a number of international initiatives, with countries across the globe working together to combat environmental problems.

They have contributed to our quality of life through enhanced public services:

• improving our ability to forecast the weather and monitor sea and ice, and agricultural practices
• building our knowledge to help sustain society in Europe and in developing nations
• helping to shape environmental decision-making in Europe and beyond for the benefit of Europeans and other nations.

Equally important, the development and operation of the ERS satellites has helped European industry remain competitive by:

• encouraging a truly independent European spacecraft and ground-systems industry
• creating and securing more employment in Europe
• sharing out industrial skills within Europe
• developing a European information service business to compete in the world market.

Pollution from the cars we drive, the power stations that generate our electricity and the industrial processes that release toxins into the air is altering our atmosphere at an unprecedented rate.

To ensure we can understand and stop any further damage to the environment we need ongoing, coherent and precise data of the kind generated by ERS-1 and ERS-2.

Using the technology of the ERS satellites we have been able to observe all these elements on a daily basis, building up a library of information from which to learn and act upon.

Combating El Niño
El Niño is the weather phenomenon responsible for some of the world’s most drastic and devastating disasters. From summer droughts in Australia, Africa, Brazil, Asia and Central America to milder winters and severe flooding in other parts of the World, El Niño is now recognised by scientists as one of the world’s most serious environmental threats.

Monitoring particular aspects of the environment can provide answers to many of the mysteries surrounding El Niño. ERS onboard instruments can measure changes in sea temperature and levels – two key environmental changes associated with the El Niño event.

The huge amounts of satellite-generated data now available to scientists ensures that they are more able to understand the signs and causes of this extraordinary natural phenomenon and are better able to help governments and communities predict and prepare for the future.

Melting pot
Observation of our polar ice caps plays an important role in helping us assess changes in our climate. Fears of melting ice in polar regions are well-founded - it would result in widespread flooding across the globe with many of our coastal cities disappearing beneath rising sea levels.

Fortunately, ERS data can help scientists see whether ice is melting or accumulating. Detailed maps of the ice sheets can be drawn up on a continuous basis to watch for emerging adverse patterns or trends.

Devil’s advocate
Oil is one of man’s most valuable resources. We use it to power our cars, create our electricity and produce many of the plastic and cosmetic products that we all rely on. A key element of our modern world, it is both our saviour and our enemy.

As we become increasingly reliant on oil to drive our economies we are finding it more and more difficult to find new sources. The ERS-2 Radar Altimeter is able to produce topographic maps of the sea floor to help us identify new oil supplies.

At the other end of the spectrum, ERS monitoring is helping us to prevent the devastation that oil pollution can bring to our coastal, sea and marine environments. The highly sophisticated Synthetic Aperture Radar (SAR) can detect oil spills on the ocean surface.

This high vantage point can help special oil spill teams in clearing accidental oil disasters more efficiently and it can also act as a policing presence. Thanks to ERS satellite monitoring, oil pollution monitoring is now well established. Even illegal discharges, principally from ships clearing their tanks at night, can be identified and the offenders prosecuted.

Sun screen
The ozone layer is a composition of atmospheric gases above the Earth’s surface that acts like a sunscreen, filtering all the harmful rays of the sun and preventing the planet from overheating.

Since the early 1990s, scientists around the world have been concerned about the number of holes appearing in this protective layer. If the Earth warms up too much, agricultural crops could fail, water supplies could become scarce, and diseases and conditions such as skin cancer could increase.

To help us monitor these effects, ERS-2 includes an ultraviolet and visible light spectrometer, called the Global Monitoring Ozone Experiment (GOME) for atmospheric ozone level research.