The United Kingdom's environmental scientists will reap huge dividends from the European satellite, ERS-2, due for launch last night. The satellite will watch changes in the earth's seas and vegetation and should lead to major advances in detecting global warming and holes in the ozone layer.
UK scientists have won 60 of the 250 "principal investigator" positions, which entitle them to free access to the satellite's data in order to run approved research projects, far more than any other country, according to Stephen Briggs, head of earth observation at the Natural Environment Research Council.
Mr Briggs said ERS-2 was the most important satellite for the UK so far "for the broad commercial and science community".
The European Remote Sensing satellite carries eight instruments, which will use radar to detect the height of the sea and its waves, an absorption spectometer to measure ozone, trace gases and aerosols and microwaves to measure atmospheric humidity.
It will also carry an instrument built by the Rutherford Appleton Laboratory, the Along Track Scanning Radiometer (ATSR-2), which will record infra-red and visible rays. Chris Mutlow, project scientist for ATSR-2 at RAL, said it will enable researchers to make temperature maps of the globe and photograph vegetation.
The ATSR-2 will be able to detect shifts in the borders of deserts and in the distribution of rainforests and crops. Scientists also plan to use it to study clouds, which are poorly understood despite their influence on overall climate.
The ATSR-2 improves on the ATSR-1, an instrument which went up in Europe's first environmental satellite, ERS-1, by being able to detect in the visible as well as the infra-red regions.
But ATSR-1 has performed great work in the painstaking process of detecting global warming by measuring ocean temperatures to an accuracy of a third of a degree, according to David Llewellyn-Jones, professor of earth observation science at Leicester University.
He said: "A pressing question at the moment is whether we actually have global warming or whether we are getting normal fluctuations.
"There's definitely been a trend over the past 100 years but that's from highly non-homogeneous data. We need to measure the global sea surface temperature with a stability of 0.1 degrees celsius per decade and keep the measurements going for 10 to 15 years to be able to say, with reasonable confidence, that we have global warming."
Scientists have persuaded the European Space Agency to keep the first satellite in orbit for longer than planned so the two will fly in tandem. They can then work out how well the instruments are performing in space.
"This is giving us an amazing opportunity to compare them," said Professor Llewellyn-Jones.
The ATSR-2 will be followed by a more advanced version at the turn of the century.
ERS-2 will also carry the Global Ozone Monitoring Experiment which will generate a world ozone map every three days.