At the end of 2017, the European Space Agency (ESA) will launch a satellite whose mission will involve research into climate and air pollution. The onboard instrument that will make the necessary measurements is the most advanced and accurate of its kind ever to be sent into space. TROPOMI was conceived and designed by optical and mechanical experts from TNO and Dutch Space, and is being constructed largely by Dutch manufacturing companies.
Adriaan van 't Hof, TROPOMI's Project Manager, points out that "TNO's track record in the design and construction of optical instruments for clients such as the aerospace industry stretches back fifty years". "For instance, since the 1980s we have worked with foreign partners to develop advanced instruments, such as the Global Ozone Monitoring Experiment (GOME), followed by SCIAMACHY, which measured atmospheric concentrations of ozone and other gases. As a result, we became global leaders in this field. In 2004, the Ozone Monitoring Instrument (OMI) was launched into space aboard a NASA satellite. Its successor, TROPOMI (Tropospheric Monitoring Instrument) has a resolution that is more accurate by a factor of six, and twice the wavelength range. That represents a huge step forward for the scientists who will be using the data that it generates. All of the data beamed down from space will be sent to the KNMI (The Royal Netherlands Meteorological Institute) and SRON (The Netherlands Institute for Space Research). There it will be processed, analysed, and made available to the EU's Copernicus Programme."
TROPOMI will orbit the Earth at an altitude of 824 kilometres, scanning the entire surface of the planet each day, at an unprecedented spectral resolution. The instrument will compare measurements of sunlight with the light that is reflected back by the Earth. This will make it possible to calculate the atmospheric concentrations of certain gases, such as ozone and the oxides of nitrogen, to see how they change over time. The enormous precision of this instrument means that it will soon be possible to track pollution at the level of individual cities. Limited by the confines of such a small, compact and lightweight instrument, we really had to push the envelope to achieve the extremely high resolution and wide dynamic range required. The new technologies that our experts developed specifically for this purpose included 'free form' optics, which made it possible to create mirrors and lenses in unprecedented shapes. Another new technique involved the use of immersed gratings, which are microscopic grooves etched in glass. These grooves are used to split light into different wavelengths."
"Many of the components are being manufactured by specialized Dutch companies. This requires them to innovate, in terms of new technologies and production methods. However, some of these components were so complex that TNO had to build them itself. The input from the business community is helping to shape TROPOMI into a state-of-the-art instrument that will make the Netherlands a global leader in this field, while being of enormous benefit to climate scientists." TROPOMI was commissioned by the Netherlands Space Office and ESA. It is being built by Dutch Space, in close cooperation with TNO (as a technology partner) and with SRON and KNMI as scientific institutes. Individual components and coatings are being supplied by dozens of specialized SMEs, both in the Netherlands and abroad. The project is being funded by ESA and by the Dutch government. In 2017, it will be launched into space aboard the ESA Sentinel-5 Precursor satellite, as part of the Copernicus programme.