Europe readies ‘office fridge’ satellite

Artist's impression of the Proba-V satellite in orbit. The ‘V’ in its name stands for Vegetation: Proba-V will fly a reduced-mass version of the Vegetation instrument currently on board the SPOT satellites to provide a daily overview of global vegetation growth. © ESA - P. Carril
Artist's impression of the Proba-V satellite in orbit. The ‘V’ in its name stands for Vegetation: Proba-V will fly a reduced-mass version of the Vegetation instrument currently on board the SPOT satellites to provide a daily overview of global vegetation growth. © ESA - P. Carril

European scientists are preparing to launch a satellite no bigger than an office refrigerator that can map the entire Earth every two days.

Despite its small size, the 160 kg Proba-V satellite carries all the instruments required to supply data 24 hours a day, seven days a week, and that will enable scientists to monitor crop production and weather changes.

‘The vegetation measures of the Proba-V instrument are quite remarkable in that respect,’ said Jean-Paul Malingreau, former scientific advisor to the European Commission and chair of the International Users Committee of Vegetation and Proba-V.

Proba-V will be flying above the Earth at an altitude of 820 km. Crossing the Equator each morning at around 11am, the 80 cm by 80 cm by 100 cm satellite will map land cover across the entire planet every two days.

The tiny ‘office fridge’ satellite, weighting 95 kilograms less than its most recent predecessors, was produced in Belgium by satellite maker QinetiQ Space, and the Belgian government is its main sponsor.

VITO, the Flemish government’s environmental research centre, manages the image data processing, archiving and distribution, whilst the European Commission heads the International Users Committee, a group of experts helping to make use of its data.

‘Classically, we have had big satellites that cost very much and take a long time to build,’ Tanja Van Achteren, project manager at VITO said.

Expensive, complicated models that can take a decade to design and launch into orbit can be affected by fluctuating funding, especially at a time when Europe is facing a challenging economic environment.

‘Miniaturisation is indeed a trend in space activity. Lower mass allows us to reduce the size of launchers or allows us to launch more satellites for a given launcher,’ Karim Mellab, Proba-V project manager, said. ‘Cost is, of course, also directly impacted.’

‘Lower mass allows us to reduce the size of launchers or allows us to launch more satellites for a given launcher.’

Karim Mellab, Proba-V project manager

 

Proba V is likely to be almost ten times cheaper than the EUR 500 million price tag of a traditional satellite mission.

Hitchhikers

The best way to ensure a commercial return on the investment needed to send such a craft into space is to have a mix of public and private funding.

‘Small, low-cost missions allow small companies access to space and provide them with the experience that is essential for European industries to be competitive and innovative,’ according to the European Space Agency (ESA), which tries to ‘cram in as many technology demonstration packages as possible’.

Apart from national government sponsorship, the satellite will carry five private ‘piggyback’ payloads commonly known as ‘hitchhikers’. One of these payloads is the Energetic Particle Telescope, which monitors space radiation. In effect, its cameras and sensors will carry out a few other functions alongside the main mission objective, which is to track vegetation changes.

Continuity is key

Earth vegetation has been until now monitored by dedicated instruments on board the SPOT series. The next generation of vegetation instruments won’t be ready for two-and-a-half years.  They will be part of the new Sentinel-3 satellites, a more complex spacecraft that will also measure routinely things like sea-surface topography, sea and land temperature and ocean colour. That is why Proba-V is, in fact, a ‘gap-filler’ that will provide continuity in measuring changes in vegetation.

In land imaging, continuity is critical – it offers researchers solid references and an average against which they can compare current data and detect trends. ‘The geographical patterns of that change can only be observed over time, and it can take 20 years to get a clear picture,’ said Malingreau, who has followed the entire vegetation series, which began in 1998. ‘We are moving to a population of nine to ten billion and that will have an impact on the way we use the ecosystem and natural resources,’ he said.

The previous two vegetation devices have already gathered 16 years of data for scientific research on patterns, transitions, evolution and forecasting in domains such as agriculture, forestry or even fisheries.The Proba-V microsatellite was assembled in December 2012, at QinetiQ Space Belgium. © ESA - S. CorvajaThe Proba-V microsatellite was assembled in December 2012, at QinetiQ Space Belgium. © ESA - S. Corvaja

During that time, the vegetation instruments have built up a community of as many as 10 000 users, comprising scientists, academia and international bodies such as the United Nations, (which is interested in monitoring food sources in Africa) and the United States Department of Agriculture (which monitors agricultural crops in order to assess their import and export conditions). These 10 000 people will be using the data Proba-V provides on a daily basis.

So far, previous image-capturing systems have spotted shifting borders between desert and vegetation on the coast of West Africa, key data about geographical areas where endangered species live, extreme pollution in China, the refilling of the once-dried-out Aral Sea and decreasing CO2-absorbing phytoplankton in the Atlantic Ocean – to mention a few examples.

‘It is critical for these services to benefit from continued access to data provided by Proba-V,’ says Etienne Bartholomé, Proba-V scientist working for the European Commission’s Joint Research Centre.

‘The urgency is now to continue monitoring changes on Earth due to human activities,’ Malingreau concludes.

Proba-V

  • Proba-V scans the Earth's surface in visible light and in infrared.
  • The surface covered by one image is actually a strip about 2 250 km wide.
  • As the satellite orbits, it scans the surface, building up an image line by line in the same way as a desktop scanner.
  • The whole Earth is then covered by stitching together into one single image the strips acquired over each orbit.

 By looking at a long time series of images (ideally 30 years and more), trends may be observed in vegetation conditions related to climate change.

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