Helping to manage water

Collecting information on water resources at over large areas is often difficult. This limits national and river-basin water managers’ ability to make the appropriate decisions. Satellites can fill this information gap with timely observations. Since 2008, ESA has been working closely with international financing institutions and client states to harness the benefits of Earth observation for global sustainable development. Earth Observation for Sustainable Development (EO4SD) is a new ESA initiative that aims to increase the uptake of satellite information in regular development operations nationally and internationally.

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Giving up forests

Marking the International Day of Forests, this Copernicus Sentinel-2 image shows an area of Bolivia that was once covered by trees but has now been cleared for resettlement schemes and agriculture.

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Bolivia’s city of Santa Cruz can be seen at the mid-left. One of the fastest growing cities in the world, this important commercial centre lies on the Pirai River in the tropical lowlands of eastern Bolivia. To the east of the city, and particularly east of the Guapay River, or the Río Grande, a huge patchwork of agricultural fields can be seen. Back in the 1960s this was an area of largely inaccessible thick Amazon forest. However, as an area of relatively flat lowland with abundant rainfall, it is suited to farming.

As part of a drive to develop and improve the economy, there has been rapid deforestation since the 1980s to accommodate programmes to resettle people from the Andean high plains and develop the area for agriculture, particularly for soybean production. This has resulted in the region being transformed from dense forest into a large mosaic of fields. As well as countless rectangular fields, radial features can be seen where individual farmers have worked outwards from a central hub of communal land.

This image was captured by the Copernicus Sentinel-2A satellite on 30 September 2017, and processed in false colour.

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Satellite panel following reentry testing

Ideally, no parts of a reentering satellite would survive their fiery return through the atmosphere, so testing is being used to understand how satellites break apart as they fall.

ESA subjected samples of typical satellite structures  – such as the one shown, with a structural joint between two aluminium sandwich panels – to conditions equivalent to atmospheric reentry.

The testing made use of the Plasma Wind Tunnel of the DLR German Aerospace Center in Cologne and the Reentry Chamber of Austria’s AAC company in Wiener Neustadt to produce the hypersonic winds and high heat flux required.

“The objective was to understand the failure modes of the current structural joining technologies used on satellites,” comments ESA materials researcher Benoit Bonvoisin.

In future, the aim is to design satellites to disintegrate during reentry, known as ‘design for demise’ or D4D.

Engineer Tiago Soares is working on D4D as part of ESA’s Clean Space initiative, reducing the environmental impacts of the space sector on both Earth and in orbit: “The next step is to develop and test promising new technologies to ensure better fragmentation during reentry.”

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Grasping Gerst

What does an astronaut in the few months before flying to the International Space Station? Answer: baseline data collection.

Don’t let the wording fool you. This is an essential step before flight, when researchers collect information they will compare with data taken during and after flight.

Here, ESA astronaut Alexander Gerst is providing data for the Grasp experiment using a virtual reality headset.

The focus of this experiment is on how a brain combines the perception of its body with visual information to coordinate hand movement. Researchers suspect that, on Earth, the brain uses gravity as a reference. When reaching for an object, the brain will calculate how far your hand is by using visual clues as well as how shoulder muscles counteract the downward force of gravity to keep your arm straight.

To understand how an astronaut’s brain copes with weightlessness, Alexander is reaching for virtual objects so researchers can determine how important gravity is compared to the other factors.

The sensation of floating for months on end is something our brains never had to deal with until last century and seeing how they adapt offers interesting clues to their workings.

Virtual reality headsets offer a way to present specific situations and understand how an astronaut brain adapts to its new environment – so France’s CNES space agency had one sent to the International Space Station.

The research will help us to identify the workings of the vestibular system that keeps our balance, and how it connects to the other sensory organs. In other words, Grasp is researching the physiology behind eye–hand coordination as well as shedding light on how to treat patients showing a loss of vestibular function on Earth.

For astronauts, the research will be useful during spacewalks, where coordination in weightlessness with few visual clues is of utmost importance.

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