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The hunt for an earth-like exoplanet

Astronomer Frans Snik searches for extraterrestrial life. He doesn’t so much look at stars as at the ‘exoplanets’ alongside them.

Exoplanets are planets that orbit another star than our own sun. ‘In our research group we develop smart optical techniques for extracting as much information as possible from the little light coming off these planets,’ he says. ‘Even if a planet only emits a single pixel of light, we can still determine whether it hosts clouds, continents, liquid water and life itself even.’

Ten billion times less bright

The problem he is facing is an extreme one because a planet’s light can be up to ten billion times less bright than that of its companion star. To dim the starlight, Snik’s research group has developed technology based on painting liquid crystals onto pieces of glass. This technology has now been integrated into most of the largest telescopes on earth.

Although observing space through earth’s atmosphere comes with additional challenges, the Extremely Large Telescope that is under construction will be able to detect liquid water on planets orbiting red dwarf stars and oxygen in their atmosphere. ‘But to find an earth-like planet orbiting a sun-like star, we have to go into space,’ says Snik. In a collaboration with SRON, NASA and others, he is therefore working to make this technology suitable for the next generation of space telescopes. 

The ultimate selfie

Many of Snik’s optical techniques end up being used as a spin-off for earth observation purposes. He is currently working with the Faculty of Aerospace Engineering in Delft on projects at the point where earth observation and exoplanet research meet. The aim is to observe the earth from the moon and the International Space Station. ‘We are going to take the ultimate selfie. We’ll compress our entire planet into a single pixel and measure everything possible – the light intensity, the spectrum and the polarisation. This will allow us to validate our models for characterising exoplanets using the only planet we know for sure to contain life.’

With the rise of commercial space travel and the rapid development of nanosatellites, Snik can see opportunities for the LDE Space for Science and Society programme. ‘It brings back a kind of cowboy mentality,’ he says. ‘We’re right in the middle of an ecosystem of small and large aerospace companies. We have all we need to turn a scientific idea into an instrument and place it on the moon within a matter of years.’

‘This is where everything comes together’

Another opportunity, says Snik, is if all the data from big and small earth observation satellites can have an impact on our daily lives. Space technology might be able to help us achieve the sustainable development goals and improve society. ‘In addition to technology, this also involves entrepreneurship and space law,’ he says. ‘This is where everything comes together.’

This article was previously published on the website of Leiden-Delft-Erasmus Universities, an alliance between the universities of Leiden, Delft and Rotterdam. 

Picture: Artist’s impression of the exoplaneet 51 Pegasi b. Credits: ESO/M. Kornmesser/Nick Risinger (skysurvey.org)

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