Is there life beyond our solar system?

Are there earth-like planets in other solar systems and do these planets have life?

In 1995 scientists discovered the first planets in other solar systems, so called exoplanets. The discovery led to a significant development of the instruments used, in an attempt to find even more planets around other stars. The search resulted in hundreds of new exoplanets. The discoveries raise the question; are there earth-like planets in other solar systems and could these be home to living organisms? So far it has been proven that there are exoplanets with mass and composition similar to our earth’s.

The next logical step in the exploration of exoplanet is to try to find atmospheres and to analyse their compositions. The earth’s atmosphere is the most important factor stabilising temperature and distributing the sun’s heat across the surface of the earth. The atmosphere also contains molecules which are products of biological processes and show that there is life on earth. The same analysis is not easy to perform for a planet in another solar system, since light from the nearby star drowns out the light from the planet. However, it is possible to detect the planet’s very weak contribution if you analyse certain spectral lines in a high-resolution infra-red spectrum.

The first observations of large Jupiter-like exoplanets were done using the instrument CRIRES at one of the European Southern Observatory’s (ESO) 8-meter telescopes in Chile. The observations show that spectroscopic studies of an atmosphere around an earth-like planet are possible, but not using current instruments.

The Uppsala scientists Nikolai Piskunov and Eric Stempels will now lead an international collaborative project, CRIRES+, which will modify the current instrument. The modifications are expected to take two and a half years and the new instrument with its new detectors will be more sensitive and more stable. CRIRES+ will among other things make it possible to study wide wavelength bands containing spectral lines from important molecules in the planet atmosphere. This will create a completely new and unexplored window to the stars and their planets. It is already known that several exoplanets have an atmosphere, but it has not previously been possible to study these atmospheres compositions.

CRIRES+ will, for the coming decade, be the only instrument in the world with the capability to study the earth-like exoplanets’ atmospheres. Next generation of large telescopes are expected to be finished at the beginning of the 2020s.