So far, the search for extra-terrestrial life has been a dismal endeavour, with countless promising worlds turning out to be home to nothing more than environmental conditions hostile to every kind of life we could possibly imagine.
And yet, there may still be hope – a new study, recently presented at the Goldschmidt Geochemistry Congress in Barcelona, raises the possibility of the Universe being populated with exoplanets even more hospitable to organic life than Earth.
The study was primarily concerned with oceans, which the researchers think may hold the key to abundant life off-world:
“Life in Earth’s oceans depends on upwelling (upward flow) which returns nutrients from the dark depths of the ocean to the sunlit portions of the ocean where photosynthetic life lives,” said geophysicist Stephanie Olson from the University of Chicago.
The more upwelling – the greater the supply of nutrients and the more intense the biological activity. According to Olson, this is exactly what we need to look for if we are to have any hope of every bumping heads with alien life.
Based on computer models developed with ROCKE-3D – a piece of software used by researchers to model rocky exoplanets – for the purposes of identifying the factors which contribute to higher upwelling rates, Olson and her colleagues have found that some exoplanets are exceptionally suited for the evolution of organic life.
If the authors are correct, Mars, Europa, Enceladus, Callisto, and other rocky bodies currently hoped to be hosts to alien life are probably barren, as none of them meet such criteria as the presence of continents and a thicker atmosphere.
These findings may eventually be used to expand the list of biosignatures (the key one currently being a planet’s proximity to the “habitable zone”), as well as to develop new instrumentation optimised for future space missions.
“In our search for life in the Universe, we should target the subset of habitable planets that will be most favourable to large, globally active biospheres,” explained Olson, “because those are the planets where life will be easiest to detect – and where non-detections will be most meaningful.”