Could life really exist on these planets? How likely is it?
It is a big jump from identifying a potentially habitable world to telling if the world is inhabited, even by microbial life. We are focusing now on measuring the potential for life on these planets for life as we know it, as if we’re going to go there. If Earth- like life is common in the universe, then these worlds also have a good chance of being populated, but this is an unsolved problem in astrobiology. Eventually, we will have the capability to detect biologically relevant gases – like oxygen and methane – in the atmosphere of these worlds and be able to tell which ones are even likely to be inhabited.
What might life on super-Earths look like?
If life is common in the universe, then it will probably be microbial rather than complex life. Surface complex life, like animals and plants, have more hard requirements such as the presence of oxygen, not too much carbon dioxide, and temperatures between zero to 50 degrees Celsius (32 to 122 degrees Fahrenheit). Earth has only had these conditions for less than a quarter of its history, which led to the development of complex life. Our planet has been populated by microbial life for most of its history.
Is it even possible that any of these planets could potentially be habitable by humans?
The suitability for human life on any of these planets is always a possibility. Even finding a planet with a tolerable atmospheric pressure and temperature – but not necessarily oxygen, will allow walking on its surface without a spacesuit – just with oxygen.
What are the next steps in determining whether life exists on these super-Earths?
The next step on assessing the potential for life on exoplanets is the determination of their atmospheric composition. The NASA Transiting Exoplanet Survey Satellite (TESS) space telescope will start searching in 2017 for suitable candidates for observation and the James Webb Space Telescope (JWST) in 2018. JWST should have the capability to analyse the atmosphere of many super-Earths in search for the requirements of life like water and oxygen.