Earlier, scientists believed that terrestrial planets with hydrogen-rich atmospheres were unsuitable for life to exist. However, Dr Nikku Madhusudhan, an astronomer an the University of Cambridge and his colleagues and found that these planets could support life if certain conditions are met. This realisation led to the start of an investigation into the conditions that are favourable for life to thrive and whether we can observe biosignatures on those planets.
Astronomers call this new class of planets “hycean” exoplanets. These are planets with massive oceans beneath hydrogen-rich atmospheres. These planets have a mass of 2.6 Earths and may have atmospheric temperatures of upto 200 degree celsius. Their ocean conditions are similar to that of Earth.
Such planets are very common. Therefore, there may be many suitable planets that contain life as we know it.
Dr Nikku Madhusudhan said, “Some of the conditions in the oceans of these worlds could be similar to habitable conditions in Earth’s oceans, i.e. similar temperatures and pressures, presence of liquid water and energy from the star.”
“There are many open questions but this is only a first guess at this stage. The assumption is that if microbial aquatic life can form in these oceans in the same manner as they did on Earth then some of the biosignatures may also be common.”
The researchers have identified many potential Hycean planets that are important candidates for study with the next generation of telescopes. All these candidates orbit red dwarf planets and are 35-150 light years away. The most promising candidate is K2-18b. The James Webb Telescope will be paramount to research in this area. This telescope will be launched in late 2021.
“A biosignature detection would transform our understanding of life in the Universe,” Dr. Madhusudhan said.