A study recently published in The Astronomical Journal explored the possibility that one or more Earth-sized planets orbiting TRAPPIST-1 may have had a sustained supply of water. These planets may, as a result, harbour all the basic building blocks necessary for the existence of extraterrestrial life.
TRAPPIST-1 is a dwarf star with 7 orbiting planets located around 40 light years away. Vincent Bourrier at the University of Geneva in Switzerland and his colleagues, utilised the Hubble Space Telescope to discover clues to the vital components for life on three of the seven planets. TRAPPIST-1’s 7 planets were first observed in 2016 when the Kepler spacecraft recorded minuscule changes in the brightness of the star. Scientists then used those tiny changes to extrapolate the existence of the star’s planets, a method that has revolutionised the way we search the only barely observable universe for planets.
Of the 7 planets, the team of researchers discovered that three orbited the star’s habitable zone, a narrow band of space where temperatures are mild enough to allow liquid lakes and oceans that do not freeze or boil away. As TRAPPIST-1 is a dwarf star, it is prone to emitting powerful flares of UV radiation. As a result, for a planet to remain habitable orbiting around the star, it would need a thick protective atmosphere to prevent water molecules from breaking up and escaping the upper atmosphere.
During their study, the researchers found that the innermost planets of TRAPPIST-1 have most likely lost “20 times more water in the last eight billion years than all the Earth’s oceans combined.” However, the outer planets may have lost less than three Earth-oceans worth of water over the same time allowing for the possibility of a sustained source of liquid water. The outer planets of TRAPPIST-1, as a result, may very well have all the basic building blocks of life.
Although this is a small step forward in answering the question, “Are we alone in the universe”, we are unlikely to ever make the journey to TRAPPIST-1. With current technology, it would take us 37,200 years to travel just one of the 40 light years between there and Earth. Even with a hyper-advanced multi-generational starship, it is unlikely such an undertaking will ever be attempted. The most we can hope for is an AI-assisted spacecraft making the journey for us and reporting back centuries in the future.
Image source: spaceengine.org
Journal reference: The Astronomical Journal, Vol. 154, No. 3