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Life in the solar system may not be over when the sun begins its spectacular metamorphosis into a red giant star. Instead, recent study suggests that Europa, Jupiter's frozen moon, may experience a brief period of possible habitability. Scientists currently believe that when the sun grows and its habitable zone spreads outward, Europa may momentarily provide ideal circumstances for life, albeit the possibility would last only a few hundred million years, which is brief on cosmic timescales but not inconsequential.
Europa may host microbial life for 200 million years after the Sun becomes a red giant
According to a new research from Cornell University's Carl Sagan Institute, which will be published in the Royal Astronomical Society's Monthly Notices, the energy output of the red giant sun might approach Jupiter's orbit. While Jupiter will remain uninhabitable, its moon Europa may get enough heat from solar radiation and Jupiter's enhanced reflection to melt some of its ice shell. This warming has the potential to reveal or even evaporate underlying seas that were previously thought to reside beneath the ice shell.
Researchers expect that Europa's surface will sublimate extensively on the Jupiter side, while equatorial parts would see water loss owing to convective heat transfer. However, the northern and southern parts of the side opposite Jupiter may retain more water, resulting in a small water-vapor atmosphere. Scientists believe that method might keep life-sustaining conditions for up to 200 million years.
Microscopic life may have thrived over Earth's short history, especially if it exists beneath Europa's ice. This discovery may open up new avenues for astrobiological research, such as future observatories capable of fishing for biosignatures on ice-covered worlds orbiting red giant stars.
The finding of an exomoon may lead to a new chapter in the quest for life in the solar system, with the prospect that Europa may be the only source of life once humans are extinct or destroyed.
