From ice to fire: Study dismantles theory that other planets have ingredients for life
The theory held that planets, or moons, go through phases where the conditions are right to hold liquid water when they are in the so-called “goldilocks zone,” where they are warm enough so that the water isn’t trapped in ice and also not so hot that the water vaporizes.
This phase would happen when a young, dim star starts warming and melts the ice on planets orbiting it at just the right distance.
Saturn’s moon Enceladus and Jupiter’s moon Europa were touted as potential candidates for such celestial bodies in our solar system. However, a new study published in Nature Geoscience suggests that these worlds would likely not be habitable, even after their icy surfaces melt.
The researchers, from Peking University in China, used 3D climate models to simulate the evolution of icy planets and found that the simulated worlds would likely have skipped the habitable phase because of the incredibly high amount of energy required to melt their surface.
The team found that when the star becomes hot enough to melt the ice, the models quickly transitioned to a “greenhouse state.” The oceans evaporated and the planets skipped over the habitable phase.
"We find that the stellar fluxes that are required to overcome a planet's initial snowball state are so large that they lead to significant water loss and preclude a habitable planet,” the team wrote, according to Phys.org.
Earth was different, because when it thawed, approximately 600 to 800 million years ago, it required less solar heat to melt the ice due to planet-warming atmospheric greenhouse gases emitted by volcanic eruptions.