Volcanic hydrogen spewing into the atmosphere of planets once thought to be ‘icy wastelands' could warm the surface enough to support life. Astronomers have found that the effect of volcanic hydrogen and atmospheric warming could extend a solar system's habitable zone by as much as 60 percent. In the newly discovered Trappist-1 system, it's thought that three of the seven Earth-like planets could be habitable – but, the new research suggests the number may be higher. The astronomers from Cornell University say the presence of volcanoes on icy planets could improve our chances of finding alien life. ‘On frozen planets, any potential life would be buried under layers of ice, which would make it really hard to spot with telescopes,' said lead author Ramses Ramirez, research associate at Cornell's Carl Sagan Institute. ‘But if the surface is warm enough, thanks to volcanic hydrogen and atmospheric warming – you could have life on the surface, generating a slew of detectable signatures.' The combined greenhouse warming effect of hydrogen, water, and carbon dioxide could extend habitable zones by 30 to 60 percent. Not only would that increase the chances of finding life elsewhere in the cosmos, but it improves the odds in our own solar system as well. ‘Where we thought you would only find icy wastelands, planets can be nice and warm – as long as volcanoes are in view,' said Lisa Kaltnegger, Cornell professor of astronomy and director of the Carl Sagan Institute. An Earth-like planet can only contain its hydrogen for a few million years, the researchers explain. But, the presence of volcanoes could change this. These hydrogen emissions would also ‘puff up' the planet's atmosphere, as this gas is very light, and scientists could use this to detect possible signs of life. ‘You get a nice big warming effect from volcanic hydrogen, which is sustainable as long as the volcanoes are intense enough,' said Ramirez. ‘Adding hydrogen to the air of an exoplanet is a good thing if you're an astronomer trying to observe potential life from a telescope or a space mission. ‘It increases your signal, making it easier to spot the makeup of the atmosphere as compared to planets without hydrogen.' The habitable zone of our own solar system extends to 1.67 times the Earth-sun distance, just beyond the orbit of Mars. But, accounting for volcanic hydrogen, its reach could push as far as 2.4 times the Earth-sun distance, to roughly where the asteroid belt sits, between Mars and Jupiter. While many planets were previously thought to be too cold to support life, scientists now say this may not be the case. ‘We just increased the width of the habitable zone by about half, adding a lot more planets to our ‘search here' target list,' said Ramirez. With the capabilities of next-generation instruments, like the James Webb Space Telescope set to launch in 2018, or the European Extremely Large Telescope that will light up in 2024, astronomers could soon be able to detect signs of life in distant atmospheres. The research could also add exciting new possibilities to the Trappist-1 star system. Three of the seven Earth-like planets orbiting the star are thought to be potentially habitable. But, one that was previously deemed ‘too cold' may now be in the running as well. This could bring the number of potentially habitable planets up to four, instead of three. ‘Finding multiple planets in the habitable zone of their host star is a great discovery because it means that there can be even more potentially habitable planets per star than we thought,' said Kaltenegger. ‘Finding more rocky planets in the habitable zone – per star – increases our odds of finding life. ‘Although uncertainties with the orbit of the outermost Trappist-1 planet ‘h' means that we'll have to wait and see on that one.' This could bring the number of potentially habitable planets up to four, instead of three. ‘Finding multiple planets in the habitable zone of their host star is a great discovery because it means that there can be even more potentially habitable planets per star than we thought,' said Kaltenegger. ‘Finding more rocky planets in the habitable zone – per star – increases our odds of finding life. ‘Although uncertainties with the orbit of the outermost Trappist-1 planet ‘h' means that we'll have to wait and see on that one.'
