![]() On Earth, life prefers dynamic environments over stagnant locations like the Moon, which is a lifeless rock. Hydrogen sulfide in particular is probably common below the surface. In principle, geothermal activity and reduced sulfur compounds could provide microbial life with sufficient energy sources. What about the subsurface? Water and carbon (at least in the form of carbon dioxide) may still be abundant there, although the driving force for Io’s volcanic vents seems more likely to be sulfur dioxide or other sulfur gases. However, due to Jupiter’s unforgiving radiation and tidal heating, Io subsequently lost most if not all of its water, and the surface became uninhabitable. In those early days, the combination of liquid water and geothermal heat could have led life to develop. Early in its history, Io may have held as much water as Europa or Ganymede, since it formed in a region of the Solar System where water ice was plentiful. The moon’s surface is constantly being reworked, which means that we see no fresh impact craters. The characteristic yellow / orange / red surface of Io, dominated by different types of sulfur, earned the moon its nickname among scientists: the Pizza Moon. Hot lava flows pour over some of the sulfur dioxide snowfields. Some volcanic vents eject gaseous sulfur dioxide into the ultra-wispy atmosphere, which later condenses as frost on Io’s surface. While the average surface temperature of -130° C is very cold, temperatures near volcanic centers reach up to 1,600° C or more, hot enough to keep the lava liquid. Some of Io’s volcanic eruptions are so violent that lava is ejected hundreds of kilometers into space. Recent simulations show that tidal heating on this most volcanically active body in the Solar System is keeping magma liquid below the surface. ![]() Microbial growth is common in lava tubes on Earth no matter the location and climate, whether it’s ice-volcano interactions in Iceland or hot, sand-floored lava tubes in Saudi Arabia. Galileo found, among other things, an active lava lake (perhaps crusted over) and a lava “curtain,” along with active lava flows, calderas, mountains, plateaus, and plains. A quick recap: Io is roughly the size of our Moon, but otherwise couldn’t be more different. Most of what we know about Io dates from more than 20 years ago, when the Galileo spacecraft toured the Jovian system. Juno recently passed by Io at a distance of 80,000 km, and over the course of this coming year will get much closer, within 1,500 km. While Europa and Ganymede (the Solar System’s largest moon) have typically been of greater interest to astrobiologists due to their subsurface oceans, another Jovian satellite - hot, volcanic Io - has largely been dismissed as a possible abode for life now or in the past. The giant planet and its stormy atmosphere were initially Juno’s main focus, but in the mission’s current extended phase, close fly-bys of the Jovian satellites are on the menu as well. NASA’s Juno spacecraft, which has been studying Jupiter and its large inner moons up close for the past six and a half years, is currently humanity’s most distant planetary orbiter.
0 Comments
Leave a Reply. |