Slashdot Mirror
Nearby Ocean Worlds Could Be Best Bet For Life Beyond Earth, Says NASA (cnn.com)
NASA has new evidence that the most likely places to find life beyond Earth are Jupiter's moon Europa or Saturn's moon Enceladus. In terms of potential habitability, Enceladus particularly has almost all of the key ingredients for life as we know it, researchers said. From a report: New observations of these active ocean worlds in our solar system have been captured by two NASA missions and were presented in two separate studies in an announcement at NASA HQ in Washington today. Using a mass spectrometer, the Cassini spacecraft detected an abundance of hydrogen molecules in water plumes rising from the "tiger stripe" fractures in Enceladus' icy surface. Saturn's sixth-largest moon is an ice-encased world with an ocean beneath. The researchers believe that the hydrogen originated from a hydrothermal reaction between the moon's ocean and its rocky core. If that is the case, the crucial chemical methane could be forming in the ocean as well.
Europa should be better hunting grounds than Enceladus because Europa has been similar to how it is now for probably most of its life. Enceladus's condition may merely be a coincidence in time: nobody really knows yet what heats Enceladus; its heat may be periodic or temporary.
But we know that tidal forces with Jupiter and its other big moons are what heats Europa. Its big neighboring moons have been around probably since the formation of the Jupiter system.
Europa's heat matches tidal models, meaning it probably had lots of time to evolve and nurture life. Saturn has only one big moon, Titan, and it's rather far from Enceladus, and thus not a notable tidal force.
Plus, Europa is much bigger than Enceladus, giving life more chances to form.
Table-ized A.I.
It's not the proximity of another moon that produces tidal forces. Just going around Saturn is enough to produce the stresses that induce heat.
Only if the orbit is eccentric. If there aren't other moons, viscoeleastic damping circularizes the orbit until the tidal heating disappears-- it's the other moons that perturb Europa's orbit to make it slightly eccentric, giving it the tidal forces that heat it.
http://www.geoffreylandis.com