EGU 2012: Life and weather away from home

By Rachel Berkowitz

Far out in the uncharted backwaters of the unfashionable end of the Western Spiral arm of the Galaxy lies a small unregarded yellow sun. Orbiting this at a distance of roughly ninety-eight million miles is an utterly insignificant little blue-green planet.

—Douglas Adams, The Hitchhiker’s Guide to the Galaxy

That little blue-green planet is habitable by life. Earth is the perfect example of a narrow range of habitable conditions in that it not only has water but is close enough to a sun that the water is liquid. Farther away from the sun is a much wider, potentially habitable domain, where water is found in other forms. In our solar system, that zone includes Ganymede and Europa, the icy moons of Jupiter.

At the European Geosciences Union general assembly in Vienna last week, space physicist Michele Dougherty of Imperial College London explained that conditions at the bottom of the liquid oceans of Ganymede and Europa may be similar to those of ocean bottoms on Earth, despite the fact that their ocean bottoms are trapped beneath layers of ice. Europa is the best example of an “active” and potentially life-supporting world, in which material is recycled from the surface to the interior.

“Life is like a battery, pushing electrons from one place to another,” said Britney Schmidt in a press conference. Schmidt is a geophysicist at the University of Texas Institute for Geophysics. To survive, life needs an environment capable of oxidation-reduction chemistry. Evidence that Europa has an oxidizing environment on its surface and a reducing environment in its interior makes it a prime candidate for habitability. Heat transfer by mantle convection might be responsible for creating thermal exchange between the deep interior and the surface.

Europa’s surface “chaos terrain"—characterized by icebergs, polygonal matrices, and major cliffs—is good evidence that such surface and deep-water interactions are taking place. On Earth, Antarctica’s Wilkins Ice Shelf looks a lot like chaos terrain and was formed by water getting inside a bit of ice and breaking off huge icebergs.

Schmidt and her colleagues have developed an analogue model of Europa’s surface. Warm water from below finds its way into a fracture and heats the surface ice; the ice melts and collapses, causing the surface level to drop down and refreeze; and finally the surface is raised back up when it refreezes into a brine-rich matrix with chaotically distributed icebergs on top.

Back on Earth, videos of the calving front of glaciers show icebergs tipping over and falling into the ocean. The instability of the floating ice churns up the water and, similar to Europa, “material is moving up, down, and sideways!” said Schmidt.

The European Space Agency plans to launch the Jupiter Icy Moon Explorer (JUICE) in 2022. Once JUICE arrives at the Jupiter system in 2030, it will observe Jupiter’s atmosphere and magnetosphere and conduct flybys of the icy moons. Its ice-penetrating radar will be used to detect subsurface water and measure the thickness of Europa’s icy crust. Thus JUICE will explore a dimension to which we Earthlings have never had access.

Forecasting space weather

The potential habitability of other planets could be affected by weather patterns created by our “small unregarded yellow sun.” Because solar activity influences dynamic environmental conditions in space, the Coronal Mass Ejections and Solar Energetic Particles (COMESEP) project began in 2011 to forecast space weather.

People have known about the 11-year sunspot cycle since the 1960s. At the peak of the cycle, coronal mass ejections throw into space blobs of plasma, which can interact with Earth’s magnetic field and create geomagnetic storms. Energetic particles can also be ejected.

“The effects of space weather are [perhaps] more important on other planets,” said Manuel Grande from the Institute of Mathematical and Physical Sciences at Aberystwyth University in Wales. With a new technique called interplanetary scintillation, coronal mass ejections can be mapped using ground-based radio telescopes to detect density irregularities carried out by solar winds. And it does work: A 2009 spacecraft orbiting Venus saw a mapped ejection hit the planet.

The start of 2012 saw a lot of solar flares and coronal mass ejections. NASA wasn’t worried about their effects on Earth, but space weather instruments observing the surface of Mars saw huge amounts of radiation. “That’s okay for a robot, but not for pilots in a spacecraft!” said Grande.

But energetic particle events can interact with Earth’s ionosphere and cause communication issues with satellites. Geomagnetic storms from coronal mass ejections can induce currents that cause erosion in pipelines and burn out transformers in power grids. “Grid companies…alert systems to shut down parts of the system so the load is not so high,” explains Norma Crosby of the Belgian Institute for Space Aeronomy.

Don’t panic, though: The International GPS Service Ionosphere Working Group monitors the ionosphere via satellite. It maps total electron content and makes forecasts based on that information.

That can only be helpful for humans as we continue to venture further into space.