Jupiter's Europa- Will It Provide the 1st Proof of Extraterrestrial Life?

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April 29, 2008

Jupiter's Europa- Will It Provide the 1st Proof of Extraterrestrial Life?

Jupiters_europa_2 "It is critical to know what to look for in the search for life in the solar system. The search so far has focused on Earth-like life because that's all we know, but life that may have originated elsewhere could be unrecognizable compared with life here.  Advances throughout the last decade in biology and biochemistry show that the basic requirements for life might not be as concrete as we thought."

John Baross, Professor of Oceanography and the Astrobiology Program at the University of Washington.

As the New Horizons mission  -currently en route for the newly christened dwarf planet Pluto and its three moons, Charon, Nix and Hydra- made its way past Jupiter in the early half of this year it was able to take detailed scans and imaging of our solar system’s largest planet. New Horizons zipped by Jupiter, making its closest pass on February 28, and used the gaseous planet's considerable gravity to slingshot itself toward Pluto.

“The Jupiter encounter was successful beyond our wildest dreams,” says New Horizons Principal Investigator Alan Stern, of NASA Headquarters. “Not only did it prove out our spacecraft and put it on course to reach Pluto in 2015, it was a chance for us to take sophisticated instruments to places in the Jovian system where other spacecraft couldn’t go, and to return important data that adds tremendously to our understanding of Jupiter and its moons, rings and atmosphere.”

The New Horizons spacecraft, also snapped images of the tiny rings encircling Jupiter, studied a huge, swirling storm and explored the planet's long magnetic tail.

The New Horizon flyby at its closest came within 3 giga-meters of the planet and made important discoveries focusing on Jovian weather. Heat-induced lightning strikes were found occurring in Jupiter’s
Polar Regions, the first polar strikes observed anywhere else other than earth.

New Horizon also made the single most detailed analysis of waves that traverse the entire width of the planet. These waves indicate the presence of massive storms below the levels of ammonia that make up the clouds obscuring much of Jupiter’s surface.

But while in the neighborhood, the fastest spacecraft ever launched from Earth aimed its cameras and sensors at Jupiter and its four largest moons, making about 700 observations.

Due to New Horizon’s primary purpose for visiting Jupiter – a gravitational speed bump – it was out of range to properly focus on the 60 Jovian moons. However, as it is designed to focus on dim targets, the teams were able to acquire some data from Jupiter’s four largest moons, including Europa, thought by many planetary scientists as the Solar Systems best bet for the first discovery of extraterrestrial life.

The recent publication of the National Research Council of its report, Limits of Organic Life in Planetary Systems, urged NASA to expand its search for life in the Solar System to include non-carbon forms of life. On the microbial level, most serious astronomers and scientists have little doubt that life will be found within the next decade within our Solar System in the Martian soil, or in the methane seas of Saturn's moon, Titan, or the turbid seas of Jupiter's smallest moon, Europa.

Europa might not only sustain, but foster life, according to the research of  University of Arizona's Richard Greenberg, a professor of planetary sciences and member of the Imaging Team for NASA's Galileo Jupiter-orbiter spacecraft.

Europa, similar in size to Earth's moon, has been imaged by the Galileo Jupiter-orbiter spacecraft. Its surface, a frozen crust of water, was previously thought to be tens of kilometers thick, denying the oceans below any exposure. The combination of tidal processes, warm waters and periodic surface exposure may be enough not only to warrant life, but also to encourage evolution.

With Jupiter being the largest planet in the solar system, its tidal stresses on Europa create enough heat to keep the water on Europa in a liquid state. More than just water is needed to support life. Tides also play a role in providing for life. Ocean tides on Europa are much greater in size than Earth's with heights reaching 500 meters (more than 1,600 feet). Even the shape of the moon is stretched along the equator due to Jupiter's pull on the waters below the icy surface.

The mixing of substances needed to support life is also driven by tides. Stable environments are also necessary for life to flourish. Europa, whose orbit around Jupiter is in-sync with its rotation, is able to keep the same face towards the gas giant for thousands of years. The ocean is interacting with the surface, according to Greenberg, and "there is a possible that extends from way below the surface to just above the crust."

"The real key to life on Europa," Greenburg adds, "is the permeability of the ice crust. There is strong evidence that the ocean below the ice is connected to the surface through cracks and melting, at various times and places. As a result, the , if there is one, includes not just the liquid water ocean, but it extends through the ice up to the surface where there is access to oxidants, organic compounds, and light for photosynthesis. The physical setting provides a variety of potentially habitable and evolving niches. If there is life there, it would not necessarily be restricted to microorganisms."

Tides have created the two types of surface features seen on Europa: cracks/ridges and chaotic areas, Greenberg said.The ridges are thought to be built over thousands of years by water seeping up the edges of cracks and refreezing to form higher and higher edges until the cracks close to form a new ridge.
The chaotic areas are thought to be evidence of the melt-through necessary for exposure to the oceans.
The tidal heat, created by internal friction, could be enough to melt the ice, along with undersea volcanoes - a combination of factors would give organisms a stable but changing environment -- exactly the type that would encourage evolution.

The future NASA DepthX mission to Europa, scheduled for 2019, is a mushroom-shaped machine, an underwater hydrobot that 'thinks' for itself. DepthX is currently undergoing tests in one of the world's deepest flooded cave systems -the El Zacaton cave complex in Mexico- to simulate penetrating the Europa's ice-covered seas. The next version of the machine will be tested in Lake Vostok, a deep ice-covered lake in the Antarctic. The craft sent to Europa would use nuclear power to melt through the 10km of ice that cover the moon's ocean. The mission will be one of the most complex ever attempted by the American space agency NASA.

Posted by Josh Hill and Casey Kazan.

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photos - http://pluto.jhuapl.edu/gallery/sciencePhotos.html


How could there be tides if Europa has always the same face towards Jupiter?

Europa's orbit is eccentric enough that the height and direction of the tides changes significantly over each orbital period. The tides crack the ice, warm the interior, and probably cause slightly non-synchronous rotation. See my book "Europa, the Ocean Moon" (Springer-Praxis Books), available from Amazon. The above is in response to the question posted by dromeiro.

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