Scientists say Jupiter moon landing best shot at finding habitable world

New research indicates Jupiter’s moon Europa is the most likely spot in our solar system to support life outside of the Earth, and NASA is currently developing a mission to explore the planet's icy shell and a subsurface ocean that may resemble our own.

Leading planetary researchers have published a paper detailing plans for a possible “lander” to be launched within the next decade. The plan includes instruments resembling those used by the Mars Curiosity rover, such as a drill and a complement of cameras. According to the paper - published this week in the journal Astrobiology - the frozen, crackled surface of the moon is a compelling choice for robot landers.

What makes Europa an appealing target for planetary scientists is its subsurface ocean of liquid water - evidence for which was first collected by flybys of robotic probes, including Voyager in the 1980s and Galileo in the 1990s.

The moon is thought to be affected by Jupiter’s huge gravitational presence, which scientists suspect generates tidal forces that heat the interior of the celestial body and drive geologic activity similar to plate tectonics. Of particular interest are the dark, reddish fractures present throughout the surface of the moon’s ice shell that suggest that water has welled up and frozen on the moon’s surface.

NASA scientists have previously suggested that the red spots on Europa’s surface mean that the moon acts as a sort of lava lamp, carrying material from near the surface down into its ocean, potentially transporting living organisms up towards the surface as well.

Europa could potentially host extraterrestrial life, due to its liquid ocean and warmer core which is thought to be similar to Earth’s deep-water hydrothermal vents.

“Landing on the surface of Europa would be a key step in the astrobiological investigation of that world,” said Chris McKay, a senior editor of the Astrobiology journal, who is based at NASA Ames Research Center in California.

“This paper outlines the science that could be done on such a lander,” said McKay. “The hope would be that surface materials, possibly near the linear crack features, include biomarkers carried up from the ocean.”

Italian astronomer Galileo Galilei first discovered Europa in 1610. It wasn't until NASA’s Galileo reached the Jupiter system in 1995 that scientists were able to study the moon’s surface in greater detail.

Since then, some research has speculated that Europa’s ocean may be fed by far more oxygen than was previously thought. Research produced by scientist Richard Greenberg at the University of Arizona in Tucson in 2009 theorized that beyond microscopic organisms, the moon’s ocean could support some three million tons of fish-like creatures.

"There's nothing saying there is life there now," said Greenberg, who presented his work at a meeting of the American Astronomical Society's Division for Planetary Sciences in 2009. "But we do know there are the physical conditions to support it."

So far, however, speculations of life on Europa are based on calculations of flybys and imagery of its surface, as well as evidence collected by instruments on the Hubble Space Telescope and the Galileo spacecraft – both of which have confirmed the presence of an atmospheric layer composed mostly of molecular oxygen. 

“The highest priority is active sampling of Europa's non-ice material from at least two different depths (0.5–2 cm and 5–10 cm) to understand its detailed composition and chemistry and the specific nature of salts, any organic materials, and other contaminants,” said the new report.
 
“A secondary focus is geophysical prospecting of Europa, through seismology and magnetometry, to probe the satellite's ice shell and ocean.”

The next steps for NASA and other space programs like the European Space Agency (ESA) will be to further map out the surface of Europa and select a prime landing spot for a robotic lander. NASA’s Juno probe is currently scheduled to orbit around the Jupiter system in 2016.

Meanwhile, the ESA plans to launch its JUICE mission (Jupiter Icy Moons Explorer) in 2022 aboard an Ariane 5 rocket, arriving at Jupiter in 2030 and spending some three years exploring the planet’s moons, including Europa, Ganymede, and Callisto.

A number of previous plans to explore Europa have been abandoned since the early 2000s, including the Europa Lander Mission, which proposed a nuclear-powered lander. Another project known as Ice Clipper - which would have used an impactor similar to NASA’s Deep Impact mission – was also scrapped. The Deep Impact mission launched into Earth’s moon in 2005, generating a plume of debris which was then studied by a smaller spacecraft.