America’s 2016 federal budget has designated funds for the first phase of a mission to Jupiter’s icy moon, Europa, orbiting almost 500 million miles from Earth. Planetary scientists who examine the possibilities of alien life across the universe gathered at a workshop at NASA’s Ames Research Center in California last Wednesday to deliberate strategies for finding life on Europa. Current studies of Europa by NASA are centred on assessing whether Europa is habitable. However, given the recent sighting of plumes of water vapour picked up by the Hubble Space Telescope, astrobiologists are now considering if life already exists on Europa.
Europa is mostly made of silicate rock and has a water-ice crust, surrounded by an atmosphere composed mostly of oxygen. Its surface is covered in brown cracks and fissures. Scientists maintain it appears to cover a titanic ocean of water hundreds of miles deep, with a hot iron-nickel core at its centre. In December 2013, NASA reportedly detected the presence of clay-like phyllosilicates on the icy crust, which is often associated with organic matter.
Scientists and engineers at NASA have posited a voyage to Europa for a couple of years. A spacecraft named ‘Clipper’ has been designed, which aims to orbit Europa for three years to study its surface with an ice-penetrating radar to examine signs of life beneath. The detection of sporadic water plumes on Europa rising 125 miles above the surface near its south pole finally motivated NASA’s Washington headquarters to call for action.
The icy plumes have only been spotted once, when they were first observed in 2012, however they offer a pertinent and interesting opportunity in the search for life in the universe. The plumes strongly suggest volcanic activity on Europa, powerful enough to rupture the thick, icy crust allowing water to erupt above the surface. Space geophysicist at NASA’s Ames Research Center, Christopher McKay explained, “That ocean could be a soup of organics, and we’ll take finding life there whether it’s [extinct] or alive — because [extinct life] is evidence of life anyway,” as he spoke to hundreds of scientists at last week’s meeting.
The current mission concept is estimated at around $2 billion and might begin as early as 2022. Given the possibilities Europa may hold, scientists wish to modify the current mission concept to include other gadgets capable of searching for signs of life. Scientists are even calling for wild, seemingly unconventional ideas since the next Europa mission may likely occur a lifetime from now. For example, one idea is to penetrate the moon’s crust and sample any material that comes out. Ideally, NASA might melt through the crust and traverse Europa’s massive oceans using submersibles.
Apart from figuring out how to reach Europa, astrobiologists have been debating the fundamental question of what exactly to look for on Europa. Scientists believe it may be possible that Europan life-forms are chemically different to Earthly creatures, making it challenging to envision what Europan signatures of life might look like. In other words, it may be possible that scientists might encounter a multitude of Europan microbes without even knowing.
Christopher McKay has suggested that the search should focus on amino acids – the molecules essential to all known life and thought to be responsible for the origin of life itself (at least on Earth). Other scientists recommend looking for complexity as a clue to living organisms functioning nearby.
Last week, John Grunsfeld, chief scientist at NASA and veteran astronaut showed his support for the mission as he told planners, “We’re going to do a Europa mission. It’s too good a chance to miss, so let’s think outside the box or in it. Let’s get your best ideas out on the table.”
What might be the most fundamental differences between how life adapted to Earth’s environment versus, potentially, Europa’s?