Sending a probe to look for alien life is just half of the work – it’s the tools you send there that will actually do the job, and NASA has decided which tools it wants to send to Jupiter’s moon Europa, a place considered by many the likeliest to hold alien life.

Realistic-color Galileo mosaic of Europa, highlighting the mysterious lines. Image via Wikipedia.

Hundreds of years ago, many people were convinced that the Moon was inhabited by aliens. Even decades ago, some still had the belief that Venus might be inhabited, and up until very recently, Mars was considered the likeliest place in the solar system to hold alien life. We now know a lot about Mars, and while Martian life is still an open possibility, there are other, seemingly unlikely places, where astronomers hope to find life. Such is Jupiter’s Europa.

Water on Europa

Europa is one of Jupiter’s many moons, orbiting the gas giant in just over three and a half days. Naturally, when it’s so far away from the Sun, its surface is frozen. So why then do researchers have such great expectations? The first clues about Europa’s potential came when astronomers realized that it is extremely smooth. It’s so smooth that it seems there’s a liquid ocean beneath the frozen surface, one which might have the potential to host life.

But how could it have liquid water? The key is something called tidal flexing – basically, Jupiter is so massive that it tugs and pulls Europa, creating heat through friction and maintaining liquid water under a frozen crust, while also driving geological activity similar to plate tectonics. There were also other, more direct indications, such as in 2013, when astronomers spotted 200 km high water plumes spurting from its surface. Also in 2013, astronomers “tasted” the surface of Europa and found evidences of salt, something which was confirmed in May 2015. This suggests that the ocean is in interaction with the seafloor, which holds even more promise for life existing in the liquid water.

In December 2013, NASA reported the detection of “clay-like minerals” (specifically, phyllosilicates), often associated with “organic material” on the icy crust of Europa. But Europa’s most striking feature is a series of dark streaks crisscrossing the entire globe, called lineae (which is just “lines” in English). These lines are more than 20 km (12 mi) across, often with dark, diffuse outer edges, regular striations, and a central band of lighter material. But what could have caused them? While there are a few competing theories, it seems that they are “scars” from warm water erupting through the surface – again, an indication of liquid water.

Artist’s drawing of Europa. Image via Slate.

All in all, Europa is an intriguing place, and despite its appearance, it may very well harbor life beneath its frozen surface – hence why NASA is so keen to explore it and see if this is the case.

NASA’s mission to Europa

NASA has been planning a mission to Jupiter’s satellite for quite a while, but things seem to be finally coming together.

“We’re excited about the potential of this new mission and these instruments to unravel the mysteries of Europa in our quest to find evidence of life beyond Earth,” said John Grunsfeld, associate administrator for Nasa’s Science Mission Directorate.

The mission will come at a $30 million price tag, which honestly doesn’t seem that crazy when you consider that the objective is to send a probe 628.300.000 km away to study a frozen moon and look for alien life beneath its surface. To me, the very fact that we can actually do this is remarkable. The fact that we can do it at a lower price than a Eurocopter Tiger is even more exciting.

But as I said above, it’s not just about sending the probe there, there’s also the rather complicated issue of choosing what instruments you send on the mission. NASA received 33 proposals from universities and research institutions across the country for the mission’s science instruments; from these, they chose nine, which we present below:

• Plasma Instrument for Magnetic Sounding (PIMS). This instrument is key for determining the location, thickness and salinity of Europa’s under-ice ocean. It works in conjunction with a magnetometer (next line)
• Interior Characterization of Europa using Magnetometry (ICEMAG). Working together with PIMS, this magnetometer will measure the magnetic field near Europa and use multi-frequency electromagnetic sounding to help determine the parameters of Europa’s ocean.
• Mapping Imaging Spectrometer for Europa (MISE). It will identify and map the distribution of organics, salts, acid hydrates, water ice phases, and other materials, to help determine the habitability of the ocean.
• Europa Imaging System (EIS). This is basically a wide and narrow angle camera that will map most of Europa at 50 meter (164 foot) resolution, and will provide high resolution images of Europa’s surface.
• Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON). This dual-frequency ice penetrating radar instrument is designed to characterize and sound Europa’s icy crust from the near-surface to the ocean, revealing its internal structure.
• Europa Thermal Emission Imaging System (E-THEMIS). This is a “heat detector” that will highlight Europa’s active areas, specifically hotter vents and potential plumes.
• MAss SPectrometer for Planetary EXploration/Europa (MASPEX). This instrument will determine the composition of the surface and subsurface ocean by measuring Europa’s think atmosphere and any material that might be ejected into it.
• Ultraviolet Spectrograph/Europa (UVS). The main focus of UVS will be to spot out any water plumes spurting out – even smaller ones.
• SUrface Dust Mass Analyzer (SUDA). The name pretty much says it all – SUDA will measure the composition of small, solid particles (dust) ejected from Europa.

Aside from the tools above, the SPace Environmental and Composition Investigation near the Europan Surface (SPECIES) instrument has been chosen for further technology development. This is a trove of instruments, a myriad of tools to help scientists figure out whether or not Europa might host life.

“This payload will help us answer all of these questions,” said Niebur, “and take great strides forward in understanding the habitability of Europa.”

However, astronomers stress that while these instruments can detect indicators of life, they are not directly life detectors.