For years, scientists have gathered evidence that a salty ocean lurks beneath the icy crust of Europa, one of Jupiter’s moons.
More recently, they’ve become confident that this ocean could be hospitable to life. Recent models have suggested that Europa may be capable of producing oxygen and hydrogen, a sign it could have the energy necessary to support life.
In an upcoming mission, NASA aims to take the next logical step: sending a lander to find out whether the moon harbors life. A report submitted on Tuesday by the mission's Science Definition Team details how and why it could be done.
“Europa may hold the clues to one of NASA’s long standing goals – to determine whether or not we are alone in the universe,” the report's authors wrote. “The highest-level science goal of the mission presented here is to search for evidence of life on Europa.”
This proposal has been in the works since June. In its press release, NASA explained that studies like these take a first look at a space mission’s scientific value and feasibility.
This report proposes that a Carrier Relay Orbiter and lander launch from Earth in the mid-2020s, arriving at Europa five years later. The moon has no appreciable atmosphere, so instead of parachutes, a “sky crane” would use retro rockets to gently set the lander down on the ice cap.
Then, the 20-day search for life could begin. Scientists estimate that the icy shell covering the moon is 10 to 15 miles thick, but NASA isn’t about to send a drill bit all the way down to the ocean. Instead, the lander could collect samples from just 10 centimeters below the surface.
That may be enough to determine whether or not the moon has life. In 2013, scientists found bacteria in Antarctica’s Lake Vostok, a body of liquid water trapped beneath miles of ice.The SDT report's authors liken that lake to the environment on Europa, and note that, over thousands of years of freezing, “cellular life, organic carbon, and inorganic materials can become entrained in overlying ice.”
That bodes well for finding life and its chemical signatures near Europa’s surface – assuming, of course, that the moon harbors them. “If life is present in Europa’s ice at a level comparable to one of the most extreme and desolate of environments on Earth (Lake Vostok ice),” the scientists argue, “then this mission could detect life in Europa’s icy surface.”
In a sign of NASA officials’ enthusiasm for this possibility, this on-site mission would be the first since the Viking Mars landers of the 1970s to be tasked with detecting life.
Even if the lander’s microscope doesn’t pick up any microbes with its microscope or chemical signatures of life with its spectrometer, these and other instruments will enable it to fulfill two other science goals for the mission: assessing the moon’s habitability, and studying the surface for future robotic exploration.
Fulfilling these goals – and studying miles-high plumes from the ocean using a “flyby” spacecraft currently in development – could deliver an unprecedented amount of data from Europa in coming years.
There hasn’t yet been much official discussion of the lander mission, but the proposal submitted Tuesday makes the 2015 remarks of John Grunsfeld, associate administrator for NASA’s Science Mission Directorate in Washington, even more relevant.
“Observations of Europa have provided us with tantalizing clues over the last two decades,” he said in a press release, “and the time has come to seek answers to one of humanity’s most profound questions.”