Most people understand the merits of planning a trip, but the researchers at NASA will have their work cut out for them with a rover mission to Europa, one of Jupiter’s 67 moons. A new paper published in the science journal Astrobiology has outlined major questions that a rover will need to be able to solve before it could head out on a 390-million-mile journey to discover life.

“Europa is the most likely place in our solar system beyond Earth to have life today, and a landed mission would be the best way to search for signs of life,” said Robert Pappalardo, the study’s lead author, based at NASA’s Jet Propulsion Laboratory, in a release. Over the years, researchers have been able to capture portraits of Jupiter’s moon by using probe fly-bys—including Pioneer 10 in 1973, Pioneer 11 in 1974, the two Voyager probes in 1979 and most of all the Galileo probe from 1995-2003.

These portraits reveal what scientists believe to be a massive liquid ocean under an ice sheet and red-brown lines running along the moon’s surface. Scientists think these lines and patches could indicate ocean water bubbling up from cracks—a potential primordial soup.

These hints of life are intriguing to scientists, but so far they remain conjectures. In order to discern what they are and what their potential is for holding life, NASA will have to send out a rover. “The prospect of a future soft landing on the surface of Europa is enticing, as it would create science opportunities that could not be achieved through flyby or orbital remote sensing,” the researchers write in their paper.

The research team labels determining the moon’s habitability as the top priority, and NASA is hoping to receive the same success from a Europa rover mission as it did from the Mars rover. The rover would send home surface accounts of the moon and also samples from at least two different surface depths to determine whether or not it has liquid water and the chemical compounds needed to build and support life.

“A future landed mission to Europa would offer a unique opportunity to sample and observe the surface, directly addressing the goal of understanding Europa’s habitability by confirming the existence and determining the characteristics of water within and below Europa’s icy shell and evaluating the processes that have affected Europa,” write the scientists in the paper.