Life on Mars? Unlikely. Life on Europa? Maybe. And there’s only one way to find out.

The chance is strong enough that NASA is moving forward with their plan to send a probe to Jupiter’s watery fourth moon. They’ve been thinking about it since the late 1990s, when the Galileo mission showed strong evidence that Europa has a giant ocean of water — more than twice the amount we have on Earth — under its surface. For scientists, the presence of water always points to one thing: the possibility of life. And it seems like NASA’s researchers are fed up with pondering. They’re finally moving from the concept phase to the development phase, taking us one step further toward perhaps answering one of universe’s biggest questions.

The Europa Clipper mission, which is being managed by NASA’s Jet Propulsion Laboratory, is set to launch its spacecraft in 2020. After a journey lasting several years (likely six or so), the spacecraft will orbit the moon, dipping in and out of its atmosphere, for a total of 45 flybys — one every two weeks — allowing it to repeatedly gather data. The spacecraft is equipped with nine powerful tools, including a high-res imaging system to photograph the moon’s surface, radar to penetrate its icy crust for a glimpse at the ocean below, and a magnetometer to determine the direction of flow in the ocean. Evidence from Hubble Space Telescope images has fed speculation that plumes of water may shoot up from the underwater ocean through the frozen surface. Huge if true! NASA says a probe could fly through such plumes to “taste” the water from below.

The trip could make for some true-life sci-fi during the next decade. Europa has many ingredients for life: abundant water, energy from tidal heating, and a rocky ocean floor. The Europa mission probably won’t identify life directly, but it may at least confirm signs of habitability. The associate administrator for NASA’s Science Mission Directorate in Washington, John Grunsfeld, has high hopes. “Today we’re taking an exciting step from concept to mission, in our quest to find signs of life beyond Earth,” he said in a NASA release. “Observations of Europa have provided us with tantalizing clues over the last two decades, and the time has come to seek answers to one of humanity’s most profound questions.”