In the international space community, there is no quest that plagues mankind more than the search for extraterrestrial life. Driven both by necessity and curiosity, a discovery of an environment hospitable to even the most primitive form of life in Earth’s own backyard would strengthen the argument that there are likely tens of hundreds of solar systems in the universe that harbor the same potential.

With ever-shrinking financial resources and substantial technological challenges, fierce competition has raged on concerning the best scientific investment for the future of human civilization. Several missions to various planetary bodies have been proposed, but realistically our limited space exploration infrastructure can support only a handful of these.

It was with this in mind that NASA had to make a major decision as to where in the solar system it would devote the bulk of its efforts. The leading contenders, Titan and Europa, are two names that have long conjured sentiments of promise and intrigue.

Titan, Saturn’s largest moon, is a rocky planet interspersed with water and ice. In fact, it is the only object other than Earth in which clear evidence of stable bodies of water has been found. The moon is also relatively young, has a nitrogen atmosphere, and may have tectonic activity. This leads some scientists to the conjecture that Titan may be a lot like primordial Earth, only at a much lower temperature.

It is also important to note the presence of methane in the atmosphere of Titan. Though many believe the gas is originating from Titan itself via cryovolcanoes, it is possible that the methane’s source is biological. Methane is released in the process of decomposition of organic matter. Hence: if it lives, it rots.

Orbiting Jupiter and nestled between neighboring moons IO and Ganymede, Europa is a relatively young and smooth planet, covered with a layer of ice. Due to its composition, it has been hypothesized that below its top layer lays a liquid ocean. Heat energy generated from tidal movement could keep the ocean from freezing over, making Europa a likely home of the closest thing to life as we know it on Earth.

In February of this year, NASA made an announcement that will have a giant impact on the future of space exploration. Both Titan and Europa remain targets for future NASA missions: the Titan Saturn System Mission (TSSM) and the Europa Jupiter System Mission (EJSM). However, the mission to Europa will take priority, with a potential launch date of 2020. The main reason the EJSM will be launched first is that it was determined to be more technically feasible than the Titan-Saturn mission.

The undertaking will consist of three proposed components which are: The Jupiter Europa Orbiter—developed, launched, and controlled by NASA and planned to study Europa and Io. Second, the Jupiter Ganymede Orbiter—developed, launched, and controlled by the European Space Agency (ESA) and planned to study Ganymede and Callisto. Lastly, the Jupiter Magnetospheric Orbiter—developed, launched, and controlled by the Japan Aerospace Exploration Agency (JAXA), and planned to study Jupiter’s magnetosphere.