There were 12, NASA chose 2. But in the end, there will be only one. The US Space Agency announced Wednesday, December 20, 2017 that it has shortlisted two different concepts of exploration of the solar system. On one side, a return to the famous comet Tchouri – yes, that of the European mission Rosetta! – on the other, sending a probe to Titan, the largest moon on the planet Saturn. The final choice between these two projects will be known in July 2019, for a launch in the 2020 decade.
Titan or Chouri? Between the two, the heart of NASA balance
The mission which would see a return to Tchouri (in other words Comet 67P / Churyumov-Gerasimenko) was named Caesar, for Comet Astrobiology Exploration SAmpleReturn. The idea would be to collect samples from the nucleus of the comet to bring them back to Earth. What Rosetta did not do, the European probe resting since September 30, 2016 on Tchouri. Samples of Tchouri could deliver valuable information about the origin of the formation of our planet, oceans and earth life: comets are indeed witnesses to the birth of the solar system, because they are made of materials from ancient stars and interstellar clouds appeared like him five billion years ago. As a result, they are precious witnesses of the past. (In a video shot in 2016 and presented below, astrophysicist Catherine Cesarsky, former president of the International Astronomical Union, explained to Sciences et Avenir the main teachings of the Rosetta mission).
The trip for Titan is called Mission Dragonfly. It would be a question of using a kind of drone – said dragonfly – to explore the habitability of dozens of sites on Titan. The biggest moon of Saturn has a thick atmosphere, lakes and rivers of liquid methane on its surface. As a result, some scientists believe that Titan could contain an ocean of water under a thick crust of ice and that life could exist there. The selected mission will be the fourth selected by NASA as part of its “New Frontiers” program, with a budget of some 850 million dollars. These predecessors are the New Horizon mission, which flew Pluto in 2015, Juno, orbits around Jupiter, and OSIRIS-REx, a ship that has to take samples of the asteroid Bennu in 2023 to bring them back to Earth.