A mission to return a comet sample to Earth and one to explore different parts of Saturn’s moon Titan, to see if it hosts life were selected today by NASA as finalists in a competition for a future robotic mission in our Solar System, part of a program called New Frontiers.

The first mission, spearheaded by Steve Squyres at Cornell University, is called CAESAR, or Comet Astrobiology Exploration Sample Return. It will involve sending a spacecraft to comet Churyumov-Gerasimenko, the same comet recently explored by the European Space Agency, collecting at least 3.5 ounces of samples from the comet’s surface, and returning those samples back to Earth. The mission will collect the organic compounds which constitute the building blocks of life in order to try to understand how comets contributed to life on Earth. “Comets are among the most scientifically important objects in the Solar System but they’re also among the most poorly understood,” Squyres said at a press conference. “I think it’s going to produce groundbreaking science for decades to come.”

The second mission, spearheaded by Elizabeth Turtle at the Johns Hopkins Applied Physics Laboratory, is called Dragonfly. It’ll involve sending a helicopter-like robot to the surface of Titan, one of Saturn’s moons. Titan’s considered one of the best candidates for alien life. The Dragonfly mission proposes a so-called dual-quadcopter, which will hop from site to site to take a variety of measurements, including what the surface is made of, how it’s layered, and what the atmospheric conditions are.

NASA’s New Frontiers program aims to develop missions to explore planets and bodies in the Solar System. Missions conceived through the program are considered medium-class, meaning they’re not as costly as NASA’s big, multi-billion-dollar flagship missions, like the Curiosity Mars rover. But these missions usually run around $1 billion, making them a little more expensive than the space agency’s smaller Discovery missions — like the Dawn spacecraft orbiting around the dwarf planet Ceres — which hover around less than half a billion dollars.

So far, three missions have been created through the New Frontiers program and are currently exploring the Solar System: the New Horizons spacecraft that flew by Pluto, the Juno probe in orbit around Jupiter, and the OSIRIS-REx spacecraft, which is on its way to grab samples from an asteroid. NASA started accepting proposals for a fourth mission in December of last year, and all submissions had to be sent in by April 28th. The proposals had to follow six different exploration themes that are considered top research priorities by the scientific community:

Bring back samples from a comet Bring back samples from the south pole of the Moon Travel to either Titan or Enceladus to understand if these moons of Saturn can host life Figure out the composition of Saturn’s atmosphere Meet up with asteroids in Jupiter’s orbit Study the atmosphere and crust of Venus

At the press conference today, NASA also announced the selection of two other mission concepts that will receive technology development funds. One, called Enceladus Life Signatures and Habitability, is aimed at developing techniques to keep Earth’s spacecraft from contaminating other worlds. The second, called Venus In situ Composition Investigations, is aimed at improving an instrument needed to study rocks in the harsh conditions of Venus.

The comet and Titan mission concepts were chosen by NASA out of a pool of 12 proposals. The finalists will now have a year to keep refining their idea, assessing risks and coming up with a final proposal. NASA will pick the winner in July 2019, and missions will launch by the end of 2025.