Watch NASA Announce Final Contenders for Next-Generation Robots to Explore the Solar System

What Juno, a current New Frontiers mission, might look like at its target, Jupiter. NASA/JPL-Caltech

On Wednesday afternoon, NASA will be announcing the missions it might pursue as part of its New Frontiers program, which sends relatively cheap robots to explore our solar system. It should be an exciting announcement, since we don't even know for sure right now what the candidates are—and the whole thing will be livestreamed on NASA's website beginning at 2 p.m. ET.

You may recognize the current missions in the New Frontiers program, since they're some of NASA's most interesting projects—New Horizons, the spacecraft that flew by Pluto and is now approaching a mysterious Kuiper Belt object; Juno, which is taking the best photographs we've ever seen of Jupiter; and OSIRIS-REx, which is en route to retrieve a tiny piece of an asteroid.

The New Frontiers set of missions is special in that contenders must meet a couple of very specific rules. First, the program has a strict cap on the amount of money a project can cost—$700 million. Second, it has to be a robotic mission exploring a set of specific targets NASA has identified as high priorities.

The projects that would become finalists during today's announcement needed to tackle one of six of those themes, which include retrieving a piece of a comet or of the moon's south pole, visiting Saturn or at least one of its most interesting moons, Titan and Enceladus, touring a special class of asteroids called Trojans that linger at special points in a planet's orbit, or exploring Venus.

Bringing a piece of space back to Earth will let scientists study it in laboratories with much more detail than they can apply to celestial bodies we don't visit, and both Titan and Enceladus are high on scientists' list of potential places to find life beyond our planet.

Read more: Venus Is More Like Earth Than We Thought Despite Nightmare Atmosphere

NASA hasn't released much information about the proposals it's considering, but there are some rumors flying around about what the missions could be, and a few contenders have discussed their plans publicly. Those missions include two comet missions, a Saturn probe and three proposals to visit Saturn's moons.

After the finalists learn they've moved on to the next round, they'll have about a year to put together a deeper report on their missions, with NASA making its ultimate decision in 2019. Whatever mission is chosen would be looking to launch before the end of 2025.