Now that Cassini is history, having taken its death plunge into the atmosphere of Saturn, scientists are dreaming of what kind of million should follow it to the system of the ringed planet. As the New York Times reports, nothing had been funded yet, but a lot of ideas are being proposed.
Exploring Titan
At least three different types of missions are being proposed for the moon Titan, the world with liquid methane seas, shrouded in a thick nitrogen atmosphere. The Dragonfly would be a quadcopter that would hop around Titan, exploring various parts of the landscape.
Oceanus would orbit Titan, studying the moon remotely for signs of life. NBC News mentions a far more ambitious mission, called Titan Submarine, which would ply the methane oceans of Saturn’s largest moon.
Exploring Enceladus
The other moon of Saturn that has scientists interested is Enceladus. It is an ice-shrouded world that is thought to contain a subsurface ocean, much like the one on Europa, a moon of Jupiter. Cassini detected geysers erupting through cracks in the surface, spewing out water and other elements into space.
Enceladus Life Finder would orbit the ice-bound moon, flying through those geysers, using instruments to detect amino acids and other signs that life may exist in the subsurface ocean.
Another concept is the Enceladus Life Signatures and Habitability mission of which not much is known publically at the current time.
Exploring the atmosphere of Saturn
One final mission idea would penetrate the atmosphere of Saturn but would be designed to survive longer. The Saturn Probe Interior and Atmosphere Explorer would slowly descend by parachute, take readings of the planet’s atmosphere and its dark interior, lasting all of 90 minutes after a several year's long voyages to the planet.
When will a follow-on to Cassini fly?
Most of these and other mission concepts are being mulled under NASA’s New Frontier program, which also includes proposals for Venus, the moon, and a comet sample return. The various mission concepts will be culled down in November for further study with a final mission selected for a launch in 2024 or 2025.
The funding cap for a New Frontier mission is one billion dollars.
The Titan Submarine is a particular case as it is being developed under NASA’s advanced concepts program. No one knows when or if it would get funded or how much it would cost. It would be one of the most unusual space missions ever to be attempted, designed as it is to explore a sea on another world, albeit one of liquid methane and not water. The Titan Submarine is likely to cost more than a billion dollars.
