The UOP will image the surfaces of the moons in their entirety to search for ongoing geological activity. This raises the possibility that one or more of these moons, such as Ariel, Titania and Oberon, could have potentially habitable liquid water oceans underneath ice shells. Uranus's five largest moons, which scientists predicted were cold, dead worlds, being too small to hold much of the heat from their creation, all showed evidence of recent surface activity. For example, Voyager 2 could only image the southern hemispheres of Uranus' satellites. Uranus's tilt also limits what astronomers can see of its moons. (Image credit: X-ray: NASA/CXO/University College London/W. Uranus is tipped on its side, and scientists aren't sure why. Related: Why scientists want NASA to send a flagship mission to Uranus

The UOP can help shed light on Uranus's atmosphere, with the probe gathering detailed wind and temperature data at one location and the orbiter collecting information across the entire planet, Mandt said. The sideways nature of Uranus causes the planet to experience extreme seasonal variations over its 84-Earth-year orbit unlike those of any of the solar system's other planets, and what little astronomers can see of the world from Earth cannot explain what they know of its weather patterns. 'We can figure out if this is true by studying what the planet is made of and its interior structure,' Mandt said. This unusual orientation might be due to a collision with a planet-size body, or several small bodies, soon after Uranus formed. 'The tilt is crazy - it's the only planet in the solar system that is completely on its side,' Mandt said.

One of Uranus' strangest features is the fact that, unlike the solar system's other planets, Uranus is tilted so far that it essentially orbits the sun on its side, with the axis of its spin nearly pointing at the star.

The mission is recommended to last for at least five years. The aim of the mission - currently given the placeholder name of the Uranus Orbiter and Probe (UOP) - is to explore how Uranus and the rest of the solar system formed and to help solve mysteries regarding the planet, its moons and its rings. The proposal involves both an orbiter to gather data about Uranus over time and a probe dropped into Uranus' atmosphere to scan the planet from the inside. 'The potential findings will be groundbreaking in the same way that the Cassini mission has revolutionized our understanding of Saturn, its moons - especially Titan - and its rings,' Mandt said.

Neptunes missions