Outer Solar System
Outer Solar System
Planetary Science missions to the outer planets help reveal secrets about the solar system by observing those outer distant worlds up close. Jupiter’s moon Europa and Saturn’s moon Enceladus are now thought to hide liquid water beneath their frozen surfaces and are high priority targets for NASA. Unlocking their secrets and those of the outer planets will help scientists understand more about planet Earth and the formation and evolution of the solar system.
Jupiter has more mass than all other planets in the solar system combined. It helps protect Earth by steering comets either towards the sun or ejecting them to the outer reaches of the solar system or beyond. Jupiter has dozens of moons orbiting it, one of which, Europa, is thought to have a sub-surface liquid salt water ocean. It therefore may possibly harbor life as heat and water, the two ingredients required for life on Earth as we know it, are seemingly present below the moon’s surface.
Saturn, is the sixth from the sun. Another Jovian planet, Saturn is also primarily condensed gas, with a minute rocky core. The contraction of the planet caused the enormous pressure of Saturn's atmosphere causes so much heat, that it radiates as much into space as it receives from the sun. Saturn is perhaps best known for its rings, which are known by their letter designation, indicating when they were discovered. From the planet outward, they are D, C, B, A, F, G, and E rings, which are comprised of hundreds of thousands of ringlets.
Neptune poses a number of important questions regarding how giant planets form and what truncates the formation of multiple giant planets in a planetary system. Residing on the edge of our planetary system, Neptune may hold, deep in its interior, chemical clues concerning the nature of the rocky and icy debris that formed the giant planets. A comprehensive study of Neptune, and its moon Triton, is considered a priority for the third decade by the Solar System Exploration roadmap team.
Uranus - Over the 2006–2016 timeframe, there are no strategic missions planned to Uranus and only one spacecraft, the extremely productive Voyager II, has ever visited the distant planet. Ultimately, deep-entry probes into Uranus will be necessary in order to understand its composition and compare it to that of the other “water giant,” Neptune.