When NASA's New Horizons spacecraft arrives at Pluto in 2015, humanity will have completed its initial reconnaissance of our roughly 4.6-billion-year-old cosmic backyard. Robotic spacecraft will have visited each planet in our solar system, a few intriguing moons - including our own - and several mysterious comets and asteroids. Each mission since the first spacecraft traveled beyond Earth's atmosphere in 1958 is part of the foundation for the next century of exploration.
NASA's current solar system exploration efforts seek to answer five fundamental questions developed by the science community. They are:
- How did the Sun's family of planets and minor bodies originate?
- How did the solar system evolve to its current diverse state?
- What are the characteristics of the solar system that led to the origin of life?
- How did life begin and evolve on Earth and has it evolved elsewhere in the solar system?
- What are the hazards and resources in the solar system environment that will affect the extension of human presence in space?
Each planet harbors a wealth of clues - and collectively they tell the story of our solar system. Some of the most intriguing science targets are: Pluto and the Kuiper Belt; Neptune and its frigid moon Triton; Saturn and its moons Titan and Enceladus; Jupiter and its Galilean satellites - especially Europa - and comets that make long sweeps through our solar system.
Mars and Venus are both believed to harbor clues about the origins of life and the fate of Earth. Asteroids and dwarf planets, such as Ceres, also may offer a look back to the early solar system. Closer to home, humanity is again looking to its own moon both as a crucial source of historical information.
NASA Solar System Exploration Planetary Database