The Solar System is a vast database of information. By sending spacecraft to study the planets, moons, comets and asteroids, we can find out about our own planet's past and future. However, it's a bit like the Internet - there is so much information, that you need to limit your search to a few key questions:

1. Where did we come from?
2. How did life begin on Earth?
3. Is there life elsewhere in the Solar System?
4. What is the Earth's future?

1. Where did we come from?

Our Solar System formed 4.6 billion years ago from a vast cloud of gas, dust and ice. Since then, some objects (like the Earth) have altered profoundly due to asteroid impacts and volcanic activity. Other objects, such as comets or the topmost layers of the Sun, remain relatively unchanged.

Comets give us a snapshot of the early Solar System as they still contain the materials from the original nebula. ESA's Rosetta mission to Comet Churyumov-Gerasimenko will land on the comet's nucleus and analyse samples in an on-board laboratory. NASA's Stardust mission has brought samples from the tail of Comet Wild 2 back to Earth for testing.

NASA's Genesis spacecraft collected particles from the Solar Wind and brought them back to Earth for analysis. The concentrations of different elements and isotopes in samples from Rosetta, Stardust and Genesis will reveal the composition of the early Solar System.

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Everything in the Solar System originated from the same gas cloud. However, we know that different planets contain different concentrations of elements. To understand why, we need to discover the mechanisms by which planets formed. Saturn's rings provide an opportunity to look at these mechanisms on a small scale. Using images taken by the Cassini spacecraft, we can study the motion of the rings and deduce how material behaved around the newborn Sun. Saturn's magnetic field will also give clues about the planet's internal structure and formation.

The early Solar System was a violent place with newborn planets colliding, breaking up and reforming. SMART-1's investigation of the Moon's origins will show us our planet's early history.

2. How did life begin on Earth?

The Huygens probe's mission was to land on Saturn’s moon, Titan, and search for clues to how organic chemicals turned into life. As Huygens plunged through the haze towards Titan's surface, it measured the chemical and physical properties of the moon's atmosphere. The probe landed on an icy surface that showed evidence of weathering by monsoon downpours of methane rain.

Data collected by Cassini in orbit and by Huygens during its descent and after landing will help scientists understand the processes shaping Titan’s surface, and (perhaps) find conditions where life could survive.

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3. Is there life elsewhere in the Solar System?

As far as we know, water is essential for life. Recent missions to Mars have gathered evidence that water once flowed over the Martian surface. ESA's Mars Express mission is using radio waves to probe beneath the surface to look for liquid water.

All life-forms leave tell-tale chemical signatures. To gather more direct evidence for life on the Red Planet, the Beagle 2 lander was to look for these signatures by digging up samples of Martian soil and analysing them in an on-board laboratory. Although Beagle 2 was lost on landing future European landers, such as ExoMars, may show whether there is or has ever been life on Mars.

NASA's Mars Reconnaissance Orbiter will identify landing sites for future missions including, perhaps, the first manned mission to Mars.

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4. What is the Earth's future?

Our closest planetary neighbours are very different places. Venus has a runaway greenhouse effect and clouds of sulphuric acid. Mars has very little atmosphere at all. Could either of these fates await the Earth? The Venus Express and Mars Express missions are finding out!

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