Introduction

On 2 January 2004, the US space agency's Stardust probe encountered Comet Wild-2. It captured particles from the brilliant 5km-wide (3.1 miles) ball of ice, dust and gas, in the hope of gaining an insight into the creation of our Solar System.

Dust Catcher

Approaching at 6.1km/s (13,600 miles per hour), Stardust flipped open a particle catcher shaped like a tennis racket.
Shields protected Stardust on its 10-hour passage through a hailstorm of debris. The comet particles - thought to be relatively unchanged since the Solar System's birth - are being returned to Earth in a special capsule.

World's Lightest Solid

Stardust's dust catcher is filled with the world's lightest solid - a glass foam called aerogel.
The foam, pictured on the left, is 99.8% empty space and insulates 39 times better than fiberglass.
It was designed to slow the dust particles as they collided with it at high speed - minimising the risk of the impact damaging or altering them.

Round Journey

Stardust reached Comet Wild-2 during its third loop around the Sun.
Following its launch in February 1999, it completed a session of collecting interstellar dust before performing a flyby of Earth. This set up the probe on its second loop around the Sun and gave it the trajectory and correct momentum to approach the comet.

Sample Return

Having passed Comet Wild-2, Stardust has taken a further two years to return to Earth.
On 15 January 2006, a parachute set the sample capsule on to the salt flats of the Utah desert.
Scientists will retrieve the samples for analysis, which could open new frontiers in our understanding of the Solar System.