Stardust lands at 10am today. What secrets will it reveal?

Scientists, including several from Britain, will be waiting to receive the container at Nasa's Johnson Space Center in Houston, Texas. For inside the capsule lie dust particles frozen since the comet formed some 4.5bn years ago during the birth of our solar system.

If the capsule's re-entry is successful, the Stardust will be the first spacecraft to bring back material from a comet. Scientists preparing to analyse Stardust's cargo believe the particles will help to further our understanding of the origins of the solar system.

Because comets are frozen solid - except for their brief, infrequent visits to the inner solar system, the material they hold has not changed since they were formed.

Stardust was launched from the Kennedy Space Center in Cape Canaveral, Florida, in February 1999, and its 3 billion mile (4.8 billion kilometre) journey took the craft through the path of the comet Wild 2.

After travelling more than 2 billion miles, it rendezvoused with the comet in January 2004. At the time of the encounter, Wild 2 was 242 million miles from Earth.

Travelling at a speed of 13,000 mph (21,000 km/h), Stardust was protected from debris and rocks by shields at the front, which allowed it to ram its way through the comet's path without damaging the spacecraft.

Using a racket-shaped device, which opened into the comet's tail, Stardust collected thousands of particles of dust. The device contained more than 100 ice-cube-sized compartments filled with "aerogel", the world's lightest-known solid. The captured particles were then locked within a "clam shell" capsule to protect them on their journey back to Earth.

Dr Simon Green, an Open University scientist who will be part of the team analysing the samples, described the material as a "little time capsule of what things were like 4.5bn years ago". It could reveal information about the origins of life, he added.

Professor Monica Grady of the OU said: "The grains we will be looking at are pristine bits of dust left over from the birth of the solar system. We have never seen anything like this before."