Artist’s impression of the Rosetta orbiter deploying the Philae lander to comet Churyumov–Gerasimenko (not to scale) © ESA–C Carreau/ATG medialab

Artist’s impression of the Rosetta orbiter deploying the Philae lander to comet Churyumov–Gerasimenko (not to scale) © ESA–C Carreau/ATG medialab

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Comet-chaser prepares to probe the early solar system

The spacecraft Rosetta is set to wake up from nearly three years of hibernation today, more than 807 million kilometres from Earth, ready to explore the composition of a comet.

The European Space Agency (ESA) launched the unmanned probe Rosetta in 2004, setting it on a course to travel past the Earth three times as it gathered momentum to swing out towards the comet, currently flying near the orbit of Jupiter.

The target, comet Churyumov–Gerasimenko, is a mass of ice and dust on a 7-year orbit around the Sun. The comet is thought to have formed in the early solar system, more than 4.6 billion years ago.

As Rosetta gathered speed, it also flew past Mars and two asteroids, Steins and Lutetia, taking pictures as it went. As it was finally flung out towards the orbit of Jupiter in mid-2011, Rosetta entered hibernation, shutting down most systems to save energy, but still travelling towards the comet.

Building a solar system

Now, Rosetta is set to wake up and prepare to encounter the comet, which it is expected to reach in August. It will then map the surface, looking for a suitable landing place for its detachable probe named Philae. Once deployed on the surface in November, Philae will analyse the make-up of the comet, looking for hints of conditions in the early solar system.

Comets are thought to have remained relatively undisturbed since they first formed in the cold, outer regions of the solar system.

‘Comets therefore contain the most pristine examples of the materials available during the early history of the solar system,’ said Museum extraterrestrial materials researcher Dr Penelope Wozniakiewicz.

Materials like those to be analysed by Philae would have recorded details of the environment in which they formed, or have since been subjected to. ‘Studying cometary samples provides us with the opportunity to learn about the conditions and processes that operated in the early solar system,’ said Dr Wozniakiewicz.

A dynamic beginning

Dr Wozniakiewicz worked on material collected during NASA’s Stardust mission that brought dust back to Earth from a comet’s tail in 2006. 

Key findings from these samples include the discovery of material that formed close to the Sun, pointing to a dynamic early solar system with large scale transportation of materials; and the identification of the amino acid glycine – one of the building blocks of life.

Although Rosetta and Philae won’t physically return anything to Earth, the probe has an on-board laboratory capable of analysing material and sending the information back to researchers on the ground.

Rosetta was set to wake up at 10 am today, but will take a number of hours to warm up and send a signal back to Earth. ESA scientists are holding their breath for a sign that Rosetta is ready to continue its mission.