In Summary

After a decade long trip through space the European Space Agency’s Rosetta spacecraft will attempt to make history with a `soft’ landing of the Philae probe onto the surface of the comet Churyumov-Gerasimenko / 67P.

The Rosetta spacecraft was piloted to within 20km of the mountain-sized ball of ice and dust taking detailed images to identify the safest landing site.

Philae will be dropped from this height at no more than walking pace in a slow fall taking 7 hours, without thrusters to change course once the fall begins.

As the comet and craft are over 500 million km from Earth, command signals from ESA’s space operations centre in Darmstadt will take too long to reach Rosetta meaning the entire historic journey is automated.

Swinburne University of Technology astronomer, Dr Alan Duffy, said that no one should underestimate the difficulties in such a journey, yet the potential scientific gains of such a mission are worth the risk.

“The surface of this comet couldn't be less inviting, with sharp lander destroying rock and ice shards, as well as crevices it could be trapped in or boulders it could tumble off,” Dr Duffy said.

“While ESA is minimizing the risk by a slow descent it can’t aim Philae well enough to guarantee the landing site is free of hazards.

“This dangerous surface is just the latest surprise that comet Churyumov-Gerasimenko has given us, with the 4km long object seemingly two separate bodies stuck together, resembling some kind of cosmic ‘rubber duck’.

“The Philae lander will fall onto the ‘crown’ of the head and try to harpoon itself onto the surface as the comet’s gravity is so weak it could bounce off into space. 

“If all goes to plan we can dig into the surface of a comet, take pristine samples of material dating back to when our solar system began. This comet is a frozen fossil of the material that the planets formed from billions of years ago.

“Over the next few months the comet will heat up as it gets closer to the Sun causing the ice to sublime off into space, forming the comet’s tail giving the Philae lander a spectacular but likely fatal unique view.

“After orbiting around the Sun, the comet will head off back into space, and Rosetta will continue to orbit around the comet as a silent companion having made history.”

Information on the Rosetta mission by ESA can be found here.

For more information please contact Dr Alan Duffy on Twitter@astroduff