After launching ten years ago, yesterday the European Space Agency’s Rosetta Mission is made its historic bid to land on comet 67P/Churyumov–Gerasimenko using the Philae lander: it became the first comet landing in history. The success of the landing was far from guaranteed due to the unexpected shape and surface of the comet.
Dr. Matthew Genge, a Senior Lecturer and Planetary Scientist at Imperial College London, said
“This is the most difficult landing in space history, like landing a balloon in a city centre on a windy day with your eyes closed.”
The odds against a successful landing got larger when the cold thruster on top of Philae was found to be faulty on the morning of the attempt. It was designed to push the lander onto the surface of the comet, however it’s failure meant that Philae must to rely on its harpoons and drills to anchor itself onto the surface at the landing site. This significantly increased the chance of the lander ‘bouncing ’ off in the low gravity. Despite initial optimism Philae is now thought to have bounced a km after it first touched the surface since its harpoons failed to deploy. It should now be able to remain securely in place at the landing site, Agilka – named after an island in the Nile – as it was chosen carefully for its inactivity.
The entirety of the Rosetta mission is said to have cost Europe around €1.4 billion. However, when this figure is broken down, per European citizen this is only €3.50 over the period between 1996 and 2015, working out to around €0.20 per year per person. The fact that it costs more per person to watch a film about blasting into space, such as the block buster “Interstellar”, than to be part of a real space odyssey, however, rather puts this in perspective.
Philae has the capacity to take samples of up to 20cm below the surface of 67P, whist also being equipped with an x-ray spectrometer, radio sensors, cameras, gas analysers and microscopes. Comets are an important repository of information about the early solar system as they are as they are believed to preserve early materials in an eternal deep freeze.
Ptolemy is a British-lead instrument in the lander’s lab, built to take in-situ isotopic measurements of the light elements Hydrogen, Carbon, Nitrogen and Oxygen. The measurement of isotopes may answer whether comets delivered water and organics to the early Earth to generate the oceans and life. Ptolemy, however, needs to drill below the surface, which may reveal fresh ice that could explode as water vapour and threaten the probe. It is safe to say that the challenges for this exciting mission have only just begun.