Your questions answered: Rosetta and Philae

Landing a spacecraft the size of a washing machine on a 4km-wide comet billions of miles away is one of the most notable feats in the history of  space exploration. Questions from readers for our team of experts from the Rosetta mission flooded in; we’d especially like to thank the students of the STEM Academy Rocket Club and Year 13 Physics Group of the Buttershaw Business and Enterprise College in Bradford. Thanks are also due, of course, to the panel.

• We heard the sounds generated by the lander. Given that sound doesn’t travel in a vacuum, exactly how were these sounds generated, what do they tell us and why is sound the best way to understand that data?

PM: The sounds are picked up by the feet of the lander. The sensors are in the feet — an experiment called SESAME (Surface Electric Sounding and Acoustic Monitoring Experiment). It picks up the vibrations at acoustic frequencies.