Rosetta, originally a word with historical underpinnings, has now come to mean, metaphorically, a clue for solving a puzzle. A 1200-kg spacecraft, named Rosetta, has recently hit the headlines, for it is the first in history to get into an orbit around a comet. It was launched over ten years ago on March 2, 2004 by the European Space Agency (ESA).

    The comet in this game is 67P/ChuryumovGerasimenko, (67P, for short). Rosetta carries instruments to collect scientific information about 67P such as its composition and atmosphere, from as close as 20 – 30 km. Philae, a lander weighing 100 kg, separated from Rosetta and fell like a feather on the surface of 67P on November 11, 2014. Philae also carries several instruments including a drill to dig out materials from the comet’s surface for analysis.

    Rosetta had a 6 ½ billion km-long journey before it would come close to 67P. No available rocket can lift a....