Comets have been harbingers of omens, marking the collapse of empires, the death of kings and signals of profound worldwide change.
Halley’s Comet passed near Earth in 1066, which philosophers opined meant doom for King Harold II of England, who later fell to William the Conqueror at the Battle of Hastings, marking the Norman Conquest and the last time Great Britain was successfully invaded. An image of the comet appears as a fiery star on the Bayeux Tapestry above an image of Harold who appears to cower in a castle surrounded by his retainers.
The speed with which comets travel through our solar system made catching images of them our best and only means of study. However, on Nov. 12, we finally reached out and touched one of these comets — a profound moment of world history marking the achievement of our species to do the near-impossible.
A little more than 10 years ago, the European Space Agency launched a rocket from French Guiana on a bold mission. Scientists from 14 European nations and the United States built a 3-ton spacecraft called Rosetta, which they broke free from Earth orbit and sent out to circle the sun four times, Mars once and the Earth three times to build up enough speed to approach Comet 67P/Churyumov-Gerasimenko, a 4-kilometer-wide comet which was traveling through our solar system at approximately 135,000 km/hour.
To save power for the decade-long journey, scientists turned off nearly all of Rosetta’s power, using just their gravitational calculations to send the spacecraft to the comet.
The ability to send the Rosetta spacecraft from Earth to the comet and safely land on it is equivalent to throwing a hammer from Seattle to hit a nail in Caracas, Venezuela — while the nail is moving the equivalent of about a mile an hour.
After reaching stationary orbit of the comet — in this case “stationary” means traveling alongside at 135,000 km/hour — Rosetta released a lander called Philae, which took seven hours to slowly descend down to the surface, landing only about 100 feet off-target.
Due to lack of gravity on the tiny comet, Philae used harpoons and grappling hooks to grasp the surface and avoid merely bouncing off. It will now conduct experiments and gather surface samples, riding with the comet over the next 13 months as it passes by the sun, warms and begins to shed ice into the iconic comet tail.
After the lander successfully touched down, it began transmitting images back to Earth, offering humans our first view of the surface. Without context, the images themselves are not impressive, just grey ice and rock split by black shadows. But what they capture is profound: A human-built device that reached across the heavens to land on a tiny comet traveling at an immense speed — proof that with patience, teamwork and dedication, nothing in the universe is beyond the reach of our collective human curiosity.
