It wasn’t that long ago, especially by cometary standards, that humans viewed the unpredictable and spectacular arrival of a comet, its tail spread across the sky unlike any star or planet, as an obviously unnatural event. How could an object flying so dramatically and briefly through the heavens be anything other than a message from a divine force? Even a few hundred years ago…
Today a human-engineered spacecraft descended out of the starry blackness and touched one.
We have known for quite some time that our ancestors widely maligned these icy rocks, often thinking them messengers of death and destruction. Yes, a comet is, at some level, not much more than an icy rock. Yet, heated by the sun, it can create one of our sky’s most bewitching spectacles. Actually two, because not only can a comet itself be a fabulous sight, the dust it leaves behind can give us meteor showers for many years afterward.
But it doesn’t stop there. For comets, believed to be frozen relics of the ancient past, born in the early days of the Sun and its planets, may have in fact been messengers not of death but of life. When they pummeled our poor planet in its early years, far more often than they do today, their blows may have delivered the water for the Earth’s oceans and the chemical building blocks for its biology. They may also hold secrets to understanding the Earth’s history, and perhaps insights into the more general questions of what happens when stars and their planets form. Indeed, as scientific exploration of these objects moves forward, they may teach us the answers to questions that we have not yet even thought to ask.
Will the Philae lander maintain its perch or lose its grip? Will it function as long as hoped? No matter what, today’s landing was as momentous as the first spacecraft touchdowns on the Moon, Venus, Mars, Titan (Saturn’s largest moon), and a small asteroid — and also, the first descent of a spacecraft into Jupiter’s atmosphere. Congratulations to those who worked so hard and so long to get this far! Now let’s all hope that they, and their spacecraft, can hang on a little longer.