Comets have secrets to spill.
After a ten year chase, the European spacecraft Rosetta arrived at Comet 67P/C-G early last month, an event live-streamed by the European Space Agency. Having executed a number of maneuvers to gradually bring Rosetta to within miles of the comet, the spacecraft snapped a selfie just this week with its target in the background.
Why are comets interesting? They offer scientists a time capsule, a look at the chemical and mineral composition of material present during the earliest periods of our solar system, a time when our star had accreted a debris disk with a radius of (very) roughly 177 billion miles, but before much of that debris would gravitationally collapse into the planets we recognize today. In contrast with asteroids, comets contain volatiles that sublimate, or pass directly from a solid to a gas without going through a liquid state. That phenomenon is responsible for comets' tails.
Sure, you could examine the comet from afar, and the spacecraft, equipped with sensors to look at the body's spectra from the infrared to ultraviolet, will, but the mission of Rosetta is equal parts cosmogenic sleauthing and Buck Rogers. In November the mother craft will dispatch a smaller companion craft called Philae to the surface of 67P/C-G. The diminutive probe will lash itself to the gravitationally poor body, bore into the depths of the stone and gently begin to relieve, mission managers hope, the streaking comet of its primordial secrets. The findings will be passed to the orbiting Rosetta for transmission to Earth. If all goes well, scientists will get a first hand look at the state of nature billions of years in the past.
I hope you will make plans now to hear Lee Billings at IdeaFestival 2014! Author of the sensational book "Five Billion Years of Solitude," he'll discuss the current understanding of these ancient bodies, the discovery in the last twenty years of hundreds of extrasolar planets and touch, I'm sure, on the very ancient questions of life and its place in the universe that inevitably accompany these finds. You don't want to miss him.
I hope to see you at the IdeaFestival!
Image credits: Upper right, ESA/Rosetta/Philae/CIVA Lower left, Philae DLR (CC-BY 3.0)