Potential Life Under the Ice: Planetary Porpoises and Cosmic Calamari
The Solar System – and in fact, the entire universe – appears to be littered with the building blocks of life. The six main components that form amino acids, tholins, and many other life-related compounds are simmering in the hearts of nebulae and the regolith of asteroids and comets. Those elemental substances that inform and energize life-giving operations include carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur (see Chap. 6). The four main types of organic molecules (carbohydrates, proteins, lipids and nucleic acid) are all constructed from these six items, making up the acronym CHNOPS. The materials of life fall upon our planet on a regular basis, coming in on meteors and comets. They linger in lakes on Titan and simmer in subsurface seas across the outer planetary realm and into the Kuiper Belt, and even beyond (Fig. 10.1).