Adrian Tchaikovsky, SHROUD

SHROUD is a look at alien sentience, by the (alarmingly prolific) science fiction writer Adrian Tchaikovsky. Two engineers are stuck in their spacecraft (which is actually more like a bathysphere) on the surface of an alien planet they call Shroud. Shroud is actually a moon of a gas giant in some solar system far from ours; but it is larger and denser (and hence with greater gravity) than Earth. It is enclosed in a thick hydrogen/methane/ammonia atmosphere, so thick that atmospheric pressure at the surface is twenty times that of Earth at sea level, and also so thick that no light can get through. Even the searchlights of the spacecraft can only cut through the murk for small distances. The astronauts are stranded; they have to travel halfway across the planet to reach the space elevator cable, dropped by the spaceship they originally came in, which is the only point from which they can be rescued (and indeed the only point from which any message they send can reach space beyond Shroud’s atmosphere at all). It turns out that Shroud is filled with rich and abundant life, which gets its energy from “planetary radiation, vulcanism, and a tiny greenhouse effect” (in this respect, Shroud is similar to some of the moons of Jupiter and Saturn). As the protagonists struggle to move across the surface of Shroud, they interact in multiple indirect ways with the native life, which is blind (since there is no light on Shroud) but which senses its surroundings by emitting radio waves (radar sensing, communication, and thought, all in the same medium). The human protagonists’ survival involves interacting with these native life forms in all sorts of ways. The novel is both an adventure story, and a sort of philosophical meditation on the possibilities of sentience.