Sneak peek extract:
Introduction by Nick Gevers
Imagine you’re the captain of Earth’s first interstellar spaceship. The twist is, though, that the spaceship is the sort of vessel dreamt up by SF writers of the mid- to late twentieth century. This could be an advantage: the further back in SF’s history you go, the freer writers seem to have felt in ignoring the obstacle posed by the speed of light. So your spaceship is an FTL one, Faster Than Light, propelled by some sort of hyperdrive. You can reach the stars in a few weeks of subjective time.
Now imagine, further, that your conception of exotic solar systems—even close ones, like Alpha Centauri’s—is based entirely on guesswork. Your ship is twentieth century, your knowledge is twentieth century. You know nothing of what orbital telescopes and other technologies have in fact revealed over the last couple of decades. Like any SF writer of the 1960s, 1970s, or 1980s, you have had to rely on intelligent extrapolation from the nature of our own, familiar, solar system. Rocky terrestrial planets near the sun, gas giants further out, plenty of rocky moons orbiting the gas giants, lots of comets and other ice objects in the outermost reaches. Surely this pattern must often repeat itself, especially in the case of yellow dwarf stars like our sun? And thus there must be many Earth-like worlds, home to complex forms of life, worlds with breathable atmospheres, potential New Earths?
You and your crew sally forth as outright discoverers, using direct close-up observation to confirm or disprove your suppositions. You are aware of the possibility of shocking outcomes. Perhaps other stars simply have no planets at all. Perhaps you will find peculiar configurations; after all, writers like Hal Clement, Larry Niven, Poul Anderson, Jack Vance, and others conceived of very odd, even crazy, planetary arrangements in their time. Might godlike aliens have engineered entire solar systems closer to their hearts’ desire, fashioning ringworlds, Dyson spheres, shapes more fantastic still?
So you are ready for surprises; your imagination has been primed by the cognitive shocks implicit in a thousand SF stories. Your imagination is a capacious one (after all, you’ve come up with a starship and yourself in charge of it, so you’ve a bold enough fancy.) But the universe has a tendency to overwhelm us with its cosmic ingenuity…
Thus your tour of the stars in our galactic neighbourhood astonishes you. Colossal superjovians, gas giants eight, ten, fifteen times the size of Jupiter, barrel along in grotesquely irregular orbits around their suns, creating gravitational chaos, spinning planets and moons of more ordinary size all over the place, even into interstellar space. Such displaced rogue worlds can wander for billions of years between the stars, unless captured by another stellar primary. There are plenty of smaller gas giants, some like Jupiter, some like Neptune; also no shortage of rocky Earth-like bodies; but in many cases a star’s entire family of planets orbits it extremely close in–inside the equivalent of Mercury’s orbit–enduring temperatures of many hundreds of degrees centigrade and thus qualifying as so-called hot Neptunes and hot Jupiters. They must have formed much further out, so how did they migrate inwards with such freakish consistency? Their years are equal to a few of our days. And those terrestrial-type worlds: so often these are super-Earths, a lot bigger than Earth itself, with several times our gravity and very thick atmospheres. Indeed, even a less imposing super-Earth can boast a bizarrely thick atmosphere, earning the designation ‘super-puff’. Or a rocky planet drowns beneath an ocean thousands of miles deep!
You and your starship crew are in due course both drunk on novelty and in the grip of alarm. You had hoped to locate a reasonable number of worlds physically resembling Earth and safely within the Goldilocks zone, that orbital space around a star where it is neither too hot nor too cold for life to evolve on a stably orbiting rocky planet with an atmosphere thick enough to shelter fragile organisms, yet thin enough not to stifle them. But there are discouragingly few such havens; and even if they carry liquid water, misadventures like solar flares, nearby supernovas, errant superjovians, asteroid and comet strikes, gamma ray bursts, and huge volcanic eruptions can render them no refuges at all. Where are the New Earths to be found?
A member of your crew makes a suggestion: why not direct the search to red dwarf stars? If planets so frequently orbit very close in, wouldn’t the comparatively dim output of light and heat by a red dwarf leave its terrestrial planets potentially habitable, despite their proximity? So you set course for a selection of these stars, and you begin to approach your El Dorado. Many worlds huddle around these ember-red fires; there are Earths and super-Earths in great numbers, and could that gleam over there be home to a mighty alien civilization, dreaming under a blood-red sun?
The answer to that last question is Probably Not, but this is an imaginative exercise, after all. All the facts about exotic stars and their planetary companions, revealed to us over the last twenty-two years by astronomers using the Kepler and other space telescopes and employing various methods for filtering information out of complex observations, can be summarized, though very inadequately, as I’ve done above. The implications of these findings are dismaying, in confirming that complex organic life is unlikely to occur often; but also encouraging, demonstrating the extraordinary talent Reality has for defying our expectations, and opening up grand new vistas for the scientific intellect to explore and the science-fictional imagination to populate with scenarios of far-ranging wonder.
For Extrasolar, I asked fourteen leading SF writers to take on the new possibilities, whether in hope or in fear or a mixture of the two. The results are gratifyingly and fascinatingly diverse; so here we go, beyond our comfortable solar system, out to others, enticing, menacing, always bracingly strange…
–Nick Gevers, Cape Town 2017