Just about all the exoplanets identified so far seem distinctly hostile to human life. Our species will be hard pressed to find anywhere comfortable away from our home planet for the foreseeable future – a subject we discuss in the latest edition of Odyssey, which has just been issued.
Science fiction gives us frequent images of attempts to live on totally inhospitable worlds, or to deal with the life-forms that inhabit such planets. Hal Clement’s 1953 novel Mission of Gravity depicts human contact with the intelligent centipedes living on a planet where gravity is an enormous 700 times Earth normal at the poles, but only a mere 3g at the equator due to the high centrifugal force there when the day is only 17 minutes long. No way can humans survive the polar gravity to reach a scientific probe stranded there, but they make friends who can.
In another of his imaginative novels, Cycle of Fire from 1957, Clement envisaged a world with a highly eccentric orbit in a binary system, where periods of intense heat and cold lasting for decades make the surface effectively uninhabitable for prolonged periods. And the planet Tenebra in his 1958 novel Close to Critical is another careful depiction of a highly unsavoury world – three times Earth’s gravity, an atmosphere of dissolved oxygen and sulphur oxides, along with a surface pressure of 800 atmospheres. Of course, Frank Herbert’s planet Arrakis from his Dune series is probably the archetype of an arid, desert world which is entirely inimical to human life. Yet in all such cases indigenous life and, when necessary, human beings find a way to survive.
Sometimes people may not have a choice. In Tom Godwin’s 1958 story The Survivors, a group of humans are stranded on the high gravity planet Ragnarok, surrounded by aggressive beings and a fever which kills rapidly. Things don’t look good. Or there’s the disturbing possibility that the threat may not be immediately apparent, as in Clifford Simak’s 1951 short story Beachhead – once it’s clear that something on an alien planet is actively destroying the metal which forms the basis for human technology, the situation seems desperate indeed.
The indigenous life-forms of a planet might themselves be the problem. In Murray Leinster’s 1954 novel The Forgotten Planet, plant and insect life originally seeded on the planet in question, and which have rapidly evolved to enormous scale, pose more than a minor threat to those who have no choice but to fight for survival in such an environment. The idea of plant life as a menace on other planets was described back in 1943 by Robert Bloch, probably best known as a horror writer and for his novel Psycho on which Hitchcock’s famous film was based, in his short story The Fear Planet.
But for a description of life-threatening alien plants and animals which seem unstoppable, Harry Harrison’s Deathworld stories, which we talk about in Odyssey, take some beating. And the consequences for the human colony fighting for survival against them are inevitable, as described in the original 1960 novel in the series – it developed into “a simple black-and-white society. To prove your value to yourself and your world, you only had to stay alive. This had great importance in racial survival, but had very stultifying effects on individual personality.”
So far, exoplanets look very unfriendly. Which might suggest that, if life has developed elsewhere in the universe, it will have evolved to survive in such environments, unbelievably hostile though they appear to us. They may even be the home of advanced civilizations, who can exist only on such worlds. This might just be a reason why we don’t see any sign of them around here – it could be that Earth is as unpleasant in their eyes (if they have any) as planets anywhere else look to us.
Richard Hayes, Assistant Editor (Odyssey)