Surviving Seveneves

This is a follow up to my review which can be found here.

Stephenson’s novel continues to generate discussion in all its Marmite-glory. I feel the need to write some spoilery things so if you haven’t read Seveneves don’t continue beyond the jar of yeast extract.


In the novel Seveneves the Moon, for no good reason, explodes into tiny bits. Those bits tend to smash into each other creating even smaller bits until eventually the Earth is inundated with ‘hard rain’ of millions of tiny rocks burning through the atmosphere. With the earth’s surface under constant bombardment and the atmosphere aflame through the re-entry of lots of moon rock, the Earth becomes uninhabitable.

The question is therefore, what to do.

The salient facts are:

  1. the atmosphere burning up and hence nothing to breathe
  2. hideously hot temperatures burning everything burnable
  3. the seas evaporating
  4. constant bombardment of rocks
  5. the process will last several thousand years

To win the game of Seveneves humanity has to find somewhere to hide while the Hard Rain scenario plays out and then rebuild when it is done. The question is how. Seveneves follows one solution but three others also appear with mixed success. The four solutions are:

  1. hide in orbit
  2. hide underground
  3. hide under the sea
  4. hide on Mars

All of these solutions have some technological problems in common: you need food, water and breathable air and you need the technology to support all three of those. So each strategy gets for free magic hydroponics, seed banks, air-scrubbers and water purification systems.

Hide in orbit

Pros: lots of space to move around. Because the moon is now in tiny bits there is lots of material to work with. Because it is space the human survivors do not have to deal with horrible heat. Easy access to sunlight and solar power. Lots of space to dump stuff you don’t want.

Cons: it is space. It is cold. There is little protection from radiation. The rocks are whizzing by at high speed and even a tiny micrometeorite can kill. Orbit is difficult to get to and hence very few people can be sent there. Water is in short supply unless you can snag a comet. Also the radiation and the more radiation and the radiation.

Note that in Seveneves, the strategy of hide in orbit almost completely fails. The human population drops to just 8 people and is only saved by magic genetics.

Additional pros: if you survive and prosper in space it is a great sport from which to terraform Earth by dropping watery comets on it once all the hubbub has died down.

Hide underground

Pros: underground is right here. Digging deep underground is old technology and humans have been doing it successfully for hundreds of years. It is warm underground which is good for plants and animals. Rock provides great protection from impacts and can absorb a lot of heat. Dig in the right place and you can find fuel. Dig in a different right place and you can find water. Radiation is not a big problem (assuming you aren’t in a uranium mine or your nuclear reactor isn’t leaking.)

Cons: digging is slow. Tectonic activity could leave your underground home crushed. Adding more space once the Hard Rain has started is difficult. All the rock you dig out of a tunnel ends up being a greater volume of rubble than the space you dug out.

Note that in Seveneves the diggers appear to have maintained a large but limited society for several thousand years.

Additional con: once underground you are stuck there. It is difficult to start rehabilitating the planet surface from underground.

Hide underwater

Pros: lots of water. Nice steady temperature. The seas absorb heat well and impacts well. Access to fish and sea life for food. Safe from radiation (assuming your nuclear reactor isn’t leaking.) Easy to be mobile (at least at first).

Cons: most of the sea is going to boil away. You have all the problems of living on a cramped spaceship but with the additional problem of multiple atmospheres of pressure trying to crush you into tiny bits.

Note that in Seveneves the ‘pingers’ appear to be humans who have survived by living underwater but we know little about them.

Additional con: with the seas largely evaporating you can’t move around as much.

Hide on Mars

Pros: it is a planet. It is a long way from the whizzing about bits of the moon. Radiation is a bit less of a problem than being in space.

Cons: Mars is a long way away. Feasible only to ship a few people.

Note that in Seveneves the hopeful Mars colonists are never heard from.

Additional pro: Ice caps etc mean that it might be possible to terraform Mars.