Posts Tagged ‘planets’

Charles Stross on Planetbuilding for NEPTUNE’S BROOD (Part 2)

Earth (Photo: NASA)
“It won’t be long until you have to answer another question: why would they ever want to have anything to do with a planet, ever again?”

You can find Part 1 of this piece at this link, posted last week on the Orbit blog.

If you posit a future populated by human beings – or posthumans – who are able to live in space without rapidly dying of asphyxiation or radiation exposure, it won’t be long until you have to answer another question: why would they ever want to have anything to do with a planet, ever again?

Planets are bundles of matter so massive that their own gravitational field smooths out their bumps, dragging them into a roughly spherical shape. They’re so massive that most of their volume is inaccessible, hundreds or thousands of kilometres underfoot when you’re standing on the surface. They’re also a royal nuisance if you are a spaceborne society: it takes an inordinate amount of work to give an object lying stationary on the surface sufficient kinetic energy to overcome its gravitational potential energy, i.e. to put it into orbit.

It seems logical that a space-based civilization would therefore only bother with a planet if it provided resources unavailable in smaller gravity wells, such as asteroids. And the fly in the ointment with this issue is that most planet-bound resources are far too cheap to be worth boosting into orbit. Oxygen? Water? They’re everywhere. Carbon? There’s an entire class of asteroids – carbonaceous chondrites – made of dirty carbon. Metals like platinum? They might be rarer in free-floating rocks than in planets, but in the process of planetary formation they’re likely to sink towards the iron/nickel core while the proto-planet is still mostly molten. (We know from seismic studies that the core of the Earth is not only incredibly hot and under tremendous pressure, but it’s almost certainly made of heavier elements than the upper mantle and crustal rock formations.)

So what can you mine on a water world that would justify the expense of settling its hydrosphere?

The answer depends on how long it is since the planet formed . . . (more…)

Charles Stross on Planetbuilding for NEPTUNE’S BROOD (Part 1)

Photo showing the launch of the Kepler spacecraft (Photo: NASA/Jack Pfaller)
The launch of the Kepler spacecraft, 7th March 2009

We are living through the golden age of exoplanetography, and nobody seems to be paying any attention!

I’ve spoken a lot about the economic side of NEPTUNE’S BROOD (UK|ANZ), but pretty much forgot to say anything about one of the other aspects of this novel – the planet much of the action is focussed on, and in orbit around. So it’s time to fix that . . .

Until the tail end of the 20th century, the existence of planets outside our solar system was widely believed in by astronomers – but never directly observed. Planets do not (with a very few extremely odd exceptions) emit heat or light directly: we can only see them by the light they reflect from their sun. This in turn makes them extremely hard to see. If you approximate a star to a light bulb a kilometre away, then the planet you’re trying to see is a dust mote orbiting within a metre of the light bulb. Any photons reflected our way from the planet are drowned out by the comparative torrent from the light bulb itself.

There are ways to measure planets indirectly, of course. In 1992, several planets were detected orbiting the pulsar PSR B1257+12 – their mass perturbed the spin of the pulsar, adding slight irregularities to its output. But improvements in experimental design, and then the launch of the Kepler planet-finder telescope, brought a deluge of new exoplanets to light. We now know of 899 planets in 698 planetary systems, and the Kepler mission has detected another 18,000 candidates: astronomers are still trawling through the embarrassment of riches.

One thing has, however, become clear: extrasolar planets are weird. In fact, they’re so weird on average that it’s beginning to look as if our home solar system is itself the exceptionally weird one, and star systems where multiple gas giants whirl in orbit single-digit millions of kilometres from their primary are the new normal.

So, in NEPTUNE’S BROOD I decided to have some exoplanet-building fun. (more…)