Earth and other unlikely worlds

Paul Raven @ 12-08-2009

Apologies to Paul Mcauley for pinching the name of his blog for a post title, but it felt appropriate!

In addition to raking over our old friends the Drake Equation and the Fermi Paradox, COSMOS Magazine looks at the possibilty of the sort of planets found in classic space opera actually existing… you know the sort, solid globes of diamond or iron or ice or whatever else.

THE EARTH FORMED in a region of the Solar System’s protoplanetary disc that was relatively rich in the element oxygen. So on top of an iron-rich core, our planet is mostly built out of oxygen-containing silicate rocks. But further out in the protoplanetary disc, the ratio of the elements carbon and oxygen was probably different.

A class of meteorites found on Earth, called enstatite chondrites, may have formed in this region – they have a ratio of carbon to oxygen that is a thousand times larger than the ratio found on Earth.

“If an entire planet were to have condensed from this kind of raw material, it would have ended up enormously different from the Earth,” says Marc Kuchner, an expert on exoplanets at NASA’s Goddard Space Flight Centre near Washington DC.

Built out of relatively more carbon than oxygen, such a planet would still have a metallic iron core, but the outer layers could be composed of ceramics – silicon and titanium carbides – with a shell of pure carbon on top.

These ceramics and graphite would make the entire planet extremely hard and heat-resistant, and it could survive much closer to its star. Even more bizarre is that the high pressure beneath the surface would convert the bottom of the graphite layer into an entire shell of diamond that would be many kilometres thick.

That’s your sensawunda fix for the day, I reckon. And if you’re a fan of the OMG-we’re-so-insignificant angle, try this for size: Earth’s habitable period may nearly be over, at least on a cosmological time-scale [via SlashDot].

“The Sun does not seem like the perfect star for a system where life might arise. Although it is hard to argue with the Sun’s ‘success’ as it so far is the only star known to host a planet with life, our studies indicate that the ideal stars to support planets suitable for life for tens of billions of years may be a smaller slower burning ‘orange dwarf’ with a longer lifetime than the Sun ― about 20-40 billion years. These stars, also called K stars, are stable stars with a habitable zone that remains in the same place for tens of billions of years. They are 10 times more numerous than the Sun, and may provide the best potential habitat for life in the long run.”

Take that, Rare Earth Theory! Turns out we’re not so special after all… though whether that’s reassuring or depressing is a matter for debate.


Kim Stanley Robinson on why space is a bad idea… and a good idea

Paul Raven @ 23-07-2009

Planet EarthSpace exploration tends to be a black-and-white debate, with interested parties falling into either enthusiastic advocacy or strident denouncement. But as with most things, there’s a considerable middle-ground to explore – and over at the Washington Post, Kim Stanley Robinson brings the humanist pragmatism as he argues that space exploration is a worthy goal provided it helps us become a species that doesn’t have its finger hovering perpetually over the self-destruct button:

Eventually, if things go well on Earth, we may begin to inhabit the moons and planets of the solar system more completely, with populations living their entire lives off Earth. At this stage, Mars will always loom as the best candidate for a viable second home. If we alter that planet by importing Earth’s organisms into a rehydrated Martian landscape, that would make it safer for us to live there long-term. These big possibilities, described at length in my Mars novels, will make the planet one of the best 22nd century answers to the question, “Why space?”

And later, if things are still going well on Earth — always the necessary condition — we might live throughout our solar system. This civilization would be a great thing, as a healthy Earth would have to exist at its heart. But given all we have to do first, the full flourishing of such a civilization is surely centuries away.

So why even talk about this? Because it is useful to take the long view from time to time. This is what science fiction does, and though science fiction has been bad about space, it has been good about time. Taking that long view, we no longer seem like the most sophisticated culture ever; indeed, much that we do now will look silly or even criminal in the future. The long view also reminds us that we are a species only about 100,000 years old, evolving on a planet where the average lifetime of a species is 10 million years. Unless we blow it, humans are going to be around in 1,000 years — and if we make it that far, it’s likely that we’ll last much longer than that.

So, what actions, taken today, will help our children, and theirs, and theirs? From that perspective, decarbonizing our technology and creating a sustainable civilization emerge as the overriding goals of our age. If going into space helps achieve those goals, we should go; if going into space is premature, or falls into the category of “a good idea if Earth is healthy,” it should be put on the science fiction shelf, where I hope our descendants will be free to choose it if they want it.

What do you think? Is escaping the gravity well a means to an end in itself, or should we concentrate on tidying up our own back yard before heading out into the local neighbourhood? [via BoingBoing; image courtesy NASA]


What do we call ourselves?

Adam Roberts @ 22-04-2009

The Adam Roberts Project

I don’t mean “what do we call ourselves as SF fans”. I mean, what do we, SF fans and writers, call ourselves as inhabitants of this planet? It’s been troubling me. Continue reading “What do we call ourselves?”


Activate asteroid defence shields!

Paul Raven @ 09-12-2008

Earth-asteroid impactA lobby group of scientists have urged the United Nations to invest in a system for detecting near-Earth asteroids that could collide with the planet. We’ve got a lot of existential risks on our plate right now, of which being clobbered into a prehistoric state by a lump of space rock is just one – and a fairly remote possibility, thankfully. But it’s also one that we’d need every spare moment of advance warning to deal with… Bruce Willis will need time to put on a clean vest, if nothing else. Forewarned is forearmed, and all that. [image by goldenrectangle]

That said, space rocks striking planets might have their upsides… at least on currently uninhabited planets. A paper from a Japanese university suggests that meteorites colliding with Earth may have been the source of the amino acid groups that began the chain of life. Not quite as science fictional as panspermia, but still quite a mind-bending thought.


‘Flux transfer events’ connect Earth and Sun

Tom Marcinko @ 03-11-2008

News to me:

Like giant, cosmic chutes between the Earth and sun, magnetic portals open up every eight minutes or so to connect our planet with its host star.

Once the portals open, loads of high-energy particles can travel the 93 million miles (150 million km) through the conduit during its brief opening, space scientists say.

Called a flux transfer event, or FTE, such cosmic connections not only exist but are possibly twice as common as anyone ever imagined, according to space scientists who attended the 2008 Plasma Workshop in Huntsville, Ala., last week.

Ten years ago I was pretty sure they didn’t exist, but now the evidence is incontrovertible,” said David Sibeck, an astrophysicist at the Goddard Space Flight Center in Maryland.

There must be a use for these things, in fiction or real life…

[Image: NASA]


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