All These Worlds Are Yours - Part 3

How many "Goldilocks" or Earth-like planets are there? Without being able to survey other planetary systems in detail we can only estimate this value based on largely untested theories of how stars and planets form. A recent hand-waving estimate (http://news.bbc.co.uk/1/hi/sci/tech/7891132.stm) suggests there is one for each star, making perhaps 300 billion of them in our galaxy. I think this is perhaps optimistic, but we have to wait for the real data to decide.

Once you have an Earth-like planet, what are the chances that life will develop on it? What is the chance of that life developing intelligence, civilisation, technology, spaceflight? What are the chances of that planet being close enough to us, and both our civilisations lasting long enough to detect a signal from the other? These questions have been combined into a single statement known as the Drake Equation.

N = N* x P x E x L x I x C x t/T

N is how many alien civilisations we can potentially contact within our galaxy.
N* is the number of stars in our galaxy.
P is the fraction of those stars with planets.
E is the average number of planets per star that may support life.
L is the fraction of planets that do develop life.
I is the fraction of lifeforms that develop intelligence.
C is the fraction of intelligent lifeforms that send signals into space.
t is the length of time these civilisations send signals.
T is the age of the galaxy.

Most of these terms are impossible to even estimate with our current knowledge. We only have one example of life developing on a planet, one example of life developing intelligence - the inhabitants of Earth. A single data point does not a useful graph make. The Drake Equation is not a part of science like the Theory of Relativity or Maxwell's laws, but it is a useful starting point for understanding the conditions for meeting extra-terrestrial life.

You can fly into space, but you can't hide

One of my favourite questions is 'why do we want the human race to survive?' People seem very keen on the idea, but when I question this instinct they either look blank or think I'm crazy. Quite possibly both.

So when Cobweb posted on escaping to another planet the question formed on my lips as predictably as a lemming walking off a cliff. (Some 1990s gamers seemed overly keen on our green haired friends living on, but I digress).

Why does it matter if we, as a species die out? I can understand why individuals take their own survival pretty seriously, but to worry about a 'lucky' few moving onto some far flung rock not particularly suited to sustain humanity in a few hundred years seems like a bad idea. The idea of my descendants eeking out some dreary existence away from earth seems...pointless.

The other arguments put forward for space exploration are generally two fold. Firstly that it produces spin off science that is useful for helping people on earth. Don't get me started on that one - it's basically saying that the best way to give clean drinking water to the world (estimated cost £1 billion) is to spend £60 billion on sending a probe to Mars. It's just that the second way is more fun.

Second is the curiosity factor, exploration, knowledge, the final frontier. This makes more sense to me and seems more honest - there is a curiosity and enterprise in the human spirit and I can see that collaborative space exploration edifying to the collective human condition. And at least it's not dressing exploration up as some gloriously ethical idea. Fairly sure it's not worth the money, but I see the argument.

We're on this planet together and on the whole it's a pretty great place until we started screwing with it. If we can't figure out a way of saving it then we shouldn't be so presumptious to assume that it's worth us homosapiens trying to run off somewhere else.

All These Worlds Are Yours - Part 2

Of course, life might already be out there. It is hard to imagine (for non-sci-fi authors at least) lifeforms that call deep space their home, or thrive on the surface of a star, so planets are the place to look. Gas giants like Jupiter and Saturn lack a stable platform for organic molecules to meet and react making life less likely on the largest of planets. Liquid matter appears to be essential for biological processes - as a solvent, lubricant, transport mechanism or temperature regulator. Water is a perfect (although probably not unique) solution to this requirement, so a planetary temperature that allows for liquid water is optimal. Gases and liquids will not remain long on an object that lacks a strong enough gravitational field, so we can perhaps rule out the small rocky bodies such as asteroids and tiny moons like those of Mars (Deimos and Phobos). Gases are important for without our atmosphere trapping some of the heat from the Sun, Earth would be too cold to support life as we know it. "Goldilocks" planets are so called because they are not too hot nor too cold. They have to be the right distance away from the right kind of star and be the right kind of size.
Improvements in astronomy have lead to the detection of planets orbiting other stars. Spotting these extra-solar planets is incredibly difficult so they are sought through indirect means. Measurements are taken of the dimming of a star as a planet passes in front of it or the slight positional wobble caused by the planet's gravitational pull. Large planets close to their stars are the easiest to detect with these methods, so we've found mostly blazingly hot Jupiter-sized objects orbiting at Mercury-like distances. As our equipment and measurements improve, we are getting closer to seeing Earth-size objects at Earth-like distances.

All These Worlds Are Yours - Part 1

Thursday.

I could never get the hang of Thursdays. You know where you are with a Friday, that is, perched precariously to the outside of a spinning ball of rock orbiting a much larger ball of exploding hydrogen.

It has been my firm belief for many years now that the quicker we (the human race, not you and me specifically) get ourselves off this aforementioned ball of rock and onto a few others the better. We may by some chance survive the many potential disasters of the future, caused either by ourselves or the uncaring universe, but there's a final deadline. Eventually, our Sun will explode to an even greater extent than it is now and scorch our tiny rock ball clean. You may say that such an event is a long long time away, nothing to worry us, we'll be long gone. But think - medical care is improving. Life expectancy is going up. The younger you are now the older you'll get. Try telling that the apocalypse is coming in 10 billion years to a class of 10 year olds and watch the panic set in. Kids are wiser than we think.

So we need to get going. Get to orbit, get to the Moon, get to Mars. Get out of the Solar System. While our eggs are in one basket we are vulnerable. Only when we have colonised the stars can we start to relax. Would it not be a shame if intelligent life was snuffed out simply due to the fact its exploratory instinct was burnt out on this otherwise insignificant little planet?