If you look at things over a broad span of time, things that are less important fall away. And if you look at things with the broadest possible span of time, with regards to the evolution of life – primitive life started 4 billion years ago – what are the important steps in the evolution of life? Well, obviously there was the advent of single celled life; there was the differentiation between plants and animals, life moving from the oceans onto land, then the development of mammals, and the ignition of the spark of human consciousness. And on that scale, I would argue that on that scale should also fit life becoming multiplanetary.
Life becoming multiplanetary is the natural successor to consciousness, because you need consciousness in order for a species to reach the point at which they are able to develop the technological ability to migrate from one planet to the next. This involves travelling millions of miles through irradiated vacuum, all the while living in an environment they did not evolve to exist in. We are currently living in just such a technological window where this may be possible, and we should exploit that fact. The window will not be open forever. All civilisations rise and fall, and with it, the abilities of that civilisation.
I think that if one can make the argument that something is important enough to fit onto the scale of evolution, then it is important, and maybe worth investing a little of our resources into. This doesn’t need to be a lot; it should definitely be a lot less than what we spend on healthcare, but maybe it should be more than we spend on lipstick.
The Earth, at first glance, seems a pretty unique place. It’s the only known planet to support life. However, anyone with a basic grasp of arithmetic can see how that shouldn’t be the case; there are somewhere in the region of 300,000,000,000 (three hundred billion) stars in our galaxy, and most are thought to have planets in orbit around them. Furthermore, our galaxy itself is only one of roughly 1,000,000,000,000 (a trillion) that are known to exist in the universe. If only one in a million stars had a planet around it, and only one in a million of those planets supported life, and one in a million of those living planets had intelligent life, there would be literally hundreds of thousands of civilisations in the universe.
Our human civilisation is really very noisy. We leak communications into space. The Wi-Fi box in your living room doesn’t aim its signal at your computer, it broadcasts in every direction; your mobile phone is the same, broadcasting in every direction. Some of the signal created by your conversations goes straight up into space. Of course, telephones and internet routers are small, low powered devices. The real loud-mouths are the television and radio masts, which boom their signal into the cosmos. So if alien civilisations exist, and if they are as noisy as us, why haven’t we heard them?
Our planet, Earth, is as far as we know, the only body in the where life has managed to evolve and survive to the present day. It is probable that the conditions required for non-living matter to arrange itself in such a way that it becomes alive are very unlikely to ever be met at all. The universe is a hostile, dangerous place, and Earth just happens to be relatively benign.
What are the very absolute basic requirements for life to evolve? Life needs three things: an energy source, a liquid solvent, and a source of carbon. Too close to a star and there is too much energy; too far away and there is too little. A tight range of thermal energies must be sustained for liquids to form. Carbon-based organic molecules can be form spontaneously in most places, but unsurprisingly, their synthesis requires the right chemical and energetic conditions. These all need to be present together for long periods (i.e. millions of years).
Filed under Biology, Space
In just 50 years, the reach of humankind in our solar system has expanded enormously. We have sent probes to orbit every planet, and landed on (or dived into, in the case of gas giants) most. Probes have seen the sunrise on Mercury and felt a cool breeze on Mars. Some missions have even succeeded in acquiring rock and dust samples, and returning them to earth. Apollo 11 in 1969 was the first to do this; later the process was automated in the Soviet Luna probes of the 1970s. In the 1990s samples of the solar wind were captured, and in 2006 particles from the tail of a comet were brought to earth for further study. Sample return mission to Mars have been proposed for the future, and given enough time, mission to and from the Jovian moons may be possible.
When planning an exploratory mission to another celestial body that could (in theory) support life, scientists make every effort to sterilise the probe of all earthly lifeforms. Microbes from earth might colonise the foreign world, and might even displace the native wildlife (in other words alien microbes). Proof of life on another planet those that would be of immeasurable interest to scientists and the public alike, but earthly organisms in the equipment would most likely pollute the result of the off-earth experiments.