Since I was a little girl I have been interested in space travel. I loved Fireball XL5, but struggled to understand how the cast (giving televisual ‘life’ to puppets) could breathe in space without spacesuits. I now understand that they took ‘oxygen pills’. (Decompression and radiation aside, even for puppets.)
I have been reading the NASA posts about Curiosity – the Mars rover. It has drilled its first rock sample and will analyse the resulting grey powder over the next few days. Although the mission was not intended to look for life, its on-board equipment can analyse the samples it takes, allowing scientists to detect the components of carbon chemistry and look for mineral evidence of water. Visual inspection of pictures of the surface give clear indications that Mars had a ‘wet past’ and running water on the surface.
Mars could once have had abundant water and a thicker atmosphere, but now the surface is near vacuum and exposed to radiation from the solar wind. Despite the appearance of the surface – it reminds me of the Canary Islands – it would not be a healthy place to visit, even with ‘oxygen pills’ like the crew of XL5. Any remaining life on Mars would be hardy indeed – but we have found microbes surviving on nuclear fuel rods and exposed in orbit around Earth. Perhaps there are some bacteria that cling on to life beneath the surface.
We can take microbes and put them in extremely hostile environments and find they survive unprotected. But they originate on Earth as part of a complex interdependent system that – amongst checks and balances – allows the organism to develop and thrive. If there was life on Mars, it would have been part of its own bigger picture, but likely this would have been quite restricted given the narrow window of opportunity when Mars perhaps had a decent atmosphere and abundant water. We have evidence that Mars once had a magnetic core like Earth’s that acted as a planetary radiation shield. It is believed that this core shut down some 4 billions of years ago, allowing the solar wind to peel off the atmosphere and radiation to excoriate the surface.
Thermodynamics shows us that life works in accordance with the basic laws of physics, and that order is created at the the expense of degrading energy. It is a one-way ticket. It could be a driver for the development of life – if energetic conditions are favourable then life is likely to arise. ‘Energy’ here includes the free availability of suitable nutrients for complex – infomationally ordered – organisms to flourish within an energy conversion cycle.
But life creates stresses on the system that contains it, and things happen within it to compensate to regain stability. Earth has developed an extraordinarily complex eco-system. Humans can’t survive without bugs and plants and microbes etc. The healthy operation of our bodies depends upon microbes living within our gut and on our skin. Our oxygen and other nutients are produced by plants, which in turn depend on microbes and bugs. We can send people into space, even to Mars, but they could not survive there without technological support.
If life on Mars is found – extant or deceased – it will provide insight and understanding into our own world. We do not live in a privileged position; humans are enormously successful as a species, but we are part of a planetary energy cycle operating under the laws of physics. We are doing a fantasic job of converting high grade energy into greenhouse gases and low grade energy. But this produces a thermodynamic back reaction, which we are beginning to feel as signs of climate change. There is no doubt that our planet will respond, and the machinery will work to optimise the energetics of the system. This may not make conditions so favourable for humans in the timescale of the human race. Thermodynamics plays the game both on the short timescales of molecules and men, but also on the scale of the universe itself.
As a footnote – it is possible that life on Mars (as microbes) migrated to Earth via meteorites, and took root as our planet became fertile. Curiosity is a great name for a Mars robot – a quality associated with intelligence, and a quality that may help humankind to stick around for a little while longer.