Gaia: Why Mars is Probably Dead

As a tangent to yesterday’s post (and also because discussing bleak prospects for Mars appears popular), there’s another point in James Lovelock’s Gaia: A New Look At Life on Earth that seems relevant for today.  It’s just been announced that NASA will send another rover to Mars in 2020 to compliment the work of the current Curiosity rover in its search for life.  While Curiosity has been generally examining the environment with its hi-tech equipment to see if it could ever have been fit for life, this new rover would focus on studying the planet’s geology.

When writing the book, it was Lovelock’s view that the development of life on a planet inevitably acts to terraform that planet to make it even more fit to harbour life – such as how on Earth life has regulated our atmosphere in the last 3 billion years to keep the temperature constant, despite the fact it ought to be lowering.  If Mars has ever had life on it, then this life should have modified the planet to make it more habitable, thereby leading to more life.  This doesn’t necessarily mean that Mars should still be habitable now if it ever sustained life – some catastrophe could have destroyed the atmosphere, for example – but signs of former life ought to be more obvious.  Certainly, it would suggest with certainty that no life exists now.  In this theory I think it’s still possible that life never developed past basic bacteria before being wiped out, but the chances of such a short lifespan can be considered unlikely.  If this is true then our search for life on Mars is probably in vain.

That’s not to say I don’t think we should be sending rovers to Mars.  Quite the contrary!  There is still so much we can learn from our neighbours whilst developing our own technological capabilities.  I just don’t think we should be getting our hopes up for any big announcements.

Death on Mars

As far as we are aware, no organism has ever lived or died on our red neighbour, Mars.  Perhaps evidence will one day emerge of fossilised bacteria hidden within Martian rock.  There is indisputable proof that water once flowed freely on the surface after all, which is one prerequisite for life as we currently understand it.  Some scientists have even suggested life could exist today in underground, water-filled caverns, though I’m not sure how likely this is.  Whatever the truth, nobody has doubted that Mars’ oxygen-less, atmosphere-limited, distant surface would be an easy place to live, but this hasn’t deterred humanity’s persistent dream of one day walking on the red planet.

The Curiosity Rover’s latest discovery, on the other hand, might do just that.  Apparently the level of radiation potential astronauts would endure in both traveling and settling on Mars are far beyond what is considered safe for a human to experience.  Here are some figures, taken from the BBC (measure in millisievert, the unit of equivalent radiation dose):

  •  Annual average: 2.7mSv
  • Whole body CT Scan: 10mSv
  • 6 months on the International Space Station: 100mSv
  • Traveling to and from Mars (excluding time spent on planet): 660mSv

For the average human in a developed country exposed to 2.7mSv a year (so perhaps just over 200mSv in a lifetime), the chances of developing a cancer are around 1 in 4.  If I understand this correctly, this makes the chances of developing a cancer after traveling to Mars far greater than ought to be acceptable.

This, understandably, poses huge problems for the future of space exploration.  It’s incredible that such a haven for life could ever develop on the Earth considering how many dangers exist to us outside of the planet.  While I think some scientists are still optimistic, I find these figures very depressing.  They serve to remind me that the Earth is not a cradle, but a prison.  We are trapped here for each of our tiny lives until the prison walls break down and then even here won’t be inhabitable – once the solar flares beam down, or the surface becomes irradiated by ultra-violet light, or a stray piece of rock slams into us, or…

Mars is a world of death and Earth a world of life.  But Earth is defying the norm of the Universe – how long before it joins Mars?  It’s as if the Universe were designed with the strict intention of making life impossible.

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