Mars has had quite the year. A lot of its secrets have been unlocked in 2015; the discoveries of the Curiosity Rover and NASA’s MAVEN (Mars Atmosphere and Volatile Evolution) mission will undoubtedly prove to be key events in the history of Mars. Certain betting agencies had even begun to advertise odds on finding life on Mars – yet this year, they surely regret that decision: 2015 has shown us that life on the Red Planet is not as far-fetched as it might once have seemed.
For years, NASA researchers have operated according to the mantra ‘follow the water’ – and this year, they finally caught up with it. The existence of hydrated salt crystals was the smoking gun. The Curiosity Rover then found evidence of liquid water flowing beneath the surface of the Red Planet. Even though the surface temperature of Mars is well below freezing, a salt found in Martian soil is thought to have kept the water in its liquid state (if nothing else comes of this, at least science has discovered something better to grit the roads with).
2015 has constructed an image of Mars that makes it look a lot more like Earth: we have even found that this water used to be active, and there is evidence of ancient lakes and great flows of water on the surface of the planet.
Yet, if Mars is just about within the habitable zone of the Sun, and if we are discovering it to be more and more like Earth, how is it that life never prospered there to begin with? NASA’s MAVEN mission has very recently been able to tell us. Billions of years ago when the Sun was more active, the more frequent solar winds were problematic for young Mars. On Earth, we are shielded from these solar events by our planet’s magnetic field. Mars is not, and huge winds of energetic particles from the Sun stripped Mars of its atmosphere. The planet still loses a small amount of what is left every day. Without this atmosphere to protect it, heat could no longer be retained on Mars and gas also left the planet.
Mars is also subject to quantities of radiation much greater than our astronauts have ever faced. Auroras akin to our northern lights have been seen covering whole hemispheres of the planet at once.
However, there is one interesting gas left on the planet. We have known for a while that there is methane on Mars, which is hugely exciting because methane is normally a product of life. Paradoxically, the lack of atmosphere makes this more intriguing as methane on the planet is constantly being stripped away by the aforementioned solar winds. The result? At least a few scientists will be fumbling eagerly for those betting slips if it is still being produced somewhere on Mars.
2015 has shown us that it is increasingly likely that our neighbouring planet at one time harboured life. But this is just another part in a much longer story; there is still a lot to be discovered and the aim of an independent colony by 2030 still seems ambitious. We have also learnt of all the dangers that need to be overcome if we ever want to get to Mars, but this has not stopped astronomers wanting to leave our planet for another. Perhaps this is a part of an ever bigger narrative: born too late to discover the world, we may yet be around to explore the universe.