Minerals and the search for life on Mars

Understanding if life could ever have existed on Mars is one of the most challenging scientific questions facing us in the 21st Century. We know that the Martian surface at present is an arid environment bombarded with ultraviolet radiation, so the chance of finding living organisms existing there today is extremely unlikely. However, Mars has not always been this way, its history is divided into three distinct geological periods; the Amazonian, Hesperian, and the Noachian. The oldest of these, the Noachian, is likely to have been a significantly more promising time for life to potentially evolve as liquid water persisted on or near the surface long enough to carve valleys into the Martian surface and leave behind distinctive rock units. For example, in Gale Crater Curiosity Rover discovered minerals that indicated the presence of a freshwater lake at the time of their formation billions of years ago, an environment favourable to life or at least life as we understand it on Earth.

Dendritic channels in the ancient Southern Highlands of Mars. From http://history.nasa.gov/SP-441/ch4.htm

Dendritic channels in the ancient Southern Highlands of Mars. From NASA history

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Polar explosions: Carbon dioxide geysers on Mars

Images sent back from the surface of Mars can make the planet look like the hot dry deserts of Earth. However, in reality Mars is incredibly cold. The average surface temperature is 210 kelvin (-63 °C or -82 °F) and the minimum temperature is 130 K (-143 °C or -226 °F). While many of the processes and landscapes we see on the planet have equivalents on Earth this extreme cold means that Mars also has some bizarre features that we have no direct comparison for. Dark spots and strange spider like channel networks are seen to form predominantly in the southern polar region of Mars year after year. They have been interpreted as the result of jets of carbon dioxide erupting out of the winter ice sheets as they start to defrost during the Martian spring. Such a dynamic and violent process is not something you would initially expect from what is generally viewed as currently being a quiet and well behaved planet. Kieffer et al. wrote a paper in 2006 which outlined the possible formation mechanism for these strange features. This article is a summary of their work and I’ve put a link at the end.

Spooky spiders

Images of the strange polar features by the HiRISE camera on Mars Reconnaissance Orbiter. On the left are examples of dots and fans and on the right some of the spider like channel networks.

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A beautiful new impact crater on Mars

This will be quite a short post as I’m currently experiencing heavy outbreaks of paper corrections and lab work planning (this is how life goes as a third year PhD student) but an awesome new discovery has been made and I wanted to write about it. There are currently several spacecraft orbiting Mars, one of these missions is Mars Reconnaissance Orbiter, which is run by NASA/JPL. It’s equipped with an incredibly powerful camera known as HiRISE (high resolution imaging science experiment – scientists go nuts for acronyms). HiRISE imaged a region within the Terra Sabaea area of Mars in July 2010 and again in May 2012; scientists noticed that between these observations a dark patch had appeared. HiRISE acquired a high resolution image of the area on November 19th last year and the spectacular result was released yesterday.

This spectacular recent crater stands out against its lighter coloured surroundings.

This spectacular recent crater stands out against its lighter coloured surroundings with its dark ejecta rays.

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The first glimpse of another world

On the 28th November 1659 Christiaan Huygens observed Mars with the relatively new invention of the telescope and became the first person in history to document a feature on another planet’s surface. He did not have sufficient magnification to discern much detail but he could track and sketch a dark triangular shape which appeared on each rotation of Mars. As telescope technology improved cartographers raced to name the area, resulting in the dark patch ending up with at least four different names. This confusion came to an end with Giovanni Schiaparelli’s classic map of Mars produced in 1877. In his work Schiaparelli called the feature Syrtis Major and today we call the region Syrtis Major Planum (planum meaning a highland plain).

Huygen’s sketch of Syrtis Major (the optics of his telescope inverted the image) compared to telescope observations of Mars by Christopher Go in 2010. Syrtis Major can be seen moving from left to the centre of the image.

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Over the ramparts

Amid all the distractions of life it can be easy to forget that we live on a rock flying around a big fiery ball at over 100,000 kilometres per hour. Beyond our little world there are an essentially infinite number of planets out there and we’re lucky enough to be alive at a time when we are just beginning to understand their diversity. Ranging from our neighbouring rocky worlds to the gas giants and dwarf planets of our solar system, and beyond to the rapidly growing menagerie of exoplanets. Arguably the alien world to most capture our imagination is Mars, close enough that shifting details on its surface have been tantalising observers for centuries but still at a distance where any mission requires years of preparation and a speed dial to a cardiologist.

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