Book review: ‘Mars: The Pristine Beauty of the Red Planet’
Improvements in imaging technology continue to improve our knowledge of Earth’s nearest neighbour planet
When Mariner 4 flew by Mars in 1965, it dashed any hopes that remained of finding Lowell’s ‘canals’ on the Red Planet, let alone H.G. Wells’s Martians; its cratered surface seemed as barren as the Earth’s own Moon. But from late 1971, when Mariner 9 entered orbit, our view of Mars began to change: its imaging camera revealed volcanoes, canyon systems and what appeared to be water-worn features. Now we know that water is plentiful on our planetary neighbour, not only in the icecaps (along with prominent carbon dioxide deposits) but also beneath the surface as permafrost.
Our image of Mars has continued to change throughout the 60 years of the Space Age, largely thanks to improvements in space technologies and imaging systems that deliver a resolution and beauty previously unimagined. ‘Mars: The Pristine Beauty of the Red Planet’ by Alfred McEwen, Candice Hansen-Koharcheck and Ari Espinoza (University of Arizona Press, £65.00, ISBN 9780816532568) is a mammoth 430-page book – a slab of publishing excellence measuring 30-by-35cm and 4cm thick – that highlights some of the latest imagery.
The residual cap of left on Mars’s South Pole by the planet’s middle to late summer consists of carbon dioxide ice over layers of water ice, mixed with small amounts of dust. Rapid sublimation of the carbon dioxide ice causes slope retreat and creates characteristic ‘Swiss cheese’ holes.
While Mariner 9’s early imager had a resolution of some 100m per pixel at best, the High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO) delivers an incredible 0.3cm per pixel. As the lead authors (HiRISE Principle Investigators) explain, although this was NASA’s basic requirement for monochrome imaging, it was considered “important” to provide colour. Thus HiRISE includes additional CCDs for the red, blue-green and near infrared bands, which (dependent on processing) produce false-colour images of enhanced contrast (to counteract “scattered light from the dusty air”). This has proved “extremely valuable to HiRISE science and landing site reconnaissance”, confirm the authors, adding: “more importantly for this book [they] are beautiful”.
In the region known as ‘Inca City’ underlying terrain is covered by polygons produced by expansion and contraction of shallow subsurface ice.
The concept of beauty – as reflected in the book’s subtitle – is clearly important for these planetary scientists and has informed their choice of “never-before-published” images, revealing the stark but sometimes serene beauty of geomorphology. In landscapes sculpted by wind, water and ice, we see the results of recent ice melts, water flows, land slumps and dust-devil tracks that show Mars as an active planet, nothing like the Moon. Each of these processes, and others, are given their own section, making this far more than a pretty-picture book.
Strata along the plateau to the south-west of Melas Chasma may have formed by deposition from the wind, volcanism, or water activity. Dunes that eroded into strange shapes cover some of the strata.
A useful addition for serious researchers is the inclusion of ‘image identifiers’ for all the pictures in the book, allowing readers to visit a website where they can view the whole image and all related data products (captioned in more than 20 languages). So while the book might at first be seen as a coffee-table art form, it is actually more of a gateway to a database of scientific research. As of August 2016, more than 45,000 images had been acquired, each one typically some 80 megapixels in size – not what you’d call a snapshot! Despite this, HiRISE has imaged only two per cent of the surface and less than 0.5 per cent in colour.
Even this ‘cursory glance’ reveals the potential of Mars for future research and appreciation of the ‘pristine beauty’ recognised by the authors. And it begs a question for the future: how could anyone who sees these pictures even think about terraforming such a world?
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