Saturday 26 October 2013

Nuclear Winters From Mars

Ever since the idea of a nuclear war affecting Earth’s weather was first written about in 1957 in “The Effects of Nuclear Weapons” by Samuel Glasstone many science fiction writers and film-makers have used a bleak post-nuclear world with dramatic climate change as a setting for their work. While this “nuclear winter” is still only a future scenario on earth it is based on scientific research on the present atmospheres on other planets.

While the scenario has been around for much longer, the actual term “nuclear winter” first appeared exactly 40 years ago in 1983. It was coined by Richard Turco, member of a team of scientists referred to by the initial letters of their surnames – TTAPS. Turco was the first “T”, “S” was the famous Carl Sagan, and “P” was the openly gay astrophysicist James B. Pollack.

It was images of dust storms on Mars which led directly to an understanding of the dangers of a nuclear winter on Earth and placed Pollack as a leading figure in ecological studies.

Described as “the best planetary scientist of his generation” by David Morrison, head of the space-science division of NASA Ames Research Centre, Pollack had key roles in all of NASA’s planetary missions from the Mariner 9 mission to Mars in 1971. He was involved in all the big missions, like the Viking Mars missions and the spectacularly successful Voyager missions, and many others. Images from these missions have reached iconic status.

After his arrival at Ames in 1970 Pollack was immediately put to work analysing data obtained from Ames’s observatory. To give you an idea of the importance of his work we take for granted many things he discovered – for example, Saturn’s rings are made of ice particles, and Venus is hot because of the greenhouse effect and has clouds of sulphuric acid.

But it was by analysing the data from the Mars probes that Pollack began to realise how it tied in with his studies into the effects of volcanic eruptions on Earth’s atmosphere. Pollack has seen the greenhouse effect on Venus and applied the same mathematical modelling technique onto Earth. Pollack suggested that the greenhouse atmosphere created by an asteroid impact on Earth (not itself an original theory) was the leading factor in the extinction of the dinosaurs.

Working extensively on the atmosphere of Mars Pollack acquired masses of data that was crucial in the work of the TTAPS team mentioned above. The data helped to formulate a theory of the historic Martian and Venusian atmospheres which gave a model for the future atmosphere on Earth following a nuclear winter.

It could be argued that the nuclear winter theory contributed to the anti-nuclear movement in the 1970s and 1980s and led directly to nuclear disarmament by the super-powers – both sides feared a nuclear winter more than they feared each other. No-one was really convinced by the possibility of a real nuclear winter before the TTAPS team published their research in December 1983. Like little green Martians, a nuclear winter was a fictional scenario. If anyone doubts the usefulness of spending billions of pound/dollars on interplanetary missions they only need to think what would have happened if a nuclear winter had remained a science fiction scenario.

Pollack was recognised as a great scientist from very early on. His mentor at Harvard, Carl Sagan, spotted his talents immediately and they remained close friends, working together on many research papers.

The scientific community showered Pollack with honours and awards, most of which mean little to laymen like myself outside scientific academia. Yet they were the Oscars and Emmys of his world and very few reached higher in respect than James B. Pollack.

In the early 1990s Pollack developed a rare type of spine cancer called chordoma. He continued to work for as long as he could, helping to plan more missions to Saturn, Mars and Venus. His death in 1994 was a great loss to astronomy, climatology and society. Within months of his death he had the honour of having an asteroid named after him and, more appropriately, a crater on Mars. Who knows, perhaps one day a manned mission to Mars will be able to land in that crater thanks to Pollack’s own data from the 1970s.

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