Life, Earth, Astronomy, Transpennine, culture

Transpennine culture: November 14th 2009

Panspermia or meteoritic bombardment?
Paths to life on Earth.

How did life arise on Earth? This was the topic of last Thursday's annual Bolton Lecture in astronomy at The University of Leeds, delivered by Terry Kee, a senior lecturer at the School of Chemistry.

Were the seeds of life wafted here by radiation pressure, or did meteorites carrying bacteria slam into the Earth? These were two of the answering theories presented by Dr Kee to his audience of school children, general public, University students and colleagues.

Dr Kee and a colleague, Matthew Pasek, from The University of Arizona's NASA Institute of Astrobiology, head a £0.5 million research project aimed at establishing whether the phosphates trapped in 4-billion year old meteorites that hit the Earth might have contributed to the origin of life on Earth.

Entitled Interstellar Trash and Treasure: Meteorites and the Origin of Life, Dr Kee's lecture was the tenth Bolton lecture given at the University and part, this year, of a public series that the University's Astronomy department is running to mark the UN's International Year of Astronomy. This year's lecture coincided also with the 200th Anniversary of the birth of the father of modern evolutionary thinking, Charles Darwin, as well as with the 150th anniversary of the publication of the Origin of Species. The University is celebrating these two events, along with the scientific community globally, at both specialist conferences and occasions for the general public.

Dr Kee's talk started with events 4.6 billion years ago when the Sun and the Solar System accreted from the centrifugal forces swirling the debris of earlier derelict solar systems in our galaxy.

He took us through a creation myth, culled from Wikipedia, despite the fact he forbids his students to turn to Wikepedia. Then he introduced the concept of panspermia, a theory positing seeds arrived here from elsewhere. He had found a mini cartoon on You Tube that showed the dance of emerging arboreal life, and which drew amusement from his audience.

Next he outlined one definition of the attributes of life. A popular acronym, he said, is MERRING (movement, excretion, reproduction, respiration, irritability, nutrition, reproduction, and growth), but the question of what life actually is is still an open question exercising philosophers and ethicists, some of whom work with the scientific community. If life exists on other planets, asked Dr Kee, would we recognise it? We could, he said, be looking at life and not know.

If seeds did not arrive here from elsewhere then perhaps they arrived on meteorites. If they did then the bacteria would have had to survive the harsh conditions prevalent in space: extreme cold, high radiation levels, lack of oxygen, low gravitational forces and then, on impact with the Earth, pressures a million times those of the atmosphere or a thousand times greater than at the bottom of the Mariana Trench in the Pacific Ocean. He argued it is convincing that bacteria might survive the conditions in space. But for both his theories the evidence is not yet in.

His rousing finale was a Japanese You Tube cartoon of a massive meteorite approaching silently from outerspace and obliterating life on Earth. Tsunamis, shockwaves and displaced crust crept in cartoon form over the limb of the Earth, wiping out life as we know it.

His audience were unphased and entered enthusiastically into a question and answer session. Most questions were unanswerable, at least without a lecture series to tease out elements of an answer. How many seeds would be needed to create life on Earth, asked one student, and, surely, if life came from elsewhere you are simply displacing the question of how life began, said another. To the first Dr Kee said he thought very few seeds would be needed and to the second he agreed that he had merely shifted the geography of the question.

The final lecture in this series will be given on 8th December by Professor Lianne Benning, from the University's Earth and Environment Department, and is entitled the survival of prebiotic molecules in harsh environments. It is open to the public and schools and will be given in the Rupert Beckett lecture theatre close to the main entrance of the University on Woodhouse Lane. The lecture is 5.30 to 6.30 and the free Leeds City Bus stops by the University's main entrance.