*****************************************************
With ground-based and space-based telescopes, astronomers have now discovered the building blocks of life in space in the form of many complex organic molecules and solids. These extraterrestrial organics enriched the early solar system and evidence for widespread organic star dust is found in meteorites, asteroids and comets.
The emergence of life on Earth and the existence of life on other planets are fundamental questions. To enable the public to learn more about life in the universe, the Hong Kong Science Museum has organised a new exhibition entitled "Life in the Universe" which will be held at its Science News Corner from today (August 20) to January 5, 2011. The exhibition, with content provided by the Dean of Science of The University of Hong Kong, Professor Kwok Sun, and members from the Astrobiology Group in the Faculty of Science of The University of Hong Kong - Dr Lee Man-hoi, Dr Li Yiliang and Dr Stephen Brian Pointing - introduces the insights gained from research on life on planets in the universe.
Earth's first 700 million years were hellish. Seventy million years after the formation of our solar system, a giant collision by a Mars-sized planet turned Earth into a magma ocean, which made the surface of the whole planet molten. The process was important because it accelerated the differentiation of Earth, and released carbon dioxide and water vapour which made the proto-atmosphere. The surface on Earth finally solidified after 215 million years. An ocean was formed 400 million years after the formation of Earth. During the 700 million years of Earth's early history, it was impossible for life to emerge. But the rocky crust contained life's essential elements: the ocean was formed, carbon was already in the air and the temperature was becoming suitable for organic syntheses. Life was ready to emerge.
The first firm evidence for life was stromatolite 3.5 billion years old. It was these tiny microorganisms that gradually changed the chemistry of the ocean, the composition of the atmosphere and finally the surface of Earth. The geobiologists from The University of Hong Kong are looking for mineral evidence for the great evolutionary events in the history of the biosphere and Earth.
Life has undergone a long evolution on Earth. But humans took less than 10,000 years to establish the modern civilisation in which we are now living. It has long been a human ambition to conquer the solar system. Human civilisation, however, has limited knowledge of its own nature and of life and the universe.
Scientists have attempted to identify life on Mars but have reached no concrete conclusions. One way to evaluate whether Mars may be habitable is to look for analogous environments on Earth where conditions approximate those on Mars, and see what sort of life can survive there. The closest analogue we have to Mars is the McMurdo Dry Valleys of Antarctica. These valleys are ice-free rocky deserts where surface soils are so dry they have about the same moisture content as talcum powder for much of the year. Below ground large volumes of permanently frozen water-ice occur. Temperatures can reach as low as -80℃. The relatively thin atmosphere above the Antarctic continent results in higher than average ultraviolet radiation to the Dry Valleys. No higher animals or plants can be found anywhere in this barren desert, and some previous expeditions have claimed that the Dry Valleys are abiotic.
Every year, over 20,000 tons of extraterrestrial materials fall on Earth. From the craters recorded on the Moon, we know that the external bombardment rate was much higher in the first few hundred million years of Earth's history. Asteroids and comets in the early solar system brought large amounts of organics to Earth, providing a readily available pool of ingredients for the creation of life. But if they helped to accelerate the creation of life, then the fact that these organics are also distributed to every corner of the Milky Way galaxy suggests that life easily could have developed elsewhere in the galaxy.
The astrobiologists from The University of Hong Kong have made great efforts to establish a roadmap of co-evolution of the geosphere and biosphere on Earth as a model of the habitability of life elsewhere in the universe.
The Science Museum is located at 2 Science Museum Road, Tsim Sha Tsui East. It opens from 1pm to 9pm from Monday to Wednesday and on Fridays, and from 10am to 9pm on Saturdays, Sundays and public holidays. It is closed on Thursdays (except public holidays). Admission is $25 with half-price concession for full-time students, people with disabilities and senior citizens aged 60 or above. Admission is free on Wednesdays.
For enquiries, call 2732 3232 or visit the Science Museum's website at http://hk.science.museum.
Ends/Friday, August 20, 2010
Issued at HKT 16:32
NNNN