THE QUEST FOR A SECOND ORIGIN OF LIFE

摘要

It is difficult to imagine any greater goal for science than searching for life beyond Earth. Everything we know about life is based on a sample of one: life on Earth. We can only imagine the consequences of discovering life elsewhere, provided it had a separate origin. That, ultimately, is why we are exploring Mars. However, in the process, we are learning about the origin and evolution of the Solar System. Mars preserves a very ancient history that has largely been destroyed on Earth by tectonic recycling processes. The Mars Science Laboratory (MSL) rover, Curiosity, is one of the latest in a long series of missions to Mars that started in 1960 with launches by the former Soviet Union and later the USA. The first successful mission was NASA's Mariner 4, which was launched on 28 November 1964, half a century ago. More recently, the European Space Agency launched very successful missions, followed by an Indian Space Agency mission, and the Japanese have also joined the quest. There have been more than 40 attempted missions, of which about half were successful at least to some extent. MSL is perhaps the most amazing mission of all. Who can forget the "seven minutes of terror" that constituted the landing sequence?