Planetary science and origins
Our planet has been driven by forces within its depths for almost all of its 4.6 billion year history – and without those processes it is unlikely the Earth would have ever become suitable for the rise to intelligence and a technological civilisation. Understanding our restless planet is also part of the key to understanding how we came to be here and what our future might be. Those aspects are two of the three that make up the science of astrobiology. The third is looking for life elsewhere in the universe.
The rocks and minerals that make up the Earth tell us one basic thing – Earth and all of the life on it on once existed in the cauldrons of several stars (suns) before our solar system formed. We know this because heavy elements like iron can only be created in the explosive heat of supernovas – when larger, unstable stars suddenly blow apart and scatter the results of new elements into the galaxy, one of a hundred billion other galaxies in the universe that formed from the Big Bang at an estimate of 13.7 billion years ago. New star and solar system formation are observed directly, and almost several hundred extrasolar planet systems have been detected indirectly.
The one solar system that can be observed directly is our own, but like all areas of science, there is much that remains a mystery or is not well understood or not understood at all. Gathering direct evidence can be done for Earth, but even that is limited by the best tools and current interpretation. The 3.5 billion year old Stromatolites in the Pilbara of Western Australia are a good example of being able to collect direct evidence, but where interpretation of that evidence is still controversial. New tools and interpretations are needed.
To gather direct evidence from planets, moons, comets and asteroids in our solar system, we need robotic or human space missions. Again, the tools and interpretations will be key – and both improve with time, as history has shown. In 1609 Galileo used a tiny telescope to see, for the first time, craters on the Moon and the four major moons of Jupiter. In 1969 humans landed on the Moon, and by 2006 it was known Jupiter has more than 60 moons.
There are now four other solar system bodies known where at least microbial life might have arisen or still survives – Mars, Europa, Titan and Enceladus. All are extreme environments, but what we discovered on Earth more than three decades ago was that life can survive, and actually thrive, in extreme heat, cold, pressure, salinity and without sunlight – extremophiles. All of the kingdom of Archaea are extremophiles and form one of the three branches of the tree of life with bacteria and eukaryotes.
The geology, plate tectonics and the biosphere are all closely inter-related in understanding our origins, our destiny and in looking for life elsewhere in the universe.