Life on Mars?
Box 3 | ET, can you speak up?
Are we alone in the universe? Countless people have looked up into the star-studded night sky and asked this question. So far, there has been no convincing answer.
OK, there may be microbes on Mars, stunning enough if proved true. Yet perhaps the bigger question is whether any intelligent life exists elsewhere in the universe. The prospect both scares and excites people.
Scientists and radio-astronomers have started the search for extraterrestrial intelligence (SETI) in a systematic manner. Several international organisations, including the SETI Institute and the SETI League, are using radio telescopes to 'listen' for signals that might have been produced by intelligent life.
Such signals are most likely to be in the form of electromagnetic radiation. This travels at the speed of light and is generally unlikely to be scattered or absorbed as it flashes across space. The universe is fairly quiet in the microwave region of the electromagnetic spectrum, so most SETI enthusiasts tune their receivers to look in this band.
In 1995 the SETI Institute started Project Phoenix at the Parkes radio telescope in NSW. This initial phase of Project Phoenix searched for extraterrestrial signals from 202 sun-like stars up to 155 light years away. Project Phoenix used radio telescopes to scour 800 nearby stars for signs of life. The Parkes telescope detected some cosmic noises, but none that could be attributed to aliens. Nevertheless, it has continued to play an important role in more recent SETI projects.
Now anyone can become involved in the search for extraterrestrial intelligence through their personal computer. SETI@home is a project run through the University of California that makes use of the general public's computers to increase the amount of radio telescope data that can be analysed.
As the search continues, it is worth thinking about what would happen if a call did come in from outer space. Will our global society be shattered by it, or more closely bonded? Will the reaction be one of fear, or hope?
Should we try to make contact with the extraterrestrials? If we did, there's one crucial question that we cannot answer: what on Earth will they think of us?
Boxes
Box 1. Mars: Earth's cool cousin
Box 2. Cyanobacteria: The simple things of life
Related sites
How SETI works (How Stuff Works, USA)
The SETI Institute (USA)
The SETI League (USA)
Posted November 2008.