The Search For Alien Intelligence and Structures

Could a NASA mission be used to hunt for alien spacecraft? The Kepler spacecraft is currently set to launch for its four-year mission in November 2008 to monitor 100,000 stars and look for planets orbiting them, particularly Earth-sized planets. As a planet orbits its star, if it crosses the face of the star in sight line of Kepler then Kepler will see the dip in brightness. But it is possible that it might not be a planet crossing the star. If it were an alien structure, a signal if you like, would we notice?

Kepler has sufficient resolution to distinguish triangular or slotted structures. The idea of signalling across space was suggested by a German mathematician in the early 1800s, he said that if large forests in Siberia could be planted in the shape of a giant triangle, this would clearly indicate to the Moon's inhabitants that there was intelligent life on Earth.

So the Kepler could also look for interplanetary signals. However as some astronomers have pointed out a detectable signal would have to be enormous, almost the size of a planet itself. Or possibly we may observe a signal that is not intended to be a signal, but just a massive piece of space technology.

There is some support for a visual search for extraterrestrials as much emphasis is placed on traditional radio searches.
If there really are extraterrestrials out there then we have more chances of seeing something artificial as our telescopes and equipment become more powerful. For example, the Hubble Space Telescope has been used to investigate planet TrES-ib as its parent star has been seen to flicker before and after the planet passes in front. It is as if something is leading and trailing the planet.

In the 1960s scientist Freeman Dyson proposed we might look for evidence of an advanced civilisation by detecting excess heat given off by a space-based construction. Unfortunately infra-red radiation from heat was blocked by the Earth's atmosphere so radio telescopes were used in the hunt for alien communication. But, in 1982 IRAS the Infrared Astronomical Satellite became the first infrared observatory in orbit. IRAS has observed millions of celestial objects emitting infrared, including some ‘infrared excess' stars. Possibly the alien excess heat that Dyson suggested? But there were hundreds of stars pumping out more infrared than expected. The stars were surrounded by swirling discs of dust that were heated by the star and would then radiate infrared. So much for Dyson's hunting technique.

It may be our future power requirements and the spectre of global warming that cause us to create a space construction detectable to others inadvertently. Massive solar power satellites, space stations, larger radio telescopes and solar sails - these future necessities may all contribute to our own Dyson Sphere .