Colossus: Heat-Seeking, Alien-Hunting Telescope Ready In 5 Years

We might find aliens through the heat their civilizations give off, astronomers say, but it will take a megatelescope to do the job. Such a telescope, in fact, is planned.

The Colossus telescope would be a massive 250-foot (77 meters) telescope, which is more than double the aperture of any telescope yet constructed.

To keep costs down, the proposed $1 billion telescope would use thin mirror technology and few large aperture mirror segments.

The sensitivity of the scope, though, could be enough to spot cities or other signs of aliens for planets as far as 60 to 70 light-years from Earth, its backers said.

Jeff Kuhn

"If we had an investor come and say 'look, here are the resources you need,' we could have the telescope built within five years," said Jeff Kuhn, an astronomer at the University of Hawaii's Institute for Astronomy, who is on the proposal team.

Building on Dyson spheres
In searches for extraterrestrial intelligence, astronomers generally focus on seeking out beamed signals from other civilizations.

In four decades of searching, nothing definitive has been found.

There were, however, a few interesting moments, such as the so-called "Wow!" signal heard in 1977 that was never repeated.

There are limitations with that method, however. Perhaps the aliens might not send out signals themselves. Perhaps they broadcast in channels we wouldn't think of using.

Moreover, humans should perhaps be cautious about sending out signals and alerting more advanced civilizations to their presence, as Stephen Hawking has said.

This is where Colossus can shine, Kuhn said. The telescope is a passive receiver that allows astronomers to seek out extraterrestrials without alerting them to the search.

Kuhn's team builds on a concept first proposed by physicist Freeman Dyson in the 1960s. Humans can capture only a fraction of the energy sent out by the sun, but a more advanced civilization would want to grab as much as possible.

Dyson suggested an extraterrestrial civilization would surround their star with a structure — now known as a "Dyson sphere" — that would capture the energy needed and then bleed the rest off into space.

From Earth, a star that is faint optically but very strong in the infrared could be an indication of such a sphere, Dyson mused.

Kuhn's team, rather than focusing on stars, is instead looking at the surfaces of alien planets.

"Similarly, an exoplanet that was optically dark, but thermally bright, would be evidence of extraterrestrial civilization," Kuhn said.