Washington: If extraterrestrials really exist then where are they hiding? The Pioneer and Voyager probes, having travelled hundreds of millions of miles into space, are still looking for signs of life, even of the most rudimentary kind. But may be we haven`t searched enough.
A pair of postdoctoral researchers at Penn State University, approaching the problem mathematically, shows that we have not looked in enough places to ensure that no extraterrestrial artefacts exist in our solar system.
"The vastness of space, combined with our limited searches to date, implies that any remote unpiloted exploratory probes of extraterrestrial origin would likely remain unnoticed," report Jacob Haqq-Misra, of the Rock Ethics Institute and Ravi Kumar Kopparapu, of Earth and Environmental Systems Institute, according to the journal Acta Astronautica.
So far, we have not found any non-terrestrial artefacts in our solar system. The Fermi paradox, originally formulated by Enrico Fermi, asks, if intelligent life is common, why have no technological civilisations been observed, they said, according to a Rock Ethics statement.
Even without actual contact, like us, other civilisations could be sending unpiloted probes to quietly peek at our civilization.
These probes, like ours, would be small and might be hidden in a variety of places. In the asteroid belt they would probably go unnoticed, especially if these nonterrestrial objects are only three to 33 feet in size, weighing little more than a tonne, said the authors.
"Extraterrestrial artefacts may exist in the solar system without our knowledge simply because we have not yet searched sufficiently," said Haqq-Misra and Kopparapu. "Few if any of the attempts would be capable of detecting a one to 10 metre probe."