WASHINGTON-Where scientists are still making efforts to contact or discover alien life, NASA scientist claims that an intelligent alien life might have already visited Earth and we just didn’t notice.

A NASA scientist Silvano P. Colombano believes that alien life might have already visited the Earth and we may have missed it, as it could be very different from the traditional carbon-based building blocks of life the humanity is used to.

“I simply want to point out the fact that the intelligence we might find and that might choose to find us (if it hasn’t already) might not be at all be produced by carbon based organisms like us,” Colombano wrote in his study.

He said that the current thinking about alien life is way too narrow and it might have gone far beyond human technology, international newspaper reported. Colombano also suggested that extraterrestrials may have found out technology that human cannot yet comprehend, such as making interstellar travel a possibility.

“We need to re-visit even our most cherished assumptions,” Colombano wrote. “Our typical life-spans would no longer be a limitation (although even these could be dealt with multi-generational missions or suspended animation), and the size of the ‘explorer’ might be that of an extremely tiny super-intelligent entity.”

Colombano suggested that scientists are too preoccupied with modern human technology that makes it difficult to imagine the technology that could have been produced by aliens living on planets older than Earth.

Talking about UFO sightings, Colombano said that these sightings cannot be ‘explained or denied’ and that scientists should be more open-minded about the possibility of alien visitors, as per The Sun. Also, he warned that radio waves can be out of date too.

“In the very large amount of ‘noise’ in UFO reporting there may be ‘signals’ however small, that indicate some phenomena that cannot be explained or denied. If we adopt a new set of assumptions about what forms of higher intelligence and technology we might find, some of those phenomena might fit specific hypotheses, and we could start some serious enquiry.”