"We will complete our survey in one year": Alien hunters "tune in" to planets found by NASA

“We expect to complete a meaningful survey in less than one year.” says Gerry Harp of the Search for Extra -Terrestrial Intelligence (SETI). "Check back very soon."

As soon as NASA announced the discovery of two new Earth-like planets last week, alien-hunters began to listen with an array of 42 radio telescopes in California.

The survey aims to intercept alien radio signals, proving the existence of extraterrestrial life - and the scientists behind it hope for a discovery that could turn all human knowledge on its head.

Although the search for extra-terrestrial life has been met with stubborn silence for 50 years, new technologies allow scientists to sift radio waves millions of times faster.

“Our surveys improve on previous, generally narrowband SETI by covering the radio frequency range where Earth’s atmosphere is most transparent, including many frequencies never before observed," says Harp. 

The new planets are in a star system with five planets orbiting a sun - and two rocky planets orbiting within the "habitable zone" where liquid water could exist.

[Related: Hunt for Mars colonists launches this week]

NASA's Kepler mission has found 2,740 potential planets so far - and SETI researchers are now targeting those for its search.

The Allen Telescope Array, in Mountain View, California is a significant upgrade from telescopes that previously “listened” for radio signals - listening to radio frequencies which have never been observed before.

Previous telescopes tended to focus on a narrow band of signals - whereas ATA can search tens of millions of radio channels at once, across a huge range of frequencies.

Since December 2011, the telescopes - funded by donations from supporters such as Contact star Jodie Foster - have been scanning on planets found by NASA’s Kepler telescope, and in particular those believed to be “habitable.”

Kepler “looks” at a field of 150,000 stars, looking for the telltale dips in brightness caused by planets passing in front of the stars.

It has found 2,740 planet candidates with estimated sizes from Mercury to larger than Jupiter. the ATA is focusing on Earth-like worlds in the “habitable zone” around stars - where liquid water could exist.

Jill Tarter of SETI - the researcher on whom Jodie Foster's character in Contact was based - said when the telescopes began their search: "For the first time, we can point our telescopes at stars, and know that those stars actually host planetary systems.That's the type of world that might be home to a civilization capable of building radio transmitters."

"In SETI, as with all research, preconceived notions such as habitable zones could be barriers to discovery," Tarter said. "So, with sufficient future funding from our donors, it's our intention to examine all of the planetary systems found by Kepler."

SETI’s Seth Shostak says that any such signals could be “disruptive” to our society, bringing new technologies - or could be incomprehensible. “We could become privy to knowledge that would otherwise remain unknown until developed by our descendants centuries or more in the future.

"While this manna from the skies could be profoundly disruptive, you can't argue that ignorance is blissfully preferable. It's not.”

Shostak also warns that it is entirely possible that we might not be able to understand the transmissions at all - "the meaning might eternally elude us".