Nasa is less than a decade away from discovering crucial signs that we are not alone in the universe, the space agency’s top officials said.

“Giant leaps” in space exploration and new missions under development have placed humanity on the brink of proving that alien life exists elsewhere in our solar system and beyond. However, they added that the chances were that the only life we would be able to detect in the near future would be microbial rather than little green men.

“I think we’re going to have strong indications of life beyond Earth within a decade and I think we’re going to have definitive evidence within 20 to 30 years,” said Ellen Stofan, Nasa’s chief scientist. “We know where to look. We know