We are talking about little microbes. Share this article Share He said: Former astronaut, John Grunsfeld pictured , says that an advanced alien civilisation may spot humans from afar from the changes we've made to Earth's environment. Pictured on the left is the Parkes Radio Telescope that has picked up strange radio bursts from space Dr Nathalie Cabrol, who is leading the hunt for alien life at the Seti Institute in California, told MailOnline that while in our lifetime we'll find simple alien organisms close to Earth and a replica of our planet in another galaxy, detecting intelligent life may not be as easy because of our limited view of the universe. Dr Cabrol says searching for radio signals is just one of the ways we may be able to pick up alien life. Her views echo that of former astronaut, John Grunsfeld, who earlier this year said if aliens are out there, they already know we exist.