Discovering aliens could be "catastrophic" for the human race.
Aliens could wage war on the human race
Space expert Shreedhara Somanath is convinced that extraterrestrial life exists but fears that humans making contact could spark a war that has disastrous consequences.
Somanath, who masterminded India's recent Moon landing, said: "This is the nature of life - one will not allow the other to survive. It must suppress and destroy the other.
"Unless these aliens realise we are different... it will be catastrophic."
The chairman of the Indian Space Research Organisation says that aliens exist "absolutely without a doubt" and even suggests that some of the more advanced extraterrestrial civilisations could have already made a trip to Earth.
Somanath said: "If they are ahead in technology by just a thousand years, or 10,000 years, they would definitely visit us."