TOKYO: The US commander of space shuttle Discovery believes life probably exists somewhere in outer space, but there is a simple reason why aliens have not visited earth — the journey is too tough.

“We have seen some evidence that there is a possibility of some life on Mars in the past, so there is probably life all over the universe,” astronaut Mark Kelly told a news conference in Tokyo on Tuesday, where he was joined by other members of the Discovery crew.

“From our experience, it is very difficult to travel through space, and I personally think aliens have not visited our planet.”

The Discovery delivered Japan’s Kibo orbital laboratory to the International Space Station in June. Kelly described the $1 billion, 32-ton module as a “Lexus of a space station” where everything worked perfectly.

“Certainly like a Japanese car, Kibo was very well-made,” he said. “It is going to be the premier laboratory of the space station for many years to come.”

Japan, the last of the 16-nation partnership to get its hardware in space, is expected to complete the three-part lab next year.—Reuters