The human race will find life elsewhere in the universe as it pushes ahead with space exploration, astronauts back from the latest US space mission said Monday.

"If we push back boundaries far enough, I'm sure eventually we'll find something out there," said Mike Foreman, a mission specialist on the Endeavour, which returned to Earth in March.

"Maybe not as evolved as we are, but it's hard to believe that there is not life somewhere else in this great universe," he told a news conference in Tokyo.

The crew members on the 16-day Endeavour mission, which included a Japanese astronaut, said that so far they have not seen anything inexplicable or mysterious in terms of other life forms.

"I personally believe that we are going to find something that we can't explain," said another astronaut, Gregory Johnson.

"There is probably something out there but I've never seen it," he said.

Dominic Gorie, the crew commander and veteran of four space flights, pointed out that explorers in past eras did not know what they would find before setting off across the ocean.

"As we travel in the space, we don't know what we'll find. That's the beauty of what we do. I hope that someday we'll find what we don't understand."

But it could take a while before human beings come into contact with extraterrestrial life, Richard Linnehan, a fellow mission specialist and believer in the possibilities of extraterrestrial life, told the news conference.

"Unfortunately we are taking only baby steps in outer space efforts and we left our planet barely a few hundred miles above the atmosphere," he said.

The latest hitch-free Endeavour mission went to the International Space Station, carrying part of Japan's first space laboratory along with a Canadian repair robot.

Foreman described the Japanese laboratory -- named "Kibo," or "hope" -- as smelling like a "new car."

Takao Doi, the Japanese astronaut on the Endeavour mission, agreed "life like us must exist" elsewhere in the universe.

The comments come after a surprisingly high-level debate in Japan about UFOs.

Nobutaka Machimura, the number two in government, said in December that he personally believed aliens existed, in an unusual rebuttal to a government statement that Japan had no knowledge of UFOs.

Defence Minister Shigeru Ishiba went as far as to say that he was studying the legal ramifications of responding to an alien attack in light of Japan's post-World War II pacifist constitution.