Japanese astronaut Norishige Kanai came back to earth last month but is still dreaming of space, especially after the discovery of an underground lake brought mankind one step closer to unravelling the mystery of life on Mars.

“I was so excited about the news,” the 41-year-old doctor told AFP in an interview on Friday, calling it “a major discovery that inspires dreams”.

“I believe there is,” he said. “In the vast universe, anything could be possible.”

“I have high hopes that finding extraterrestrial life forms could open a new page in learning.”

But his social media foray came with some growing pains: he was forced to apologise and issue a correction after mistakenly claiming he had grown by nine centimetres just weeks after he arrived.

When a colleague suggested the growth was unlikely, despite the fact that astronauts’ spines do extend in the zero-gravity environment of space, Norishige had himself remeasured.

He has been shrinking since he arrived back on Earth on June 3, but is still one centimetre taller, he said.

“It’s interesting to see how long it will take to get back to my original height.”

But one of the skills he picked up as a child turned out to have a surprising application during the strict JAXA screening process.

In the final selection stage, 10 candidates spend a week in a capsule performing various tasks including folding paper cranes, which the agency says tests patience and steadiness under stress.

Even as he spoke, he deftly folded a piece of origami paper into a crane, without so much as leaning on a table for support.

He so enjoyed making small cranes that he folded more than 100 of them in the test capsule.

He doesn’t yet know if he’ll be chosen for new missions, and admits that he had mixed emotions as he headed back to Earth last month.

“I felt sorry that it was ending. But I was also happy that I was finally going back to Japan, because six months is a long time.