Olsen, who paid 20 million dollars (16.5 million euros) to the Virginia-based Space Adventures for his 10 days in space, told reporters at Russia's Star City training centre he hoped his example would kindle enthusiasm for science and space exploration.

"I would hope I could motivate my grandchildren and other children to study science and engineering and even maybe go into space," he said.

"I was very happy to have my daughter and grandchildren at the launch and also for them to see me. I told them I really was enjoying the feeling of weightlessness, just floating around and seeing the outside world."

"I saw the earth and it was kind of like wondrous. Just to see it with your own eyes really is fascinating, how finite it is -- it takes an hour and a half to go round."

Olsen, 60, returned to earth on Tuesday, after being fired into space aboard a Russian Soyuz rocket and docking with the International Space Station (ISS), where he spent eight days living with Russian cosmonauts and US astronauts and helping to carry out experiments.

He had travelled to the ISS aboard a Russian Soyuz rocket -- a craft he noted is more no-frills workhorse than luxury liner, but is the only means of taking humans to the ISS due to the grounding of the troubled US space shuttle fleet.

US astronaut John Phillips had to be revived with smelling salts after the capsule carrying him, Olsen and Russian cosmonaut Sergei Krikalev crashed down on the Kazakh steppe on Tuesday.

Showered and rested in the wooded surrounds of Star City, near Moscow, Olsen took issue with the term "space tourist", cautioning that his experience had been costly not only in cash terms, but also in the two years of rigorous training he had undergone.

"It's like a combination of college and military training. It's not five star, you're not babied... I was expected to do whatever was asked of me. There are frequent exams and I was expected to pass the exams. I haven't had that in over 30 years, the fear we all have -- here's the test, I'd better not fail it," Olsen said.

Once in space however, he had no regrets, even enjoying the food, including American reconstituted meals, identical to those given to US forces in the field in Iraq.

"The American prawn cocktail is great. I've had worse in a number of restaurants on the ground. It's basically dried prawn with the cocktail sauce and you reconstitute it with hot water," he said.

"I love the Russian mash potatoes and onions," he added.

As for regrets, there were two: not being allowed to take aboard equipment produced by his electronic sensors company Sensors Unlimited, and losing his own mini digital camera, Olsen said.

"I had a little mini camera and I took a lot of pictures and it's floating around somewhere in the ISS... It slipped out of my pocket. One of the things you learn on board is everything just floats around. You have to tie it down, velcro it or somehow fasten it. Hopefully they'll find it and maybe download some pictures for me," he said.

Two other "space tourists" have preceded Olsen in what is becoming a profitable sideline for the Russian space programme: American Dennis Tito in 2001 and South African Mark Shuttleworth in 2002.

All rights reserved. copyright 2018 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.