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He has logged over 374 days in orbit, including four spacewalks lasting all together more than 22 hours.

In 1997, he spent 145 days on the Russian space station Mir, during which he experienced a string of problems including a collision with a cargo craft, repeated computer crashes and a loss of power.

In 2003, he returned to space as the commander of the International Space Station, completing his tour of duty on 30 April 2004.

What is it like to live and work in space? Is it hard to cope with zero gravity? What does the future hold for space exploration? Will man ever reach Mars?

Your comments:

It has happened countless times in history that world changing discoveries have been made by accident while trying to solve a completely different problem. Who knows what discoveries will be made as we try to cope with the enormous challenges of human space exploration.
Stewart Allen, South Africa

Having watched the build up to the rocket launch on Nasa TV streamed over the internet, I am struck by the amount of co-operation between the American and Russian space agencies, and the amount of hard work needed for the Russians to build and launch the rocket. Space flight is wonderful and exciting, but we can learn a lot from the example of the people down on earth as well. Thanks to everyone involved in getting the astronauts safely to the station - you deserve it.
Michael Perrin, London, UK

Man will reach Mars and walk on it before the 22nd century Damien, Valence, France

I hope one day I'll be there, I'll spend a little time in space. I really enjoy just thinking about zero gravity, free flying. We can't know the future, space exploration is really mysterious, lot of surprises are certainly waiting for us... I'm very optimistic; man will reach Mars and walk on it before the 22nd century.
Damien, Valence, France

I agree that space exploration is a long term investment, but I'm not sure it will be useful for humanity before centuries... So developed countries should maybe think about solving every day's problems and spend money to avoid conflicts or help African countries instead of wasting it. And space is becoming a dangerous place, as it is more and more polluted. Men have already polluted their own planet, and they're going to create another dustbin over their head...
Cedric Clement, France

Please people, cut the clich�s. Phrases like: "Let's spend the money on Earth helping poor sick people" are entirely ideological. Do we really think that if we didn't have space programs our governments would give it all to third world nations and the unprivileged? No, they would spend even more on weapons, ships, planes, missiles and munitions. I agree in principle with some of these views, but folk are not being realistic. Lets keep both aims in parallel: advance science whilst trying to relieve Earth bound poverty too.
Jim Jones, Luton

I think it's a crying shame that people think that the exploration of space is not worth the money/effort/lives that it will ultimately cost. Mankind has a keen spirit of adventure and what cause is more worthy than finally seeing mankind leaving the cradle and setting sail for the star; who can say they have never looked up on a clear night and thought "I wonder what is out there?"
Paul Gray, Cwmbran, Gwent

I think we've abused our own planet enough, without venturing to distant worlds Liam Nulty, West Sussex

I think we've abused our own planet enough, without venturing to distant worlds to eat away at their natural resources and pollute their atmospheres. Hollywood has made countless movies about aliens that do exactly the same before coming to earth to bleed it dry. Why is it OK for us to do the same in reality?
Liam Nulty, West Sussex

To those who say that the amounts being spent on space exploration and technology are too excessive, I would point out that they are not that large when compared to the amounts spent by governments on weapons systems and armaments. Perhaps if we spent less on these items we could afford to have both space exploration and things like universal health care, full education and a decent environment.
Jim Walsh, Ireland

Yes it costs a lot to send missions to Mars and men into space, but eventually Earth's resources will be gone and the nearest are on the Moon, Mars and further a field. Robots and computers can be programmed for a range of expected events, but only humans can adapt to cope with the totally unexpected - WE, men and women, have to.
Gary, UK

Firstly, space exploration; be it by humans or remotely controlled machines is a long-term technological investment. We need to explore space in order to better understand the complex systems that govern Earth's environment. Secondly - yes, we are steadily ruining the planet, but the end of our species could just as easily come to pass in other ways, such as large comet/asteroid impacts, nearby supernovae, interstellar clouds and probably a host other unknown horrors that could occur at any given time.
Jurgen Zimmermann, London

Astronauts, like Michael Foale, are one in a million. Their fortitude, endurance, knowledge, determination, and fearless quest for the truth make them almost exclusive pioneers into space. Their amazing contributions so far will spur man to reach Mars and beyond. Living and working in space at zero gravity must be challenging, arduous and is definitely mind-boggling.
Pancha Chandra, Brussels, Belgium

It's time that the world unites and pool their resources in the conquest of space Steve, Australia

Do you think it's time that the world unites and pool their resources in the conquest of space because Man's destiny and future is Space. To really "go where no man has gone before" by doing this, short cuts would not be taken and the lives of the astronauts would not be lost because of money skimping?
Steve, Australia

In future, when we hopefully go to the Moon, Mars and beyond, it's quite clear that we will need an international cooperation. I would like to know if there will be different roles between USA, Russia, Europe etc... For example, Russia does have a cheap and quite ready way to launch big payloads into space (Energia rocket). So it would be a logical choice to use Russian rockets to launch big payloads than every nation would design their own heavy lift capability. We would save a lot of money for other projects and keep costs down. I know there is a lot of politics involved with these, but if we want prices down I think this is one way for that.
Ville Tikkala, Kemi, Finland

Why do we fund NASA with a budget of a medium country, and in return go to the Moon once every so often and send probes to Mars? Surly we need to fix our own planet before we go finding new ones.
John Gearing, St Helens England

To John from St Helens: NASA's 2004 budget was roughly $15bn. This is about the size of the GDP of the Dominican Republic - hardly what most people would think of as a "medium country". More relevant is that it is roughly 0.14% of US GDP. This is equivalent to an average Briton spending some �25 per year. I'm sure almost all of us spend a lot more than that on unnecessary frivolities. Perhaps we should give up drinks, meals out, sweets, fashion, cosmetics, holidays etc., until we have "fixed our planet first". It would be a lot more effective than abandoning the space programme.
Nick, Swansea, UK

Do you think that all the world leaders should be taken into orbit for a few days, just to look down on the planet that they are trying to manage. Perhaps there would be less confrontation and war.
David, Cornwall, UK

Some scientists are against human spaceflight because they believe robots are better. But one of the purposes of human spaceflight is to learn how to live permanently beyond Earth, in settlements on Mars or the moon. I think NASA should emphasize the concept of "space settlement".
Bill Turner, Sydney, Australia

With so many aspects of our planetary life left wanting, are not the amounts spent on space exploration / experimentation somewhat excessive?
Paul Smith, London