The world-renowned astronaut is here for a live webchat on Monday 28 October at 11am. Post your questions now

This week's live webchat is with Chris Hadfield, the only astronaut to have recorded Space Oddity while circling the earth. The video has now been watched more than 18m times on YouTube.

He can answer your questions about spacewalking, having been the first Canadian to walk in space, and about day-to-day life onboard the International Space Station. Where do the astronaunts sleep? What do they eat? How do they wash their hair? Chris has all the answers.

Chris will be with us live at 11am on Monday 28 October, but please feel free to get your questions in early and start posting right away.

We have posted the questions and answers here to make the conversation easier to follow:

I read that on the ISS you was on GMT (British Time). Does that mean at 3pm every day you had a sudden urge for a cup of tea and scones?

Yes! As Commander, I decided tea and cakes was a fine idea for the crew, but we lunch was late so had it in the AM, and thus called it elevenses.

Was there anything that you were surprised by, or not prepared for, the first time you went into space?

The overpowering, humbling beauty of the Earth. It fills your eyes and thought.

I teach junior high sciences and my entire school loved watching you on the NFB Space School. One of my students wanted to know about all of the beautiful photos you took from space. When you are looking down at earth how do you know exactly what you are looking at? Is there some kind of GPS to what you see below or do you just have mad geography skills!?

On the ISS, computers have a moving that shows roughly where we are, and after a while you get to know the Earth like you know your own neighborhood - which is a nice perspective to have.

You've looked down on Earth and experienced space in a way that most people never will. Does being an astronaut change you in any profound way?

Seeing the world in its entirety, inexorably, becoming familiar with every part of its surface and where and how we live, seeing everyone and everywhere, makes for a fundamental feeling of shared humanity. It deepens your faith, and your optimism.

Does making music in microgravity present physical challenges? Is it easier or harder to pick notes or chords on a guitar? Does the effect of microgravity on the human body make the physical act of singing feel different?

Playing guitar on the space station was harder - not for picking, but on the fret board. As I moved my left hand up and down the frets, since the guitar was just floating, it moved right along with my hand. Made for a lot of missed notes and noisy squawks. It took practice to get better at it.

When you're up in space, do astronaughts on the ISS have chance to stay up-to date with the news and events from back down on earth. If so, how? Web, TV, radio?

While on the space station I kept up with news a couple of ways - Mission Control sent daily summaries, and I would scan headlines on Google News when we had an internet connection, which was about half the time.

Flying in space is very difficult, and opportunities are rare. But when I was young, it was impossible. Commercial spaceflight is beginning, and with it and continued invention access will only improve. It is a wondrous experience, worth the competitive wait.

Flying in space is very difficult, and opportunities are rare. But when I was young, it was impossible. Commercial spaceflight is beginning, and with it and continued invention access will only improve. It is a wondrous experience, worth the competitive wait.

Being constantly in Zero Gravity for weeks and months, how does it effect the body Physically as well as Psychologically?

Weightlessness leads to complete relaxation. You don;t even have to hold up your head. Thus, if you did nothing, your muscles and bones would erode and waste away badly. We work out 2 hours per day onboard, and as a result I kept my strength and skeleton, only losing bone across my hips - and it's growing back now. Should take a year or so for the osteoporosis to reverse. Makes me a big, interesting lab rat.

Hi Commander, my boys were honoured to meet you this summer in Ottawa while with their dad at a conference. I would love to encourage them to be more interested in science and technology (and not the iPad kind). How did you become interested? Was it something you loves as a child? Or did you figure it out later in life?

I was inspired by the earliest space explorers, Gagarin and Armstrong and Leonov and Aldrin and Collins. I decided to become an astronaut on the day we first walked on the Moon - 20 July 1969. I was 9.

In all of your years as an astronaut and in the Royal Canadian Air Force, what was your most frightening situation?

I once made myself black out by pulling G too quickly while flying an F-18. Being unconscious in a single-seat airplane is not good. Fortunately I woke up in time. I learned how to better plug-in my anti-G suit.

Chris is proprioception affected by zero gravity? E.g. if floating with your eyes closed is proprioception normal?

On the ISS, if you attempted to pour a glass of whisky (say) would the whisky really form a ball and float around the space station like it does in the Tintin book "Explorers on the Moon"?

All spilled liquids on the Space Station form a ball and float around like a bubble. We do it all the time, just for fun. Sometimes we drink them out of mid-air, but we miss, so good to keep a towel handy. Alas, just water, juice and coffee, though - whisky is not allowed on spaceships.

How do you accept that you probably will not be going into space again?

It has been a wonderful part of my life so far, but by no means the only part. Most of the things I have done I won't do again, just like everyone. I deliberately seek joy and accomplishment daily, and intend to learn new things all my life. Spaceflight wasn't a measure of my life - it was just a challenging, rich part. There are many things I am glad I have done, and many things I still hope to do.

Hello Commander! My second question is: Which is the closer simulation to a real spacewalk: the swimming pool or the virtual reality simulation?

Sorry for having more than one question!

Best wishes!

The best simulator for spacewalking is underwater - it allows full visuals and body movement in 3D. Virtual reality is good too, and has some advantages, like full Station simulation, not just part. Like all simulators, they have parts that are wrong and misleading, and important thing to remember when preparing for reality.

What was the most difficult thing to get used to when you first arrived on the ISS and what was the most difficult thing to get used to again when you got home?

After docking, the most difficult things to adapt to were the small things that are easy on Earth. Tying my running shoes was hard, as it required 2 hands and one foot, leaving little to keep my stable in space. (we wear them to run on the bungee treadmill). After landing, balancing was the hardest. My inner ear had forgotten what to do with gravity. It took a week or so to be able to move normally, and 4 months to be able to run as before.

Good morning,

I teach high school science in Abbotsford, BC. I was chatting with my students (biology11) about you last Thursday and was shocked and ashamed that they hadn't heard of you. That changed immediately. We spent the rest of the class watching youtube clips about your adventures. They know about you now. In fact, one of my students had a great question that I'm hoping you can answer.

He wanted to know how you arrive at a specific point in space? How do you avoid all of the satellites and space junk up there?

Thanks for making space rock!

Navigation in space is hard. On Earth there are references to go by, things to look at, roads to follow. The problem is worse in orbit since we're going so fast - a small error gets worse quickly at 8 km/sec. We navigate using reference to the Earth and the stars, have a computer onboard that tracks our speed and direction, and constantly updates. On ISS we also use GPS, modified for our speed and height. And big antennae on Earth track us. We avoid other objects with help from NORAD - they track space junk, and tell us when we have to fire thrusters to avoid it.

If anyone want to see the ISS come over the UK look on NASA's "Spot the Station", also N2YO website and Heavens Above

One thing I've always wanted to know is. does food taste different in space due to the process foods have to go through ?

The food is good, but our sinuses can't properly drain, so taste is a bit subdued. It's like tinned and camping food. I liked it!

Hi Chris, we're big fans of yours in our house, esp my 2yo boy. Hopefully you'll visit Ireland soon so we can pop in for a book signing.

My question is, do you believe in aliens of any description?

I believe the odds are that we're not alone in the universe, but I don't think little green men are sneaking around spying on us :) We're looking for life on Mars right now. It's a big question, worth trying to answer.