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What's it like in zero-g?

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by Tanya
Publish date
25 September 2011
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Last week was pretty special. Over at ACMI, they celebrated the launch of their fantastic new exhibition, Star Voyager: Exploring Space on Screen. To help them out, they had the real deal in town – someone who has experienced space, not just seen it in the movies – a NASA astronaut.

Mission Specialist Rex Walheim, has flown in space three times. It so happened, that each of his trips was on the Space Shuttle Atlantis, including the final ever flight of the space shuttle program. That last mission was just over two months ago.

Rex Walheim
NASA astronaut Rex Walheim.
Source: NASA
 

I remember staying up until 1.30am on that July evening to watch Atlantis’ final launch – little did I know that I’d soon meet one of the amazing people that I saw zooming into space that morning.

At the opening of the Star Voyager exhibition, Rex won our hearts as he described seeing the aurora australis on his recent trip into space. He noticed Melbourne had left its lights on for him and said how much he’d hoped he would get to visit the city that looked so beautiful from space.

Aurora Australis The aurora australis as seen during the final flight of Atlantis. The space shuttle is in view on the right and one the space station's solar panels can be seen on the left.
Source: NASA
 

There are so many things you want to ask an astronaut and so many amazing things to learn. It’s refreshing to hear that even astronauts have to pinch themselves before take-off, to be certain they’re really there. And encouraging to know that when you practise hard enough, even a spacewalk ends up feeling commonplace. Like with anything else, all that practice just kicks in and you simply realise you’ve done this a hundred times before, once more will be a breeze.

We all imagine how hard it must be do to all the everyday things of life in space – but it seems that adjusting back to Earth is also quite a challenge. As someone who loves their sleep, I was surprised to hear that sleeping in space is easy - as long as you tie your sleeping bag down so you don’t float away. Whereas, it’s when you get back home and have to deal with gravity pushing against you, making your head feel like lead against the pillow, that sleep is hard to find.

Rex Walheim spacewalk Rex Walheim working on the Columbus Laboratory outside the International Space Station in February 2008.
Source: NASA
 

Rex Walheim night spacewalk What a difference a day makes! This is the same spacewalk as above but since the ISS orbits the Earth every 90 minutes, the astronauts work in the sunlight for 45 minutes, followed by 45 minutes of night.
Source: NASA
 

But the best thing for me, was hearing how zero-gravity works from someone who has been there and done that. Now believe me, I’ve described this effect many a time, but there was something special hearing it first hand and the way Rex set it up was just perfect.

If you could take an elevator 350km up into the air (that’s how high the International Space Station flies above us) and you were silly enough to step out, Earth’s gravity would grab you just as you’d expect and send you plummeting back to Earth. Of course, it's kind of obvious, but what an image it creates! And I did the maths – at that height the gravitational force is only 10 per cent smaller than what we feel on the ground. Your instincts would be spot on.

Of course the trick of zero-g is the speed at which Atlantis or the ISS are travelling, and here Rex fell back to Isaac Newton’s famous description. But where Newton used a cannon, Rex described a tennis ball. Using his fist as the Earth, he got us to imagine throwing that ball hard into the air. It might manage to fly a little way before falling back on our knuckles. Throw it harder and it might go half way round our fist. Throw it at 28,000 km/hour, the speed of the shuttle, and it will keep going, forever circling the Earth and always falling, just never re-connecting with the ground.

Newton Gravity
Newton's description of free-fall using a cannonball that's shot around the Earth.
Image: Brian Brondel
Source: wikimedia commons
 

When we watch astronauts floating around it looks like zero-g. But it isn’t. We’re told microgravity is the correct term, but I must admit, that never really did work for me. Both those terms seem to say that the gravity up there is insignificant. From now on, I’ll always call it free-fall. That experience of falling without ever hitting the ground because speed has overwhelmed gravity. Rex says it's just like being a kid and dreaming you can fly.

NASA’s been under some criticism as it closes-out the shuttle program with only a hazy view of what might come next. But with people like Rex Walheim involved, you can but hope that NASA gets the support and backing it needs to build a future just as amazing as our science fiction dreams.

  Rex Walheim on ISS Rex Walheim enjoys a final look at Earth from inside the cupola on the ISS, as he completed his week long visit to the Station.
Source: NASA
 

Links:

MV Blog: Chat with an astronaut

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