Jim Reilly, astronaut: One of my favourite memories is hanging out with just one hand on the space station, and then swinging
out so I could look across the Earth. The atmosphere is really transparent, so you can see a lot of detail on the surface below. One time when I had a chance to hang out on the bottom of the station, the sunset was coming. I left my lights off so I could watch the Sun go down. And as it went down, the stars started popping out. Of course they don't twinkle. They're all
different sizes, and even different colours, in space... At night you can see lightning flashes from thunderstorms on the surface down below. You can get this blue light flashing, and in this case I was able to see it flashing off the bottom of the station. And as I was watching all this, we flew through the edges of the aurora, kind of green and white curtains as we flew past.
It was pretty spectacular, he added with a degree of understatement.
Space walking
astronauts like Reilly can't afford to be star-struck, though. They do a dangerous job that requires concentration. Floating two hundred miles overhead where a careless motion could send them spinning into the void, modern-day astronauts connect power lines, deploy antennas, haul supplies. They service satellites and bolt modules to the space station. They're construction workers, points out NASA engineer Phil West.
On Earth, most construction workers need little more than a hardhat for protection. They can move their arms anywhere they want. And if they drop something, it doesn't drift away.
In space, all that changes.
The thing that Jim Reilly was always most conscious of, he recalls, was the need to slow down his motions. The astronauts train in water, explains Reilly, who's flown two missions, and who last summer installed an airlock on the International Space Station (ISS). That training accustoms them to weightlessness. But water is not the same as space. Unlike vacuum, water is dense; it pushes back. The water helps dampen your movements, says Reilly. You can do things that if you did them in outer space, you would go out of control.
If you turn a bolt, for example, you must remember there is no water to hold you in place, and that you can push yourself off pretty fast if you don't pay attention. You learn, he says, to bring yourself to a stop, and then make yourself motionless, without any momentum remaining. Then, you can do whatever needs to be done. You always have to think, he says, do I need to do this task a little slower?
But it's not only weightlessness that the astronauts deal with. The space suit itself forces astronauts to adjust some deeply ingrained habits. The suit is pressurized to 4.3 psi (pounds per square inch). That's less than one-third of the pressure of Earth's atmosphere at sea-level (14.7 psi). The air pressure outside a airplane flying at 35,000 feet is near 4.3 psi. It's also about the same as the extra pressure that keeps a football inflated, says Reilly. And, like a football, the suit is hard to bend.
To make it easier for astronauts to move, the suit's engineers designed in joints: elbows, shoulders, knees. But those joints can offer only a limited range of motion.
That means, Reilly explains, that in space you can only work in the approximately three foot by three foot by one foot area directly in front of you. It takes some getting used to. When you start your training, you have to start thinking about the different ways you need to manoeuvre to get to the different positions, says Reilly. There are certain moves that you don't want to try, because you'll be working against the suit.
For example, let's say that you wanted to grab an object off to the side. You wouldn't just reach out for it, like you would on Earth. The shoulder joint rotates front to back - not side to side. You could move your arm sideways by bending the inflated arm of the suit. That's not impossible, notes Reilly, but it dfort. It's easier to rotate your body until you're facing the object and then reach it by moving your arm forward.
The gloves, Reilly says, are one place where the pressure is especially noticeable. They're designed so that there's little strain when your hand is at rest, but as a result, when you open your hand, you push against the resistance of the glove. To understand the effort involved, Reilly suggests this exercise: Close your hand, put a rubber band around your fingers, and then open your hand fifteen times as far as it will go. The strain on the muscles in your forearm, he says, is exactly the same as in space.
There's more, of course. You can't whistle in a spacesuit, because the air pressure's too low. Tools must be two to three times larger than normal because the gloves are so bulky. You hear the constant loud whine of the fan that circulates the atmosphere within the suit. But you adapt.
The suit became very comfortable, says Reilly, and wearing it began to feel like second nature to him.