If you get sick in space, are there medicines to help you feel better? Do these medicines react differently inside your body in microgravity?

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When you first get to space things are so different that sometimes people feel sick. Your eyes tell you that you're sitting in a room, but your inner ear — your balance system—tells you that you are falling. That dizziness can make people feel sick. Of course when you first get to space, you don't want to spend your time being sick when you should be hard at work.

We do take medication. There are two medications available which combat nausea. One is called Fenegrine and the other is called Scopolamine. Both are depressants. They slow you down, so we actually mix them with a little bit of sugar (Dexedrine). These mixtures are called FenDex and ScopeDex. You can take either one of these medications in pill format before going into space so that you don't feel sick for your first time in orbit.

However, once you get to space, it takes a while for your digestive system to start working normally again. If you take these medications orally or if you get sick once on-orbit they don't work. We can also take them as suppositories or we can get either medication injected so that we can still work hard when we get to space.

When you are in zero gravity how do your internal organs respond? Do they shift?

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In space you are in almost no gravity at all— basically weightless. As you are floating around inside the spaceship, whatever you ate for lunch is floating around inside of you. It tumbles inside your stomach churning around because there is no gravity to hold the fluids and the solids in the bottom of your stomach and the gases at the top. As a result you can't burp in space. If you tried, you would likely burp foam. It would be almost like throwing up. All the gas that you normally ingest when you swallow ends up going right up into your digestive system so your gastrointestinal (GI) track has more gases in it than normal. The rest of your organs stay in their normal place since they are attached internally by ligaments and by tissue.

Do your ears pop during ascent or descent as they would in an airplane?

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The reason that your ears pop (in an airplane) is because the pressure of the air around you doesn't match the pressure on the inside of your eardrum. If there is more pressure outside the ear then you have to blow pressure to the inside of your eardrum (usually done by closing your nostrils and blowing gently). If the pressure outside drops then your eardrums bulge out (because there is too much pressure on the inner ear). In this case you have to open up your Eustachian Tube and let some of the pressure out. So, you are always trying to balance the pressure on your eardrum. Unlike in an airplane where they let the pressure drop off, the pressure remains constant in the space shuttle all the way to space so that your ears actually don't pop.

In a microgravity environment, how do you ensure that food particles are not ingested into the crew's lungs?

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Eating in space (in microgravity) is fun. Of course you play with your floating food! You tumble a banana, or spin your spoon in mid air because it is fun to be able to watch your lunch float in front of you. You do have to be careful though that when you inhale you don't get some particle of dust or even bits of food going down into your lungs. We are very careful, however, like on earth, it sometimes happens that a little bit of something goes in the wrong way and you have to cough to get rid of it.

In order to be a spacewalker does an astronaut have to work on increasing their cardiovascular capacity and their muscle tone?

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Walking in space is a lot of fun, but the number one thing that it really is, is hard. It is hard physical work. You are wearing a suit that holds your arms and fingers out straight. Every time you want to grab or move something you have to fight the built up forces of the suit— the inflation of the suit. It's like being inside a stiff balloon. It's almost like you're working out in the gym the whole time you're in there. The worst part is on the hands. You want to be able to protect your hand against the hostile environment of space. At the same time you want to give yourself enough tactility and flexibility to be able to grab wrenches. You end up paying the price in the hand; it takes a lot of forearm strength to be able to work in those gloves for eight hours. Because it is a physical exercise you do have to increase your muscle strength and work out before you go to space and you want to have a good cardiovascular system so that you can work for the whole eight or nine hours that you are outside.

Why did the designers of Canadarm2 choose hinge joints instead of ball joints?

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When you design a robot like Canadarm2, you have a lot of examples to consider. You could look at how the human body, a bird's skeleton, or really anything from nature is put together. When we design an arm for a space station, our own arm serves as a pretty good model. You might look at the hip bone as well, where you have a ball and socket joint that pivots around, as an interesting design element.

The trouble with the ball and socket though is that you cannot have it go all the way around and pivot more than 180 degrees because it would pop out of the socket. If you want something that will both pivot 180 degrees and actually pivot right around the other way you need a hinge design. That's one of the reasons why they didn't use a ball and socket joint in designing Canadarm2. The other reason has to do with the fact that Canadarm2 is staying in space for 15 to 20 years. Eventually parts of it will get old or break or need to be replaced. Canadarm2 was designed to be as modular as possible so that you could have the same kind of joint working in several different locations— as if your wrist, your elbow and your shoulder were all exactly the same. Designing the robot in this way means that no matter which joint fails, a new standard model could replace it.

What type of motor is used to move Canadarm2 at the shoulder and at the elbow joints?

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Electricity is the force that moves the arm. We could have tried using hydraulics or some other type of application to move the arm around, but the power source that we have available on the Station is electricity— primarily direct current. The arm is designed to take quite a wide range of voltages up to a maximum of almost 60 volts. It is designed to take the direct current voltage coming from the Space Station. That current powers a brushless electric motor that works very much like a brushless motor in a drill (something that spins and has a gear tray). 

How does Canadarm2 move around the Station when it has a payload or the SPDM attached to it?

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Canadarm2 is an interesting design; it is like your own arm except that there is a hand at both ends. Of course if one end is holding onto something and the other end is attached to the Station, it can no longer walk itself around the Station. It has to let go of what it is holding before it can grab anywhere else and move itself around.

This is why Canada has built three different parts to the system—the mobile base, Canadarm2 and the Special Purpose Dexterous Manipulator (a smaller two-armed robot)— to extend its mobility. When Canadarm2 is grappled onto this mobile base it will be able to pluck something out of the shuttle, trundle down the length of the Station, install it and then trundle back into the work site again. It is almost like being on a railway car. The smaller two-armed robot doesn't really affect the mobility of the whole robotic system. It does, however, ensure that the system can perform more delicate operations like replace joints and mobile replacement units around the outside of the Station. The only other way to extend the robot's mobility would be to use the arm that is on the shuttle (the original Canadarm) and have it reach down and grab a payload and hand it off to Canadarm2 by having the two arms working simultaneously. You could actually reposition it and have the two work, like your own hands, in a cooperative effort to move around as we position things onto the Space Station.

How is power provided to Canadarm2?

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Canadarm2 is provided with electricity from the Station. That's how it is powered. The electricity comes from the sun. It travels through space and hits the solar arrays. The solar arrays turn the solar energy into electricity. The electricity is then run through various transformers and the battery system in order to store the energy. It is also run through copper wires that are attached to the length of the truss elements, through the distribution system and then through wires that go all the way through right to the start of Canadarm2. When Canadarm2 grabs on to a grapple fixture, it plugs into the electrical connections that receive energy through those copper wires.

Can Canadarm2 collide with itself or the Station?

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Yes, Canadarm2 could collide with itself. Your own arm can only swing through about 180 degrees. Canadarm2 has an elbow that can swing through 270 degrees each way. All of the knobby parts of the arm including the cameras and computers that are on it could collide as the arm moves over itself. You have to plan ahead as a crewmember to ensure that this doesn't happen. The software doesn't warn you of the danger of self-collision. Of course, we don't want the software to keep us from operating the arm so we've designed an application that will tell you "hey you're in danger of colliding!" It may kick you out of mode for a while so you have to manually select the proper controls that tell the computer that you are aware of the danger and can handle it— it's the price you pay for flexibility.

How do you think flight will be revolutionized in the next 100 years?

I wish I could accurately predict a technological revolution - I'd be rich! In lieu of being clairvoyant, however, my best guide is to look at revolutionary events of the past. I suspect that many have been lost in history, but the most significant recorded events in flight include:

• the Montgolfier balloons
• Cayley's glider research
• Lilienthal's research and flights in kites and gliders
• Daimler's internal combustion engine
• Tsiolkovsky and Goddard's research into rocket propulsion and spaceflight
• Wright Brothers' flight
• Von Ohain and Whittle's invention of the jet engine
• German rocket flights during WWII
• Gagarin's spaceflight

These revolutions can be broken down into a few categories: lift, propulsion, control, and practical application. I think we currently have a pretty good understanding of lift and control, and thus I think revolution will happen in propulsion and practical application. My prediction is that we will invent new forms of propulsion, and will find new ways to apply what we know in flying faster, further and more safely. My best guess in propulsion is the research being done in particle physics.