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Make Contact: Astronaut Greg Chamitoff Answers Your Questions
Week 3
ISS018-E-007817 -- Expedition 18 Commander Mike Fincke and Flight Engineer Greg Chamitoff

Expedition 18 Commander Mike Fincke (foreground) and Flight Engineer Greg Chamitoff work the controls of the Canadarm2 robotic work station in the International Space Station's Destiny laboratory. Image credit: NASA

Greg, How do you deal with computer software and hardware failures? Also, does the computer hard disc rpm speed differ up there than from Earth's atmosphere? - Sam, 38, Sydney, Australia

> View Greg Chamitoff's video response

No, there’s no difference in the RPM in the disc drive. That spins exactly how it’s designed to spin. But as you know there’s problems with computers. Pieces of equipment fail from time to time. Nothing is designed to last forever. Everything has what they call an MTBF – meantime between failures. So we expect things to fail, and we expect to have to repair them or replace them.

Of course, for a space mission, it’s really critical that we handle that properly. So, basically we have different ways to handle these kind of malfunctions on orbit. First of all, we have a lot of redundancy. For a lot of critical functions, there’s multiple computers, multiple systems, actuators, sensors, and so we have redundancy and backup. So, if something fails, we have another one right there ready to take over, or we’re already looking at data from several sensors, for example, and start ignoring the one that is getting the anomalous readings. Otherwise, we have procedures, and we have tools, and we have parts. So we can fix things, things that are designed to be repaired or changed out when their lifetime expires or when a part fails. And the other thing is we can just have completely spare units to replace something, and we have a lot of that. We call them ORUs – Orbital Replacement Units. So, we often do that as well.

But, this is a really important topic because we really need it to learn how to build really reliable systems. It’s a big part of what the space station’s all about. While we’re up here, we should be testing out all the systems we need to live on the moon, to go to Mars, travel further because any mission like that has to be self-sufficient. We need to have hardware that’s reliable and hardware we know how to fix and know exactly how it’s going to break and have the tools, techniques and parts in order to fix those things when we’re very far away from Earth and don’t have a supply chain. So, that’s going to be really important in the future, and the space station is the perfect test bed for all these things – computers and all kinds of life support systems and so on. That’s what we’re doing up here. So, that’s a great question. Thank you.

What is the purpose of the international space station? - Jonathan, 12, U.S.

> View Greg Chamitoff's video response

That’s a good, simple question, and I don’t want to give you too complicated of an answer, although – to me – it’s a really multi-purpose project with rules and objectives across many fields that are being investigated by 15 different countries.

But, fundamentally, in my opinion, the purpose of the space station is basically to establish a foothold off our planet from where we can begin to explore the rest of the universe. I don’t mean that we’re going to travel directly from the space station but that in terms of the engineering and the scientific capability, that’s where we’re going to learn how to live and work in space. Everything we do up here contributes to the database of human knowledge.

Some of that is related to studying the Earth itself. Some of it is related to understanding chemistry and physics and the properties of those and biological systems in the zero gravity environment. And, some of it is just related to exploring and living here without gravity and how the human body behaves in this environment. Toward that end, we have a lot to learn. We have to learn how to build systems that can sustain us, life support systems that can take care of us while we’re away from the protection of the Earth environment. We essentially have to build those systems ourself, and we want to build recycling capabilities and the ability to provide our own food and handle our own waste disposal. All these things are going to be critical capabilities for us to live on other planets and explore in other places.

The space station is a proving ground for all the things we need to develop in order to essentially build our own environment that’s away from Earth that provides everything to us that the Earth environment provides. In the long term, I think the overall purpose of being out here – the resources on Earth are very limited. We’re having an energy crisis, and the planet is very populated, and the needs only grow more and more and more. The energy is limited, and so are the resources and materials. So, I see that in the future what we’re going to be doing – what’s really going to drive us here – is the need for more material resources and energy because it’s out here. It’s available. It’s here for us. We just need to learn how to come out here and exploit it and explore it. So, I think this is the ultimate goal for humanity.

Assuming that you have a small cube of the strongest metal/ceramic, would you be allowed to throw it to Earth? Are there any rules that forbid you to throw things at Earth which can reach the ground and might be harmful? - Rick Meier, 24, Germany

> View Greg Chamitoff's video response

That’s a good question. Of course, unless we’re doing a spacewalk, we really can’t thrown anything out. There’s no windows that we can open, no ports we can open, really, to eject anything, but during a spacewalk, yeah, somebody could throw something.

The thing is, though, that we’re moving at an orbit of 17,500 miles an hour. The fastest you could throw something - if you were a baseball pitcher – might be 100 miles an hour, and in a spacesuit, I bet you you’d probably get lucky to get a couple dozen miles per hour. So, the change in the speed you’re going to get on anything that’s already moving with you at 17,500 miles an hour is really imperceptible. It’s negligible. So, throwing it doesn’t really matter.

But, if you had it and let it go or threw it, then it doesn’t matter. Eventually, it would come down on the Earth, and when it comes down and how it comes down depends on what altitude it starts at, how big the object is, how heavy it is. Basically, there’s some drag because there are still some molecules here, and we’re not high enough to be completely out of enough molecules that there’s a noticeable drag. So the more surface area something has and the less mass it has, the faster it’s going to slow down. When it slows down to the right speed, then it’s going to re-enter and become basically a meteorite.

If it was something that you could hold, I’m quite sure that no matter what material you made it out of, it would probably not get all the way to the ground. And most likely hit the ocean anyway. But, anyway, that’s an interesting question.

ISS018-E-005026 -- Expedition 18 Flight Engineers Greg Chamitoff and Yury Lonchakov

On a computer screen, Expedition 18 Flight Engineers Greg Chamitoff (left) and Yury Lonchakov watch live video of the Expedition 17 crew's post landing activities on the steppes of Kazakhstan. Image credit: NASA

What types of exercises do astronauts usually perform in the ISS? What is the maximum time astronauts can spend doing repair work outside? - Eason, 20, Singapore

> View Greg Chamitoff's video response

Well, we have different types of exercise equipment, which are really great and not too dissimilar from what you’d find at a gym.

We have what’s called a Resistive Exercise Device, called the RED, and basically it’s where you can pull against cables, so we can hook up a harness and, basically, like a curling iron – curling bar. And, we can do all kinds of different exercises working against some cables, and we can adjust the tension in those cables.

We have, basically, a bicycle, and we also have a treadmill. And, for the treadmill we have to wear a harness with bungees that pull us down so that we can feel a similar effect to being in gravity and actually run.

So, these are really good exercises to basically keep us fit and to simulate – some of the things like the treadmill – has to simulate some of the activity we do on Earth in one-g, including impact on the bones and the legs and hips. So these are really good exercises, and we spend about two hours a day doing exercise to try to maintain our fitness up here. So, thank you for that question.

Does living aboard the International Space Station have side effects on your health? Also, are there any extra steps in your morning routine and evening routine that would differentiate from a normal day on Earth? And greetings from the Great White North! - Chris, 14, Ontario, Canada

> View Greg Chamitoff's video response

Greetings to you, and yes.

The radiation environment up here is higher than on Earth, and that’s definitely a long-term risk. We manage that in the sense that there’s a lifetime limit on astronauts – how much radiation they can be exposed to, as well as a daily dose limit that we keep track of and a mission dose limit. Essentially that limit is kept well within what’s considered an acceptable range by some standards that are developed for radiation workers, for example, people who work in nuclear power plants.

But, essentially we’re only allowed to increase our risk of cancer due to radiation by one percent due to the work we do in space. So, when you compare that to an increased risk of cancer – let’s say by smoking – of 20 percent in your lifetime, it’s really a pretty small increase. I mean, if somebody smoked versus quitting smoking and coming to live on the space station, supposedly the long-term health benefit would be positive. So, this is the tradeoff that we make. It’s pretty low additional risk based on the way we’re doing our spaceflight right now.

A mission to mars, though, or something like that – or even to the moon – the risk would be higher because we’d be outside of those protective layers of these radiation belts that surround the Earth and protect us from some of that radiation. Also, the magnetic field of the Earth protects us from some of that radiation.

As for the effects of zero-g, yes, that’s also an impact on our health. We can lose bone mass from not having impact on our bones and not having any stress on our bones while we’re up here. We lose muscle mass, and there’s also a reduction on the load on your heart. Your heart just doesn’t have to work very hard to pump blood up here. So, returning to one-g after being in zero-g – I’m curious how that’s going to be because it definitely is an additional load on your heart that your heart’s not used to. So, if you stayed up here a really long time, that could be a problem.

But as for the routine, we basically just do a lot of exercise up here and try to maintain our health as best as we can. Do a couple of hours of exercise – cardio and weight workouts every day – and that goes a long way toward helping us get back on the ground, be fit when we return. Excellent question. Thank you.

Hey Greg! How's everything going up there? It's pretty spectacular to be able to track the station here on the ground and be able to see it glow in the night sky. I remember viewing the ISS on July 4 and wondering if you could see the fireworks being blown off in Boston or in NYC. What are some of the awe inspiring light displays you have seen from space since your docking to the ISS? Have a safe mission! - Stephan Wlodarczyk, 19, Newark, NY

> View Greg Chamitoff's video response

Well, thanks a lot Stephan. I really hoped to see the fireworks on July 4. I was looking for them, but the problem was our orbit track didn’t pass over the U.S. at any time during which the fireworks were going off. At that time of day, for each of the time zones, we were off in the South Pacific or something like that. I was looking for that opportunity, and I never got it. So, that was too bad.

So, I don’t know the answer to that question, but there are a lot of light displays we do see from here. One of the most spectacular places I’ve seen from here is Italy, and I don’t know why Italy looks this way compared to other places. You can always see the glow of city lights when you pass over a big city, and it’s really beautiful to see that at night. But, Italy is a little different. It seems like the whole country is lit up, all the way around the shoreline. The entire coastline of Italy – the whole boot – is lit up. And so, from up here you can look down, and you just see the whole boot of Italy at night. It’s just an amazing thing to see, and I haven’t seen any other place in the world that’s lit up like that, where the outline of the country is lit up by lights. It’s just spectacular.

The other thing you see from here is shooting stars. Maybe we can see more of them because, I guess, on the ground when you look up, you have a limited view of the sky. From up here, we’re looking over a larger part of the planet, so we see a thousand miles in each direction. So, we can see shooting stars over a wide space, and so, we see them a lot. So, if you look out the window at night, and you look for them, you can see them pretty regularly, which is really, really neat. And it’s really neat to look down and see a shooting star. That’s an unusual feeling. There’s lots of great stuff to see at night.

ISS018-E-008782 -- Expedition 18 Flight Engineer Greg Chamitoff

Expedition 18 Flight Engineer Greg Chamitoff works in the Destiny laboratory of the International Space Station. Image credit: NASA

How many sunsets and sunrises do you see everyday (or how many times do you see Earth’s day and night) as the station goes around the Earth? And what about the station's movement and position? Does it eventually spin or turn or is it always the same position and direction as it goes straight? Greetings from Brazil and float safe! - Freddie Diniz, 22, Floriano, Brazil

> View Greg Chamitoff's video response

Thanks a lot for that question Freddie. Basically, well, it depends. Right now, we currently have the shuttle docked to the space station, and when we do that, we fly the space station backwards. The space station has done a 180 flip, and the Russian side of the space station is going forward – the direction of the velocity vector. That supposedly protects the shuttle a little bit from micro-meteorite damage, so that’s one of the reasons we do that.

It used to be that we’d fly the space station in a lot of different orientations. We were basically trying to maximize the power capability that the station had and also protect it thermally from thermal variations – heating and cooling from the sun and the shade – but once the station got bigger and our large solar panels had multiple joints on them and they could point in any direction, we no longer needed to do that. So, the space station now mostly flies in what we call LVLH – Local Vertical, Local Horizontal. The front part of the space station, the front part of the U.S. part heads forward. Most of our windows are facing down, and we pretty much fly in that orientation.

But, the orientation oscillates a little bit because really we’re flying an orientation that tries to require no thrust, no energy, in order to keep us in that equilibrium orientation. It’s actually an orientation that’s not exactly level but slightly tilted, and it depends on the shape of the station and mass distribution. So, we optimize that to make sure we don’t need thrusters to hold us in position.

Otherwise, as we go around the Earth, it’s pretty darn fast. We’re moving 17,500 miles an hour, and that means we go around every 90 minutes. So, that means we seen 16 sunrises and 16 sunsets every day. Of course, we’re not by the window to look at all the beautiful sunsets and sunrises, but we try to catch some of them. And, it’s really beautiful to see from here.