Ep. 121: Spacesuits

Shownotes

• The Human Body in Vacuum — GSFC
• The Human Body in Space — How Stuff Works
• Understanding How Space Travel Affects Blood Vessels — NASA
• Temperature in Space — Wise Geek
• Spacesuits — NASA
• Spacesuits –– Astronautix.com
• How Spacesuits Work — How Stuff Works
• History of the Spacesuit — Science Museum Learning Network
• Primer on Spacesuits — About.com
• How to Design a Spacesuit
• Different parts of the Apollo/Saturn spacesuit — John Duncan
• How is a spacesuit made and other information — About.com
• What Causes ‘The Bends’ — How Stuff Works
• How to prepare for a spacewalk — How Stuff Works
• The space shuttle orange ACES suit, the Advanced Crew Escape Suit — Astronautix
• Current spacesuits, the EMU — How Stuff Works
• Spacesuit Gallery — About.com
• Spacesuit technology, such as joints, etc — Clavius
• Hubble Servicing Mission 4 –– NASA
• What a Little Lunar Dust Can Do — Wired
• All the things a spacesuit does –– How Stuff Works
• Space Adaptation Syndrome (Space Sickness) — Wiki
• Why Do Astronauts Suffer from Space Sickness? — Medical News Today
• Subsistence in Space
• Going to the Bathroom in Space — Dr. Zebra
• Book:  The Right Stuff by Tom Wolfe
• Movie:  The Right Stuff
• Astronaut diapers, AKA Maxiumum Absorbency Garments — Wiki
• Manned Maneuvering Unit— the big “jet pack” formerly used by shuttle astronauts– NASA History
• Current “jet pack”, the SAFER Unit, to used for emergencies — Wiki

American Astronomical Society Meeting, Long Beach, CA, Jan 4-8, 2009

Transcript: Spacesuits

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Fraser Cane: As we mentioned before, the Universe is out to get you. For our astronauts, that’s truer than ever. One step outside into the vacuum of space would be a world of hurt for an unprotected astronaut. The freezing cold temperature, lack of atmospheric pressure and the deadly radiation just to name a few hazards and that’s why the smart astronaut puts on the spacesuit first.

Let’s look at the smallest possible spaceship around. Pamela so I guess we have to go back to our constant theme, our regular friend, a Universe trying to kill us. So, human body meets the void of space, what can go wrong?

Dr. Pamela Gay: What won’t go wrong is the better question. If you’re in the shadows there is a good chance that you will start to flash-freeze while simultaneously all your skin starts to try and bruise and the blood vessels in your eyes start to burst.

Your body is trying to figure out whether it wants to bruise or freeze at the same time while you’re also going radical decompression you have nothing to breathe. All sorts of things, it’s really a rush to see which thing causes you to die first.

Fraser: And that’s if you’re in the shadow. If you’re in the sunlight then you fry.

Pamela: Right, right so by fire by ice, neither is nice.

Fraser: Obviously those will kill you fast. You’re talking like a minute and you’re done. But if you could stick around then the radiation, the cosmic rays and the radiation coming from the sun, micrometeorites would chop little holes through your body.

Pamela: Just little things like the ultraviolet from the sun that normally gets a lot of it taken out by our atmosphere, we’re talking massive sunburns.

Fraser: Yeah, so needless to say, it’s a very bad thing. There’s just no possible way to get out into space without some kind of protection.

Now I use the term the smallest spaceship. That’s really what a spacesuit is, right? It’s like a portable spaceship.

Pamela: That’s exactly the way to look at it. It’s nothing more than a device that provides pressure for your body and protects you from ultraviolet. It provides some measure of protection from radiation and allows you to lug around everything you need to breathe and eat and maybe a few other bodily functions.

Fraser: Let’s run through each of those things you talked about. First let’s talk about temperature. How does a spacesuit work to keep you from freezing or frying?

Pamela: There are two different things you have to worry about. First of all, what is the temperature outside? And then what is the temperature inside? The first thing the spacesuit does is works to protect you from the massive thermal gradient outside. It works to reflect to protect you from high heat to prevent you from losing heat into the cold through massive amounts of insulation.

Once you have this wonderfully insulated spacesuit you have to worry about what’s going on inside. We’ve all been in that really well insulated room that has too many people in it and the temperature starts rising and rising. The human body is nothing more than a heat factory. Your spacesuit has to be able to also cool your body off or heat it up depending on what the needs of the various parts of your body are.

The outer layers of the spacesuit act sort of like the insulation around the spaceship. Then right up against your skin, there’s this really neat layer that is basically a cooling garment. It has all sorts of tubing that flushes fluid around your body to help maintain a constant temperature so that you don’t overheat on a spacewalk or flash-freeze, whatever the case may be.

Fraser: Give me a couple of examples. Let’s say you’re out in the sunlight. You’re outside your spaceship in the sunlight, what is your spacesuit going to be doing to regulate the temperature?

Pamela: First of all, they’re painted white. They’re highly reflective. Then they just have layer after layer of material. One of the neat things about space is well, it’s a vacuum. If you’re able to have one layer cast a shadow onto the layer beneath it, there’s really no easy way for the temperature to conduct from one layer of the spacesuit to the next.

So by having pockets between the different layers of material the same way you might have pockets between multi-panes of glass, it’s able to protect that heat from getting into your body on the inside.

Simple reflection and then pockets that prevent the heat from trying to conduct through the spacesuit is the same thing you might do to protect your house just with the vacuum of space making it all that much more effective.

Fraser: Then if you go into the shadow then the heaters will kick in, right?

Pamela: Here this is where the fluid that is going around your body maintains it at a constant temperature. Because of the wonderful insulation you don’t really have to worry about heaters kicking on so much.

You don’t have the heat escaping from the suit either. The same insulation that prevents the heat from getting in is also going to prevent the heat from getting out.

Fraser: So the astronaut’s own body is doing a lot of the work of just keeping them warm.

Pamela: And keeping the astronaut cool is actually one of the bigger problems. You’re out there, you’re working hard, and you’re heating up. In your spacesuit in general there is nothing to wick away your sweat.

There’s nothing to help to allow your body to effectively cool itself off. So this is where they actually need to have a cooling system around the astronaut pretty much all the time.

Fraser: Let’s move on to the pressure part. As we said, no air in space, almost total vacuum, it’s not the nice pressure that we experience here on Earth. You said you’re getting bruised, right? So without pressure what’s going to happen to your body?

Pamela: Without pressure the first thing that’s going to start to happen is all the little tiny blood vessels on the surface of your skin, on your eyes, they’re all going to start to rupture. It’s the pressure from the outside pushing down on your skin that’s helping these blood vessels not explode from your own blood pressure inside of them.

You have these fragile vessels with your body’s own blood pressure pushing away on the outsides of the vessels. Air is normally pushing back. Remove that air and those vessels rupture. So the first thing you have is massive bruising. You also start to suffer from what is called the Bends. This is what happens when you start getting Nitrogen bubbles built up inside your system. It causes terrible, terrible pain and will actually kill you.

You start to also run into problems with the things in your lungs starting to burst. All the small pockets, your lungs are very sponge-like and the pockets of air inside of the sponge-like tissues are going to start to rupture as well. You have lots of parts of your body that are starting to rupture and experience severe, severe pain. It’s not something you want to experience.

Fraser: How does the spacesuit protect us on that front?

Pamela: There’s two different ways. The way it is generally done is you provide pressure inside the spacesuit with an artificial atmosphere. Your spacesuit itself will have either an elastic or hard membrane that is pushing down on a bladder that’s filled with air. You live within this inflated balloon essentially.

It’s kind of hard to move inside of an inflated balloon. You have to move the outer edges of your suit and there’s this pressure that you’re constantly fighting against. As you bend your joints you actually end up changing the volume inside the spacesuit which makes everything even harder to bend.

Fraser: It’s kind of like imagine you put on a sleeve and imagine you could inflate the sleeve so that it was like a great big balloon and then try to bend your arm. You can imagine that the air is trying to stop you from being able to actually bend your arm.

Pamela: The best thing they can really do is just not inflate these things that much. That’s actually not that big a problem. We have a lot of pressure here at the surface of the Earth but we also are in an atmosphere that’s majority Nitrogen. So, every breath I take doesn’t contain that much Oxygen. It contains mostly Nitrogen.

While if you remove that Nitrogen and still allow every breath to have as much Oxygen in it as before, you can decrease the total pressure around you. The Oxygen itself can fill up all the space that’s necessary. All that matters is the number of atoms of Oxygen you inhale, the number of molecules actually, not so much all the Nitrogen that’s around them.

Fraser: I’ve seen some spacesuits and the wearing the big balloon problem; they do have some solutions for that, right? As you say the lower pressure using just Oxygen is one way but actually have like rotating I guess hard points and sort of rotating pivots as opposed to wearing a big balloon.

Pamela: There are several different ways of putting together a spacesuit. There is the all cloth variety. This is what you see in the spatial astronauts during landing and takeoff. They are big orange highly flexible, not inflated that much suits that are only really designed for emergency evacuation of the space shuttle. You’re not going to be wearing one of those on a spacewalk.

Then there are also the suits that we do use for the spacewalks. These are the extra-vehicular mobility units. They’re a combination of a soft shell and a hard shell. The reason that you might want to use a hard shell is it’s more robust. You don’t have to worry about puncturing it as much and if you start to do hard joints you can get into problems though.

We’ve all had the various toys with flexible joints and you can eventually get your Ken doll or your Barbie doll posed into positions that you have to figure out how to un-pose them from because the joints are no longer particularly happy with how you move them.

That can happen with spacesuits too. You start to bend around and twist to grab something and all of a sudden the joints hit the end of their limits. Quite often your spacesuits will have a combination design where they start looking at doing the torso as a hard shell but then they start doing the limbs where you need the extra flexibility as soft.

Then they do neat things with the joints where they bevel it and they have extra folds that allow some parts to expand out and some parts to compress down as you bend and flex your joints. The only problem with this is you still are always going to have limited mobility where the limits are placed by how much extra cloth they can provide to balloon out and take care of well where does that extra volume of gas go as you bend your arm?

Fraser: You can just imagine how difficult it is to try and get the job done while wearing a balloon with these beveled joints. You can just imagine how much more difficult it is for mobility and for flexibility.

For some of the jobs that they have to do where they’re turning wrenches and grabbing small parts and having to grab small objects in their hands, grab a handle and stuff, it’s quite amazing that they’re able to get their work done at all.

Pamela: Anyone who has ever tried to do detailed work in the winter where you’re wearing heavy thick gloves and a jacket and snow pants, you feel like the sta-puff marshmallow man. It’s really hard to function with small tools.

The Hubble servicing mission astronauts are going to be going out and essentially removing screws that are like the ones that hold together a lot of modern computer cases, little tiny screws. They’re going to have to do all of this while wearing these giant bulky suits.

Now they’ve been training and they will be able to do this thanks to adapted tools and just being used to working in this bulky situation. But it’s certainly not pleasant and there have been a variety of attempts to figure out how can we provide the pressure the body needs?

We keep coming back to basically Buck Rogers’ lycra-spandex-elastic putting pressure on your body simply through the tension of the material type suits. But there you still have to worry about radiation. How do you make that so it’s thermally as protective? Just trying to take care of all the needs at once is very problematic.

Fraser: Right, this is an alternative way of providing counter-pressure, right? You’re talking about instead of essentially surrounding the astronaut in a bubble of air, you use stretchy fabric and sort of wear a very tight stretchy fabric outfit where it’s the pressure of the fabric that is pushing against the skin that is providing that counter-pressure that the body needs so that you don’t get the bruising.

Pamela: And in this case the only place that your skin is actually up against the air is in your helmet where you’re doing your inhalations. The rest of your body is just basically – you can imagine being surrounded by a giant Ace bandage.

Another problem is, this is really hard to get in and out of and you have to do all of it inside the spacecraft. You need people helping you and the probability of something going terribly wrong is much higher.

Fraser: Out on the show notes there is a really neat spacesuit that was developed at MIT that followed this direction. It’s pretty cool because the model that’s wearing it, it just looked kind of like a very sleek suit with a great big astronaut helmet on as opposed to the big bulky astronaut outfit.

You could imagine you put on this as you say this Ace bandage over your whole body and then you put on a coat. You put on a warm outfit [Laughter] on top of that. It keeps you warm. But essentially you have so much more mobility. I know that one of the other problems with these suits is at the joints. It’s very difficult.

You can imagine sort of feel your knee or your elbow, it’s very difficult to apply pressure on the opposite sides. Sew on the inside of the elbow and the inside of the knee with an elastic band and not end up with a gap or bad pressure there. So you get bruising on the inside of your joints. It’s sort of the new idea and they’re still trying to figure out if they can make a go of it. Chances are we’ll see hybrid versions of this kind of thing, right?

Pamela: Right, they’re very sexy. You have to worry also about subtle things like an astronaut gains ten pounds or loses ten pounds even worse. Then it’s not going to be providing as much pressure. You also with the moon in particular have to worry about mitigating dust.

Some of the modern designs they are coming up with, you basically dock the back of your spacesuit up against your spacecraft or your rover and you just climb in and out through a hatch in the back of your spacesuit. It’s sort of like someone getting in and out of some sort of a crazy magician’s outfit. It’s complicated and you do have to be highly flexible to get in and out of your spacesuit.

The nice thing about that design is it keeps all of the space dust, all of the lunar dust out of your spacecraft. Lunar dust is an extremely abrasive substance. Getting it into the spacecraft is one of the things you most don’t want to do. It will irritate skin and lungs. It’s like working with asbestos.

Trying to figure out how to keep this out of the spacecraft is something NASA is struggling with. The best way to do it is these big bulky suits that you just sort of climb in and out of and rove around without ever getting the suit itself into the spacecraft. It also cuts down on problems with airlocks and just having to carry an airlock around with you because your spacesuit IS your airlock.

Fraser: Right so the spacesuit always stays outside. That’s cool.

Pamela: And so does the dust.

Fraser: And so does the dust and the dog. [Laughter] Now we talked about I guess relative to pressure is breathing. There’s no air in space and we need air. You mentioned enjoy some pure Oxygen.

Pamela: Pure Oxygen is one solution. It makes it so that you have less pressure inside your spacesuit but it also raises the risk of something called Bends. If you’re going to be in a pure Oxygen environment you have to pre-breathe.

You have to essentially change the atmosphere that you’re breathing slowly over time so that you can get all of the Nitrogen out of your system before you start breathing pure Oxygen and before you start experiencing the lower pressures associated with the pure Oxygen environment. This takes time.

It means that you can’t randomly decide: “Oh no, I need to go fix the solar panel right now.” You have to decide a few hours ahead of time. We are looking at different ways to make spacesuits that you have the pure Oxygen ones that are lower that in some cases have been used.

We’re looking at ways to build things in the future where the atmosphere is more like being a thousand feet above sea level, more like the atmosphere when you’re flying on an airplane. It’s lower than what you get at sea level but it is still a mixture of Nitrogen and Oxygen and it’s something that you can have on the International Space Station, in a lunar rover and in your spacesuit that allows you to have the sudden, oh I want to go outside right now without having to worry about getting the Bends and without having to worry about the Oxygen environment affecting your body different that the mixed environment inside the spacecraft.

Fraser: Radiation. [Laughter]

Pamela: That’s the bad one. So mitigating against that is a lot harder. We can do minimal protection by incorporating deflective things into the fabrics. The Apollo spacesuits actually I read had gold thread in them because the gold thread was extremely malleable and was extremely good at reflecting radiation.

We’ve moved on but it’s still a matter of just using specially woven fabrics that help protect you. In a way it’s the guys with the aluminum helmets. But at the end of the day high energy particles are still going to get through. You still are going to experience significant radiation.

Fraser: Right, the only real form of protection of high energy particles and radiation is stuff, right? [Laughter] Mass in between you and the radiation, so if you’re willing to lug around a few centimeters of lead in your spacesuit then that would help out very much. I think in this case it’s more like prevention is the best way.

There are new detection mechanisms now where NASA satellites can detect an inbound solar storm and give the astronauts a chance to go and hide somewhere safe as opposed to just getting caught out in space when the solar storm passes by and they get irradiated. I think in that situation there is some light protection but most of it is go hide. It’s coming, go hide.

Pamela: Right. One of the convenient things is water is a very good deterrent against many forms of high energy particle radiation. So at least by surrounding your body in a cooling system containing liquid, that provides a little; by having special high-tech fabrics that provides a little bit.

It’s not enough but it’s enough to make it so that every spacewalk doesn’t equal cancer. And UV is of course easy to protect against. You just stay out of the sun and put a mask between you and outer space. Fabric is great that way. We’ve all done it – wear a hat. That’s essentially what the astronauts do as well.

Fraser: And glass too, the glass of the spacesuit, the helmet, will protect you from ultraviolet. Okay, so the radiation – not so much. Now what about micrometeorites? Aren’t there little particles zipping around in space?

Pamela: Yes and that’s actually one of the cool things about the outer-most layer of the spacesuit. It is made out of a really durable material. It’s the thermal micrometeorite garment.

It actually does protect against micrometeorites. It’s again these high-tech fabrics that basically act just like bullet-proof vests. Bullet, micrometeorite – they’re really the exact same thing. So our astronauts are set.

Fraser: Obviously there’s a limit.

Pamela: Well yeah but the same thing is true of bullet-proof vests.

Fraser: Right there’s a certain point where you’re outfit isn’t going to be able to stop something big coming through. It’s sort of a numbers game.

Chances are the amount of time you’re going to spend out walking around in space and the size of the human body; you’re not going to get hit by anything dangerous. That’s the numbers that NASA runs.

Pamela: And you’re protected usually on at least one side by the spacecraft. That’s even enhancing your probabilities.

Fraser: Right, of course. What about space-madness?

Pamela: Well, that one the spacesuit can’t help against. The astronauts who have accidentally gotten space sickness in their spacesuits is really not pretty.

Fraser: Auugh! So, I’m kidding about space-madness, there’s no such thing but [Laughter] there are as you said, other bodily functions.

You just talked about space nausea. [Laughter] I can’t even imagine what that would be like, vomiting in your helmet.

Pamela: Not only that but it’s jet propulsion against the back of your helmet. There’s really no winning here.

It’s only happened twice that I could find documentation of with US astronauts and yes, not pretty. That is just when you go inside and hide your head in shame.

Fraser: But eating?

Pamela: There are liquids and gels – basically toothpaste is the way to think of it. You turn your head one way and you have a little thing you can suck water out of.

It’s kind of like camelback technology. Think of what bike riders use, the same principle applies to the astronauts.

Fraser: Then turn your other way and you get to suck this kind of protein gel paste.

Pamela: Yeah, not fun. That’s exactly what bike riders deal with as well.

Fraser: For some of the longest spacewalks, the astronauts are out for six and one half to seven hours out in space doing pretty hard physical labor. They’ve got to get hungry.

Pamela: The Apollo astronauts were out for twenty hours.

Fraser: Wow. They just had to get so hungry and so thirsty. With those kinds of times though you’re going to have to go to the bathroom, right?

Pamela: Right and here it’s actually interesting to look at the evolving technology. We started off where in the beginning we sort of forgot that this could possibly be a problem. You’ve got to wonder how they think that this won’t possibly be a problem.

If you’ve seen the movie “The Right Stuff”, you know about this. Poor Alan Shepard, he’s out there waiting to launch, waiting to launch, waiting to launch. What they don’t help you realize during the film is this guy is flat on his back with his legs elevated which puts pressure on your lower body. It increases blood flow. It does everything possible to increase kidney production.

This poor man drank coffee all morning. No one had thought ahead and he actually relieved himself inside of his suit which provided a moment’s relief and a lot of embarrassment and discomfort later. There are some things you just don’t want to have wet.

From there they moved on to technologies that applied best to men. Tubes were involved. It worked and they captured things and it was kind of like a bad hospital adventure. But it worked.

As women astronauts started to come along, they were trying to figure out how to solve this problem. Everything they came up with, the general response from the women was: “I’m not even going to try that. Don’t make me.”

They eventually realized that diapers of all things are really the best technology to sort out. There are diapers provided to the astronauts. One for take-off, one for landing, one just in case and then they also have diapers that are for use during all of the spacewalks.

They’re special high-tech ones that pull on and off just like underwear, sort of like the ones that they advertise for toddlers. They contain special chemicals that absorb a thousand times their weight in fluid. They are very effective at absorbing fluids and keeping the poor astronauts dry.

One Google link I found actually documented that astronauts tend to wait to participate in ‘number 2’ until they are back on the orbiter which I found interesting that they felt the need to document. Again, it’s just diapers – it works. The low-tech solution is sometimes the best solution.

Fraser: Yeah, I think that makes sense. Anyone who has had kids with the disposable diapers these days, they’re pretty magical you know? [Laughter] It’s pretty amazing how well they absorb and sort of deal with that.

I’m not going to go into anymore grim details but I think that’s the right solution for the problem. That’s like the cold hard reality of space travel, right? If you want to be an astronaut you gotta be okay with wearing a diaper. [Laughter] Alright Pamela did we run out of risks? I think we did.

Pamela: I think we did and other than that it’s just trying to figure out how to get around in space and the answer there is jet propulsion, just basically a gun filled with air was one technique early on used.

Since then we’ve realized ropes are really the best option to attach yourself to the spacecraft. In general they found small ways to use Nitrogen canisters or other gas canisters to just basically fire themselves around the spacecraft as they need to. It’s kind of cool.

Fraser: There’s a pretty cool technology where it’s like a backpack that they wear.

Pamela: The man maneuvering unit. They used it up until 1986. After the Challenger disaster it was deemed to risky to have the astronauts just sort of flying free.

But up until then they were used to occasionally try and rescue broken commercial satellites. It was everything you ever dreamed of in a jetpack as a small child kind of cool.

Fraser: When you’re in microgravity it is way easier to have a jetpack that lets you fly around in space. [Laughter] That’s very cool. Well, I think we’re done with spacesuits for this week.