Why Astronauts Burn Their Dirty Underwear
An interview with the guy responsible for dressing astronauts.
Robert Trevino is a senior engineer with NASA's Crew and Thermal Systems Division. Among other duties, that means he's responsible for what astronauts wear in outer space. Whether it's regular cotton polos and cargo shorts on the International Space Station or textiles resistant to fire and bacteria designed for the mission to Mars, Trevino and his team must consider every aspect of astronaut wear, from comfort to weight to durability. The question of laundry might sound banal at first, but it in fact reveals how even the most trivial aspects of spaceflight must be considered long and hard if humanity is to push its boundaries.
I spoke with Trevino at length about the current state and future development of space-wear. The conversation has been edited for clarity and brevity.
Motherboard: Within the International Space Station, the astronaut uniform consists of a polo and cargo pants. Is there anything special about these?
No, that's just very comfortable clothing that the astronauts like. The space station is what we call a one-atmosphere, or shirtsleeve, environment. The air is just like the air we breathe on Earth–20 percent oxygen, 80 percent nitrogen–so we don't have the flammability concerns that we have in Apollo or Skylab, which have a much higher oxygen level.
Motherboard: This may be a stupid question, but where do you buy all the polos and cargo pants? Costco?
We have a contractor, Lockheed Martin, which provides the clothing, and they purchase from Lands' End, Cabela's, Blackhawk. They are commercial products, but we do test them to our requirements.
Motherboard: Besides flammability, are there any other concerns about the current uniform?
The clothes we're talking about are their daily wear, what they wear going through their daily routine inside the station—operating the equipment, doing experiments, doing maintenance, things like that. All the crew members are also required to do at least an hour of exercise a day. We have to do exercise to mitigate the effects of zero gravity on the body—muscle atrophy, loss of calcium in the bones. We have a whole different ensemble for exercise. The exercise clothes are also commercial, but we have been looking at new material that is much more breathable, odor absorbing and sweat resistant.
We don't have a laundry system, so the space station crew basically wear clothes until they smell bad, then throw them in the trash
Motherboard: Are the exercise clothes just tracksuits?
When the crews get assigned to a space station mission, they go to our lab that has clothing. In their training they get to evaluate some of the clothing, and they select what they like. For example, with exercise clothing, just like you might want a loose fit on a T-shirt, another crew member might want to have more of a compression fit. Almost all the exercise clothes are breathable, 100 percent polyester, and then the shorts, the socks tend to be polycotton. The underwear is up to them.
We don't have a laundry system, so the space station crew basically wear clothes until they smell bad, then throw them in the trash. After the Progress, the Russian cargo vehicle, docks and all the cargo's unloaded, they load it up with trash, which burns up on re-entry. In the future, on missions farther from Earth, we're not going to have that luxury, of the space station having cargo vehicles that bring them fresh clothing. We've done trade studies of providing a laundry system which uses water and power and requires something to take it up, versus the cost of just replacing the clothing, and right now it's essentially cheaper to replace the clothing because water is just too valuable of a resource.
Unless we find so much ice on Mars that we have plenty of water, water will still be a problem. We're interested in developing clothing that will be much more antibacterial, and I also have some research projects going on looking at alternate laundry systems that are not water-based.
We've looked at putting clothing that's already perspired on and has an odor into an airlock and exposing it to the vacuum of space. We did that and saw a decrease in bacteria, but odor comes from decaying bacteria. Ultraviolet is already being used in hospitals to disinfect rooms, so we've done some testing of exposing different material swatches to ultraviolet. We have a crew that's testing the frequency of microwaves and the amount of power provided because we know that microwaves will kill bacteria, but we don't want to also melt the clothing.
Even if we don't get the clothes as clean as you would in a full laundry cycle in your home with water and soap and everything, if we can just extend the life or the use of that clothing for two weeks to four weeks or six weeks, we've already cut the amount of clothing in half. We have a project here at NASA called Logistics Reduction for Advanced Exploration Missions, where we want to look at ways that we can reduce some of the logistics for these missions, because when you go to Mars, you're not going to have cargo resupply coming. It might be a three-year mission with a one-year stay on the surface, and you really need to bring everything with you. It would be too expensive to send cargo vehicles with clothing.
Motherboard: How long do the uniforms currently last?
They wear exercise clothing for not more than two weeks, but their other clothes last much longer. What they do in the space station is they get a certain amount of daily wear—polos and shorts. You normally have a rotation of three to six months. If they wear one shirt that they really like for a couple of months, they might throw that one away.
Motherboard: Are you looking into any wearable technology?
Before the term "wearable technology" came up, we were doing a lot of that – for example, in the spacesuit. Inside the spacesuit, one would wear a liquid cooling and ventilation garment. It basically looks like a pair of long johns that go from your ankles up to your wrist. In it, there's a series of tubing through which we circulate water. It acts just like a radiator in your car. As you're working in space and generating metabolic heat, you have air that will create conduction in the spacesuit. You've got to get that heat away from your body, so this garment will conduct your body heat. Water will circulate in cold and come out hot. It's basically keeping you comfortable by removing heat. We attach these tubings to the garment, and then underneath that we wear a heart monitor to measure heart rate. We also have looked at a CO2 sensor to monitor the amount of CO2 inside the suit because we're circulating oxygen inside the spacesuit, but we don't want a CO2 build up.
Motherboard: Any big upgrades to the spacesuit coming up?
We've looked into a lot of heads-up displays for the spacesuit. The difficulty there is, first of all, it has to work in 100 percent oxygen. Usually when you have electronics in 100 percent oxygen, you have to be very careful. There are safety issues there. The other thing is, there are some displays that are sort of like Google Glass or microvision, but if you mount anything on the head, you can't reach in there and adjust it. It has to be mounted on the spacesuit, outside in the vacuum of space, where it's exposed to really high and low temperature swings. The environment can be from minus 275 degrees Fahrenheit to plus 300 degrees. We are interested in technologies—some of them are inside the suit, some of them are outside—to provide the information astronauts need to monitor the suit. The status of their oxygen remaining, power remaining, their CO2 level—those are all things they have to monitor.
Motherboard: How do they receive that information now?
On their chest. You always see this module that's mounted on their chest called the Displays and Controls Module. If you look straight down at your chest, this module sticks out, maybe four, five inches above the chest outside of the spacesuit, and it has an LED display there. You press a button and it cycles through the different parameters. That's the aspects of the suit, but procedures or checklists could also be on the heads-up display. We actually have a laminated plastic checklist that's mounted on the wrist of the spacesuit. Many years ago we did look at an electronic checklist. We experimented with it on the space station, and we would've gone with that one, but at the time we used LCD, liquid crystal screens. We did some testing, but it got much colder than we expected and the crystal displays don't work very well in the cold, so the images started fading out.
Motherboard: Apparently fluid in the body shifts without gravity, so sometimes astronauts' limbs can become bloated?
Right, that's called a fluid shift. Our bodies have evolved for millions of years in one gravity. Gravity is always pulling you down and all of your fluids are fighting gravity, so when the heart pumps the blood out to the extremities, it doesn't have to pump back down because gravity is assisting it. When you get to zero G, you lose that. You don't have the evolutionary pull of gravity on you, so the fluids and your blood-flow re-distribute. Right now, when you're standing on Earth in one gravity, you have more fluids in your lower torso than your upper torso, so when you get to zero G, it [shifts]. The astronauts do get sort of puffy in their heads. Their bodies get a little bit less than their heads and torsos. It takes a little bit of adaptation to get them stabilized. Some are not so extreme, others are very, very puffy. We've heard the expression that they look like Charlie Brown. It's the Charlie Brown effect.
Motherboard: Is that something you guys have been trying to address?
For the spacesuit, [fluid shift is]critical. You have to have a very proper fit in the spacesuit for their arms and the gloves and the legs. Crew members actually grow, depending on their height on Earth, an inch or an inch and half. That is primarily in the spinal area because your spine is under compression under one G, so when you have zero gravity the spine stretches.
Motherboard: How quickly will they grow?
I think it's within the first few days that you start stretching. We take measurements to find out what's a comfortable fit for the spacesuit, then we'll add an inch or so to the height of their torsos anticipating this growth. It's not an issue with their daily wear because those are a little bit more adjustable. Your polo, if you get a little bit taller, is just not tucked in as much.
One more thing that also has a lot of applications in the future here on Earth: Outside the spacecraft, when you do a space walk, it's minus 275 degrees to 300 degrees. We have to provide insulation in the spacesuit for that. The current technology in the spacesuit for that is aluminized mylar with material between it in separate layers. That is called multi-layered insulation. It's the same as a thermos bottle, where you have a vacuum layer. There's nothing better than a vacuum layer in a thermos bottle because there's nothing to conduct the heat or the cold to the inner layer. In the spacesuit, we have that insulation that keeps the astronaut from getting the extreme heat or the extreme cold.
The problem is that insulation only works in a vacuum. It works on the moon because the moon doesn't have an atmosphere, but on Mars, where we have an atmosphere of carbon dioxide, that technology will not work, so we'll have to provide another insulation. We can use the technology you have right now in your parka, thinsulate or permaloc, but those are very bulky and very thick. So we have been doing some research into insulation for future spacesuits that would work in an atmosphere like Mars, and we're working with this company called Aspen Aerogels that makes a really neat material called aerogel that's a super insulation. It's the world's lightest solid material. You can get a cube of this in your hand and you can hold it, but you won't feel it because it's so light. We're looking at it as kind of a flexible insulation. If we can develop this material, it can theoretically replace two or three inches of current fibrous insulation of thinsulate or permaloc with maybe like a base of a quarter inch of this aerogel. So in the future you could have a parka that would be as thin as a windbreaker and it would provide you the same insulation.
Motherboard: Any other interesting projects?
Most of the exercise clothing is polyester, and a lot of our food containers are plastic. Right now, with trash, we're just throwing it all away. But we've looked at something called a heat melt compactor, like a trash compactor but it gets to a high temperature. You can separate your plastics from your other trash and put it into this compactor, melt the plastic and compress it into a hockey puck—maybe an inch or three-quarters of an inch thick, maybe six inches in diameter. Plastic happens to be a really good radiation shielding material, so we can make these thick bricks and line the space station's sleeping compartments with them to provide radiation shielding for the astronauts. If we can get some of these materials from clothing and reuse them, turn them into these pucks, then, instead of flying hundreds of pounds of radiation material, we can be using this trash for long-term missions, making our own radiation shielding from the plastics in the clothing.
The other thing is 3D printing. If we have this hockey puck of plastic, could we develop a system that would heat that and put it into another device that would extrude it into a fiber? 3D printers use a feedstock that almost looks like spool, that sort of texture. We had the idea of converting our discarded clothes and plastics and other things to develop a plastic that would provide the feedstock for a 3D printer. We're thinking—again, long-term—of designing clothing that, instead of throwing it away, we can do something with it. Can we convert it into radiation shielding? Can we convert it to feedstock for a 3D printer? Do other things with it? If not, we have the mentality that we've had on previous missions, that we have all these logistics and we throw them away and get new supplies. But for three-year missions, our whole mentality for recycling air and water and clothing and trash has to be different.