Challenges of Living in Zero Gravity on the International Space Station
Based on my interest with human survival without gravity, I've done a lot of research on how astronauts live in space. My college background and my Masters Degree in Computer Science give me the advantage of understanding and explaining the scientific endeavor of the International Space Station.
The work with the ISS has begun in 1998 and it’s continually being built with additional modules, external trusses, and solar arrays that are launched to the site by Russian Proton and Soyuz rockets, American Space Shuttles, and more recently by Elon Musk’s privately held SpaceX aerospace manufacturer.
Elon Musk has a goal of enabling the colonization of Mars, which is making this whole scenario even more fascinating.
The International Space Station
The mission of the ISS is to conduct science experiments, research projects, and investigate life without the amenities of gravity or limitless life supporting necessities that we take for granted on Earth. The work being done may lead to knowledge of how to colonize the Moon and possibly Mars.
The ISS consists of 14 pressurized modules that have been added one by one. These modules contain science labs and living quarters.
The first module of the ISS was placed in low Earth Orbit in 1998. That’s an average altitude of about 248 miles (or 400 kilometers) above the Earth. It circles the Earth every 90 minutes.1
The ISS is constantly falling back to Earth. However, the magic of making it remain in orbit is the speed it moves, known as “orbital velocity”. This speed (close to 18,000 MPH) is required to cause any object to be perfectly balanced between gravitational pull and its forward thrust around the planet.
Orbital velocity is what causes the Moon to stay in orbit around the Earth and the Earth to stay in orbit around the Sun.
There are sometimes up to ten crewmembers inhabiting the ISS at one time. It truly is an international expedition, as they are from the United States, Russia, Japan, Canada and European Partners. The U.S. has been footing more than half the cost to build and maintain the mission ($100 Billion as of 2014).
Most countries refer to their crewmembers as astronauts. The Russians are known as cosmonauts.
Until recently they stayed on board only six months before returning to Earth because life in space takes a toll on the human body, as I’ll explain later. However, lately they stay is a full year to extend the experiment.
A trip to Mars takes two years, so this extended living arrangement on the ISS helps collect vital data about the impact on humans.
What Do Astronauts Need to Survive in Space?
Water is the most precious commodity, especially in a self-contained living environment where new supply is impossible to attain. Therefore, all wastewater needs to be collected and recycled. This includes perspiration as well as urine.
Perspiration is collected from sweaty cloths as well as removed from the air. A pleasing name has been made up for the water collected from perspiration: Humidity Concentrate.
Using distillation, about 85% of the water in urine is recovered. Overall, about 94% of all the wastewater from the astronauts is recycled.
Creating Breathable Oxygen
Oxygen is replenished by separating it from the water through electrolysis. I used to do that as an experiment in high school science class. We learned how water is chemically made up of two Hydrogen atoms for every single Oxygen atom. That’s why it has the chemical name H2O, which represents that configuration of molecules.
The method is simply done by inserting electrodes in the water with a DC current. The DC current splits the water molecules into its individual atoms. The negative electrode collects hydrogen gas and the positive electrode collects oxygen.
Besides oxygen, other atmospheric components such as nitrogen, carbon dioxide, hydrogen, methane, and humidity, are monitored and controlled by a device called the Major Constituent Analyzer.
Maintaining a Healthy Heart While Living in the Space Station
Astronauts lose muscle tone while in space due to the lack of gravity on the body. However, the heart is also a muscle and it will weaken to the point that it fails if a human spends too much time in space.
The solution is to exercise against the resistance of elastic ropes. Think of it as running on a treadmill with oversized rubber bands holding you to the mill. The same had to be done with exercising every part of the body.
The astronauts have to be diligent about this exercise routine. They need to exercise two and a half hours each day while in space.
What Is It Like In Space for Astronauts?
How Astronauts Have Personal Privacy
Each astronaut has his or her own personal quarters, known as a crew cabin. This is the only place where they have privacy. It contains a sleeping bag and personal effects. The crew cabins are small, just big enough for one person.
They also have a laptop to keep notes, write about their thoughts and feelings, and communicate with friends and family back home. WiFi is available on the ISS, so they can use email or Skype.
Personal Hygiene in Space
They do need to get haircuts occasionally. Female astronauts tend to leave their hair long. The men get haircuts with a buzz cutter that has a vacuum machine attached to it to capture the hair as it’s cut off. Otherwise, the hair would float away since there is no gravity.
The lack of gravity also rules out the ability to have running water. Water would just float around the space capsule. Therefore, they wash their hair with a no-rinse shampoo.
When brushing their teeth, they need to keep their lips closed. Otherwise, the saliva and toothpaste will just float out. Not a pretty sight.
How Astronauts Eat in Space
The lack of running water makes eating a very different task than you can imagine.
Food is dehydrated or freeze-dried, and stored in plastic packages. The astronauts squeeze water into the food packages before eating. Hot water is used to make hot meals. Freeze-dried fruit can be eaten dry.
Cooking in Space
How Astronauts Sleep in Space
As I mentioned earlier, each astronaut has his or her own crew quarters. They spend their alone time in there and when they sleep, they usually use sleeping bags so they don't float around.
The sleeping bags can be attached to a wall or upside down on the ceiling. Remember there really is no up or down in space, so they can sleep anywhere in their cabin.
They generally sleep eight hours for a good night’s rest to be ready for another busy day.
Inside Look at an Astronaut's Personal Crew Cabin
Keeping Health Records
They keep a record in the computer of what they eat so NASA can keep track of everything: How many calories, protein, how much salt they are getting, and so on.
When they lift weights they even have to keep track of how much weight and how many reps they did. The computers record their heart rate when they are working out. Everything needs to be kept track of with accuracy. By the way, lifting weights is not the same as on Earth. It’s done by pulling or pushing against resistance of springs or elastic bands.
There are no secrets in space. They even have to keep a record of when they use the toilets.
Exercising in Space
How Astronauts Go To the Bathroom in Space
Both urinating and bowel movements need to be handled in a completely different manner in a weightless situation. You wouldn’t want that stuff floating away from you.
A vacuum system is built into the special toilets. Astronaut Samantha Cristoforetti shows you how space toilets work in this next video.
How to Use a Space Toilet
How Astronauts Clean in Space
Living in such a cramped space, it’s important to keep a clean environment. Once a week they go around with a vacuum, but they also need to clean everything with a wet wipe that kills germs.
They use wet wipes to clean their eating utensils too—their forks, spoons, and trays.
The Difficulties of Life in Space
People don’t only pollute our land and oceans. We pollute space too.
A major concern is the existence of orbiting space junk that can be deadly if any of it strikes the ISS. This junk consists of over 100,000 pieces of discarded satellites and rockets—and increasing.
A solution that has been tested in labs is the use of two layers of shields around every part of the ISS that is important to the survival of the crew.
If small objects the size of a grain of sand that can’t be detected were to strike, the outer shield slows it down and causes it to dissipate, so that it’s too weak to penetrate the second shield.
Larger space junk is monitored by mission control. They are constantly making changes to the path of the ISS to avoid these larger pieces. They do this from the ground control so that the astronauts don’t even have to think about it.
The Cygnus Orbital Delivery Capsule
You can’t just go to the local grocery store or Home Depot when you need something.
The Cygnus Orbital Delivery Capsule is a space vehicle that is used to replenish needed items. It’s launched about every six weeks containing groceries, clothing, and new science experiments.
Once the Cygnus Capsule is within 10 meters of the ISS, they use a robotic arm to capture it and guide it to connect with the locking hatch. The astronauts can then open the hatch and enter the capsule to get all the new goodies.
How Trash Is Handled on the ISS
We take it for granted, but trash accumulates among the astronauts just the same as out trash builds up in our homes. They deal with it the same way, filling garbage bags.
The bags also contain the dirty laundry since they can't wash anything. They wear things much longer for that reason, but then they dispose of it with the rest of the trash.
They store those garbage bags in the Cygnus Orbital Capsule. The Cygnus takes the trash with it when it leaves.
When Cygnus enters the Earths atmosphere it burns up, just as most meteorites do, and all the trash burns up with it.
The recent SpaceX Dragon Capsule, which also delivers supplies to the ISS, has the added advantage that it successfully returned 5,400 pounds of science equipment and other gear in March 2017.
Keeping Busy on the ISS
Scientific Lab Experiments Done on the ISS
Experiments are constantly being carried out on tests such as how crops will grow and how animals are bread in weightlessness. These experiments are being done in anticipation of journeys farther out someday.
Ants are studied to see how they handle weightlessness. They get confused as they fall and just float around.
Variations of vaccines are also tested to study how they develop in a weightless environment.
Keeping Things Cool on the ISS
Equipment and experiments that need temperature control are kept cool by a cooling pump that's attached outside the ISS.
If that fails, mission control can try to repair it remotely. In some cases that’s not possible and a couple of astronauts need to do a space walk to go out and fix it.
Space Walk to Fix the Cooling Pump
Astronauts need to wear a space suit that is a complete life support system to do a space walk. This includes the ability to hold waste if they need to relieve themselves.
When working outside the ISS, they have no sense of touch since they are literally floating in their space suits. They need to inch their way along, holding on while they work their way to the cooling pump to replace it with a spare.
At least carrying an 800-pound pump is easy since in space they are weightless, but they still have to be careful not to rub up on anything that might tear their space suit.
One thing they have no control over at all is the concern about micrometeoroids. These small particles can hit their space suit at any time and there is no way to avoid the possibility.
Daily Life on the International Space Station
For a final review of almost everything I explained, you’ll find this video entertaining as NASA Flight Engineer Cady Coleman discusses daily life on the ISS.2
1. National Geographic Channel - Living on the ISS
2. Video from CBS News Program "The Talk" on January 18, 2011
Questions & Answers
© 2017 Glenn Stok