Living In International Space Station

How do astronauts live in this Space-House?

Is there any difference in the day to day activities they perform ?

What do they eat? Can they eat Pizza ?

How do they sleep?

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WHAT IS THE ISS

The ISS or International Space Station is the third brightest object in the night sky and clearly visible when there’s no cloud cover. It moves much faster than anything else you are likely to see up there, too. While a typical aeroplane travels at around 965 km/h, the ISS moves at 28,000 km/h. Unlike a plane, there are no flashing lights on the ISS and it travels in a perfectly straight line. A cool thing about ISS that makes it different from Earth is that gravity over there is approximately 0. 

How is Gravity Almost 0 on the ISS ?

Figure 1: The path of the ball being thrown changes with increasing the initial speed.

Let's consider a thought experiment- Let's suppose you are throwing a ball on the surface of Earth. It will take path like path A mentioned in the figure 1, and afterwards, will fall on ground due to gravity. If you can keep a ball throwing hard enough, it will take more and more curved paths until eventually the it will start to orbit the planet ( path C,D). What's happening now ? The ball is still constantly falling towards the ground but is also moving side wards fast enough to miss it. Thus, ball or similarly ISS is in orbit around the earth.

Now, let's consider another experiment - Take a rock and a feather, hold them at a height and note the time each of them takes to hit the ground. As also common sense will suggest, Rock will hit the ground first, thus it falls faster. Now take a vacuum chamber and then repeat the same experiment. Now, you will notice that despite of the mass difference between them, both the rock and feather hit the ground at the same time. It was resistance due to air that was slowing down feather in initial setup! 

Damn! What you just did is the experimentation of one of the central laws of classical physics given by legend Galileo - All Objects of different masses fall at the same speed . Thus, both the space station and the astronauts are in falling or as we discussed above are in 'free fall together', which creates the notion of weightlessness. This weightlessness is essentially responsible for making the life of space station different from Earth.

Even the most basic activities like eating, sleeping, writing and even pooping are affected by it. How ? Let's have a look at them one by one -

1. Writing in Space

 Writing isn't as simple as it looks. Whenever you write something using your pen, it's the force of gravity that is responsible for pushing the ink downwards.( Sounds unbelievable ? Give it a try yourself by writing with tip of pen upwards ;) ) In ISS, there is essentially no gravity so normal pens don't work there, thus initially Astronauts used Pencils to write. But using pencils is kind of unsafe as tips can easily break and drift freely in ISS threatening other sensitive equipments. Moreover, pencils are also flammable, a quality that NASA wanted to avoid after Apollo 1 disaster. 

Figure 2: Fisher's Space Pen

Writing Sounds like a problem now, but not to Paul Fisher, a private investor who reportedly spent 1 million dollars all by himself to create a 'Space Pen' all by his funding. This pen can write in essentially 0 gravity, in extreme temperature limits( -50 to 400 ° F) and even underwater. Instead of gravity the cartridge of this pen is pressurised with Nitrogen at 35 pounds per square inch. The ink also stays gel-like until movement of ball point pen turns it into fluid. In February 1968, these pens were first ordered by NASA ( at $2.39 per pen) and since then astronauts are using this Anti-Gravity pen for writing. Fun fact : According to the Fisher Space Pen Company, the Apollo 11 astronauts also used the pen to fix a broken arming switch, enabling their return to Earth. 

 2. Eating in Space

Figure 3 : Space Food

Eating is less trickier than writing. Swallowing and digestion are possible in space. Free-floating droplets of water can be problematic as they could find their way into sensitive equipment. The same is true of small particles too, and that has implications for eating in space. Food for Astronauts is prepared at Space Food Systems Laboratory at Johnson Space Centre in Houston, Texas. Earlier, Astronauts used to consume food from tubes and in form of dry cubes. Now, the variety and quality has increased as astronauts get to select the meals they like. Currently the variety of food ranges from a fruit salad to spaghetti, from Chinese to Swedish. The lab creates food ensuring peak health and performance for the astronauts. 

Pizza Party in Space
Credit: nasa.gov

The procedure of preparation involves a 'freeze - drying process'. The food is first frozen to -40° F. Then it is put into vacuum chamber and heated so that water content of the food sublimates. This process is repeated multiple times to remove almost all the water content. Exposing cans or pouches to extreme heat and temperature, by a process called thermostablisation (heat treatment) is also applied to make the shelf life of food longer. All these processes aim to prevent the bacteria from multiplying and spoiling the food along with drastically reducing the weight of food, allowing a lighter payload. Space food normally comes in plastic packaging or cans. Tapes, magnets are also used to attach items to surface. Eating liquid is easy as it remains attached to the surface (due to surface tension ). Water used for re-hydration of food is available in pouches.

After eating, they use disinfectant wipes or apply some soap and water solution which is wiped out using a towel.

3. Defecating in Space

 On earth, the force of gravity pushes the waste away from the body which is not the case in space and that is what exactly makes using bathroom in space a tricky business. Any loose drops or dribbles can float around. Thus, the toilets today rely on suction techniques. 

Figure 4: Space Toilet
Credit: nasa.gov

The space is known as bathroom and hygiene compartment. For peeing, astronauts use a funnel ( yellow coloured in Fig 3) attached to a hose that uses a fan to pull the urine into a tank. Urine is normally recycled to be used again. Today's pee is tomorrow's coffee. 

For defecating, there is a toilet which consists of a seat and a container below it which holds about 30 deposits. Astronauts poop by sitting on toilet that relies on the same fan to pull their business. The seat is about 5-6 inches in diameter and there is a plastic bag there where the deposit goes. When done, they seal the bag, push it down the container and install a new one. The solid waste is finally sent back to earth where it burns in atmosphere. 

Figure 5 : NASA's New Space Toilet 
Credit : nasa.gov

However, in the view of the new Artemis 2 mission, which will go to the moon, NASA wanted a new toilet which is more compact and efficient. For this, a brand new space toilet - Universal Water Management System has been built and recently sent to space station for testing. This has been installed next to the adjacent one.

This new space toilet that is more energy efficient, roughly 65 percent smaller and 40 percent lighter than the ones currently in use. In many ways, the new toilet essentially works the same way as its predecessors. It also deals well with 'dual ops' as it allows astronauts to poop and pee at the same time by having urine funnel next to the seat. It also features a 3D-printed titanium dual fan separator, that creates a strong air flow which helps to pull the astronauts’ urine and waste into the toilet. It also has a built-in system that pre-treats urine before it's passed off to the station’s life-support system. Urine can occasionally contain solid material that gets stuck inside the toilet, to mitigate that, there is a highly acidic solution to break down any deposits that might be in the urine. 

4. Sleeping in Space 

Figure 6: Sleeping in space

Astronauts in ISS get 16 sunrises and sunsets in a day, so to schedule the time of sleeping they use cues from the Earth. Sleeping is important as it regulates proper body functioning. For sleeping, astronauts are alloted crew quarters. They are about the size of refrigerator and unlike the space station, it is quite there. Switches regulate the mode of light ( dim, bright, off ) in quarters. For sleeping, there is a sleeping bag in which they sleeping just standing on with the help of chords attached to the bag which keep astronauts attached to the wall, so that they do not break the instruments, or be affected by sir currents on ISS in general. 

This was a mini tour of some of the most basic activities on ISS. Clearly, living in ISS is dominated by the weightlessness. In addition to the complex science experiments that take place there, simple human like activities on ISS also feature high technological requirements and advancements. "Ideally, the ISS program is an incremental step on an expanding, incredible journal of exploration and understanding, taking us higher and farther"