The International Space Station (also known as ISS) is an artificial satellite that orbits the Earth at an altitude of at least 321.8 kilometers (200 miles). There are 5-6 astronauts on the ISS doing research, experiments, and so on. They do a range of things that give us a better understanding of how everything will work in space.

International Space Station

International Space Station: The International Space Station is the most expensive object ever built by man (Photo: Wikipedia)

It is obvious that there must be some mechanism, some system to ensure that the astronauts are as comfortable as possible on the space station.

As we all know, water, food and oxygen are the three main necessities for human to survive. In other previous articles we have described how astronauts get drinking water in space, so in this article we will learn how astronauts get air to breathe on a space station far from the Earth’s surface.

Electrolyzed Water

In fact, electrolysis of water is the most basic method of oxygen production on the International Space Station. But what exactly is “electrolysis” in electrolytic water?

The word “electrolysis” refers to the process of chemically breaking down a liquid or solution containing ions by passing an electric current through it. Therefore, electrolysis of water means passing an electric current through water to break it down into its basic chemical components, hydrogen and oxygen.

Electrolysis of water: Schematic diagram of electrolysis of water

Such way to produce oxygen is not only used on the ISS.  Think about it, the oxygen we breathe on the Earth is actually formed by a similar process. The difference is that water is not broken down into hydrogen and oxygen by a mechanical process like electrolysis, but by photosynthesis of grasses, algae and plankton(the conversion of water into oxygen and other organic matter and the release of oxygen).

As shown above, water is composed of two hydrogen atoms and one oxygen atom. During the process, these two parts are separated and reconstituted into hydrogen and oxygen.

NASA has designed an oxygen production system (also known as OGS) to produce oxygen by electrolysis of water. The oxygen thus produced is vented into the ISS module. Thus, this oxygen production system is part of the Environmental Control and Life Support System (ECLSS) on the ISS.

The three cabinets in the picture display the environmental control and life support systems on the International Space Station, including water purification systems, and oxygen production systems.

On this system, the water purification system is also very important, which will work together with the oxygen production system.

Oxygen can be obtained through electrolysis of water, and how does the water on the ISS come about? Well, let’s go into the water purification system on the International Space Station

Collection of water in the space station

Water purification system is a member of the environmental control and life support system on the International Space Station, which can recycle the astronauts’ urine, and other waste water generated by various activities inside and outside the cabin.

The water in the purification system must be  tested rigorously so that it is absolutely pure and able to meet the needs of the astronauts, laboratory animals, extravehicular activities, and daily activities inside the cabin.

The water is also electrolyzed to create the oxygen needed for breathing.

Pressurized Oxygen Cylinder

Pressurized oxygen cylinders provide a backup source of oxygen for the module in addition to electrolysis. These oxygen cylinders were delivered to the station by an unmanned space cargo ship. These oxygen cylinders are placed on the ISS for emergency use.

In addition to these two methods, the astronauts also generate oxygen through solid fuel tanks (known as SFOG), which store lithium perchlorate. Each fuel tank is capable of providing a limited amount of oxygen for the crew.

Relative Knowledge

The International Space Station (ISS) is a scientific research facility operating in  low earth orbit  and the ninth manned space station in human history. The main function of the station is to serve as a research laboratory in a microgravity environment , including the fields of biology, physics, astronomy, geography, meteorology. It is currently operated in cooperation with five countries or regions, including NASA, the Russian Federal Space Agency, the Japan Aerospace Exploration Agency, the Canadian Space Agency, and the European Space Agency.

Russia’s Mars-500 building’s three-dimensional plan is based on ground-based tests to complement those based on the International Space Station – for preparing a manned mission to Mars.

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