Oxygen in Space

How Do Astronauts Breath in Space Station and Outer Space?

Science & Technology

Astronauts (the driver and passenger themselves) who visit the space have to undergo so many difficulties. They need to be expert in all the aspects of space science and technology.  We have an abundance of oxygen for breathing on the earth up to 80kms. Above which, no one can hear you talking, because there’s no air in the space. If this so, then how astronauts breathe in outer space? Come let’s find it here:

How Oxygen(O2) is Generated and Carbon Dioxide(CO2) is Recycled

The primary requirement for any astronaut is to get oxygen to stay alive in space, which is possible only when oxygen is supplied externally to them. For this, the electricity at the International Space Station (ISS) is used to run systems and convert water into hydrogen and oxygen.Oxygen in Space and ISS

The mechanism at ISS replicates the science adopted by the plants to provide oxygen, the photosynthesis process. ISS has two modules that perform this task the ‘Elektron’ (Russian Module) and the ‘Oxygen Generating System’ (American Module). To understand the breakdown of water into hydrogen and oxygen below mentioned equation can be referred:

2H2O >>>> 2H2 + O2

The hydrogen generated in the reaction is dumped overboard to Sabatier System for further processing and oxygen is sent over the internal atmosphere of ISS for breathing. This process of electrolysis of water provides about 5.4 kgs of oxygen per day for four people. However, it can be increased up to 9 kgs when there are six astronauts on board.

What about the CO2 (Carbon Dioxide) Exhaled by Astronauts?

To recycle the CO2 to oxygen another mechanism is used. In ISS, CO2 is captured by preinstalled CO2 scrubbers. The hydrogen generated due to the above-shown mechanism in again combined with CO2 exhaled by astronauts in Sabatier System. This, in turn, makes Water and Methane as per the below-shown equation.

4H2 + CO2 >>>> 2H2O + CH4

The water produced in this reaction is again converted into hydrogen and oxygen through electrolysis. The water recovery systems in ISS catches water from showers, sinks, and water vapors in the air inside ISS, and feed it into the oxygen generators. This process continues and astronauts get the regular supply of oxygen.  

Production of Water from Urine of the Astronauts

The Urine of astronauts is also a source of water. It is also processed to produce more water. Generally, the systems can extract out 85% of the water in the collected urine. But, due to the microgravity (vacuum) conditions of the ISS, astronauts experience loss of bone density, which increases calcium levels in the urine resulting in reduced water recovery (about70%) from urine.

Electricity for Oxygen Generation

Space Station uses solar cell arrays to generate electricity and run all the systems. ISS solar cells can generate around 131 kilowatts during a sunlight period (i.e. only for slightly more than half of each orbit while the ISS is in sunlight). When ISS is in the Earth’s shadow for around 35 minutes, nickel-hydrogen batteries provide electricity to our space home. These batteries are rechargeable.

Backup Oxygen Systems

ISS has backup for oxygen supplies. It has solid fuel oxygen generator canisters having Lithium Perchlorate. It can provide enough oxygen for one person for one day. As a backup of this canisters system, emergency cylinders of compressed oxygen are available. a Russian Progress spacecraft flies to ISS to provide necessary water and other supplies to the ISS in the emergency situations.

What Happens during Spacewalk?spacewalk

Obviously, astronauts cannot breathe in space as there is vacuum all over outside the ISS. On a spacewalk, they wear the pressurised suit, equipped with oxygen cylinders to breathe. This suit is EVA (Extra Vehicular Activity) suit. The NASA astronauts Jim Voss and Susan Helms on Year 2001 performed the longest spacewalk. They worked on repair of some equipment outside the ISS and used the oxygen cylinders for the duration of 08 hours and 56 minutes.

About the International Space Station (ISS)International Space Staion

The ISS is huge. We from the earth can easily see it with the naked eye, especially at night. It’s dimensions are:

  • 108 metres wide
  • 73 metres long
  • 20 metres high

It revolves around the Earth orbits every 93 minutes, (i.e. Orbit Time = 93 Mins) at a speed of 27,700 Kms/hour. It is at a height of 330 – 435 Kms above the Earth’s surface.

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