The International Space Station at 20

This week marks the 20th anniversary since the International Space Station was first inhabited. Let’s take a look at what it is and what happens there. The International Space Station is an orbiting space station and laboratory. It was built and is operated by an international consortium of space agencies. The five agencies involved are NASA (USA), ESA (European Space Agency), Roscosmos (Russian Space Agency), JAXA (Japanese Space Agency) and CSA (Canadian Space Agency).

International Space Station from the Space shuttle in 2010 Credit: NASA

Construction of the ISS was a major engineering challenge. It was built module by module and each module was lifted to orbit by either a Russian proton rocket or the Space Shuttle and assembled in space. This all happened around 400km above the Earth while the station orbited at about 27,500 km/ph. The first module to be sent into space was a Russian module called Zarya, which was launched on 20th November 1998. It was followed by the Zvezda module. The first crew, called Expedition 1 arrived to the station on 2nd November 2000. Since then, the ISS has been permanently inhabited by astronauts. Over subsequent years, the station has had modules added but progress on the construction was halted for a number of years after the Columbia disaster in 2003. Although the station was mostly finished by 2011 the station does continue to evolve. The below gallery shows the evolution of the station over the years.

The next diagram shows each of the modules and components that make up the International Space Station and what county contributed it. Modules have various functions. Some are pressurized living areas, others are laboratory space. In addition to this, there are robotic arms, solar panels, airlocks, docking ports and a viewing window called the Cupola.

Diagram of the components of the ISS. Credit: NASA

The station has the capacity for 7 astronauts although the number of astronauts on the station can vary depending on the launch schedule. Each permanent crew to the ISS is assigned an expedition number. Each expedition is usually about 6 months in duration. Living in micro gravity is obviously challenging and living conditions aboard the station are different to those on Earth. Crew members have small sleeping quarters and given that there is no up or down in space they normally sleep in a sleeping bag which is fixed to the wall of the space station. This prevents them from floating away while they sleep. Some crew also strap themselves inside the sleeping bag.

When it comes to washing and the toilets, astronauts use damp cloths for washing as water is in very short supply. They also use edible toothpaste. To use the toilet astronauts strap themselves to the seat and a strong fan pulls down the waste and stops it from floating away. The urine from the toilet is recycled to make fresh water! In space every drop of water is precious.

The time zone aboard the space station is universal time (UT) and the astronauts work to a very strict time schedule. A typical day starts with a wake up call at 6am, this is followed by breakfast, morning safety checks and a briefing with mission control. Work starts at 8.10am. The crew will spend their day doing numerous science experiments that are sent by companies, universities and scientists. They also conduct maintenance, public relations work and many other duties. Time is scheduled for eating, exercise and they get some free time each evening. Each astronaut needs to exercise about 2.5 hours each day to ensure they don’t loose too much bone and muscle mass due to the lack of gravity.

The supplies and experiments are delivered to the ISS by supply vehicles such as the Space X Dragon. These vehicles also carry away the rubbish and waste produced by burning up in the atmosphere. The International Space Station is expensive and as of 2010 it is estimated that it has cost $150 billion to build. This is a huge amount of money but a lot of the science that is conducted aboard the station couldn’t be done on Earth. The astronauts aboard the station regularly contribute to research into long duration human space flight. There are also lots of experiments that have implications close to home. For example, treatments for many illnesses are manufactured by designing protein crystals that fit the defect in the gene. It turns out these crystals can be grown much better in microgravity and research into this is being conducted on the ISS.

Some facts about the ISS

  • 241 people have visited the station.
  • The station orbits the Earth 16 times per day. This means 16 sunrises and sunsets.
  • Nearly 3000 research investigations have been carried out aboard the station.
  • There are 350,000 sensors to ensure the station is functioning properly.

It is possible to see the ISS pass overhead from time to time and you can find the times to see it at Don’t forget to wave the next time you see it fly over!

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