That's no moon, it's the ISS

Astronauts must travel more than 200km to reach the ISS. (Nasa)

Astronauts must travel more than 200km to reach the ISS. (Nasa)

It is larger than a six-bedroom house, and with a price tag of more than $150-billion, it is possibly the single most expensive thing that mankind has made to date.

On July 12, the International Space Station (ISS) celebrated 5 000 days of occupation, marking a momentous day for science and international co-operation. On its anniversary, the space station, which is technically a habitable artificial satellite in low-earth orbit, had travelled more than 2.5-billion kilometres.

Here are some little-known facts about humanity’s only permanent habitation outside of Earth:

•?In many ways, the space station is a really big computer – technically 52 computers linked together – and everything from the temperature regulation to its ability to communicate with people on Earth is controlled through a warren of wiring. There is 12km of electrical wiring alone, and if you were to lay it out and walk its length, it would take you more than two hours.

•?The space station has its own gymnasium, and Nasa has developed an “advanced resistive exercise device” to stop astronauts’ bones from weakening in the reduced gravity. With its adjustable exercise bars and vacuum cylinders, it is the most expensive home gym machine that ever there was.

•?This metal home away from home is entirely powered with energy from the sun, and the station’s more than 4 000m2 of solar panels provide about 75-90 kilowatts of power.

•?This large hunk of metal, which hosts billions of dollars worth of scientific equipment and usually six astronauts, weighs about 420 tonnes, which is the equivalent of about three blue whales or 280 VW Golfs.

•?Between 278km and 460km from the Earth, the station travels at an average speed of 27.743km/h and orbits the planet 16 times a day.

•?One of its functions is as a space laboratory – a microgravity environment – which allows researchers to conduct experiments into how systems, such as biological and physical, among many others, operate in space. According to the ISS’s research programme, the station is well situated to test spacecraft and equipment for moon and Mars missions.

•?According to European Space Agency astronauts, you have to be careful where you attach your sleeping bag to the wall.

“Somewhere in line with a ventilator fan is essential. The airflow may make for a draughty night’s sleep but warm air does not rise in space so astronauts in badly-ventilated sections end up surrounded by a bubble of their own exhaled carbon dioxide. The result is oxygen starvation: at best, they will wake up with a splitting headache, gasping for air.”

•?No one nation could afford to build and maintain the station and the astronauts on board. That’s why the ISS programme is a joint initiative between the United States, Canada, Russia, Europe and Japan. It’s planned to continue operating until 2024.

•?The space station is still a work in progress. It’s a bit like building a very big model aeroplane, but the pieces are in a box in the corner of the room and you can only attach one piece at a time. This is why Nasa notes: “Additional launches will continue to augment these facts and figures, so check back here for the latest.” Who knows what the station will look like in another 5 000 days?

Sarah Wild

Sarah Wild

Sarah Wild is a multiaward-winning science journalist. She studied physics, electronics and English literature at Rhodes University in an effort to make herself unemployable. It didn't work and she now writes about particle physics, cosmology and everything in between.In 2012, she published her first full-length non-fiction book Searching African Skies: The Square Kilometre Array and South Africa's Quest to Hear the Songs of the Stars, and in 2013 she was named the best science journalist in Africa by Siemens in their 2013 Pan-African Profiles Awards. Read more from Sarah Wild

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