Space Stations

On space stations, the crew live in microgravity which means everything floats! This happens because the station is in free fall around the Earth. Everything inside falls at the same rate - it does not matter how much mass it has. The station, its crew, and any objects on board fall together. So if you are inside, everything floats with you.

But there is still gravity in space. Space stations fall around the Earth because of gravity and momentum. The space station's momentum wants to carry it off into space in a straight line. The Earth's gravity pulls it back towards the Earth. The constant tug of war between these forces creates a curved path. Use our orbits demo to experiment for yourself!

Space stations are science labs in space. Doing experiments in space lets us study the effects of weightlessness. 

Long periods of time in microgravity affects the human body. The crew's muscles and bones get weaker if gravity isn't making them work as hard. 

So space agencies use space stations to study weightlessness before they send people on long missions. They also test the technology that a crew will need on a long mission to Mars. 

Things act and behave in strange ways in space. Without the pull of gravity, flames are rounder and crystals grow better. Comparing the results to what we see on Earth increases our science knowledge. We also use space stations to study our own planet from above.

The most famous space station today is the International Space Station or ISS. It is a spacecraft large enough for several astronauts to live on at once. It orbits the Earth 400 km above our planet's surface, travelling at 27,600 km/hour. This means it completes an orbit of the Earth in 90 minutes! You can sometimes see the ISS at night - you don't need a telescope. It looks like a small, bright dot moving quickly across the sky. You can find out where and when the ISS will appear in the sky with Spot the Station. 

Space agencies around the world work together to build and use the ISS. NASA launched the first piece of the ISS in 1998 from the Kennedy Space Center in Florida, USA. Between 1998 and 2000, more pieces were added until the ISS was safe for the crew to live on.

The US Space Agency has announced that the ISS will be used until 2030. In 2031, it will crash down into the Pacific Ocean. This part of the ocean, known as the 'spacecraft cemetery,' is the point on Earth furthest from any land. Other space junk, including a previous space station called Mir, has crashed here. 

Russia's space program operated the Mir space station for 15 years, from 1986 to 2001. It was the first modular space station with 7 sections or 'modules'. Cosmonauts pieced the station together between 1986 and 1996 while it was in orbit.

America also had its own space station prior to the ISS being built. It was called Skylab and was in orbit around the Earth from 1973 to 1979. Inside Skylab, there was a workshop, a solar observatory, science equipment, and a living space for its crew.

NASA expected Skylab to orbit the Earth for 8 to 10 years. However, in 1977, NASA discovered that its orbit was bringing it closer to Earth. On 11th July 1979, Skylab re-entered the Earth's atmosphere, burning and breaking into pieces as it fell.

More recently, China has also built its own space station, Tiangong, which means 'heavenly palace'. The Chinese space agency launched the core module into Earth's orbit in April 2021. Two additional modules were added in 2022, which are used for experiments. The core module is called Tianhe, the old Chinese name for the Milky Way. 

The first crew arrived at the ISS on 2nd November 2000, but the station was not complete until 2011. The ISS has two sections: the Russian Orbital Segment and the United States Orbital Segment. Inside the ISS, there are science labs, control stations, and living quarters connected by 'nodes'. Energy from the Sun provides electricity to the ISS. Huge solar panels on each side of the space station collect light from the Sun.

A crew of 6 or 7 men and women from various nations around the world lives on board the ISS for 6 to 12 months at a time. The crew does science experiments and studies the Earth and space weather. They also study how materials and technology work in space and space medicine! The crew exercises for 2 hours each day to keep their muscles and bones healthy. 

The crew enter and exits the ISS through airlocks. This lets them go outside to add improvements to the ISS and fix any problems. When they are outside the station, we call this a spacewalk, though the official name is an extravehicular activity (EVA). Large robotic arms on the spacecraft help them to move scientific equipment around the outside of the space station. Docking ports allow other spacecraft to connect to the ISS to bring other astronauts or supplies.

Mir was the first research station in orbit where the crew could live for long periods of time. A crew member was on board Mir for 3,644 days (nearly 10 years) without interruption. Three astronauts could live on board Mir at a time, but more astronauts could visit for shorter periods. The first British astronaut, Helen Sharman, visited Mir in 1991. In Mir's labs, astronauts grew the first wheat from seed in outer space. 

The Skylab missions were the first to regularly include a scientist in a space crew. The crew spent time doing science experiments, making repairs to the craft, doing chores, and exercising. NASA built Skylab to study the Sun and prove humans could live in space for long periods of time. It also used Skylab to learn how much radiation the crew was exposed to in space. On Earth, the air protects us from space radiation., but in space, it is a bigger risk to human health.

In the Chinese space station Tiangong, astronauts have everything they need to live and work, including a kitchen, sleeping and hygiene areas, and safety. It is large enough for 6 astronauts to live and work there at a time, but there is usually a crew of just 3 people on board. It has been home to Chinese astronauts since June 2022.