• Experiments are happening all the time on the International Space Station, including growing food in microgravity.
  • The experiments could help people with long-term and chronic health conditions.
  • Daily routines are different from on Earth, including being strapped down to use the toilet - and having liquid salt and pepper.
  • You can see the ISS fly overhead with the naked eye.

It’s the third brightest object in the night sky, orbits the planet every 90 minutes, and has cost upward of an estimated $100 billion. But what is the International Space Station (ISS) for and what do the astronauts on board actually get up to?

a diagram of NASA's international space station
This complex structure is almost as big as an American football field.
Image: NASA

Space to grow

The ISS is a giant research facility where various experiments are under way at any given time, looking at everything from biology to technology, with implications for life in space and on Earth.

They include growing food in microgravity at the two Vegetable Production System (Veggie) plant growth units on board, and in the more sophisticated Advanced Plant Habitat growth chamber.

Being able to grow food in space could be an important part of planning longer space journeys, and in 2015, astronauts grew and ate their first space-grown salad.

NASA says: “The Veggie concept is a simple, low-power system to grow fresh, nutritious food for our astronauts to supplement their diet and use as a tool to support relaxation and recreation.”

Other experiments have more down-to-earth implications and benefits for the rest of humanity. Prolonged periods in a microgravity environment can lead to loss of bone and muscle strength.

How this occurs and how it can be reversed is helping inform treatments for people living with chronic conditions like osteoporosis or whose muscles are affected by conditions that limit their mobility.

Daily routines

When they’re not working on research, the astronauts have a regular checklist of maintenance tasks around the ISS to work through.

The crew get a daily update from Mission Control on activities they need to complete. That includes checking the life support systems are functioning properly, carrying out regular cleaning procedures and performing software updates.

There are lots of regular activities we take for granted that, on the ISS, are more complicated, such as personal hygiene. Microgravity makes using a toilet a major undertaking. There are leg restraints to keep the astronaut seated securely and an arrangement of fans and vacuum pumps to dispose of waste matter quickly and safely.

Free-floating droplets of water can be hazardous on the ISS, as they could find their way into sensitive equipment and cause problems. The same is true of small particles too, and that has implications for eating in space.

Here on terra firma, we routinely sprinkle salt and pepper onto our meals. Nothing sprinkles in a simple downward direction in space, though, and the risks of tiny grains of pepper and salt getting lodged somewhere they shouldn’t are high. So, they are available in liquid form instead.

The crew of the ISS get three meals a day and some of the food they eat is no different to what they might enjoy back home. Fruit, for example, and brownies too are available in their natural forms. Other food is stored dry and has to be mixed with water before it is cooked; there is an oven on the ISS, but there are no refrigerators.

Thinking space

There is also plenty of free time and a range of non-research activities for the crew. In 2013, the Canadian astronaut Chris Hadfield recorded himself playing and singing a version of David Bowie’s song Space Oddity, which has been viewed almost 49 million times on YouTube.

Astronauts regularly share stories and photos via social media, keeping in touch with space-watchers far below. They also take part in educational sessions via video, discussing science and space with school students around the world.

The ISS is the third brightest object in the night sky and clearly visible when there’s no cloud cover. It moves much faster than anything else you are likely to see up there, too. While a typical aeroplane travels at around 965 km/h, the ISS moves at 28,000 km/h. Unlike a plane, there are no flashing lights on the ISS and it travels in a perfectly straight line.

a diagram explaining how you can spot the International Space Station
This is how you can spot the ISS.
Image: NASA

The best time to see it is shortly before or after sunrise or sunset. That’s because it is still reflecting the sun’s rays from its elevated orbit, which makes it easier to see.