Fascinating Facts About the International Space Station

How much do you know about the largest human-made object in space, the ISS? Here are cool facts about what it is, who lives there, and where you can see it.

Sabrina Stierwalt, PhD
6-minute read
Episode #336

The International Space Station (ISS) is the largest structure humans have ever put into space. In fact, it's so large that it wasn’t launched in its entirety. It was sent up in pieces, and then constructed in orbit. The ISS is also estimated to be the most expensive man-made object ever built. Its hefty price tag exceeds $100 billion. 

So, who uses the Space Station and for what? How big is it, and can we see it from down here on Earth? Let’s get to know the ISS.

What is the International Space Station used for?

A variety of scientific experiments are being conducted on the International Space Station every day. For starters, the ISS offers us a unique opportunity to view our planet from the outside. Astronauts at the space station conduct experiments that include things like aiding with storm forecasts and testing satellite technology. 

Astronauts aboard ISS also perform particle physics experiments like using the Alpha Magnetic Spectrometer-02 to look for dark matter and antimatter particles without the background noise that would normally dampen such a signal down here on Earth. 

Inhabitants of the space station also participate in studies of how the human body—including our muscles, bones, heart, and eyes—change without the presence of Earth’s full gravity. In NASA’s unique twin study, Astronaut Scott Kelly was studied for physiological, molecular, and cognitive changes during and after spending nearly a year in space in comparison to his retired astronaut identical twin brother Mark Kelly. Among the key findings of the twin study was the determination that our immune systems work in space just like they do on Earth. Astronaut Scott Kelly gave himself a flu vaccine while aboard the ISS and his immune system responded just as we would expect it to respond.

Inhabitants of the space station also participate in studies of how the human body—including our muscles, bones, heart, and eyes—change without the presence of Earth’s full gravity.

Astronauts also learn how to keep spacecraft functioning. They get to test out new technology for future space missions. These technological developments, combined with human biology studies, are our first steps toward the longer space missions which will be required for exploring other worlds. A trip to Mars, for example, would take at least three years round trip. 

Astronauts and cosmonauts are also tasked with maintenance, including spacewalks to conduct repairs. To combat the bone density and muscle loss known to occur in microgravity, they also have to fit in at least two hours of exercise each day. You can check out Canadian astronaut Chris Hadfield’s series of videos about life on the ISS to get a look at what its like to brush your teeth, wring out a washcloth, make dessert, and even sleep in microgravity. 

Who uses the International Space Station? 

The ISS was built and is run as an international partnership, which requires a significant amount of planning, coordination, and communication between space agencies. The major partners are the United States (via NASA), Russia (via the Roskosmos program), Europe, Japan, and Canada. Each space agency has contributed different equipment and, impressively, elements launched from different countries were only joined together for the first time in orbit.  

Who is on the ISS now?

The ISS has been continuously occupied since November 2, 2000. Sometimes the crews are as small as two people; other times there are as many as 13 crew members. For example, the ISS might have more occupants during shift changes or visits from the space shuttle. As of March 2019, those visitors have included 230 individuals from 18 countries, although the most frequent visitors are from the United States and Russia. To see who's there now, check out NASA’s ISS expeditions page. 

Since the retirement of NASA’s space shuttle program in 2011, the Soyuz spacecraft is the only way for astronauts to get to the space station. There are also two Russian Soyuz vehicles docked there in case evacuation becomes necessary. 

The private company SpaceX aims to have its Dragon spacecraft be the first private spacecraft to bring crew members to the ISS.

However, the private company SpaceX aims to have its Dragon spacecraft be the first private spacecraft to bring crew members to the ISS. It already had a successful test run, without the crew on board, in March of 2019. The Dragon cargo spacecraft was the first private spacecraft to dock with the ISS and provided cargo back in 2012.

How big is the ISS?

The space station is 357 feet (109 meters) from one end of the truss—that’s the long arm spanning the length of the station—to the other. The whole station has a mass of ~925,000 pounds. The space where the astronauts live and work is larger than a six-bedroom house and includes two bathrooms and a gym. The pressurized volume on board the ISS is about the same as that of a Boeing 747 and extends 240 feet (or 73 meters).  

How fast is the ISS moving?

The Station orbits the Earth every 90 minutes, which adds up to 16 orbits every day. The ISS travels at a speed of 5 miles per second or ~18,000 miles (or ~29,000 kilometers) per hour. So each day the ISS views 16 sunrises and sunsets while traveling a path that is just shy of the distance to the Moon and back. 

Each day the ISS views 16 sunrises and sunsets while traveling a path that is just shy of the distance to the Moon and back.

How is the ISS powered?

Several arrays of solar panels collect energy from the Sun in order to power the station. Added together, these panels cover an area of 27,000 square feet or 2,500 square meters which is nearly half of a football field. 

Where is the ISS?

The space station orbits at an average altitude of 248 miles (that’s 400 kilometers) above the Earth and can be seen from down here even without the aid of a telescope. Using NASA’s Spot the Station, you can get a list of upcoming sighting opportunities for your home city or town. Then keep an eye out for what looks like a fast-moving plane. 

Keep an eye out for what looks like a fast-moving plane.

The path of the space station passes over 90% of the population. You can see photos the ISS crew has taken of us here at the Gateway to Astronaut Photography of Earth. 

What records have been set with the ISS?

The most consecutive days spent in space by an American is 340 days. Astronaut Scott Kelly set that record when he spent nearly a year at the space station in 2015-2016 along with Russian cosmonaut Mikhail Kornienko. However, the longest stretch of time spent in space is the 438 consecutive days Russian cosmonaut Valery Polyakov spent aboard the Mir space station in 1994 and 1995.

The record for longest spaceflight by a woman was set by Astronaut and biochemist Peggy Whitson who spent 289 consecutive days in space in 2016-2017. Astronaut Christina Koch, who is on board the ISS now, is expected to break that record when she returns from a 328-day mission in 2020. 

The record for longest spaceflight by a woman was set by Astronaut and biochemist Peggy Whitson who spent 289 consecutive days in space in 2016-2017.

Peggy Whitson, also the first woman commander of the ISS, has spent the most total time in space for a NASA astronaut at 665 days. She set that record in September of 2017. The world record is held by Russian cosmonaut Gennady Padalka who has spent a whopping 879 days in space. 

NASA astronauts Susan Helms and Jim Voss conducted the longest spacewalk in 2001 during the construction of the ISS. It lasted 8 hours and 56 minutes. 

NASA scheduled the first all-female spacewalk for March 2019 but then quickly canceled it because there were not enough appropriately-sized space suits to accommodate both women. 

What is the future of the ISS?

There are plans to continue to operate the International Space Station until 2024, but beyond that, the future for ISS is unclear. If the international partnership chooses not to continue to maintain and operate the space station, it could possibly be deorbited or recycled. 

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Until next time, this is Sabrina Stierwalt with Ask Science’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of Ask Science on Facebook or follow me on Twitter, where I’m @QDTeinstein. If you have a question that you’d like to see on a future episode, send me an email at everydayeinstein@quickanddirtytips.com. Listen and subscribe on Apple Podcasts, Spotify, Google Podcasts, Stitcher, or your favorite podcast app.

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About the Author

Sabrina Stierwalt, PhD

Dr Sabrina Stierwalt earned a Ph.D. in Astronomy & Astrophysics from Cornell University and is now a Professor of Physics at Occidental College.