Payload Blog

The 20 Most Frequently Asked Questions about the International Space Station

As we celebrate the 20th anniversary of humans living and working in space aboard the International Space Station, you may ask, why? Why would humankind live and work in space? President Ronald Reagan answered this question best:

“We can follow our dreams to distant stars, living and working in space for peaceful, economic, and scientific gain. … A space station will permit quantum leaps in our research in science, communications, in metals, and in lifesaving medicines which could be manufactured only in space. We want our friends to help us meet these challenges and share in their benefits.”

Keep reading below to see the answers to more of the most frequently asked questions about this achievement in science and international cooperation.

  1. What is the International Space Station?

    The International Space Station (ISS) is Earth’s only microgravity laboratory that has allowed more than 3,600 researchers in 106 countries to conduct more than 2,500 experiments – and the research continues. The space station is a symbol of international cooperation that has benefited life back on Earth economically, technologically, scientifically and educationally.

  2. Can I see the ISS from Earth?

    At dawn or dusk you’ll be able to see the space station with your bare eyes as the third brightest object in the sky. It will also be moving across the sky, similar to an airplane, but without flashing lights. Track where the ISS is right now using NASA’s Spot The Station tool.

  3. What does the ISS look like?

    This photo of the ISS was taken in 2018 by Expedition 56 crew members from a Soyuz spacecraft undocking.
    This photo of the ISS was taken in 2018 by Expedition 56 crew members from a Soyuz spacecraft undocking. Credit: NASA/Roscosmos

    The ISS is constructed of many connected modules called “nodes” connecting the station together. The solar arrays are connected to the station with a long truss, which controls the space station’s temperature. The ISS also has robotic arms mounted outside the station.

  4. How far away is the ISS?

    The space station orbits Earth at an average altitude of 227 nautical miles/420 kilometers above Earth.

  5. How big is the ISS?

    The ISS measures 357 feet or 108 meters from end-to-end, which is about the size of an American football field. The space station has a mass of nearly 1 million pounds. When it comes to living in space, the ISS is larger than a six-bedroom house.

  6. How fast does the ISS travel?

    The ISS travels at about 17,500 miles/28,000 kilometers per hour. At this speed, the ISS orbits the Earth every 90 minutes, which gives the crew 16 sunrises and sunsets every day. Since humans have been living and working on the space station, it has orbited Earth tens of thousands of times.

  7. How old is the ISS? How long has it been operational?

    Plans for the ISS first began 36 years ago when President Ronald Reagan directed NASA to develop a permanently internationally crewed space station. Over 20 years ago, in 1998, the first modules of the ISS were launched into space. Now in November 2020, the ISS will celebrate 20 years of humankind permanently occupying the space station.

  8. How many countries are involved in the International Space Station?

    The partnership of five space agencies representing 15 countries provide for and operate the ISS. These countries include the United States, Russia, Canada, Japan and the participating countries of the European Space Agency.

  9. How was the ISS built?

    Astronaut Stephen K. Robinson, STS-114 mission specialist, is anchored to the extended ISS’s Canadarm-2 during a spacewalk to repair the Control moment Gyroscopes.
    Astronaut Stephen K. Robinson, STS-114 mission specialist, is anchored to the extended ISS’s Canadarm-2 during a spacewalk to repair the Control moment Gyroscopes. Credit: NASA

    Constructing the ISS was a joint mission over the course of 13 years by many countries including the United States, Russia, Japan and Europe. Different modules of the ISS were constructed on Earth by thousands of engineers and launched by Russia’s Proton rocket and the United States’ space shuttles.

    Fun Fact: Space shuttle Atlantis on display at Kennedy Space Center Visitor Complex delivered the U.S. laboratory module Destiny along with many other vital components.

  10. Who is on the ISS?

    As of mid-October 2020, six astronauts are aboard the ISS. Keep up to date with who is on the station at NASA ISS webpage. Four astronauts are preparing to launch soon on a SpaceX Crew Dragon, including NASA astronauts Michael Hopkins, Victor Glover, Shannon Walker and JAXA astronaut Soichi Noguchi. Learn more about this launch and other upcoming launches on the launch calendar.

  11. How long do astronauts stay on the ISS?

    Expedition 42 Flight Engineer Samantha Cristoforetti of the European Space Agency (ESA) prepares her dinner.
    Expedition 42 Flight Engineer Samantha Cristoforetti of the European Space Agency (ESA) prepares her dinner. Credit: NASA

    The average mission length for an astronaut is six months or 182 days, but the amount of time varies based on their mission.

  12. Who has been on the ISS the longest?

    Astronaut Scott Kelly holds the record for the longest single spaceflight at 340 days. For the longest cumulative days in space, astronaut Peggy Whitson holds the record at a total of 665 days.

    Fun Fact: Astronaut Scott Kelly is one of the 2020 Astronaut Hall of Fame inductees. Visit the Astronaut Hall of Fame to learn more about this prestigious honor.

  13. How many people have been on the ISS?

    A total of 240 astronauts from 19 different countries have been aboard the ISS.

  14. How many people can be on the ISS at one time?

    The ISS is designed to support a crew of six people at one time.

  15. What do astronauts do on the ISS?

    An astronaut's primary job while on the space station is to conduct scientific experiments and maintain the space station. When not working, astronauts do a lot of the same things we do on Earth. Astronauts also complete a two-hour daily exercise program to remain fit. They eat a variety of foods, although some of it has to be rehydrated. When astronauts are ready to sleep, they stay in special sleep bags secured to the ways of their crew quarters.

    Fun Fact: The Space Shuttle Atlantis® exhibit contains the ISS: Triumph of Technology section that contains real space-flown artifacts from the ISS.

  16. How do astronauts use the restroom on the ISS?

  17. How many spacewalks have been done on the ISS?

    In order to maintain and upgrade the ISS, over 227 spacewalks have been completed.

  18. How many experiments have been conducted?

    More than 2,800 experiments have been conducted so far.

    Fun Fact: Part of one such experiment was conducted here at the visitor complex’s Mars Base 1 botany lab, to learn how microgravity affected the growth of tomatoes.

  19. What research is being done on the ISS?

    Over the years, many activities and research projects have been completed. For example, advances have been made in saliva testing to detect active viruses which allows for faster, less-invasive testing. Additionally, over 500 microgravity protein crystal-growth investigations have been conducted. This research helps find better treatments for diseases such as cancer and muscular dystrophy.

  20. How will the ISS help us get to the Moon again?

    Distant view of the Moon over Earth limb taken by the Expedition 37 crew aboard the International Space Station (ISS). An ISS solar array is also visible.
    Distant view of the Moon over Earth. Credit: NASA/Expedition 37 crew

    The ever-growing body of research that has been conducted on the ISS has given many insights into the needs of future lunar explorers. NASA’s next step for space exploration is to set up a permanent base for humans to live on the Moon – the long duration human spaceflight aboard the ISS has provided many answers on how that will happen. The ISS has led to advances in spacesuit design, experience on spacewalks and the creation of strong meteorite protection.

Still have more questions? Visit Kennedy Space Center Visitor Complex to explore the story of NASA, from the first rocket launches to the Apollo program to the International Space Station. Learn about the pioneers of space exploration at Heroes & Legends who proved that humans could exist in space, before humankind ever considered living among the stars. Visit Space Shuttle Atlantis® to see how the Space Shuttle Program brought new modules, supplies and astronauts to the International Space Station.