Getting to Know the ISS

On the 20th anniversary of human presence on the International Space Station, dive into the 20 most asked questions about the high-flying international laboratory.

By NASA

Capillary Flow Experiment in Node 2 (2013-05-22)NASA

Why do research on the space station?

The space station is the only laboratory in the world that allows researchers to perform long-term experimentation in microgravity. It allows astronauts to run investigations that are not possible anywhere else, and the information we gather through this has many benefits back on Earth.

Soyuz flyaround imagery of STS-134 Endeavour docked to the ISS (2011-05-23)NASA

How long has the space station been in space?

The space station has been continuously occupied by astronauts since November 2000. However, Zarya, the first module of the space station was launched in November 1998.

View of the ISS taken during flyaround by STS-114 crew (2005-08-05)NASA

How big is the space station?

The space station is about the size of an American football field including the end zones. It weighs almost one million pounds.

Kelly in the Cupola Module (2015-07-12)NASA

How high up is the space station?

The space station flies at an altitude of about 250 miles above Earth. 

Nimoy tribute (2015-02-28) by Samantha CristoforettiNASA

How fast does the space station move?

The space station travels at 17,500 MPH or about 5 miles per second. It orbits the Earth about once every 90 minutes. That means the sun will rise and set 16 times a day.

Baikonur Cosmodrome Edward T. Lu were launched onboard a Soyuz rocket from Baikonur Kazakhstan.NASA

How long does it take to get to the space station?

Travelling from the launch site in Baikonur, Kazakhstan to the International Space Station on a Russian Soyuz can take anywhere from 6 to 48 hours, depending on launch procedures and the station’s position in orbit. 

The final four astronauts to launch aboard a space shuttle wave at NASA's Kennedy Space Center in Florida.NASA

How long do astronauts stay on the space station?

A typical mission is about six months long. However, with NASA’s future long-duration missions, some astronauts have stayed for as long as 340 days to see how microgravity affects the human body during an extended stay in space.

Photos taken inside ISS during EVA day (2013-07-09)NASA

How does your body change while living on the ISS?

Immediately upon entering zero gravity, fluids in your legs and the lower part of your body move upwards towards your head, making your face feel and look swollen. Some astronauts feel dizzy and have an upset stomach while they get used to zero gravity, but this feeling usually goes away after a few days. Crew members also must exercise two hours each day to stay fit and keep their bones and muscles strong.

Expedition 21/STS-129 Crew Members enjoy a meal in the SM/Zvezda (2009-11-23)NASA

What do astronauts eat on the ISS?

An astronaut can choose from many types of foods such as fruits, nuts, peanut butter, chicken, beef, seafood, candy, brownies, etc. Preparation varies with the food type. Since there is no stove or microwave on the space station, most of the food has already been cooked, then freeze dried and vacuum packed, or it is thermally stabilized, much like camping food. These packages of freeze-dried food can be reconstituted by adding water and then warmed up in a small warming oven. Nutritionists ensure the food astronauts eat provides them with a balanced supply of vitamins and minerals. Food has been prepared in the US and by most other nations which have sent astronauts to live on the ISS.

Stefanyshyn-Piper performs first EVA during STS-115 / Expedition 13 Joint Operations (2006-09-12)NASA

What kind of work do the astronauts do on the space station?

Astronauts and cosmonauts on the space station stay busy operating the many science experiments on board. The crew has to make sure that the station is in top shape, so they clean, check equipment, and maintain, repair or replace broken equipment. Sometimes astronauts need to do a spacewalk to do maintenance work on the outside of the station. These extra-vehicular activities, or EVAs, help keep the space station running.

Usachev typing while in sleep station in the Service Module (2001-03-23)NASA

How do astronauts sleep in space?

Space has no "up" or "down," and as a result, astronauts can sleep in any orientation. However, many prefer to attach themselves to something, so they won't float around and bump into anything. Space station crews usually sleep in sleeping bags located in small crew cabins. Each crew cabin is just big enough for one person.

International Space Station (ISS) (2007-05-09)NASA

How many people have flown to the space station?

241 individuals (and counting) from 19 countries have visited the International Space Station.

Advanced Plant Habitat (2018-03-12) by NASANASA

What is the temperature on the space station?

The temperature inside the International Space Station is about 72 degrees Fahrenheit or 22 degrees Celsius. The crew can reset the temperature within a range from about 65 to 80 deg F (18 to 26 deg C). Depending o orientation and airflow, temperatures can vary from one location to another within the interior.

Kondratyev and Nespoli Take Earth Views in the Cupola (2011-03-19)NASA

What time zone does the space station go by?

The space station uses GMT or Greenwich Mean Time. GMT was selected as the time zone for the station as it is around the mid-point for all International Space Station partners.

Padalka poses with an Orlan EVA suit inside the Pirs DC during Expedition 9 (2004-06-10)NASA

How do astronauts wash their clothes?

There is no washing machine on the space station, so astronauts must wear their clothes for several days before changing them. Exercise gear is changed weekly, underwear is changed every few days, while shirts and pants can be worn for weeks.

That will transport them to Launch Pad 39A during their terminal countdown demonstration test activities.NASA

How do you become an astronaut?

To be eligible to become an astronaut in the United States, you must meet four requirements. One, you must be a U.S. citizen. Two, you need to possess a master’s degree in a STEM field from an accredited university or institution. Three, you have to have at least two years of related professional experience obtained after degree completion, or at least 1,000 hours of pilot in command time on a jet aircraft. Four, you must be able to pass the NASA long-duration flight astronaut physical.

Photographic coverage STS-116 crew training underwater in the NBL. (2003-01-07) by Mark SowaNASA

How long do astronauts train before they go to the ISS?

Astronauts are in constant training for space flight. The initial training involves learning about basic space station systems, space walking, and operating the robotic arm. They continue this training while awaiting a mission assignment. Once assigned to a flight, specific training for the mission may take as long as three years. The length of training depends on how complicated the tasks are for the mission. ISS missions require astronauts to speak Russian, which adds time to the training. 

This photo shows the waste and hygiene compartment that will be delivered to the International Space Station on the STS-126 mission.NASA

How do you go to the bathroom in space?

To keep from floating away, you must use foot-loops or straps while ‘sitting’ on the seat. This holds you on to the seat, sort of like a seat belt. Secondly, the space potty uses suction, not water, to ‘flush.’ 

Burbank plays a guitar in the U.S. Laboratory (2011-12-16)NASA

What do astronauts do for fun on the ISS when they have a break?

The space station crews can ask mission control to send them shows that they can watch during dinner or off-duty time. They can also watch movies on their laptops. They may bring books, music and musical instruments with them. Some astronauts enjoy hobbies, such as drawing, photography and HAM radio. They might also spend time looking out the window at the beautiful Earth below, listening to music, surfing the web, or corresponding with friends and family back home.

Expedition 5 astronaut Peggy Whitson has a phone call from home for the second launch attempt to the International Space Station.NASA

Can astronauts call their families from the ISS?

Until a few years ago, astronauts were not able to communicate easily with people on the ground outside of mission control. Now, they can send email to friends and family directly, and they can make phone calls using a hook-up through the computers.

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