Skip to main content
Physics LibreTexts

3.21 International Space Station

The idea of an orbiting space station was proposed as early as 1869, in a story by Edward Hale about a "Brick Moon" that helped ships navigate at sea. In the 1950s, Wernher von Braun, was an early rocket scientist who worked on the V2 rocket for the Germans during WWII then came to the U.S. to design the Saturn V rocket that went to the Moon. He conceived a space station as an orbiting “wheel.” In his model the station rotated to create artificial gravity, and it would eventually serve as a springboard for further space exploration. 

It was only ten years after the Soviet Union launched the first person into space that they launched the first space station, Salyut 1, in 1971. Two years later the United States launched their own space station, Skylab, but it was only used for a year. The Russian space program continued to concentrate on long-term habitation in space, launching a series of short-lived space stations. They launched the first “permanent” space station, Mir, in 1986. It was in operation for 15 years, until it was brought down to crash into the Pacific in 2001. 

The International Space Station (ISS) was originally conceived as a merger of the proposed U.S. space station Freedom and Russia’s Mir-2 project. The first two modules, Zarya and Unity, launched in 1998, and the first crew arrived in 2000, and new components are expected to continue arriving through the second decade of this century. It’s designed to hold 3 to 7 crew members, with 100,000 support personnel on the ground. Sixteen countries participate in its operation, making it a truly international endeavor. 

The crew on the space station performs experiments designed by scientists in many diffand the air is filtered continuously.

An extremely rare view of the world's first?space station, the Soviet?Salyut 1, as seen from the departing?Soyuz 11. Click here for original source URL.

Astronauts must exercise daily in order to prevent bone and muscle loss that occurs as a result of prolonged stays in space. They have a stationary bike and a special treadmill designed to provide the resistance that gravity normally provides. On their time different disciplines. They work with a unique environment, not just because of micro gravity (weightlessness), but also the low atmospheric pressure and exposure to solar radiation. Experiments study the effects of these conditions on how liquids flow, how fire burns, how plants grow, how tumors develop, and most extensively, on how the human body works. If humans are ever going to travel to other planets, let alone live there, we need to understand how muscles, bones, the nervous system, and the immune system are affected by long-term weightlessness. This new understanding of the human body may also lead to improvements in healthcare on the Earth. 

The first astronauts had to eat out of tubes or add water to cubes of dehydrated food. The food has improved considerably and now there is a wide variety of foods available to astronauts and cosmonauts. Some foods just need water added, some have to be heated, but many foods are in their natural state. Flour tortillas are eaten instead of bread, since breadcrumbs can easily escape and interfere with sensitive scientific instruments. All of the food is in containers that make eating convenient and not messy in microgravity. Meals are planned beforehand and analyzed for their nutritional content. The requirements for vitamins and minerals are different than they would be on Earth. For example, most people on Earth get enough Vitamin D from being exposed to sunlight. On the space station, however, astronauts need Vitamin D supplements, because they are shielded from the Sun’s radiation. 

While some water on the space station is brought up from the surface, water is heavy, and therefore expensive to carry. So water must be recycled. Urine, water from washing, and even the humidity in the air is filtered and re-used. Some of that water is used to produce oxygen. A process called electrolysis uses electricity to split water into its components: hydrogen and oxygen. Excess hydrogen is vented, along with the carbon dioxide exhaled by the crew. Other gases, such as methane and ammonia, are also closely monitored, and the air is filtered continuously. 

Astronauts must exercise daily in order to prevent bone and muscle loss that occurs as a result of prolonged stays in space. They have a stationary bike and a special treadmill designed to provide the resistance that gravity normally provides. On their time off, they watch movies, read books, or have fun with micro gravity. They also spend time communicating with their families via video-phone and email, and just enjoying the unparalleled view. 

The International Space Station is not without critics. Many in the space science community say it is expensive and wasteful, a form of international "pork barrel" spending. The price tag is in excess of $110 billion, which could pay for a lot of space missions! Companies have not flcked to do zero gravity research or develop new drugs in Earth orbit, and the cost for those who do experiments is heavily subsidized by the participating governments. Much of the work done by astronauts there is unglamorous plumbing and electrical work. A balanced view might be that has indeed been a big investment, but a space station is required if we are ever to develop a true space economy and one day live independently of the home planet.