How the ISS Works in Space and What the Crew Does

The ISS is an orbital complex made up of connected pressurized modules, where the crew lives and works in microgravity. Cosmonauts and astronauts keep the station running, conduct scientific experiments and monitor its systems.

The ISS’s design helps us understand how people live far from Earth: the station needs living quarters, research equipment and systems that support the crew’s daily work. Let’s take a look at how the station is structured and what its crew members do on board.

• от 13 до 102 мкм Particle size in crystalline suspension from ground-based experiments

What is the ISS in space?

The International Space Station (ISS) is a crewed orbital research complex where the crew conducts scientific work and carries out technical tasks. It is more than just a place for experiments: cosmonauts also monitor the station’s condition and maintain and repair its equipment.

How the ISS was built and how it is used

Construction of the ISS began in 1998 with the participation of Russia, the United States, Canada, Japan and European nations; the station has been in operation since the end of that year. International cooperation brought together the work of several countries in orbit.

The crew’s work includes scientific experiments and the day-to-day task of keeping the station in working order. Cosmonauts receive delivered cargo, inspect equipment and carry out necessary maintenance.

How is the station controlled from Earth?

Control of the ISS is shared between ground centers, which are responsible for their respective segments, and the crew in orbit: the Russian segment is controlled from Korolyov, the American segment from Houston, the European segment from Germany, and the Japanese segment from Japan.

This division links the station’s operations to control centers in different countries. Each center manages its own segment, but activities aboard the ISS must be coordinated: the systems and equipment are part of a single orbital station, and the crew works with several of its sections at the same time.

How ground control works with the crew

The crew helps maintain this coordination on board: they monitor the station’s condition, maintain and repair equipment, conduct experiments and receive cargo. Ground centers and cosmonauts coordinate tasks and technical work so that maintenance on individual segments does not disrupt the ISS as a whole.

What does the crew do in orbit?

The ISS crew conducts scientific experiments, keeps the station in working order and receives cargo. Roscosmos cosmonauts and NASA and SpaceX astronauts take part in this work: their duties involve both research and the day-to-day operation of the orbital complex.

Research and station maintenance

Scientific experiments make it possible to use the ISS as a research complex. To keep the station fit for work, the crew monitors its systems and equipment, performs maintenance and fixes faults through repairs.

Another part of the job is receiving cargo delivered to orbit and carrying out related technical tasks. The crew has to balance the research program with station maintenance: experiments depend on functioning equipment and systems operating properly across the complex.

What changes in scientific experiments in orbit?

Scientific experiments on the ISS make it possible to compare how materials and biological samples behave in orbit and on Earth. This helps researchers test whether the properties of suspensions and the methods used to make tissues change in the station’s conditions.

Ground-based experiments produced a crystalline suspension with particles measuring from 13 to 102 μm, distributed unevenly. Tests on the ISS showed that rotating mixers help distribute the active ingredient in a preparation more evenly, which could make it more effective.

From suspension to tissue

A separate experiment in orbit focused on creating biological tissue: a device produced a knee meniscus from human cells. The Crew-6 crew brought it back to Earth on September 4.

Comparing samples and results from orbit with those from Earth helps researchers study how experimental conditions affect the outcome. This approach makes it possible to determine which features of a process are linked to working on the station and which also appear in a ground-based laboratory.

Why test manufacturing on the ISS?

Manufacturing is tested on the ISS to see how the equipment and production process work in the station’s conditions, then assess the finished product and prepare it for safe delivery to Earth. Orbital manufacturing is therefore not just an experiment with a material, but also a test of technology in a real working environment.

Polymer 3D printers have already been launched to the ISS and used on board. ESA Technical Director Rob Postema noted growing interest in manufacturing in space and cited this experience as an example: polymer printing on the station has already moved from concept to practical use.

What is checked after production

A product made in orbit does not, by itself, prove that it is suitable for further use. Its properties need to be checked, and the result must also be returned safely to Earth. Only then can the entire process be assessed, from operating the equipment on the station to obtaining the finished product.

Why doesn’t an orbital experiment always replace a ground-based one?

An orbital experiment does not always replace a ground-based one because the result depends on the specific preparation, process and manufacturing conditions. Observing one experiment on the ISS does not prove that another formulation or production procedure will behave the same way: each result needs to be checked separately.

A ground-based experiment is needed as a control comparison: it helps separate the effects of microgravity from those of the equipment itself and the details of the procedure. To do this, researchers compare the conditions of an experiment on Earth with those in orbit, then assess differences in the outcome—not simply whether the equipment worked.

From equipment operation to a verified result

Orbital manufacturing depends not only on the experiment but also on the ISS’s day-to-day operations. The crew monitors the station’s condition, maintains and repairs equipment, and receives cargo; a breakdown, the need for repairs or a delivery delay can affect the process.

That is why a product made in orbit is not considered verified simply because the equipment completed its cycle. The result must be examined after production and compared with a ground-based control sample. This shows whether it retained the required properties and whether the process can be reproduced. Only this kind of testing can show whether the orbital technology has practical value beyond a single experiment.

Frequently asked questions

Key takeaways

• The ISS is a crewed research complex that has been in operation since the end of 1998.
• Control of the station’s segments is shared among Korolyov, Houston, Germany and Japan.
• The crew conducts experiments, maintains the station and receives cargo at the same time.
• Rotating mixers and polymer 3D printers are tested on the ISS.