Two Decades of Humans in Space

A symbol of exploration, possibilities, research & collaboration, the International Space Station completes twenty years of human habitation beyond planet earth

Issue: 12 / 2020By Ayushee ChaudharyPhoto(s): By NASA
International Space Station - Celebrating 20 continuous years of life in Space

Last month November 2, 2020 marked twenty years since the International Space Station received its first residents. Since then the orbiting habitat, also referred to as an orbiting laboratory, the International Space Station (ISS) has stayed occupied, making it possible for humans to live in space.

The ISS is a modular space station (habitable artificial satellite) in low Earth orbit. It is a collective project involving multinational collaboration of space agencies like NASA (National Aeronautics and Space Administration), Roscosmos (Russia), JAXA (Japan Aerospace Exploration Agency), ESA (European Space Agency), and CSA (Canadian Space Agency). The ISS is now composed of 16 modules: four Russian, nine US, two Japanese and one European.

Through these 20 years, the ISS has been orbiting earth as a symbol of possibility, exploration, potential, science, engineering, and working together. After 20 years of continuous human presence, the ISS has provided 241 visitors with an extraordinary view of Earth from outer space - the glimpse of which they have shared with the entire world.

Astronaut photography, formally called Crew Earth Observations (CEO), has resulted in more than 3.5 million photographs of the ever-changing blue planet through astronauts as well as an impressive suite of Earth Science instruments that have also visited the station to capture vast amounts of data about our planet.

However, NASA points out that space aboard the station itself is limited, and the spots are highly coveted. Instruments go through a rigorous approval process and cycle through every couple of years, turning the station into a virtual swiss-army knife of interchangeable remote sensing tools.

These instruments together provide a more complete picture of Earth systems, according to William Stefanov, Branch Chief for the Exploration Science Office at NASA’s Johnson Space Center, and Principal Investigator for the Crew Earth Observations Facility on the International Space Station.


The ISS is largely deemed as a marvel of cooperative engineering, science, and research. Throughout the mission, NASA’s Space Communications and Navigation (SCaN) networks have connected station astronauts with loved ones on Earth and empowered profound research on the orbiting laboratory.

“As we celebrate 20 years of science and research aboard the station, we also celebrate the mission-enabling support infrastructure that makes it all possible. Space communications has always been a vital piece of NASA’s crewed missions in low-Earth orbit and beyond,” said Robyn Gatens, Acting Director of the International Space Station at NASA Headquarters in Washington.

After 20 years of continuous human presence, the ISS has provided 241 visitors with an extraordinary view of Earth from outer space - the glimpse of which they have shared with the entire world

It was in November 20, 1998 that the construction of the ISS in orbit started, when the Zayra Module launched from the Baikonur Cosmodrome in Kazakhstan. Since then, the orbiting laboratory has been expanded and upgraded to meet the needs of astronauts living on the station and the science objectives of the mission.

Since November 2, 2000, the space station has been occupied continuously by astronauts from NASA and international space organisations. The million-pound spacecraft has an internal pressurised volume equal to that of a Boeing 747, providing living space for six-months long expedition crews of six people, while sometimes hosting up to 13 during crew rotations and shuttle visits.

Most of the communication and occupation on the station has been made possible by NASA’s communications networks. The station primarily relies on the constellation of Tracking and Data Relay Satellites (TDRS) and associated ground antennas. The orbiting laboratory also has a backup communications system. A series of very-high frequency (VHF) antennas around the world can provide astronauts with voice-only communications in the unlikely event of an emergency.

“NASA’s relay satellites provide the space station with robust, comprehensive services that keep our astronauts connected with mission control at all times. In combination with the redundant VHF network, TDRS assures the continued success and safety of the station,” said Network Services Division Director Susan Chang.


Throughout its history, the space station has also served as a hub for communications research and development. From 2012 to 2019, the SCaN Testbed has also allowed communications engineers to have a platform to study space-based applications of software-defined radios. The Testbed researched innovations like cognitive communications, space-based GPS, and Ka-band communications.

The station has also tested revolutionary optical communications technologies that use infrared lasers to exceed data-rates offered by comparable radio systems.

For 20 years, the astronauts aboard the ISS have conducted science in an extremely unique and quite literally in an out of the world way. Orbiting about 250 miles above our planet, the space station is the only laboratory available for long-duration microgravity research.

NASA noted that during the past two decades, the space station has supported numerous discoveries, scientific publications, unique opportunities, and historic breakthroughs. This research not only helps us explore farther into space, it also benefits us back on Earth.

While the ISS is continuously exploring our home planet, it is pushing further to learn more about the universe as well and at the same time carrying out significant research and experiments to add value to life on earth. Life science continues ramping up aboard the ISS as quite recently, the Expedition 64 crew explores cancer therapies and heart conditions. Through a new cancer study, the space medical research could accelerate the development of advanced therapies on Earth that target cancer cells.


To tap into the growing opportunities and potential that space exploration has, NASA has also been focusing on Low Earth Orbit Economy for which the space station has been a key part of supporting that growth.

NASA explains Low-Earth orbit (LEO) encompasses Earthcentered orbits with an altitude of 2,000 km (1,200 mi) or less. For the purposes of the Commercial Use Policy, low-Earth orbit is considered the area in Earth orbit near enough to Earth for convenient transportation, communication, observation and resupply. This is the area where the ISS currently orbits and where many proposed future platforms will be located.

While the ISS is continuously exploring our home planet, it is pushing further to learn more about the universe as well and at the same time carrying out significant research and experiments to add value to life on earth.

The LEO economy is about the production, distribution, and trade of goods and services within low-Earth orbit. As technology progresses, this economic space will grow to include more groups (including but not limited to governmental, commercial, and academic) that will contribute to the LEO economy’s continued expansion and support future sustainable space enterprises.

Space is a growing industry and low-Earth orbit is full of opportunity which NASA has acknowledged and aims to explore. Establishing a robust LEO economy in which many groups on Earth can participate benefits American industry, promotes technological discovery, and increases benefits for humanity that are discovered or advanced through in-space work and research, the space agency states. Once a thriving economy in low-Earth orbit has been established, NASA can purchase services as one of many customers. This should enable the agency to focus its resources on landing the first woman and next man on the moon by 2024. And when it comes to NASA, the space administration is committed to continuing the sustained human presence in LEO and stimulate this economy as the next step in humanity’s exploration and expansion into the solar system. NASA points out that LEO provides an ideal environment for crew training, fundamental and applied research, and advanced systems development, as well as other activities.


To mark the 20 years of science, NASA picked up 20 scientific and technological breakthroughs that have been achieved in the last two decades as a result of space station science

Fundamental disease research: The space station has rigorously researched on diseases like the Alzheimer’s disease, Parkinson’s disease, cancer, asthma, and heart disease.

Discovery of steadily burning cool flames: When scientists burned fuel droplets in the Flame Extinguishing Experiment (FLEX) study, something unexpected occurred. A heptane fuel droplet appeared to extinguish, but actually continued to burn without a visible flame at temperatures two-and-a-half times cooler than a typical candle.

New water purification systems: Water is vital for human survival and yet many around the world lack accessibility to clean water. NASA observes that at-risk areas can gain access to advanced filtration and purification systems through technology that was developed for the space station, enabling the astronauts living aboard to recycle 93 per cent of their water.

Drug development using protein crystals: Protein crystal growth experiments conducted aboard the space station have provided insights into numerous disease treatments, from cancer to gum disease to Duchenne Muscular Dystrophy.

Methods to combat muscle atrophy and bone loss: Space studies have contributed greatly to the knowledge of bone and muscle loss in astronauts – and how to mitigate those effects. The knowledge gained also applies to people on Earth dealing with diseases such as osteoporosis.

Exploring the fifth state of matter: 25 years ago, scientists first produced a fifth state of matter, called a Bose-Einstein condensate (BEC ), on Earth. In 2018, NASA’s Cold Atom Lab became the first facility to produce that state of matter in space. This achievement may provide insight into fundamental laws of quantum mechanics.

Understanding how bodies change in microgravity: When humans head to Mars, we need to know what challenges we face. Long-term stays aboard the space station have uncovered unexpected ways that the human body changes in microgravity.

Testing tissue chips in space: Tissue chips are roughly thumb-drive-sized devices that contain human cells in a 3D matrix, representing functions of an organ. Chips have been sent to station, seeking to better understand the impact of microgravity on human health.

Stimulating the low-Earth orbit economy: From satellite deployment to in-space research, a vibrant commercial space economy has developed, with a value that now exceeds $345 billion.

Growing food in microgravity: Many techniques for growing plants have been explored aboard the space station to prepare for these missions. On August 10, 2015, astronauts sampled their first space-grown salad, and astronauts now are growing radishes in space.

Deployment of CubeSats from station: CubeSats are one of the smallest types of satellites and provide a cheaper way to perform science and technology demonstrations in space. More than 250 Cube-Sats have now been deployed from the space station, jump starting research and satellite companies.

Monitoring our planet from a unique perspective: The capacity to host varying complements of instruments, both internal and external, has evolved the station into a robust platform for researchers studying Earth’s water, air, land masses, vegetation, and more while providing them additional views beyond those of NASA’s typical Earth remote-sensing satellites.

Collecting data on more than 100 billion cosmic particles: The Alpha Magnetic Spectrometer – 02 has provided researchers around the globe with data that can help determine what the universe is made of and how it began.

A better understanding of pulsars and black holes: Two tools installed on the outside of the space station, NICER and MAXI, have worked in tandem to advance our knowledge of pulsars and black holes.

Student access to an orbiting laboratory: Companies and professors are not the only ones using the space station for microgravity research. Station has given elementary- to college-aged students access to science in space and the opportunity to study microgravity’s effects.

Capability to identify unknown microbes in space: Having the ability to identify microbes in real time in space without the need to send them back to Earth for identification would be revolutionary for the world of microbiology and space exploration.

Opening up the field of colloid research: Toothpaste, 3D printing, pharmaceuticals, and detecting shifting sands on Mars may not seem related to each other at all, yet each stands to benefit from improvements made thanks to research on colloids aboard the space station.

The evolution of fluid physics research: Fluids cover our planet, but sending them to space can help us better understand how they flow. The study of fluids in space has progressed from fundamental research into the testing of technology applications ranging from advanced medical devices to heat transfer systems.

3D printing in microgravity: The first item was 3D printed on the space station in 2014. Since then, we have explored 3D printing using recycled materials and even printing human tissue.

Responding to natural disasters: With crew handheld camera imagery as a core component, the station has become an active participant in orbital data collection to support disaster response activities both within the US and abroad.

NASA’s investment in the ISS and its commercial activities, including commercial cargo resupply missions, commercial crew, and the ISS National Lab research and development, have led the way to return benefits to NASA and the American economy, and shall eventually look for doing so to the global economy as ISS is but an international entity. A robust and competitive low-Earth orbit (LEO) economy is vital to continued progress in space.

One year ago, NASA announced the agency is opening the space station for business, enabling commercial and marketing opportunities on the station, and the agency has moved forward toward its ultimate goal in low-Earth orbit to partner with industry to achieve a strong ecosystem. Providing expanded opportunities at the ISS to manufacture, market and promote commercial products and services will help catalyze and expand space exploration markets for many businesses.