The International Space Station: A Global Laboratory in Space

The International Space Station (ISS) is humanity’s biggest and longest running presence in space. 400km above Earth it’s a football field sized laboratory and a testament to international cooperation and scientific brilliance. As we look back at the ISS’s history, purpose and achievements we’ll see how this amazing outpost is helping us understand space and improve life on Earth.

The ISS program brings together international flight crews, multiple launch vehicles, globally distributed launch and flight operations, training, engineering, and development facilities, communications networks, and the international scientific research community. Five partner agencies operate the ISS: the Canadian Space Agency, the European Space Agency, the Japan Aerospace Exploration Agency, the National Aeronautics and Space Administration, and the State Space Corporation “Roscosmos.”

How it All Began

The dream of a permanent space station dates back to the early days of space exploration. However, the ISS as we know it today began to take shape in the 1980s. The Space Station was officially given approval by President Reagan, and a budget was approved by the US Congress in 1984. NASA Administrator James Beggs immediately set out to find international partners who would cooperate on the program. Canadians, Japanese, and many nations of the European Space Agency began to participate in the program soon after.

The Station was designed between 1984 and 1993. Elements of the Station were in construction throughout the US, Canada, Japan, and Europe beginning in the late 1980s. In 1993, as the Station was undergoing a redesign, the Russians were invited to participate.

Agreement was made to proceed in two phases:

1. During the first phase (NASA-Mir), NASA Space Shuttles would carry astronauts and cosmonauts to the Russian Mir Orbital Station. This phase took place between 1995 and 1998.
2. During Phase 2, led by the US and Russia, all of the participating nations would contribute elements and crewmembers to a new International Space Station (ISS).

Assembly

The assembly of the International Space Station was a monumental task that spanned over a decade. It began with the launch of the Russian Zarya module in November 1998, followed closely by the U.S. Unity module.

The ISS components were built in various countries around the world, with each piece performing once connected in space, a testament to the teamwork and cultural coordination. Like a Lego set, each piece of the ISS was launched and assembled in space, using complex robotics systems and humans in spacesuits connecting fluid lines and electrical wires.

Facts about the ISS

• It is the largest human-made object ever to orbit Earth.
• Construction of the ISS began in 1998. New modules were added as recently as 2021.
• Time Slows Down: Due to “relative velocity time dilation,” astronauts age slightly less on the ISS. After 6 months, they are 0.005 seconds younger than if they had stayed on Earth.
• The ISS has a pressurized volume of approximately 900 m3 (31,000 ft3) and a mass over 400,000 kg (900,000 lbs).
• The ISS solar arrays cover an area of 2,247 m2 (24,187 ft2) and can generate 735,000 kW-hours of electrical power per year.
• The ISS structure measures 109 m (358 ft) (across arrays) by 51 m (168 ft) (module length from the forward end of PMA2 to the aft end of the SM).
• It orbits at an altitude of between 370–460 km (200–250 nmi) with an orbital inclination of 51.6°.
• The ISS continually hosts a crew of seven, with the capacity to accommodate between 3 and 13 people during handover periods.
• There are 3 Nodes that join the modules of the ISS. They are: named Tranquility, Harmony, and Unity,
• More than 50 computers control the systems on the space station.
• The U.S. segment alone has more than 1.5 million lines of flight software code running on 44 computers.
• Through Expedition 60, the microgravity laboratory has hosted nearly 3,000 research investigations from researchers in more than 108 countries.
• More than 20 different research payloads can be hosted outside the station at once.
• Peggy Whitson set the U.S. record for spending the most total time living and working in space at 665 days on September 2, 2017.
• The Water Recovery System reduces crew dependence on water delivered by cargo spacecraft by 65 percent – from about 1 gallon a day to a third of a gallon.

Building the ISS required 36 Space Shuttle assembly flights and 6 Russian Proton and Soyuz rocket launches. More launches are continuing as new modules are completed and ready to become part of the orbiting complex.

Spacewalks

Spacewalks, or Extravehicular Activities (EVAs), have been crucial to the construction and maintenance of the International Space Station. In the two+ decades since station assembly began, more than 270 spacewalks for assembly, maintenance, and reconfiguration have been conducted.

Some notable spacewalk milestones include:

• The first ISS EVA was conducted on December 7, 1988, during the STS-88 mission.
• Tamara E. “Tammy” Jernigan became the first woman to perform an EVA at ISS during STS-96 in May 1999.
• The longest EVA in history (eight hours and 56 minutes) was conducted by James S. Voss and Susan J. Helms on March 10, 2001.
• Chris A. Hadfield became the first Canadian to conduct a spacewalk at the orbiting laboratory during STS-100 in April 2001.
• The US-built Quest ‘Joint’ Airlock was added in July 2001, providing the station with a standalone EVA capability.

Visit here to view the list of all spacewalk from the first to the most recent. Spacewalks have also been crucial in handling unexpected challenges, such as the repair of a torn solar array panel during the STS-120 mission in October 2007.

International Cooperation

The International Space Station represents an unprecedented level of international cooperation in space exploration. The ISS is a joint project involving five space agencies: NASA (United States), Roscosmos (Russia), JAXA (Japan), ESA (Europe), and CSA (Canada). This collaboration extends beyond construction to include shared responsibilities for station operations, scientific research, and crew rotations.

The ISS has been the most politically complex space exploration program ever undertaken, serving as a shining example of what nations can achieve when they work together towards a common goal.

Research and Science

The primary purpose of the International Space Station is to serve as a unique scientific laboratory. Its microgravity environment allows researchers to conduct experiments that would be impossible on Earth. The ISS hosts hundreds of experiments at any given time, spanning fields such as:

• Biology and biotechnology
• Physical sciences
• Earth and space science
• Human research
• Technology development

Discoveries

Over the past two decades, the ISS has supported numerous discoveries, scientific publications, and historic breakthroughs. Here are some key areas of research and their impacts:

1. Fundamental Disease Research: The microgravity environment has provided new insights into diseases such as Alzheimer’s, Parkinson’s, cancer, asthma, and heart disease. For example, researchers have studied protein clusters associated with neurodegenerative diseases and the growth of endothelial cells relevant to cancer research.
2. Drug Development: Protein crystal growth experiments aboard the ISS have led to advancements in drug development. A notable success is the research on a protein associated with Duchenne Muscular Dystrophy, which has resulted in a treatment currently in clinical trials.
3. Human Health in Space: Long-term stays on the ISS have uncovered unexpected changes in the human body, such as Spaceflight-Associated Neuro-Ocular Syndrome (SANS). These findings are crucial for planning future long-duration space missions.
4. Tissue Chips in Space: The ISS has hosted experiments using tissue chips – devices containing human cells that simulate organ functions. These studies provide insights into diseases and potential treatments, both for space exploration and Earth-based medicine.
5. Plant Growth: Experiments in growing food in microgravity have made significant progress, with astronauts successfully cultivating and consuming various leafy greens. This research is vital for supporting long-duration space missions.
6. Earth Observation: The ISS serves as a platform for monitoring our planet, hosting instruments that study Earth’s water, air, land masses, and vegetation. This research contributes to our understanding of climate change and assists in natural disaster response.
7. Astrophysics: Instruments like the Alpha Magnetic Spectrometer-02 (AMS-02) have collected data on over 100 billion cosmic particles, contributing to our understanding of dark matter and the universe’s composition.
8. Materials Science: Research on colloids in microgravity has implications for improving everyday products like toothpaste, 3D printing materials, and pharmaceuticals.
9. Fluid Physics: Studies on fluid behavior in microgravity have led to advancements in medical technologies and life support systems.
10. 3D Printing: The ISS has successfully demonstrated 3D printing in space, including experiments with recycled materials and bioprinting of human tissue.

These diverse research areas demonstrate the ISS’s crucial role as a scientific platform, contributing to advancements that benefit both space exploration and life on Earth. The unique microgravity environment continues to provide opportunities for discoveries and innovations across multiple scientific disciplines.

Expeditions

The International Space Station has been continuously inhabited for over 20 years, beginning with Expedition 1 when it docked on November 2, 2000. At that time, the ISS consisted of just three modules. Since then, the orbiting laboratory has expanded to the size of a football field and has hosted over 260 individuals from 21 countries, comprising over 60 Expeditions.

Expeditions typically last about six months, although some missions have extended to nearly a year. During their stay, crew members conduct scientific experiments, maintain the station’s systems, and engage in public outreach activities.

Commercial Space

In recent years, NASA has been developing a human spaceflight economy enabled by a commercial market. This includes both the supply side and the demand side of a robust low Earth orbit economy. Private companies are now providing access to and services in space, with customers including NASA, other government agencies, academic and research-based institutions, and other private companies.

Key developments in commercial space activities related to the ISS include:

1. Commercial Resupply Services: Private companies like SpaceX and Northrop Grumman deliver cargo to the station.
2. Commercial Crew Program: This NASA initiative has worked with American aerospace industry companies to develop U.S. human spaceflight systems since 2010. The goal is to have safe, reliable, and cost-effective access to and from the International Space Station and foster commercial access to other potential low-Earth orbit destinations.
3. Private astronaut missions: Companies like Axiom Space are now organizing private missions to the ISS, paving the way for increased commercialization of low Earth orbit.

Space Shuttle Crews

For many years, NASA’s Space Shuttle program was the primary means of transporting crews and large components to the International Space Station. The shuttles played a vital role in the station’s assembly and operation until the program’s retirement in 2011.

Each of the three Space Shuttle orbiters in operation at the end of the program — Discovery, Atlantis, and Endeavour — was designed to fly at least 100 missions. The Space Shuttle was the world’s first reusable spacecraft and the first spacecraft in history that could carry large satellites both to and from orbit.

Commercial Crew Program

With the retirement of the Space Shuttle, NASA initiated the Commercial Crew Program to develop new ways of transporting astronauts to and from the International Space Station. This program has resulted in the successful development of spacecraft by SpaceX (Crew Dragon) and Boeing (Starliner).

These vehicles now regularly ferry astronauts to the ISS, reducing reliance on Russian Soyuz capsules and opening new possibilities for space travel. The Commercial Crew Program is delivering on its goal of safe, reliable, and cost-effective human transportation to and from the International Space Station from the United States through a partnership with American private industry.

Current Management

The International Space Station is jointly managed by its international partners, with each space agency responsible for specific aspects of its operation. NASA serves as the primary coordinating body, but decisions are made collaboratively. The station is operated from mission control centers around the world, with the main facilities located in Houston, Texas, and Moscow, Russia.

As of 2023, key management positions include:

• Joel Montalbano – International Space Station Program Manager
• Dana Weigel – International Space Station Deputy Program Manager
• Dina Contella – International Space Station Program Operations Integration Manager
• Melissa Gard – International Space Station Program Chief of Staff

Transition and Future

The International Space Station continues to inspire and educate, pushing the boundaries of human achievement and scientific discovery. The Biden-Harris Administration has committed to extending space station operations until 2030, enabling the United States to continue reaping the benefits for the next decade while U.S. industry develops commercial destinations and markets for a thriving space economy.

As we look to the future of space exploration, NASA is taking steps to ensure a successful transition of operations to commercial services. In response to Congressional direction, NASA has provided an updated International Space Station Transition Report that details:

1. Goals for the next decade of station operations leading to a smooth transition to commercial services
2. Steps being taken to develop both the supply and demand side of the low-Earth orbit commercial economy
3. Technical steps and budget required for transition

The extension of operations to 2030 will continue to return benefits to the United States and humanity as a whole while preparing for a successful transition of capabilities to one or more commercially-owned and -operated LEO destinations (CLDs). NASA has entered into a contract for commercial modules to be attached to a space station docking port and awarded space act agreements for design of three free-flying commercial space stations. U.S. industry is developing these commercial destinations to begin operations in the late 2020s for both government and private-sector customers, concurrent with space station operations, to ensure these new capabilities can meet the needs of the United States and its partners.

NASA’s goal is to be one of many customers of these commercial destination providers, purchasing only the goods and services the agency needs. Commercial destinations, along with commercial crew and cargo transportation, will provide the backbone of the low-Earth orbit economy after the International Space Station retires.

Decommissioning Plans

At the conclusion of the International Space Station Program, the station will be deorbited in a controlled manner to ensure avoidance of populated areas on Earth. The station’s safe deorbit is the shared responsibility of the five space agencies — including NASA, CSA (Canadian Space Agency), ESA (European Space Agency), JAXA (Japan Aerospace Exploration Agency), and the State Space Corporation Roscosmos — that have operated it since 1998.

NASA and the International Space Station partner agencies have studied options to safely deorbit the space station, including the option of using up to three Roscosmos Progress spacecraft at the end of station operations. These efforts indicated that a new or modified spacecraft is needed to provide more robust capabilities for deorbit. NASA has engaged with U.S. industry and is proceeding with plans to procure a spacecraft (U.S. Deorbit Vehicle) that will perform the final, safe, deorbit maneuver of the space station.

The Chosen Approach

The chosen approach for safe decommissioning is a combination of:

1. Natural orbital decay
2. Intentionally lowering the altitude of the station (likely using current propulsive elements)
3. Execution of a re-entry maneuver for final targeting and to control the debris footprint

This final maneuver is expected to require a new or modified spacecraft using a large amount of propellant. Due to the high propellant requirement of this final maneuver, Earth’s natural atmospheric drag will be used as much as possible to lower the station’s altitude while setting up deorbit.

The primary objective during space station deorbit operations is the responsible re-entry of the space station’s structure into an unpopulated area in the ocean. This approach was chosen after careful consideration of alternatives such as disassembly and return to Earth, boosting to a higher orbit, and natural orbital decay with random re-entry, all of which were deemed impractical or too risky.

As of September 2023, NASA has released a final Request for Proposals (RFP) for the U.S. Deorbit Vehicle, moving forward with plans to ensure a safe and controlled end to the International Space Station’s mission.

The International Space Station has evolved from a small outpost on the edge of space to a highly capable microgravity laboratory. As we continue to push the boundaries of human space exploration, the ISS stands as a testament to what we can achieve through international cooperation and scientific innovation. Its legacy will continue through the commercial space stations that follow, paving the way for a new era of space exploration and utilization.