For the past two decades, the astronauts aboard the International Space Station (ISS) have conducted science in a way that cannot be done anywhere else. Orbiting about 250 miles above Earth, the ISS is the only laboratory available for long-duration microgravity research.

During the past 20 years, the space station has supported numerous discoveries, scientific innovations, unique opportunities, and historic breakthroughs. This research not only helps us explore farther into space but also benefits life on Earth.

Following are major scientific breakthroughs achieved during 20 years of human presence on the ISS.

Fundamental Disease Research

The Ring-Sheared Drop experiment hardware, installed inside the Microgravity Science Glovebox, helped researchers understand protein aggregation associated with devastating neurodegenerative diseases such as Alzheimer’s and Parkinson’s. (Credit: NASA/Kevin Depew)

Alzheimer’s and Parkinson’s diseases, cancer, asthma, and heart disease — if any of these conditions has impacted your life, space station research has also affected you. Microgravity research has provided new insights to scientists studying these diseases. Without the interference of Earth’s gravity, Alzheimer’s researchers have studied protein clusters that can cause neurodegenerative diseases. Cancer researchers studied the growth of endothelial cells that help supply blood in the body — blood that tumors need in order to form. ISS-grown cells grow better than those on Earth and can help test new cancer treatments. European Space Agency research has helped in the development of diagnostic tools that quantify airway inflammation — tools that not only help in spaceflight diagnostics but that also hold applications on Earth to diagnose similar conditions such as asthma.

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. The fire went out twice — once with and once without a visible flame. This is the first time scientists observed large droplets of heptane fuel that had dual modes of combustion and extinction. The second stage was sustained by what is known as cool flame chemical heat release. When we think about fire, we typically think about heat but special flames created aboard the ISS keep things a bit cooler.

Astronaut Alexander Gerst exhales into an ultra-sensitive gas analyzer for the Airway Monitoring experiment that could help diagnose conditions such as asthma. (Credit: NASA)

Removing gravity from studies of combustion allows for exploration of the basic principles of flames. Cool flames have been produced on Earth but they quickly flicker out. On the ISS, cool flames can burn for minutes, giving scientists a better opportunity to study them. Typical flames produce soot, carbon dioxide, and water. Cool flames produce carbon monoxide and formaldehyde. Learning more about the behavior of these chemically different flames could lead to the development of more efficient, less-polluting vehicles and may provide definition and direction for large-scale fire suppression tests and selection of the fire suppressant for next-generation crew exploration vehicles.

Matt Mansell is shown with containers illustrating the ISS Water Recovery System that recovers and recycles 93% of the water astronauts use in space. A mockup of the ECLSS is in the background. (Credit: NASA/David Higginbotham)

New Water Purification Systems

Efficiently recycling wastewater on the space station reduces the need to provide water through resupply missions. As we travel deeper into space, resupply would be unachievable, making these systems a necessity. The JEM Water Recovery System (JWRS) generates potable water from urine. In the past on manned spacecraft, urine and wastewater were collected and stored, or vented overboard. For long-term space missions, however, water supply could become a limiting factor.

In addition, many people around the world lack access to clean water. At-risk areas can gain access to advanced filtration and purification systems through technology that was developed for the ISS. The station’s Water Recovery System purifies and filters the station’s water, recovering and recycling 93% of the water astronauts use in space.

Drug Development

Protein crystal growth experiments conducted aboard the ISS have provided insights into numerous disease treatments, from cancer to gum disease. Studying human proteins by crystallizing them helps us learn more about our bodies and potential disease treatments. One of the most promising results of these station experiments has come from the study of a protein associated with Du chenne Muscular Dystrophy (DMD), an incurable genetic disorder. A treatment for DMD based on this research is in clinical trials. Another investigation, PCG-5, sought to grow the therapeutic antibody Keytruda® in a more uniform crystalline form. The goal was to improve the drug such that it can be delivered by injection as opposed to IV treatment.

Combatting Muscle Atrophy and Bone Loss

Space studies have contributed greatly to our 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. The effect of microgravity on bones and muscles provides unique opportunities for research. Scientists have developed an exercise routine and diet regimen that significantly reduce the bone and muscle loss astronauts otherwise would experience during their stays on station.

Understanding how to mitigate the effects of microgravity on bones and muscles is important for future exploration in the partial gravity environments of the Moon and Mars. On Earth, bone and muscle atrophy occurs from normal aging, sedentary lifestyles, and illnesses. Studying these losses in micro-gravity can help us better understand them and potentially create treatments for people back on Earth.

Future long-duration space missions will require crewmembers to grow their own food. The Veg-03 experiment uses the Veggie plant growth facility to cultivate types of cabbage, lettuce, and mizuna. (Credit: NASA)

Understanding How the Body Changes 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. Some astronauts, for example, unexpectedly developed vision changes, now known as Spaceflight-Associated Neuro-Ocular Syndrome (SANS). After helping discover the issue, space station research has served as a platform to better understand SANS.

The landmark one-year Twins Study looked at the effects of space travel on the human body. Scott Kelly (left) spent a year on the ISS while his identical twin, Mark, stayed on Earth as a control subject. (Credit: NASA)

NASA’s Twins Study compared astronaut Scott Kelly during his year in space with his Earth-bound twin brother Mark Kelly. It provided insights into the many ways long-term spaceflight affects a human body. Findings showed that Scott’s gene expression changed and his body reacted appropriately to vaccines while in space.

Growing Food in Microgravity

The ability to grow supplemental food can help humans explore farther from Earth. 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. Eight types of leafy greens have been grown in the Veggie facility for astronauts to eat, fine tuning the best techniques.

New solutions for watering, lighting, and growing plants have to be tested to create a food crop in microgravity. The ISS has served as a platform for performing these tests and for verifying what conditions allow the plants to grow most effectively.

3D Printing in Microgravity

The first item was 3D-printed on the ISS in 2014. Developed by Made in Space, the printer produced dozens of parts that researchers analyzed and compared with those made on the ground. Analysis revealed that microgravity had no significant effects on the process, demonstrating that a 3D printer works normally in space. Later experiments used recycled plastic to print objects. The BioFabrication Facility took small steps toward printing human organs and tissues in microgravity, using ultra-fine layers of bioink.

Testing printers on the ISS paves the way for future space missions to be more independent of Earth. Needed items could be 3D-printed rather than sent from Earth and carried for the entire journey. Using recycled material for printing could make use of material that otherwise would take up limited stowage space on long-duration missions.

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. Astronauts snap images of disasters such as storms and fires throughout their progression, documenting cloud cover, flooding, and changes to the land. The Lightning Imaging Sensor mounted on the ISS also detects the distribution and variability of lightning in order to improve severe weather forecasting. These data allow for more informed responses to disasters from a perspective that cannot be obtained on Earth.

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This article first appeared in the December, 2020 issue of Tech Briefs Magazine.

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