Particle physics experiments

Astronauts have conducted nearly 3,000 scientific experiments aboard the ISS

Astronaut Christina Koch during a spacewalk on the International Space Station in 2019.Credit: NASA/Alamy

Twenty years ago this week, on November 2, 2000, an astronaut and two cosmonauts opened the door of the newly built International Space Station (ISS) and floated inside. It was the start of two decades of humans living and working permanently aboard the orbiting outpost.

During this period, ISS astronauts conducted about 3,000 scientific experiments. Research spans a range of disciplines, including fundamental physics, Earth observation and biomedical studies (see “In-Orbit Research”). Once criticized as relatively insignificant and not at all relevant to people living on Earth, science aboard the ISS has blossomed as astronauts have devoted more time to research. The results include information about how humans and animals adapt to long-duration spaceflight, as well as how materials behave in space (see “High-flying science”).

Infographic: Research in orbit.  Bar chart showing the number of experiments performed on the International Space Station.

Source: NASA

Today, the ISS is packed with modern research equipment, including a recently installed high-end confocal microscope. “It’s like taking an entire world-class university and shrinking it down to space station size,” said NASA astronaut and biologist Kate Rubins, who is currently aboard the ISS, as she floated in near-zero weightlessness while taking media questions on Oct. 30. Over the past week, Rubins has been working on a plant growth chamber on the station and on a physics experiment that tests how liquid droplets interact with a surface in microgravity.

Most of the science experiments aboard the station aim to study how things work differently in microgravity — like how a flame burns or how mouse cells grow — to see if those lessons can be applied to new technologies. or medicines on Earth. Other experiments take advantage of the station’s location in low Earth orbit to observe the planet or space.

High-flying science

Some of the notable experiences aboard the International Space Station (ISS):

The Cold Atoms Laboratory. Physicists reported this year that they had used the facility to create an unusual state of matter known as the Bose-Einstein condensate for the first time in space. They studied the behavior of the atomic collective in microgravity.

The Alpha Magnetic Spectrometer. This cosmic ray detector, attached to the outside of the ISS, hunts dark matter particles. The $2 billion experiment required a series of complicated spacewalks in 2019 to repair broken cooling pumps.

Rodent studies. Countless mice and rats flew aboard the station. In a 2019 study, Japanese researchers reported that male mice could still father healthy offspring after floating in a cage on the ISS for 35 days.

Plants in space. NASA astronaut Don Pettit chronicled the life of a space zucchini aboard the ISS in 2012. Seriously, astronauts were able to grow lettuces and other vegetables to boost their diets for long periods of time. in the space.

The twins study. NASA has taken advantage of the presence of identical twin astronauts to monitor the changes that spaceflight causes on the human body. In 2015-2016, Scott Kelly spent almost a year aboard the ISS, while his brother Mark remained on Earth. The changes found included changes in gene expression in the space twin.

The Carbon-3 Orbital Observatory. This instrument, mounted on the outside of the station and pointing towards Earth, tracks carbon dioxide emissions in orbit around the planet.

“My favorite experiments are actually about human health,” says Ellen Stofan, former NASA chief scientist and director of the National Air and Space Museum in Washington DC. “A lot of people don’t realize how much research has been done on the International Space Station around human health.”

Since the early days of the space program, scientists have studied the health of astronauts in orbit, aiming to make sure they don’t lose too much muscle mass or are exposed to too much radiation. But aboard the ISS, the research has expanded to encompass investigations of, for example, how gravity affects the activation of white blood cells called T cells, which help boost a person’s immune system. . Knowing why and how astronauts’ immune systems are suppressed in orbit can help scientists develop better drugs on Earth, Stofan said.

The ISS program involves a partnership between the United States, Russia, Canada, Japan and 11 European countries. It will run until at least 2024, and discussions are underway to extend it until 2028.