Astronauts exercise on the International Space Station

Microgravity environments reduce muscle mass and bone density

Muscles that assist with balance and resistance to gravity are not subjected to their usual workload on the International Space Station. See the type of exercises that astronauts must complete for roughly two hours daily and learn why these movements are necessary to preserve astronauts' muscles, bones, and cardiovascular health.

Using fitness wearables to track muscle wasting in astronauts

All that exercising, and astronauts still are likely to lose a large amount of muscle mass while in microgravity. Astronauts can lose up to 20 percent of their muscle in as little as five days in space. Currently, tracking muscle loss means waiting until astronauts land to remeasure their muscle density post-trip. This article explains a NASA-backed fitness wearable that may be able to track muscle atrophy as it happens.

Astronauts follow strict schedules to mimic Earth days and stay healthy in space

Experiencing 15 sunrises and sunsets a day while aboard the International Space Station, visitors preserve their circadian rhythms and mental health with fixed timetables. Astronauts have described sleep as living in a vacuum cleaner due to ongoing air filtration.

Watch how dozens of everyday human tasks are performed in space

This playlist features clips of astronauts aboard the International Space Station explaining how they cook, eat, sleep, and conduct research in microgravity. Other activities to pass the time, including watering plants and playing soccer, are also shown.

Watch the Space Olympics from the International Space Station

From "synchronized space swimming" to "weightless sharpshooting," crew members in 2021 competed in microgravity versions of events from the summer Games. The "lack-of-floor routine" featured mid-air gymnastics as astronauts floated through space station modules.

Technologies developed for the ISS have brought benefits to people on Earth

About 93% of water used onboard the International Space Station is recycled through filtration and purification systems that have since been used in regions lacking access to clean water. Treatments to mitigate bone loss and muscle atrophy in astronauts can also help aging adults.

Prolonged space travel significantly impacts multiple human body systems

Astronauts can lose 20% of their muscle mass after two weeks and 10% of their bone mass after six months in space. Decreased sharpness of eyesight and changes in neural connectivity, brain structure and gut bacteria have also been observed.

Research suggests the cleanliness of the ISS may make astronauts unhealthy

The International Space Station's sterile conditions deprive astronauts of the opportunity to strengthen their immune systems through microbial exposure. To address this problem, future missions may use probiotic-based cleaners and foster diverse microbes in space habitats.

Protecting astronauts against space radiation

Outside the protective atmosphere of Earth, astronauts are constantly bombarded by radiation, which, among other dangers, increases the risk cancer. While those of us on Earth can mitigate the effects of similar radiation by limiting exposure,...

How do astronauts battle loneliness and depression?

You’re stranded hundreds of miles away from your friends and family, constantly surrounded by coworkers who also are your roommates, and you’re only allowed the shortest of walks outside. There’s also no takeout, and gravity has essentially broken up with you. You might need a little help adjusting mentally. That’s where space psychologists and psychiatrists step in, according to this article.

The crew of the ISS creates unique memorials for deceased colleagues

The continued human occupancy of the International Space Station since 2000 has led to the development of social and cultural elements by crew members, which the ISS Archaeology Project has catalogued. Records of handmade cakes, decorations, and memorabilia highlight the human aspect of living in space.

Drugs in space: the pharmacy orbiting the Earth

Researchers are developing pharmaceutical solutions for astronauts, whose bodies may not respond the same way in space as they would on Earth. Similar to how microgravity causes changes to astronaut physiology, the environmental shift enables new...

A look at the foods eaten by astronauts during and after the space race

After John Glenn became the first American to demonstrate that eating in space was possible by eating apple puree out of a tube, meals were prepared for astronauts to meet an approximately 2,800-calorie-a-day requirement via freeze-dried foods. Meal quality gradually improved throughout the Apollo program, including the Apollo 8 crew's nondehydrated Christmas meal in 1968.

Read about every visitor to the International Space Station

The US has sent the most astronauts to the ISS, with 170 visitors, followed by 64 from Russia, 11 from Japan, and nine from Canada. American astronauts Michael E. Lopez-Alegria and Peggy A. Whitson and Russian cosmonauts Yuri Malenchenko and Fyodor Yurchikhin have the most trips, with five each.

Take a virtual tour of the International Space Station

The ISS is the largest human-made object in space. Its modules were meticulously connected by robotic arms and astronauts during slow, careful spacewalks, creating a structure with over eight miles of electrical wire.

Astronauts have repaired genetic damage in space using CRISPR—a molecular tool that can make precise changes to DNA and is used in single-celled organisms to attack invasive viruses.

NASA uses extreme Earth environments to prepare for space exploration

Analog missions in volcanic terrains and craters mimic Martian and lunar environments. Crew members operating in these missions, including at sites in Utah, Nevada, Arizona, and Hawai'i, test suits and specialized space instruments under simulated conditions.

The most common spacewalk spacesuits are over four decades old

NASA's Extravehicular Mobility Unit has been in use since the 1980s, with 11 units of the model in existence and four in active use on the ISS at any given time. It consists of 11 layers, a primary life support system (which resembles a backpack), a drinking bag, and more.

A 'holoported' medical team has been beamed into the International Space Station

In 2021, using the Microsoft HoloLens Kinect camera and custom Aexa Aerospace software, NASA's flight surgeon led a team of hologram doctors on a pioneering visit to the space station, marking a significant advancement in communication and telemedicine technologies that will be crucial for future deep-space missions.

Astronauts have repaired genetic damage in space using CRISPR—a molecular tool that can make precise changes to DNA and is used in single-celled organisms to attack invasive viruses.

Exercise improves brain blood flow, stimulates neural growth, and more

Exercise has dramatic effects on human biology, including reducing some of the long-term harms associated with chronic stress. Its effects are also pronounced in the brain, including improved memory retention, sleep, cognitive functioning, and more.

Space trash forced astronauts on the International Space Station to take shelter

An inactive Russian satellite broke up into nearly 200 pieces, prompting astronauts on the space station to take shelter in a docked spacecraft and a capsule that could be used to escape in case of emergency.

Health officials recommend at least 150 minutes of aerobic exercise per week

This official guideline from the CDC defines the baseline recommendation for healthy adult activity. These recommendations also emphasize that any movement is better than no movement, and that even short bursts of activity spread throughout the week benefit the mind and body.

How endurance athletes can build resilience

Long-distance runners and other endurance athletes can improve their performances using tips explored in this article. Findings from two recent studies show that strength training, high-altitude training, and intense interval sessions are all potential methods for ameliorating long-term athletic capabilities.

Doctors are prescribing social activities—and seeing good results

Physicians, especially in the UK, are asking patients what they enjoy and then prescribing a consistent regimen of doing that type of activity to improve fitness and overall health, including community exercise classes, volunteering, and spending time in nature. This approach may provide better incentives to stick with an activity.

Watch this how-to video series on how to start strength training

Mayo Clinic put together a collection of videos demonstrating how to get started with strength training, including with exercises like step-ups, abdominal crunches, and more. The Mayo Clinic advises people to try to engage in these exercises working all the major muscles at least twice a week. It also encourages people to inhale and exhale fully between each repetition—inhaling during the less strenuous part of the exercise.

Before humans, the Soviet Union and the United States sent animals—including apes, dogs, and cats—to space during the Space Race.

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

Apollo astronauts left items in the moon's 'toss zone,' including golf balls, family photos, and bags of human waste, to make room for lunar rocks.

Explore the known asteroids, comets, and spacecraft involved in asteroid studies within our solar system with 'Eyes on Asteroids,' a 3D visualization from NASA.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

After 25 people used virtual reality headsets to practice flying with virtual wings—flapping their arms—their visual cortex responded to the wings almost as if they were real arms, treating them as body parts.

NBA superstar Victor Wembanyama spent the 2025 summer training with monks in central China to enhance his body and mind.

Children are now three times more likely to say they want to be a YouTuber when they grow up than an astronaut, with some even attending 'YouTube camps' that teach kids how to create content for the platform.

Watch the cumbersome, but necessary, precautions healthcare workers must take to care for and protect themselves while caring for Ebola patients.

SpaceX's S-1 or 'prospectus' revealed many previously unknown details about the company, including its unprofitability despite doing $18.7B in revenue in 2025, exactly how many voting shares Elon Musk will have in the company (roughly 85%), and more.

Read a deep dive on the 'all-purpose healing' peptide BPC-157.

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

Take a 3D tour of the Hajj, Islam's annual pilgrimage to Mecca, undertaken by over 1.5 million Muslims.

Firework or sparkler burns, even if they cover a relatively small area of skin, can significantly affect our range of motion.

Fish populations in the Great Barrier Reef have increased after installing waterproof speakers on the ocean floor that played recordings of sounds from healthy coral reefs.

In 1984, Operation Smash Hit intentionally crashed a 239-ton train into a nuclear waste canister at 100 miles per hour to prove the canister's safety, which remained completely intact and lost just 0.29 of its 100 pounds of pressure.

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

SpongeBob exemplifies Aristotle's philosophy for living well because he understands that happiness doesn't come from external factors like money, recognition, or power.

See how Budweiser's famous Clydesdales spend their days at Warm Springs Ranch, where roughly 70 to 80 of the beer brand's giant horses can be found at any given time.

The American Society of Civil Engineers' infrastructure report card gave the US a C in 2025, its highest grade since the project launched in 1998.

Iran's Revolutionary Guard Corps is independent of Iran's regular army and is one of the most powerful and influential military-political organizations in the Middle East.

The boiling temperature of water decreases with increasing elevation because the molecules need less energy to overcome the lower atmospheric pressure associated with thinner air.