Microgravity environments reduce muscle mass and bone density

Astronauts exercise on the International Space Station

Astronauts maintain bone, muscle, and cardiovascular health with physical activity. It's crucial that they make time to exercise for approximately two hours per day. This resource offers a behind-the-scenes look at how high-intensity workouts help prevent muscle atrophy, bone density loss, and aerobic decline during monthslong space missions.

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.

There are no established minimum fitness standards for spaceflight

Microgravity is known to cause arterial hardening, bone weakening, and other health issues, but the novelty of space tourism and the minimal exposure time for suborbital trips have limited the number of research studies. Many companies have participants sign extensive waivers to bypass the requirement of specific medical standards.

Microgravity can alter the evolution of viruses and bacteria

Experiments conducted on the International Space Station have shown that microgravity environments can delay viral and bacterial infections and induce mutations not seen on Earth. These mutations could have implications for long-term space missions and human health and suggest space can serve as a testing ground for developing new therapeutic approaches.

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.

Watch what it’s like to spend a day on the International Space Station

Microgravity makes personal care more complex on the International Space Station, where stray, floating materials must be captured to prevent them from entering vents and clogging filtration vents. No-rinse shampoo, water pouches, and other strategies help minimize obstructions.

Microgravity environments improve the success of 3D bioprinting

Gravity can cause gaps, such as those in the chambers of a 3D-printed heart, to collapse before stem cells, hydrogels, and biochemicals bind together during the bioprinting process. Rather than Earth's surface, some bioprinting is done on the International Space Station, where defective organs are also printed to test treatment methods.

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.

It is impossible for astronauts to burp in space

Due to Earth's gravity, liquids and solids sink in our digestive system, while gases rise, allowing them to be forced back up the esophagus to be expelled through burping. In the microgravity environment of the International Space Station, burping would result in vomiting if it were possible.

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.

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.

Muted smell and taste in microgravity complicate meal enjoyment

Astronauts primarily consume freeze-dried meals, which are rehydrated with water recycled from urine and perspiration, directly from bags. Condiments and select cultural items from crew members can enhance the meal experience by boosting flavor. Many individuals report experiencing "food fatigue" due to a lack of fresh produce, limited menu variety, and lingering scents.

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.

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...

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.

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,...

Gravity assists are crucial for space travel beyond Mars

By traveling near a moving celestial object, a passing object can gain or lose speed and change direction due to the acceleration provided by their mutual gravity. Some missions are planned around spacecraft performing multiple assists, or slingshots, to reduce fuel requirements for long-distance travel.

Civilians on short-term spaceflights can experience long-term astronaut health impacts

A collection of 44 studies—primarily based on data from a 2021 tourist trip to low Earth orbit—identified immune system disruption and some kidney damage in tourists, with women appearing to recover from space travel faster than men. Return trips from Mars may require human travelers to be on dialysis.

Adults may lose roughly 3% of their muscle mass each decade after 30.

Emulating Earth’s light-dark cycle is important for astronaut health and safety

Astronauts aboard the International Space Station experience 16 daily sunrises, but scientists have learned to try to promote circadian rhythms by phasing through several light settings aboard the ISS to improve astronauts’ sleep and productivity.

Longer-duration space missions may amplify astronaut motion sickness

NASA is using the Kraken, a 50-foot-long, 100-ton US Navy research device, to simulate space motion sickness and vertigo and test possible recovery strategies, including testing out different, specific head movements. The Kraken, located at Wright-Patterson Air Force Base near Dayton, Ohio, can rotate participants at exposures of up to 3G.

We don't know why astronauts get motion sick

Between 60% and 90% of astronauts get motion sick in space—and many also get motion sick during the first few days upon return. Motion sickness on Earth does not seem to correlate with whether or not astronauts get motion sick in space, so it's not possible to predict who will get ill.

How to make a burrito in space

Just because you’re living at the International Space Station doesn’t mean your cravings disappear. In this video, Chef Traci Des Jardins explains the best way to make a burrito while experiencing microgravity.

Tardigrades have not been shown to survive all space conditions at once

A 2007 mission launched several species into low-Earth orbit, exposing them to microgravity in temperature-controlled modules. Survivability rates were high for microgravity exposure alone, but plummeted when combined with exposure to the full UV spectrum and the vacuum of space.

Eleven deaf men played a pivotal role in America's human spaceflight program

In the mid-20th century, 11 deaf men volunteered for a series of experiments that offered unprecedented insights into the effects of weightlessness on the human body. Most of the men had become deaf in early childhood as a result of spinal meningitis, a condition known to damage the vestibular system and make them less susceptible to motion sickness. For a decade, these men participated in extreme motion sickness situations, including living in a slowly spinning room, spending time in centrifuge pods designed to simulate hypergravity, and flying in parabolic flights sometimes referred to as the "Vomit Comet." (Some users may experience a paywall.)

Where you are located in a gravitational field affects how quickly you age

The closer something is to the center of a massive object, the greater the strength of the massive object's gravitational field as a result of space-time being depressed more severely. Time passes more slowly the deeper an object is in this gravitational depression, meaning objects in the universe naturally seek to age more slowly.

Resistance training can help fight osteoporosis, especially in menopausal women.

Adults need 2 days of muscle-strengthening activity weekly—yet most of us aren't doing that.

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 impact of gravitational force on our bodies surprised early coaster riders and engineers

There is only a certain amount of gravitational force that the body can handle before dealing with consequences like short-term vision loss or unconsciousness. Increased scientific understanding has largely reduced these impacts, with engineers combining periods of intense pressure with periods of relief.

About 10% of the radiation people are exposed to each year comes from outer space, with higher percentages for those living at higher elevations or who fly often.

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.

Strength training appears to make for a healthier, youthful-looking brain.

The International Space Station is slowly falling due to atmospheric drag

To stay in orbit, the largest human-made object in space needs periodic rocket boosts to maintain its orbital speed and height. Its solar panels collect enough energy to power over 60 average US homes each year.

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.

Recent global health estimates suggest that inactivity is a leading risk factor for death, contributing to 6% of deaths worldwide.

Five hazards of human spaceflight

From space radiation to isolation, humans struggle when it comes to traveling and living in space. What does this mean for long-term spaceflight? This hour-long podcast episode attempts to answer that question while detailing five major spaceflight hazards.

Watch a visualization of what it would look like to move along Earth's surface as fast as the International Space Station, or about 23 times the speed of sound.

Space trash is making low Earth orbit increasingly dangerous for spacecraft

Millions of fragments from satellites, rockets, and other spacecraft that are no longer operational move thousands of meters per second as they circle Earth. Even a piece of debris a centimeter in size can cause mission-ending damage to space stations, telescopes, and astronauts.

Since 2019, a free-floating robotic system named Astrobee has helped astronauts with routine tasks on the International Space Station.

Astronauts have used a small portable device to take the first-ever X-rays in space, opening the door for new opportunities for aerospace medicine.

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.

NASA worries about the reactivation of dormant viruses during missions—particularly the virus that causes shingles—because spaceflight suppresses the human immune system and elevates stress hormones, making it more challenging to stay healthy.

NASA has partnered with several private companies to promote commercial space stations

The retirement of the International Space Station in 2030 has led NASA to refocus its efforts on continuing microgravity research through private partnerships, including the support of multiple commercial space stations' design and development.

Visitors of the International Space Station are trained in English and Russian

Different space agencies develop different modules of the ISS, meaning their controls, documentation, and instrumentation are not always written in English. Because the first modules were delivered using US and Russian spacecraft, astronauts have been historically trained in both languages.

If there were a swimming pool on the moon, where gravity is about one-sixth that of Earth, championship finswimmers could potentially launch themselves up to 5 meters (16 feet) in the air.

What is space sickness?

Mix motion sickness minus gravity with a host of other variables, and you’ve got a recipe for space adaptation syndrome. It can hit anyone, even astronauts who escaped the issue previously. This article details the history and science behind space sickness.

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.

Understanding why suction cups rely on Earth's atmosphere to work

When pressed against a surface, air is squeezed out of a sealed volume, causing the internal pressure to drop below the surrounding atmospheric pressure, and this imbalance creates the "sticking." For this reason, astronauts do not use suction cups or related technologies to stay on spacecraft during spacewalks.