Extreme challenges

What is the Kessler Syndrome? 10 serious threats astronauts face in space

Image: NASA Hubble Space Telescope

Space is the final frontier, but that hasn’t stopped humans from pushing beyond its boundaries. Space exploration, however, is fraught with danger. On Earth, we’re shielded from the cosmic hazards and extreme conditions that dominate the universe, but beyond our atmosphere, astronauts face a multitude of threats. From handling microgravity’s impact on the body to navigating the deadly vacuum, survival in space requires precision and discipline. Here are 10 essential things astronauts must do to stay alive—and continue their quest to explore the cosmos.

Image: Benjamin Recinos

A space suit is essential for survival beyond Earth’s atmosphere, providing protection from various hazards such as extreme temperatures, radiation, vacuum, and even space debris. The suit contains several layers, including thermal control and micrometeoroid shields, ensuring astronauts don’t freeze in the shadow of space or burn in direct sunlight. It also prevents depressurization effects by maintaining a stable internal atmosphere.

The suit also contains communication systems and a supply of oxygen, allowing astronauts to breathe and stay connected with their team during spacewalks. Without a suit, exposure to space would cause an astronaut to lose consciousness within seconds due to the lack of atmospheric pressure and oxygen deprivation.

Image: Joshua Chehov

As most people know, space lacks breathable oxygen. While oxygen is technically present beyond our atmosphere and elsewhere—ranking as the third most abundant element in the universe—its concentration in the vastness of space is so low that, for all practical purposes, it is equal to 0%. Thus, maintaining a sufficient oxygen supply is one of the greatest challenges astronauts face.

Fortunately, there are effective methods for generating oxygen to support long-duration missions. On the International Space Station (ISS), oxygen is produced through electrolysis, a process that splits water into oxygen and hydrogen. In the case of a system failure, astronauts can rely on emergency oxygen tanks, although these supplies are limited. Equally important is managing carbon dioxide levels. A process called carbon dioxide scrubbing is used to eliminate CO2, preventing suffocation.

Image: NASA

While there is no such thing as "zero gravity," the effects of Earth's gravity diminish the farther we travel from its sphere of influence. This near-weightless condition, known as microgravity, triggers immediate physiological changes in the human body. Without the gravitational pull that typically draws blood toward the legs, fluids shift upward, causing facial swelling and increased pressure behind the eyes. This can lead to a range of health issues, including impaired vision.

Over time, astronauts also face muscle atrophy and bone density loss, as their bodies no longer have to bear their own weight. To counteract this, astronauts must exercise daily with resistance machines, treadmills, and bikes. However, even with strict exercise regimens, muscle and bone recovery can take months once they return to Earth.

Image: NASA

While we may not always be aware of it, Earth's atmosphere and magnetic field provide essential protection against a range of invisible dangers found in deep space, with radiation being one of the most concerning. Even during a flight, passengers are exposed to elevated levels of radiation, roughly equivalent to a chest X-ray for every 10 hours spent in the air.

Astronauts, however, often operate beyond the protective layers of our planet, exposing them to even greater radiation levels. Spacecraft are equipped with radiation shields, but they can’t block all radiation. Astronauts can receive up to 10 times the radiation dosage they would on Earth, increasing their cancer risk in the long term. But the most dangerous radiation threat comes from solar flares. During these solar events, astronauts must take cover in specially shielded areas of their spacecraft.

Image: Kai Dahms

In space, every ounce of food and water must be carefully rationed. Thus, astronauts survive eating pre-packaged, freeze-dried meals that are both lightweight and rich in nutrients. They simply add water to rehydrate the meals before eating, ensuring they get enough calories to maintain energy levels. While it might not sound very appealing to live out of freeze-dried meals for months, astronauts also experience a noticeable reduction in taste due to the lack of gravity.

Drinking water presents its own set of challenges. Nothing can be wasted, so space stations designed for long-term habitation, like the International Space Station (ISS), often employ advanced filtration systems to recycle water from condensation, sweat, and even urine! Astronaut life isn’t all it’s cracked up to be, huh?

Image: NASA

Even with all their training, the deep isolation and confinement of space can significantly impact an astronaut’s mental health. Long missions far from Earth can lead to feelings of loneliness, anxiety, and depression. To deal with that, astronauts are encouraged to maintain a daily routine, exercise, and engage in team activities. Communication with loved ones back on Earth is also crucial for their emotional well-being.

Space agencies take mental health very seriously, conducting regular psychological assessments during missions. Studies have shown that astronauts on extended missions may experience a decline in cognitive abilities and an increase in stress levels—factors that can be critical in such a delicate environment, where mental clarity and emotional stability can be a matter of life or death.

Image: noe fornells

Despite the popular belief that it’s unforgivingly cold, space doesn’t have a temperature in the traditional sense—after all, it’s a vacuum. Instead, temperatures can shift dramatically, ranging from boiling hot to freezing cold, depending on exposure to the Sun. Astronauts rely on their suits and spacecraft systems to maintain a stable internal temperature. The suit’s liquid cooling garment, which contains a network of water-filled tubes, helps astronauts regulate their body temperature during spacewalks.

Inside the spacecraft, temperature control systems work to prevent the interior from becoming unbearably hot or cold. However, there have been instances where astronauts had to repair these systems themselves to avoid the dangers posed by extreme temperatures, which can fluctuate rapidly from 250°F to -250°F.

Image: Muha Ajjan

Ever wondered why most astronauts struggle to walk by themselves after returning to Earth from long missions? As we pointed out before, without the constant pull of gravity, muscles weaken very rapidly. In fact, astronauts can lose up to 20% of their muscle mass in just two weeks without exercise.

While it would be technically possible to maintain proper muscle mass through rigorous exercise, doing so would require significantly more time than it does on Earth. Astronauts lead extremely busy lives—every minute counts up there—leaving little time for anything beyond essential tasks. So, if you were thinking about heading to space to hit the gym, you might want to reconsider and stick to your local fitness center instead!

Image: NASA Hubble Space Telescope

Space debris, which includes everything from tiny meteoroids to fragments of defunct satellites and spent rocket parts, can travel at astonishing speeds of up to 17,500 mph! These high-speed projectiles can easily puncture spacecraft or damage equipment, putting astronauts' lives at serious risk.

The ISS is equipped with monitoring systems that detect nearby debris, allowing the station to perform evasive maneuvers when needed. However, this is far from a solved issue. Many scientists warn that if space pollution, much of which is produced by improper satellite disposal, is not addressed soon, it could lead to a cascading effect of collisions that would generate even more debris, and thus more collisions… you get the idea. This alarming scenario is known as Kessler Syndrome, and if left unchecked, it could threaten the safety and feasibility of future space exploration.

Image: National Cancer Institute

As if astronauts didn’t have enough going on already, space weakens the immune system, making astronauts more vulnerable to infections. This immunosuppression is caused by a mix of stress, microgravity, and increased radiation exposure. Studies have shown that astronauts’ white blood cells, which help fight infections, are less effective in space.

To make things worse, bacteria and viruses seem to behave differently out there, often becoming way more virulent than on Earth. Astronauts must be extra vigilant about hygiene, regularly disinfecting their living spaces and monitoring their health—not an easy task in the often cramped spaces where they must carry out their missions.

Mind the fruit

Who was Granny Smith, the apple? Fruits and veggies with real names

You probably know a Granny Smith from a McIntosh, and you may have ordered Hass avocado without giving its name a second thought. But many familiar fruits and vegetables are actually carrying around the names of real people. Behind those supermarket labels are farmers, judges, missionaries, immigrants, and a few very lucky gardeners. Let’s take a look at 11 people whose names unexpectedly became part of our grocery vocabulary!

Yes, Granny Smith was a real granny. Maria Ann Smith was born in England in 1799 and emigrated to Australia with her husband, Thomas, in 1838. The couple eventually established an orchard in Eastwood, near Sydney.

Around 1868, Smith showed another orchardist an unusual apple seedling growing near a creek on her property, apparently from discarded crab apples. She propagated it, but died in 1870, before seeing its success. By the 1890s, "Granny Smith's seedlings" were winning prizes, and her crisp green apple was on its way to international fame.

Rudolph Hass wasn't a famous botanist. He was a California mail carrier who bought avocado seedlings for a small orchard in La Habra Heights in the 1920s. One stubborn little tree resisted his attempts to graft another avocado variety onto it.

Luckily, Hass didn't chop it down. The tree produced delicious fruit with an unusual rough, dark skin, and his children reportedly loved it. Hass patented the variety in 1935, giving it his surname. Today, the Hass dominates the avocado business, but its namesake made relatively little money from the tree that transformed the industry.

The name behind America's famous dark-red cherry belonged to a 19th-century Chinese immigrant. Ah Bing worked for decades as foreman at horticulturist Seth Lewelling's nursery in Milwaukie, Oregon, where he supervised a large crew of Chinese workers.

Historical accounts differ over exactly how much credit Bing deserves for developing the variety, but they agree that Lewelling named it in his honor. Bing returned to China in 1889 and never came back to America. More than a century later, however, his name remains attached to one of the country's most important sweet cherries.

The boysenberry almost vanished before most people ever got a chance to taste one. California horticulturist Rudolph Boysen experimented with berry hybrids during the 1920s but eventually abandoned the project and the surviving plants.

USDA horticulturist George Darrow later became intrigued by reports of Boysen's enormous berries and enlisted grower Walter Knott to help find them. They discovered neglected vines on Boysen's former property, transplanted them, and brought them back to health. Knott sold the rediscovered fruit under Boysen's name, helping launch the business that became Knott's Berry Farm.

The clementine didn't take its name from a farmer named Clementine. Its namesake was Clément Rodier, a French Catholic missionary brother who worked at an orphanage in Misserghin, near Oran in what was then French Algeria.

Around the turn of the 20th century, a new type of mandarin appeared in the orphanage's citrus garden and came to be associated with Brother Clément. Its precise botanical origins have been debated, but his connection to the name is well established. The little seedless citrus traveled quickly: clementines were already being cultivated in Riverside, California, by 1909.

After settling in Dundela, Ontario, John McIntosh discovered wild apple seedlings growing on land he was clearing and transplanted several of them. One survived and produced particularly good fruit.

His family propagated the tree, and the McIntosh eventually became one of Canada's best-known apples. But the surname made another unexpected leap in the 20th century. Apple employee Jef Raskin named the Macintosh computer project after his favorite apple variety, changing the spelling. One chance seedling ultimately helped name a technological revolution.

Enoch Bartlett received one of the most successful cases of mistaken credit in horticultural history. The pear Americans call Bartlett was already an English variety known as Williams' Bon Chrétien when trees were brought to Massachusetts around 1799.

Bartlett later acquired the property where they were growing and, apparently unaware of their European identity, propagated and distributed the pear under his own name. Americans eventually discovered that Bartlett and Williams were the same variety, but the new name had already stuck. That's why Americans still buy Bartlett pears while British shoppers generally know them as Williams pears.

Imagine having a respectable career as a judge and being remembered mainly for a berry. That was the unusual fate of James Harvey Logan, a lawyer, judge, and enthusiastic amateur horticulturist in Santa Cruz, California.

In the 1880s, Logan experimented with berries in his garden and produced the reddish-purple fruit that became known as the loganberry. Its exact parentage has generated some historical debate, but Logan's role and the origin of its name are clear. His horticultural experiments proved remarkably durable: more than a century later, his surname still appears on jams, desserts, and berry plants.

Before Luther Burbank became one of America's most celebrated plant breeders, a potato helped finance his future. While farming in Lunenburg, Massachusetts, he noticed a rare seed ball growing on an Early Rose potato plant and experimented with its seeds.

One of the resulting plants produced unusually promising potatoes. Burbank sold the rights to his new variety for about $150: a modest-looking sum today, but enough to help fund his move to California in 1875. There he developed hundreds of plant varieties. The later Russet Burbank descended from his potato and became especially important in American agriculture.

Richard Cox was a retired English brewer who pursued horticulture at his property in Buckinghamshire, where he raised the apple that would eventually bear his surname around 1825.

The Cox's Orange Pippin became one of Britain's classic dessert apples, but Cox himself never witnessed the height of its fame. He died in 1845, while nurseryman Charles Turner introduced the variety commercially around 1850.