COSMIC THREAT: how our heart ages due to gravity
Photo by Alessandro Ferrari on Unsplash
The dream of traveling across endless starry expanses has long captured human imagination. Much of what once seemed like science fiction is now a reality. But how well is the human body, which evolved under Earth’s conditions, adapted to life in space? Scientists are forced to admit — not very well. Yet, they persist, trying to find new ways to survive in interstellar space.
FORWARD TO A MULTIPLANETARY CIVILIZATION!
Since the last American Apollo crew launched in 1972, no human has set foot on the lunar surface. But recently, astronautics has made impressive advancements. Starting this year, astronauts have begun preparing for geological work in the harsh conditions of the Moon’s south pole. NASA has scheduled a new human visit to Earth’s satellite for September 2026. Not far behind, the indefatigable Elon Musk is also making strides.
By then, his company, SpaceX, aims to launch five ships to Mars. If all goes well, crewed flights could be possible within four years. With cutting-edge technologies, people are striving to become a multi-planetary civilization. But do they fully understand the challenges they will face in space?
RADIATION RISK
In September 2024, during the Polaris Dawn space mission, the Dragon 2 crew ventured 1,400 km away from Earth. By comparison, the ISS orbits at around 400 km, which is relatively safe. However, at greater distances, the threat to human life increases significantly.
It’s crucial to remember that beyond Earth’s magnetosphere, starting from approximately 1,000 km altitude, outer space becomes highly radioactive. Even the magnetosphere itself traps charged particles in special zones known as the Van Allen belts.
«TOXIC» VACUUM
This presents a constant challenge for flight engineers: how to protect both humans and equipment from the harmful effects of space. This problem is especially pressing for spacewalks. One of Polaris Dawn’s objectives, among others, was to test lightweight EVA spacesuits in the vacuum of space.
This is no easy task, significantly since the new method of spacewalking departs from NASA’s traditional «standards». The suit must shield the wearer from radiation, extreme temperatures, and micrometeoroids. The vacuum itself is far from harmless — when interacting with many materials, it releases toxins that remain trapped inside the suit once it is sealed.
«SPACE» HEART
It’s not only external influences that pose a threat to humans in space. Biologically, it seems humans are not well-adapted for long-term space travel. One of the latest articles in the international scientific journal Nature summarizes some data on the health of space tourists and astronauts, as well as experimental findings that reveal the effects of microgravity, radiation, and other space «attributes» on the human body.
For example, researchers sent artificial heart tissue to the ISS to measure its performance. The results were discouraging — after just one month in space, the tissue weakened, and its «beating» became irregular. The heart tissue experiences molecular and genetic changes that are characteristic of aging.
MICROGRAVITY CAUSES STRESS
The culprit is microgravity, which has a detrimental impact on the human heart. Astronauts have often experienced various cardiovascular changes, such as arrhythmia.
Studying these effects during long spaceflights is very challenging, especially when it involves human subjects. However, specialists from Johns Hopkins University in Baltimore found a solution by sending artificially created heart tissue into orbit, where it spent 30 days traveling.
The sample set was constructed from human stem cells and equipped with a system of pins that simulated heart muscle contractions. The entire setup was compact, about half the size of a mobile phone. An identical setup was created on Earth. Using sensors, researchers monitored and compared data from the «space» and «earth» hearts.
GENETIC MUTATIONS
After 12 days, the contraction strength of the «space heart» had decreased by almost half compared to the «earth heart». Its beating became irregular, and by day 19, the interval between beats had increased more than fivefold. The good news is that cardiovascular stress appears to subside, and rhythm gradually normalizes once back on Earth. However, genetic mutations are a different story.
After a month in orbit, the protein filaments responsible for muscle contractions were shorter and more disorganized, and mitochondria had swollen and become fragmented. Gene expression controlling these processes deviated significantly from normal. Scientists plan to continue studying heart tissue and other organs under space conditions.
Ultimately, they hope to test drugs that could counteract some of the effects of microgravity on the human body, bringing the long-standing dream of safe, extended space travel much closer.
Original research:
