Gravity, who needs it?
Quiet and attentive, inside the Russian capsule Soyuz, the astronauts gaze at the glow of the surrounding flames. In a few seconds, the window blackens. About seven minutes of tension and silence follow. Communication with the base on Earth is off. The die is cast.
Prior preparation was crucial: the sequence of operations should have been performed flawlessly.
Three hours ago, in Baikonur, Kazakhstan, the Roscosmos space agency flight control received the signal from the International Space Station. Up in the sky, 400 kilometres above the sea level, the capsule had undocked and was heading to Earth. The room is full. Despite the routine, the tension resembles an open heart operation.
During the return, three brakes prevent the deadly free fall. First, the capsule wears a shield to face the caustic atmosphere, as if it were a dangerous enemy. Scientists often compare this transit to a surfer riding a wave. Any false movement and the scorching plasma produced by friction pulverizes the capsule. However, miles of atmosphere is an effective brake that actually does most of the work.
Seven minutes later, the friction has reduced the Soyuz speed, and the fire is extinguished. The capsule is ready for the next break: a series of parachutes opening automatically. From the Kazakhstan deserts, in contrast to the clear and sunny sky, you can see the Soyuz capsule tied to its coloured parachute.
Finally, a few small rockets at the base fire less than a meter from the ground. The total flight time is as short as going from London to Athens by commercial aeroplane. In three and a half hours, the tiny and uncomfortable capsule breaks from 28 thousand to 5.5 kilometres per hour — ensuring the astronauts return home.
Despite efforts for a landing as friendly as possible, it feels “like the head-on collision between a truck and a small car”, Italian astronaut Paolo Nespoli confesses.
Without losing sight of the capsule, the rescue teams head to the chosen landing site. The astronauts cannot fend for themselves, their bodies no longer recognize Earth’s beloved old gravity.
The International Space Station has been in orbit around the Earth since 1988. More than 60 expeditions of astronauts from 16 countries and various space agencies have been conducting experiments in microgravity conditions.
Everything at the International Space Station is under study, even the astronauts themselves. The reason: we, humans, want to go to the Moon again and stay, we want to visit Mars. But first, we need to understand how to protect ourselves from the extreme conditions of outer space.
The health problems that appear, even conditioning the ship, are numerous, and we still do not know them all. NASA classifies immediate hazards as follows: changes in gravity, isolation and confinement, closed and small environments, and radiation from space.
Our body struggles all the time to overcome gravity. At home, when we are walking, standing still or sitting, gravity pulls the blood down, and the heart must pump it up to bring it to the brain and keep it circulating.
Under microgravity conditions, the heart becomes lazy and weak, the blood in the head pressures the eyes causing vision problems. Increased calcium excretion from the bones and dehydration may lead to kidney stones. An unrecoverable loss of 1% per month of bone density occurs. To limit muscle loss, astronauts need to spend at least two hours a day exercising.
On the other hand, isolation and confinement can lead to a drop in mood, depression and even cognitive problems. Boredom and misunderstandings from impaired communications affect mission performance.
Long-term exposure to cosmic radiation in space flights is one of the biggest concerns. The Earth protects us with its magnetic field and its atmosphere. Outside of this coat, astronauts receive ten times more radiation which increases the risk of developing cancer, damages the central nervous system, reduces motor function and causes anorexia and fatigue. Food and medicines also lose their properties.
During the expedition 61, Christina Koch became the woman who has stayed the longest in space. She has been at the ISS for 328 days. Thanks to her effort, we will know more about the effect of microgravity and the severity of outer space on the female body.
The results of Christina Koch’s mission will provide more relevant information on the body’s reaction to the abandonment of our mother Earth. And the exhaustive list may grow.
However, none of these difficulties will daunt us. Paraphrasing the Martian: we will science the heck out them, with tools of medicine, science and biotechnology. Human beings have never given up solving problems, creating tools and transforming the environment, even changing ourselves, is the sign of our species.
Shortly, NASA will put men again and the first women on the Moon with the Artemis program, which is already underway. Space agencies gear up for a dreamy human-crewed mission to Mars.
Scientists work hard to ensure safe space travel and a return to our beloved Earth’s gravity. The adventure and excitement to discover more about other worlds are worth it.
This is a translation from my piece in Spanish: La gravedad y su impacto en la salud de los astronauts.
