Extraterrestrial Health: The Meaning of Medicine in Space28th Dec 2022
Although humans are the dominant terrestrial species, they can be seen as fragile and prone to many diseases. If you open a medical directory, you will be horrified by the number of known ailments and their extent. Modern medicine has learned to combat many of them, but medical science is still far from perfect. Nature constantly challenges doctors, and with the beginning of our expansion into space, new space challenges have emerged. This different and much more hostile environment requires special approaches to human health preservation. But which approaches, exactly?
In this article, we will cover space medicine, its features, evolution, and the benefits of space research for human health. You will find out what astronauts are treated for, and what skills a space medicine doctor should have.
Unfortunately, yes. Diseases haunt us not only on Earth but also in space. Everyone knows that astronauts are one of the healthiest people on Earth because space flight requires remarkable health and excellent physical shape. That is why space and medicine are inseparable. All space mission applicants are carefully selected, tested, and trained to withstand extreme loads, but even despite these measures, they still get sick.
Apollo 7 commander Walter Schirra, after half a day into the flight, managed to catch a runny nose, which was soon transmitted to the rest of the crew. And Fred Hayes developed a painful kidney infection during the Apollo 13 mission. Why did these happen?
The fact is that weightlessness is a great environment for microbes — pathogens can develop thicker cell walls, greater resistance to antimicrobial agents, and a greater ability to form so-called biofilms that adhere to surfaces. Even an ordinary runny nose in space becomes a real torture since the liquid from the nasal mucosa does not drain into the throat as it does on Earth. Instead, it remains inside under the influence of microgravity, causing constant congestion. But germs are only one part of the problem.
Astronauts in zero gravity can be injured when they collide with objects, get bruised or even cut. In addition, 30-40% of them experience vision problems due to an increase in the eyeball blood vessel’s permeability, and more than 70% suffer from space adaptation syndrome, which resembles sea sickness in symptoms. During the 1985 Discovery mission, astronaut Jake Garn became so nauseous that his colleagues jokingly coined the “garn” — a unit of scale for incapacitation in space. Its maximum – 1 garn – means complete uselessness. Fortunately, such poor fellows as Garn are few; for most astronauts, the intensity of such symptoms does not exceed 0.1 garn.
But even if you are lucky and you don’t get sick on the flight, a long stay in space does not go without health consequences. As a result of the reduced gravitational load on a skeleton, astronauts lose approximately 1% of bone mass per month, which then takes years to replenish. For comparison, patients with osteoporosis lose this volume in a year. Diet specifics, the psycho-emotional stress associated with prolonged isolation, muscle atrophy, and decompression disorders, among other issues, also affect astronauts’ health. In the figure below, you can see a complete list of disorders.
Knowledge and experience in space physiology and medicine are required, if we are to spend extended periods of time in space. So, what is space medicine?
Space medicine, in a broad sense, is the practice of all aspects of preventive medicine, including screening, providing medical care and maintaining the performance of an astronaut in the extreme conditions of space as well as maintaining his health in the long term.
In the diagram below, you can see the main concepts that underlie the theory and practice of space medicine, ranging from crew selection based on clinical considerations to the relationship between engineering systems, life support systems and human factors.
This diagram is inspired by the human factors SHELL model, which was first proposed in 1972. The SHELL abbreviation stands for:
- Software (e.g. standard operating procedures),
- Hardware (e.g. equipment, systems, vehicles),
- Liveware (individual)
- Liveware (other people).
The SHELL model is built based on aviation systems, so it can be argued that aviation and space medicine have a lot in common. The second one uses the fundamentals and experience of the first one and is, in fact, its more advanced, supplemented version. This largely explains why the first astronauts were selected from test pilots, and space medicine doctor is still called a flight surgeon.
Space medicine research began in the 1950s when competition in the development of rockets between the USSR and the USA reached its peak, and the first manned space flight was only a matter of time. Both countries began experimenting with high-altitude balloon and aircraft flights, developing various environmental management systems and life support mechanisms. Many argued that prolonged human exposure to microgravity would be fatal, but Gagarin’s 108-minute flight on April 12, 1961, dispelled those fears.
The subsequent US-manned Gemini and Apollo programs were designed to increase the duration of human stay in space, resulting in many important studies. The next step was three NASA space station Skylab missions in 1973-74, during which experiments were conducted to study the specific effects on the human body, which led to a more systematic understanding of the medical problems associated with space flight.
Longer duration missions
A real breakthrough in the development of NASA space medicine was the Space Shuttle program in the early 1980s. The shuttle made it possible for seven astronauts to simultaneously stay in space for two weeks while also carrying complex equipment for medical research on board.
The next milestone was the launch of the Russian space station Mir in 1986, which made it possible to increase the astronaut stay in space by up to several months. Russian cosmonauts Gennady Padalka and Valery Polyakov set records for the longest stay on the station — 879 days in five flights and 439 days in one flight, respectively. This helped to establish that a person can live in space for one year or more, but the space environment affects everyone differently, and not everyone can safely stay there for a long time. Since 1999, the International Space Station has taken over Mir in its watch of medical and other research in the space environment.
Today space medicine specialists all over the world continue working on programs to ameliorate the dangers associated with space flights of various durations. In particular, projects are underway to simulate settlements on the Moon and Mars. Most of these projects are designed to help researchers understand what psychological, emotional, and social consequences may occur after prolonged astronaut isolation. Besides space doctor training, ordinary astronauts are also trained to provide emergency care in space.
Now let’s find out how it all works in practice. A space doctor’s main task is to ensure medical support during the flight and in the inter-flight period. Space medicine doctors should:
- understand the principles of clinical medicine for space flight;
- participate in the selection of new staff and crew,
- conduct scheduled check-ups and medical examinations,
- form first aid kits,
- develop work and rest regimes depending on the flight complexity,
- follow up on recommendations,
- participate in a forensic medical examination,
- provide therapeutic, dental and surgical medical care,
- neutralize the consequences of an extreme environment (injuries, burns, radiation damage),
- identify and correct behavioural disorders, prevent mental disorders, and provide psychotherapeutic assistance.
Often, the job of a flight surgeon is taken on by physicians with experience in disaster medicine or emergency medicine — with basic surgical skills, proficiency in ultrasound diagnostics, cardiac resuscitation, basic training in psychiatry and the early detection of behavioural disorders. The onboard spacecraft physician must also be in good health, have good visual-motor coordination and fine motor skills, and have no problems with vision, hearing and diction.
Health workers with higher education and a completed residency in therapy or family medicine (general medical practice) are the top candidates for joining NASA. To get an opportunity to work with astronauts, they simply need to take professional retraining courses. For beginners, the entire learning process takes about eight years.
A watch at the ISS can last up to six months, so you can’t do without a first aid kit. Medical kits on board the ISS contain over 190 different medications. The list includes
- sleeping pills,
- dressings (plasters and bandages),
- eye drops,
- nasal drops,
- warming ointments;
- gastrointestinal drugs;
- drugs to normalize blood pressure;
- drugs to improve blood circulation:
- set of diagnostic equipment: phonendoscope, otoscope, ophthalmoscope;
- kit for primary resuscitation.
Fortunately, many substances remain unused, and the shortage of the most commonly used drugs is almost impossible. Resupply missions regularly update medical kits, too.
A 2017 ISS drug consumption study found that each crew member took an average of four medications per week, most commonly analgesics, decongestants, and sleeping pills.
Surgeries in microgravity are possible; after all, space medicine doctors are called flight surgeons for a reason. However, they have only been carried out on models and under flight simulation conditions so far. Astronauts have twice managed to perform a laparotomy, a mild, invasive surgical procedure used to examine and repair organs inside the abdominal cavity. In the first case, a laparoscopy of pig intestines was performed, and in the second, bleeding into the human abdominal cavity was stopped. Based on their results, both cases were considered satisfactory; however, the researchers noted the high complexity of these operations.
The problem is that bodily fluids on Earth and in space behave differently. Due to low gravity, the blood in our veins can stick to surgical tools due to surface tension; floating droplets can form currents that restrict the surgeon’s field of vision; and air circulating in an enclosed space is an excellent environment for infection.
But how likely is it that an astronaut in space will actually need surgery? The researchers calculated that during a mission to Mars, a crew of seven would, on average, have one surgical emergency every 2.4 years. The main causes may include trauma, appendicitis, gallbladder inflammation, and cancer.
So ideally, spacecraft for long missions would need to be equipped with special radiation-shielded capsules, surgical robots, advanced life support with filtered air, and a computer to aid in diagnosis and treatment. In other words, pretty much the kind of equipment we see in space movies.
The space environment is much more hostile than the terrestrial one, and this helps space medicine to diagnose the causes of some common earthly diseases that were previously not amenable to effective treatment.
Studies have shown that astronauts who have perfect vision before the flight but begin to lose it in space have genetically higher levels of the amino acid homocysteine, which requires B-complex vitamins for secretion. In space, this level drops critically, so such patients require higher doses of this vitamin group.
Women who have polycystic ovary syndrome usually also have higher levels of homocysteine. Polycystic is the main cause of infertility, affecting up to 20% of women. So, it is possible that women with this disease need to take increased doses of B vitamins.
This theory has not yet been confirmed, but NASA and doctors at the Mayo Clinic are conducting research in this direction, and perhaps this discovery will become one of the best examples of space exploration benefits.
This disease is characterized by rapid loss of bone tissue, due to which the bones become fragile, and the person loses the ability to move normally. However, body space medicine has found that astronauts in zero gravity lose bone mass ten times faster. After years of trial and error, scientists have been able to slow down this process with the right diet.
Astronauts who ate more fish, vegetables, fruit, less salt and iron-rich foods experienced little to no bone loss during their 6-month stay in space.
These findings are of great importance for all Earthly inhabitants — besides osteoporosis prevention, similar diet changes can also eliminate many other health problems.
Some people, due to their residence or professional activity specifics, experience a lack of sunlight. The same applies to astronauts. And as you know, the sun is the main source of vitamin D in the body, and its deficiency leads to problems with muscles, teeth and bones and increased excitability of viral infections, such as herpes, which is constantly present in our body.
Space medicine helped to establish that taking small doses of vitamin D can solve this problem, but increasing the dose does not have the desired effect. In addition, the response to vitamin supplements is directly related to body weight — the higher it is, the less effective such additives are. This happens because fat absorbs vitamin D and prevents it from staying in the blood.
This knowledge helped develop recommendations on vitamin intake for residents of the Northern regions and polar explorers wintering in Antarctica.
The 21st century shows that humanity is definitively rushing into space. We’re going to colonize the Moon and go to Mars. ISS has a Chinese competitor Tiangong, and passionate space billionaires promise to build the first space hotels for tourists in near-Earth orbit. The more we rush into space, the more obvious the role of space medicine becomes. Perhaps in the near future, space technology will teach us to defeat cancer, carry out the most complex operations without risk, and treat a runny nose not in 7 days but in 7 minutes.