Hello everyone and welcome to this week's blog post where I will be discussing medicine in space. In this article, I will explore the threats posed to astronauts by radiation and micro-gravity, as well as the impact space has on astronauts' mental health. I will then summarise the use of conducting experiments in space and how they support medical research on Earth.
One of the most serious threats to astronauts health, while they travel in space, is radiation. The Sun constantly spews radiation, both in the form of solar flares and as huge clouds. These huge clouds are the most powerful form of solar radiation, as they contain high-speed protons, which are incredibly dangerous. Normally, humans on Earth are shielded from this radiation by a geomagnetic field (generated by the fluid outer core underneath the mantle) which surrounds the Earth, deflecting radiation. Nonetheless, astronauts in space are not protected by this field. As the radiation is able to pass through spacesuits and spacecraft, it is able to cause major damage to astronauts, including short-term radiation sickness and cancer.
Radiation from the sun has carcinogenic properties, meaning that it causes cancer in humans who are exposed. This is because, when the radiation passes through the human body it interacts with the DNA inside cells and causes mutations in their genetic sequence. These mutations can then cause the cells, when they divide by mitosis, to divide uncontrollably, resulting in the formation of a tumour.
One of the other big challenges of space travel is combatting the severe bone and muscle loss that occurs. This occurs for two reasons. Firstly, due to the fact that astronauts are strapped into their seats when travelling in spacecraft, their muscles are not exercised as much. In addition, the lack of gravity not only means that less effort is required to move around a space station but also means that the loading force that gravity usually applies to them is gone. As such, the body no longer feels the need to use resources to build these muscles up. Instead, the body breaks them down and uses them as an energy source.
In addition, bone loss also occurs at an alarming rate. Indeed, according to a paper published in 2009, simply spending 3-4 months in space results in bone density loss which takes 3 years to regain after returning to Earth. The paper even went on to explain how some astronauts are never able to regain preflight levels of bone density, and even if regrowth occurs, it may have different structures than before.
The main reason for the loss of bone density is the same reason which causes muscle atrophy - the micro-gravity of a space environment means that the static loading of skeletal muscles and bones is virtually non-existent. In addition, the impact forces on the skeleton (due to walking and running) are also no longer present, further exacerbating the loss in bone density. Furthermore, these factors also result in the demineralisation of bone tissue
The main way to combat muscle and bone density loss simply through intensive exercise. As such, astronauts on the International Space Station typically exercise on treadmills and other equipment for two hours each day. Regardless, the effects of micro-gravity are still not able to be overcome and rehabilitation and treatment are still often needed after astronauts return to Earth.
Weightlessness, due to the micro-gravity environment, also commonly causes balance issues for astronauts when they return to Earth. At sea-level, a person feels 1g of force exerted by the gravitational field of the Earth. However, this gravitational force changes drastically when astronauts travel, which affects their balance. According to NASA, this is because blood volume decreases in space, making astronauts feel lightheaded when they return to Earth. In addition, the brain also learns to do things differently in space and, as such, it takes time for it to readjust once the astronaut returns.
While it might seem obvious, it is important to point out that if we were to send a space mission to Mars or some other faraway planet, we would need to train the astronauts to be able to perform medical tasks, including surgeries. While we could, and would, make sure that a doctor was part of the crew, the rest of the astronauts would still need to be able to perform basic surgery in the case that the doctor was incapacitated. Surgery in space is also complicated due to the weightless environment meaning that everything must be restrained and extraordinary care must be taken to ensure the surgical field doesn't become contaminated.
The mental health of astronauts is also something to be considered. Space is well-known for being an isolating environment, with astronauts having to spend months in space away from their families. While an internet connection is available on the International Space Station, so astronauts can talk to their families regularly, astronauts still have to live with the same people for months on end in the high-stress environment of space.
Astronauts on the International Space Station spend the majority of their day working on scientific experiments which require the micro-gravity environment of space. These experiments are not only used to further our understanding of how space affects the human body (in preparation for humans spending extended periods of time in space such as on a mission to Mars), but are also used to increase our knowledge in other areas, such as physics, chemistry and medicine.
These medical experiments are possible because the weightless conditions in space cause accelerated ageing and astronauts to develop similar problems to those caused by a sedentary lifestyle. According to the Canadian Space Agency, these factors can then be utilised by scientists to conduct studies into our bones, heart, blood vessels and brains. Additionally, bacterial growth is higher in space, with bacteria growing faster and forming more deadly strains than they would do on earth. This exacerbates how quickly we can identify genes in the bacterial genome which allows them to rapidly adapt, as well as help us develop vaccines.
The experiments which are performed in the International Space Station have far-reaching implications on Earth medicine. In addition to the impacts I described above, these experiments have also helped improve the methodology for remote ultrasound exams. These are when a physician invents new ways of performing different ultrasound exams and instructs an untrained astronaut on how to perform these examinations on a team member. The methodology that is developed during these experiments could prove vital in saving someone's life when they are trapped in a remote area on Earth, such as in Antarctica, as well as on an extended space mission. Moreover, experiments are also being performed by NASA in developing a treatment for asthma, cancer treatment and in the treatment of osteoporosis.
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Sources:
Williams D, Kuipers A, Mukai C, Thirsk R. Acclimation during space flight: effects on human physiology.CMAJ. 2009;180(13):1317–1323. doi:10.1503/cmaj.090628
Hodkinson, P., Anderton, R., Posselt, B. and Fong, K., 2017. An overview of space medicine.British Journal of Anaesthesia, 119, pp.i143-i153.
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