in 1976 two soviet cosmonauts were sent on a mission to the salyut 5 space station the last dedicated military space station in the soviet space program the commander and flight engineer boarded the soyuz 21 beginning a mission that was meant to last 66 days but after just 49 days the mission ended abruptly the cosmonauts were reporting something dangerous aboard the space station a noxious chemical smell ground control scrambled to get them back to earth soon after a replacement crew boarded the station with breathing equipment with concerns there was a fluid leak filling the rooms with
toxic gas but after a thorough inspection they found no odor no gas no technical problems at all subsequent reports of psychological problems in the soyuz crew led nasa to conclude the odor was probably a hallucination brought on by the long hours exhaustion and the harsh effects of the utterly alien environment of space on the human body the human body is an amazing machine but it's simply not built for a life in outer space in the last 6 million years we've evolved to thrive in earth's environments from the frigid cold terrain near the poles to the
sweltering regions along the equator but not in the weightless abyss of the final frontier nevertheless we continue to seek worlds beyond our own nasa and other space agencies have plans to send astronauts farther than we've ever traveled well beyond earth's atmosphere and even the moon crude missions to mars which are intended to take place in the 2030s will involve long duration flights and months or years-long stays on this far off planet this will have a profound effect on the human body which has already shown a wide range of health issues during stays on the international
space station which begs the question how will it be possible for the human body to injure months years or one day entire lifetimes in the unnatural inhospitable environment of outer space though we don't often consciously think about it every moment of every day an invisible force glues us to the surface of the earth our skeletons our muscles our hearts pumping blood through our veins are all perfectly adapted to exist and the specific amount of downward force created by earth's gravity but as soon as our body leaves our home planet this all completely changes in outer
space microgravity feels like total weightlessness and on mars gravity is one-third of earth's and with less force acting on the human body things start to get weird in the microgravity of space astronauts bones are no longer being used to support their weight or movements and they lose one to two percent of their bone mineral density each month for a one-way trip to mars which will take about 9 months this could amount to as much as 18 calcium from their degrading bones floods the bloodstream and can even lead to kidney stones on earth we also lose
bone density during our lives but under normal conditions it's replaced as fast as it's lost but in space that's not the case it's largely due to the bones not having to support any weight the drop in bone density is known as disuse osteoporosis and leaves bone weak and prone to fracture if left unchecked astronauts who've spent long periods in space may not even be able to walk when they return to earth in our lives on earth gravity also pulls down our bodily fluids without it astronauts blood and other fluids are pushed upwards towards the head
causing it to swell this increased intracranial pressure can lead to vision problems to try to correct these issues astronauts can wear compression cuffs to keep their fluids in their lower extremities and use resistance treadmills to build back muscle and bone mass but for longer missions this might not be enough and this is why scientists are now working to not simply combat the lack of gravity but to recreate it artificial gravity can in theory be made using centrifugal forces this type of machine is commonly found in science labs but you may have experienced the same effect
while driving fast around a curve or on a carnival ride when traveling in a circular path at high speeds in an enclosed vehicle a centripetal force is created by the outer wall that holds you inside but to you it feels like you're being pushed against the wall that push is called the centrifugal force and it can be used as an equivalent for gravity there are a few ways that this can be implemented in a spacecraft the first is by making the whole thing rotate there have been some different designs created by nasa engineers such as
these stick-like designs that rotate like a baton but rotating an entire spacecraft is tricky for a number of reasons maintenance of a rotating craft can be difficult and guidance and control can be even more difficult another option is rotating just one part of the spacecraft but again this comes with some technical issues and has even more moving parts than rotating the whole vehicle so scientists are thinking even smaller an on-board centrifuge that can fit one astronaut at a time they are currently investigating the time the astronauts would need to spend inside to keep their bodies
functioning properly in these tests the effects of microgravity are simulated using a bed rest model the test subjects lay with their bodies tilted negative six degrees head down for a miserable two months straight this unloads the bones and muscles and causes the bodily fluids to flow towards the head each day some participants spend 30 minutes in a centrifuge either over several sessions or all at once the scientists then compare a number of physiological outcomes between the two artificial gravity groups and the control group so far they found that 30 minutes of artificial gravity provided some
improvements in muscle function and balance but other negative effects such as vision loss were unaffected these results suggest that a longer duration in the centrifuge will be needed to successfully counter these health issues but even if the body is functioning correctly it does you no good if the mind is not [Music] our minds are fragile things and our mental health can be a challenge to take care of even in the best of circumstances many of us got a taste of the effect of isolation during the worst of the covid lockdowns and that was in the
comfort of our own homes with the entire netflix and steam catalogs at our disposal living in outer space stuck in a small artificial environment far from home with the same group of people with little to no privacy for long periods would be enough to obliterate anyone's mental well-being then add to that the inherent danger of the environment and the difficulty of performing a high-pressure job and it could easily be a recipe for disaster these circumstances can and do lead to cognitive impairment depression psychosomatic illness and even psychiatric disorders hallucinations like those experienced by the soyuz
crew are not uncommon other astronauts have hallucinated orange clouds flashes of light and angelic-looking figures another critical aspect for the mental health of astronauts during long-term space travel is group dynamics several missions have been interrupted due to interpersonal conflict between crew members and with mission control in fact the crew on sky lab 4 turned off communication with nasa for a whole day after arguing with mission control because of these issues space agencies like nasa have been studying people in isolated environments for many years these studies include evaluating astronauts in space as well as participants in
confinement in analog facilities here on earth stations in antarctica provide one such test bed antarctica's climate terrain temperature and isolation resemble that of outer space the landscape is uniform and boring the sensory deprivation is real and so is the danger crews there cannot be rescued quickly and everyone there is stuck with the same few people just like astronauts in outer space and under these conditions something important about team dynamics has been revealed to have a successful team you need not simply impeccable leadership or flawless decision making what you need is a clown humor it turns
out is critical for diffusing tense situations in antarctica and by that logic in outer space too joking around is also essential for coping with boredom brought on by prolonged periods of isolation scientists are now working to build a computer model that can help select the best crew based on personality traits like this one day soon nasa will be able to add the information of prospective crew members to the algorithm play various simulations and receive some predictions about which combinations of people are more or less likely to work well together as a team on board the
ships researchers have also improved lighting to help align astronauts circadian rhythm in order to improve sleep and alertness activities such as learning a new language or skill tending to a space garden or even being immersed in a vr world will help avoid depression and boost morale but the most insidious danger of outer space is one you can't see nor hear nor even feel you wouldn't even know it was killing you until it was far too late outer space's silent killer is radiation a form of energy that travels as rays electromagnetic waves and or particles we
experience it every day when we step outside into the sun turn on the lights microwave food or use our cell phones but while these and other more hazardous forms of radiation that we experience here on earth can cause adverse health effects the radiation in space is much worse that's because there are two types of radiation non-ionizing and ionizing non-ionizing radiation is less energetic and can easily be shielded out of our environment some sources of this on earth are power lines tvs cell phones and microwaves the light from the sun that reaches the earth is largely
composed of non-ionizing radiation since the ionizing far ultraviolet rays have been filtered out by the gases in the atmosphere particularly oxygen and this is a very good thing for us earthlings ionizing radiation is much more dangerous in outer space ionizing radiation comes from three sources particles that are trapped in earth's magnetic field called radiation belt particles particles usually protons that are shot into space during solar flares known as solar particle events and galactic cosmic rays which are composed of the nuclei of atoms that have had their surrounding electrons stripped away and are traveling at nearly
the speed of light ionizing radiation has enough energy to alter the substance it travels through it does this by removing electrons from the atoms in the material which ionizes them this can greatly damage the human body and even break apart our dna placing astronauts at significant risk for radiation sickness increased lifetime risk for cancer central nervous system effects and degenerative diseases the amount of risk depends on the dose of radiation that they're exposed to which is measured in millisieverts here on earth we typically experience a small dose for instance an average person in the u.s
is exposed to about 6.2 millisieverts each year mostly from radon and medical imaging however in space solar particle events and annual galactic cosmic ray exposure produces a much higher radiation dose one study measured this to be about 3 500 millisieverts for a large solar particle event and up to 700 millisieverts each year for galactic cosmic rays if astronauts are to spend any length of time in space they need high levels of protection space agencies like nasa have safety precautions in place to limit astronauts exposure to radiation currently these include things like shielding radiation monitoring exposure
caps and operational procedures like delaying a spacewalk until after a solar particle event with current precautions astronauts experience 50 to 120 millisieverts during a six-month stay on the international space station with a single day resulting in about 0.7 millisieverts while this is significantly higher than what we experience on earth it lets even the most vulnerable astronaut a 35 year old woman spend 857 days aboard the iss before reaching nasa's radiation exposure cap which in her case is 600 millisieverts nasa uses radiation exposure caps to determine how long astronauts can stay in space they calculate the
cap based on a risk estimate the limit is the amount of total exposure that would give an astronaut a three percent higher chance of dying of cancer in the rest of their life but that cap isn't equal for all astronauts women are more vulnerable because they are more susceptible to the cancers that radiation can cause due to the nature of their reproductive organs and younger people are more vulnerable because they have more time to develop cancer in their lives but more distant missions to mars which will require up to a thousand days in space will
expose astronauts to much higher doses of ionizing radiation potentially far surpassing the current radiation caps which range from 600 to 1117 millisieverts depending on the astronauts age and gender this could increase their lifetime risk of dying from cancer well beyond the three percent limit set by the cap to over 10 percent the reason for the high levels of radiation exposure even inside a well-shielded spacecraft is due to the nature of galactic cosmic rays while solar particle events can be more easily shielded galactic cosmic rays are more penetrating and move at such high speeds that typical
shielding materials can't slow them down researchers discovered that to completely block them the whole of the spacecraft would have to be outrageously thick so thick that the additional weight and fuel requirements would make the trip impossible this is why scientists are looking into other protection methods for these trips one option are wearable vests that protect the most vulnerable areas like the lungs and reproductive organs these vests are currently under development and tests of their effectiveness against radiation are planned for the upcoming artemis moon mission however the companies developing the vests are focusing on solar particle
events so it's unclear how well they'll shield astronauts from the more penetrating galactic cosmic rays another shielding technology being explored are electronic surfaces that actively deflect radiation these are known as active shielding methods and involve the generation of an electromagnetic field similar to that on earth but these have some drawbacks as well since they require a massive amount of energy their power comes from superconducting magnets which are heavy and require a cooling method but shielding may not be the only way to protect astronauts from radiation scientists are now looking to the field of medicine to
counteract its effects one radical idea is to genetically engineer astronauts to make their cells more resilient to radiation this could be done by turning on or off certain genes or by combining their dna with that of a more radiation resilient animal like tardigrades while this may sound like something from a science fiction movie scientists have already expressed a tardigrade protein in human cells grown in a petri dish leading to a reduction in the amount of radiation-induced damage this particular protein called damage suppressor prevents the animal's dna from breaking when exposed to high dose radiation the
human cells containing the protein had 40 percent less dna damage than cells without it while we're still decades away from genetically engineered astronauts extreme solutions like this may be necessary to push the human body beyond the limits of its evolution so it's able to handle environments well beyond those found on earth and long-term space missions are closer than you might think the artemis mission plans to put the first astronauts on the moon since 1972 with the goal of building a new space station in lunar orbit and eventually a habitable moon base on the lunar surface
the goal is to travel to the moon and stay there so we can learn how to build a sustainable colony on other worlds boots might be on the ground of the moon again in as little as three years and it will push the human body to its limits building the lunar orbiter and ground stations will require hours of spacewalks an activity that comes with enormous risk nebula is a streaming platform made by me and several other educational youtube content creators it's a place where we can upload our videos ad free and a place where we
can experiment with new original content we have so much exclusive content planned for nebula this year like a real science series on human evolution and real engineering's new ongoing series the battle of britain
