The Problem with Deep Space Travel

In 1976 two Soviet cosmonauts were sent on a mission to the Salute 5 space station the last dedicated military space station in the Soviet space program where the mission was meant to last 66 days but after just 49 days the mission ended abruptly where the cosmonauts were reporting something dangerous aboard the space station a noxious chemical smell where ground control scrambled to get them back to Earth where 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 where 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 demonstrating how prolonged space exposure induces psychological stress responses including olfactory hallucinations in cosmonauts.

The human body is an amazing machine but it’s simply not built for a life in outer space where 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 where nevertheless we continue to seek worlds beyond our own where 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 where crewed 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 where this will have a profound effect on the human body demonstrating how 6 million years of terrestrial evolution created physiological systems optimized for Earth gravity and atmosphere creating fundamental mismatches with space environments.

In the microgravity of space astronauts bones are no longer being used to support their weight or movements and they lose 1 to 2 percent of their bone mineral density each month where for a one-way trip to Mars which will take about 9 months this could amount to as much as 18 percent where calcium from their degrading bones floods the bloodstream and can even lead to kidney stones where 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 where it’s largely due to the bones not having to support any weight where the drop in bone density is known as disuse osteoporosis and leaves bone weak and prone to fracture where if left unchecked astronauts who’ve spent long periods in space may not even be able to walk when they return to Earth demonstrating how weightlessness disrupts bone remodeling homeostasis causing severe skeletal demineralization and structural weakening.

In our lives on Earth gravity also pulls down our bodily fluids but without it astronauts blood and other fluids are pushed upwards towards the head causing it to swell where this increased intracranial pressure can lead to vision problems where 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 demonstrating how microgravity eliminates hydrostatic gradients causing cephalad fluid redistribution with neuro-ocular complications requiring countermeasures.

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 where artificial gravity can in theory be made using centrifugal forces demonstrating how current countermeasures provide only partial mitigation of microgravity effects necessitating artificial gravity solutions for extended missions.

Artificial gravity can in theory be made using centrifugal forces where 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 where 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 where that push is called the centrifugal force and it can be used as an equivalent for gravity where there are a few ways that this can be implemented in a spacecraft where the first is by making the whole thing rotate where 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 where another option is rotating just one part of the spacecraft but scientists are thinking even smaller an onboard centrifuge that can fit one astronaut at a time demonstrating how rotational mechanics generate centrifugal acceleration mimicking gravitational effects through various spacecraft configurations.

The effects of microgravity are simulated using a bed rest model where the test subjects lay with their bodies tilted negative 6 degrees head down for a miserable 2 months straight where this unloads the bones and muscles and causes the bodily fluids to flow towards the head where each day some participants spend 30 minutes in a centrifuge either over several sessions or all at once where the scientists then compare a number of physiological outcomes between the two artificial gravity groups and the control group demonstrating how ground-based head-down tilt bed rest protocols simulate microgravity physiological effects enabling artificial gravity countermeasure testing.

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 where these results suggest that a longer duration in the centrifuge will be needed to successfully counter these health issues where but even if the body is functioning correctly it does you no good if the mind is not demonstrating how 30-minute centrifuge protocols show partial efficacy for musculoskeletal outcomes but insufficient protection against neuro-ocular effects requiring longer exposure durations.

Our minds are fragile things and our mental health can be a challenge to take care of even in the best of circumstances where 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 where 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 where 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 where these circumstances can and do lead to cognitive impairment depression psychosomatic illness and even psychiatric disorders demonstrating how prolonged space isolation in confined high-risk environments creates severe psychological stressors exceeding COVID-era isolation with increased psychiatric morbidity risk.

Hallucinations like those experienced by the Soyuz crew are not uncommon where other astronauts have hallucinated orange clouds flashes of light and angelic looking figures where another critical aspect for the mental health of astronauts during long-term space travel is group dynamics where several missions have been interrupted due to interpersonal conflict between crew members and with mission control where in fact the crew on Skylab 4 turned off communication with NASA for a whole day after arguing with mission control demonstrating how space isolation induces diverse hallucination types across sensory modalities while simultaneously exacerbating interpersonal tensions leading to mission-critical conflicts.

In fact the crew on Skylab 4 turned off communication with NASA for a whole day after arguing with mission control where because of these issues space agencies like NASA have been studying people in isolated environments for many years where these studies include evaluating astronauts in space as well as participants in confinement in analog facilities here on Earth where stations in Antarctica provide one such test bed where Antarctica’s climate terrain temperature and isolation resemble that of outer space where the landscape is uniform and boring where the sensory deprivation is real and so is the danger where crews there cannot be rescued quickly and everyone there is stuck with the same few people just like astronauts in outer space demonstrating how extreme interpersonal conflict during Skylab 4 mission prompted systematic isolation analog research in Antarctic stations to understand and prevent crew dysfunction.

Under these conditions something important about team dynamics has been revealed where to have a successful team you need not simply impeccable leadership or flawless decision-making where what you need is a clown where humor it turns out is critical for diffusing tense situations in Antarctica and by that logic in outer space too where joking around is also essential for coping with boredom brought on by prolonged periods of isolation where scientists are now working to build a computer model that can help select the best crew based on personality traits like this demonstrating how Antarctic isolation research revealed humor as critical psychological countermeasure for tension reduction and boredom management informing computational crew selection algorithms.

Scientists are now working to build a computer model that can help select the best crew based on personality traits like this where 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 where on board the ships researchers have also improved lighting to help align astronauts circadian rhythm in order to improve sleep and alertness demonstrating how computational personality modeling enables predictive crew compatibility assessment while environmental modifications like circadian lighting enhance physiological adaptation.

But the most insidious danger of outer space is one you can’t see nor hear nor even feel where you wouldn’t even know it was killing you until it was far too late where outer space’s silent killer is radiation a form of energy that travels as rays electromagnetic waves and or particles where 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 where that’s because there are two types of radiation nonionizing and ionizing demonstrating how space radiation poses invisible insidious health threat through ionizing particle and electromagnetic wave exposure exceeding terrestrial radiation by orders of magnitude.

In outer space ionizing radiation comes from three sources where particles that are trapped in Earth’s magnetic field called radiation belt particles where 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 where ionizing radiation has enough energy to alter the substance it travels through where it does this by removing electrons from the atoms in the material which ionizes them where 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 demonstrating how three distinct ionizing radiation sources create overlapping exposure hazards through direct DNA damage and cellular ionization.

The amount of risk depends on the dose of radiation that they’re exposed to which is measured in millisieverts where here on Earth we typically experience a small dose where for instance an average person in the US is exposed to about 6.2 millisieverts each year mostly from radon and medical imaging where however in space solar particle events and annual galactic cosmic ray exposure produces a much higher radiation dose where 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 where with current precautions astronauts experience 50 to 120 millisieverts during a 6-month stay on the International Space Station with a single day resulting in about 0.7 millisieverts demonstrating how space radiation doses exceed terrestrial background by 8-560 fold creating severe cumulative exposure risks.

NASA uses radiation exposure caps to determine how long astronauts can stay in space where they calculate the cap based on a risk estimate where the limit is the amount of total exposure that would give an astronaut a 3 percent higher chance of dying of cancer in the rest of their life but that cap isn’t equal for all astronauts where 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 where but more distant missions to Mars which will require up to 1,000 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 1,400 millisieverts depending on the astronaut’s age and gender where this could increase their lifetime risk of dying from cancer well beyond the 3 percent limit set by the cap to over 10 percent demonstrating how career radiation exposure limits based on 3% cancer mortality risk face exceedance during Mars missions requiring enhanced protection strategies.

The reason for the high levels of radiation exposure even inside a well-shielded spacecraft is due to the nature of galactic cosmic rays where 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 where researchers discovered that to completely block them the whole of the spacecraft would have to be outrageously thick where so thick that the additional weight and fuel requirements would make the trip impossible where this is why scientists are looking into other protection methods for these trips where one option are wearable vests that protect the most vulnerable areas and another shielding technology being explored are electronic surfaces that actively deflect radiation demonstrating how galactic cosmic ray penetration depth exceeds passive shielding effectiveness requiring mass-prohibitive thicknesses thus necessitating alternative protection approaches.

Scientists are now looking to the field of medicine to counteract radiation effects where one radical idea is to genetically engineer astronauts to make their cells more resilient to radiation where 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 where 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 where this particular protein called damage suppressor prevents the animal’s DNA from breaking when exposed to high-dose radiation where the human cells containing the protein had 40 percent less DNA damage than cells without it where 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 demonstrating how tardigrade damage suppressor protein expression in human cells reduces radiation-induced DNA breaks by 40% offering transgenic enhancement pathway for space radiation protection despite decades-long development timeline.