Per aspera ad astra

5 Major Hazards of Human Spaceflight

1. Radiation

The first hazard of a human mission to Mars is also the most difficult to visualize because, space radiation is invisible to the human eye. Radiation is not only stealthy, but considered one of the most menacing of the five hazards.

Above Earth’s natural protection from the atmosphere, radiation exposure increases cancer risk, damages the central nervous system, can alter cognitive function, reduce motor function and prompt behavioral changes.

To mitigate this hazard, deep space vehicles will have significant protective shielding, dosimetry, and alerts. Research is also being conducted in the field of medical countermeasures such as pharmaceuticals to help defend against radiation.

The risks from radiation exist everywhere in space but increase drastically in the vicinity of stars or gas giants like Jupiter. Colony cylinders and space vehicles are in constant risk of a hull breach that will cause a major hazard from radiation contamination almost immediately.

Radiation also affects metals and other materials required for building space ships. Ships can’t be entirely shielded for months and years showing no effects by constant bombardment by radioactive rays and dust.

2. Isolation and confinement

Behavioral issues among groups of people crammed in a small space over a long period of time, no matter how well trained they are, are inevitable. Crews will be carefully chosen, trained and supported to ensure they can work effectively as a team for months or years in space.

On Earth we have the luxury of picking up our cell phones and instantly being connected with nearly everything and everyone around us. On a trip to Jupiter, astronauts will be more isolated and confined than we can imagine. Sleep loss, circadian desynchronization, and work overload compound this issue and may lead to performance decrements, adverse health outcomes, and compromised mission objectives.

To address this hazard, methods for monitoring behavioral health and adapting/refining various tools and technologies for use in the spaceflight environment are being developed to detect and treat early risk factors. Research is also being conducted in workload and performance, light therapy for circadian alignment, phase shifting and alertness. 

Massive overcrowding and cramped spaces with no escape options aboard colony cylinders and spaceships have a very negative effect on the psyche and social behavior of people. The typical consequences are depression, anxiety, aggression, addictive behavior and suicide. These effects increase in people who work and live on space stations or spaceships for long periods or for life. Even several generations of colonists have not changed the genetic and biological features of humans. With the help of medication, strict rules of conduct and therapies, attempts are made to alleviate the worst of the burdens. However, the effects on the human psyche represent a permanent and massive problem for everyone who travels in space.


3. Distance

The third and perhaps most apparent hazard is, quite simply, the distance. At medium distance a ship flying from Earth to Jupiter (or any of his moons) has to cross about 792 million km of empty space. A radio signal will cover this distance in 44 minutes. A space ship that can constantly accelerate and decelerate at 0,05g would need roughly 29 days. Ships will have to start their journey in orbit as their is no way they could lift-off and cover that distance.  

Assuming producing enough thrust for so long periods is not an insurmountable obstacle (which it currently is), the vast distances of total isolation mean that the ship is completely on its own. Getting help or alerting someone via radio has huge time delays. By the time you receive a reaction to a distress call, your ship might already have vanished in an implosion or the crew fallen victim to decompression. Getting spare parts, a specialist or any support from outside is very unlikely. Even when the sip follows standard flight routes, it is unlikely that traffic is as busy as on a motorway and a support vessel just happens to be close enough (helping a damaged ship harbors its very own dangers, too).

Humans are social beings and rarely do they have their beloved ones as co-workers of the same ship crew. The impact on psyche, happiness and social life is already hard for sailors on Earth who often stay aboard for months and rarely visit their homes at all. Long-trip ships like military vessels, cargo haulers and the like most likely have crews of unbound people who don’t have anything they value left behind. Otherwise this will produce many unwanted problems.


4. Gravity (or lack thereof)

The variance of gravity that astronauts will encounter is the fourth hazard of a human mission. On Mars, astronauts would need to live and work in three-eighths of Earth’s gravitational pull. Ganymede has 1,428 m/s² gravity which still effects life aboard orbital cylinders. 

During travel atsronauts aboard ships will experience total weightlessness most of the time as is costly and risky to use rotating habitats. These are usually only used under special circumstances and not many ships have them at all.

Besides deep space there is a third gravity field that must be considered. When astronauts finally return home they will need to readapt many of the systems in their bodies to their home’s gravity. Bones, muscles, cardiovascular system have all been impacted by months without standard gravity.

High, low and zero gravity have tremendous effects on the health of astronauts over time. Besides effects like space sickness there are a myriad of complications that can arise from this, despite training, proper workout and nutrition, medical support and auxiliary tools.

5. Hostile/closed environments

A spacecraft is not only a home, it’s also a machine. The ecosystem inside every vehicle plays a big role in everyday astronaut life. Important habitability factors include temperature, pressure, lighting, noise, and quantity of space. It’s essential that astronauts are getting the requisite food, sleep and exercise needed to stay healthy and happy.

Technology, as often is the case with out-of-this-world exploration, comes to the rescue in creating a habitable home in a harsh environment. Everything is monitored, from air quality to possible microbial inhabitants. Microorganisms that naturally live on your body are transferred more easily from one person to another in a closed environment. Astronauts, too, contribute data points via urine and blood samples, and can reveal valuable information about possible stressors. The occupants are also asked to provide feedback about their living environment, including physical impressions and sensations so that the evolution of spacecraft can continue addressing the needs of humans in space. Extensive recycling of resources is imperative:  oxygen, water, carbon dioxide, even our waste.

There are many more risks apart from the big five, meteor impact, failure of critical systems, aliens (just kidding). Space is such a vast and hostile environment to humans that it’s unikely that we will travel beyond the closest planets ever. Even a trip to Jupiter seems to be pure fiction from todays point of view. Assuming the universe is not hiding an unknown superdrive technology (and god-like power sourcee) or a sneaky inter-dimensional hat-trick from us, we are trapped. Only a few brave men and women will ever leave Earth’s orbit and try to reach Mars or the asteroid field, risking their very lives in missions with a high probability for failure. In the future robotic vehicles could very well begin harvesting rare minerals and ores from asteroids or small moons and bring it back to Earth. Probes can reach places no human could reasonably do. Bringing tens or hundreds of thousands to a new habitable planet is highly unlikely, though.