User:Mjkin/sandbox

= Colonization of the asteroids = Asteroids have been suggested as a possible site of human colonization for the purpose of the survival of humanity, as well as economic incentives associated with asteroid mining. The process of colonizing asteroids does have many obstacles that must be overcome for human habitation, including transportation distance, lack of gravity, temperature, radiation, psychological issues, and energy. Many of these obstacles have feasible solutions, however, the level of current technology indicates that the colonization of asteroids is not a possibility until other advancements are made.

Survival of humanity
One of the primary arguments for colonizing asteroids is that it would help ensure the long-term survival of the human species. In the event of an existential threat on Earth, such as nuclear holocaust and the subsequent nuclear winter, or supervolcano eruption, a colony on an asteroid would allow the human species to continue on. Michael Griffin, the NASA administrator in 2006, states the agency’s reasons behind pursuing space colonization specifically in regards to ensuring humanity’s survival as follows:"“... the goal isn't just scientific exploration ... it's also about extending the range of human habitat out from Earth into the solar system as we go forward in time ... In the long run a single-planet species will not survive ... If we humans want to survive for hundreds of thousands of millions of years, we must ultimately populate other planets.”"

Challenges
The main challenge of transportation to the Asteroid Belt is the distance of the journey from Earth, 204.43 million miles. Scientists currently face a similar challenge in their mission of sending a human to Mars, which is 35.8 million miles from Earth. This trip to Mars took 253 days, based on the Mars rover mission. Additionally, Russia, China, and the European Space Agency ran an experiment, called MARS-500, between 2007 and 2011 to gauge the physical and psychological limitations of manned space flight. The experiment concluded that 18 months of solitude was the limit for a manned space mission. With current technology the journey to the asteroid belt would be greater than 18 months, possibly indicating that a manned mission is beyond our current technological capabilities.

Landing
Asteroids are not large enough to produce significant gravity, making it difficult to land spacecraft. Humans have yet to land a spacecraft on an asteroid in the Asteroid Belt, but they have temporarily landed on the asteroid 162173 Ryugu, a near-Earth object of the Apollo group. This was part of the Hayabusa2 mission that was conducted by the Japanese Space Agency. The landing was made possible by using four solar ionic thrusters and four reaction wheels for propulsion. This technology allowed for the orientation control and orbit control of the spacecraft that guided the spacecraft to land on Ryugu. These technologies may be applied to complete a successful similar landing in the asteroid belt.

Gravity
Lack of gravity has many adverse effects on human biology. Transitioning gravity fields has the potential to impact spatial orientation, coordination, balance, locomotion, and induce motion sickness. Asteroids, without artificial gravity, have relatively no gravity in comparison to earth. Without gravity working on the human body, bones lose minerals, and bone density decreases by 1% monthly. In comparison, the rate of bone loss for the elderly is between 1-1.5% yearly. The excretion of calcium from bones in space also places those in low gravity at a higher risk of kidney stones. Additionally, a lack of gravity causes fluids in the body to shift towards the head, possibly causing pressure in the head and vision problems.

Overall physical fitness tends to decrease as well, and proper nutrition becomes much more important. Without gravity, muscles are engaged less and overall movement is easier. Without intentional training, muscle mass, cardiovascular conditioning and endurance will all decrease.

Artificial gravity
Artificial gravity offers a solution to the adverse effects of zero gravity on the human body. One proposition to implement artificial gravity on asteroids, investigated in a study conducted by researchers at the University of Vienna, involves hollowing out and rotating a celestial body. Colonists would then live within the asteroid on the inner edge, and the centripetal force would be simulate Earth’s gravity. The researchers found that while it may be unclear as to whether asteroids would be strong enough maintain the necessary spin rate, they could not rule out such a project if the dimensions and composition of the asteroid were within acceptable levels.

Currently, there are no practical large-scale applications of artificial gravity either for spaceflight or colonization efforts due to issues with size and cost. However, a variety of research labs and organizations have performed a number of tests utilizing human centrifuges to study the effects of prolonged sustained or intermittent artificial gravity on the body in an attempt to determine feasibility for future missions such as long-term spaceflight and space colonization. A research team at the University of Colorado: Boulder found that they were able to make all participants in their study feel comfortable at approximately 17 revolutions per minute in a human centrifuge, without the motion sickness that tends to plague most trials of small-scale applications of artificial gravity. This offers an alternative method which may be more feasible considering the significantly reduced cost over larger structures.

Temperature
Being located between Mars and Jupiter, the temperature of the Asteroid Belt proves to be a challenge to the human colonization of asteroids. The temperatures throughout the Asteroid Belt range from between -73 degrees celsius to -103 degrees. These temperatures prevent the possibility of human life without artificial heat. Humans will need a sufficient energy source to consistently provide enough heat near the asteroid to sustain life.

Converting radiation to energy could provide a sufficient source of heat for human populations in the Asteroid Belt. There exists a nanomaterial that has been used by both the United States and Soviet Union that can turn radiation directly into electricity. This nanomaterial is able to create energy by nuclear fission, the decaying radioactive material. This technology could be used to convert the extreme amount of radiation that impacts the surface of asteroids in the Asteroid Belt into energy to provide warmth for human populations a great distance from the Sun.

Radiation
In space, cosmic rays and solar flares create a lethal radiation environment. Cosmic radiation has the potential to increase risk of heart disease, cancer, central nervous system disorder, and acute radiation syndrome. On Earth, we are protected by a magnetic field and our atmosphere, but asteroids lack this defense.

One possibility for defense against this radiation is living inside of an asteroid. It is estimated that humans would be sufficiently protected from radiation by burrowing 100 meters deep inside of an asteroid. One issue with this solution is the composition of asteroids. Many asteroids are loosely organized rubble piles with very little structural integrity.

Psychology
Space travel has a huge ability to impact human psychology, including changes to actual brain structure, neural interconnectivity, and behavior.

Cosmic radiation has the ability to impact the brain, and has been studied extensively on rats and mice. These studies show the animals suffer from decreases in spatial memory, neural interconnectivity, and memory. Additionally, the animals had an increase in anxiety and fear.

The isolation of space and difficulty sleeping in the environment also contribute to psychological impacts. The difficulty of speaking with those on earth can contribute to loneliness, anxiety, and depression. A study was used to simulate the psychological impacts of extended space travel. Six healthy males with similar educational backgrounds to astronauts lived inside an enclosed module for 520 days. The members of the survey reported symptoms of moderate depression, abnormal sleep cycles, insomnia, and physical exhaustion.

In addition, NASA reports that missions on the global scale have ended or been halted due to mental issues. Some of these issues include shared mental delusions, depression, and becoming distressed from failed experiments.

However in many astronauts, space travel can actually have a positive mental impact. Many astronauts report an increase of appreciation for the planet, purpose, and spirituality. This mainly results from the view of earth from space.