There are a number of significant psychological and physical challenges of space travel. On top of the psychological stress of being confined in small space other, there are actual and potential physical effects on the body too, which result from the relative absence of gravity and potential exposure radiation. Astronauts must show they can cope with these different challenges in order to be accepted into the space program and they must continue to show they can adjust and adapt to new stressors and conditions as they wait from their launch date. The challenges faced by astronauts will be doubly stressful for space tourists when there is only limited screening involved in selecting who will go. Additionally, they won't have the training to enable them to remain fit and healthy while they are in space.
Some of the challenge both astronauts and space tourists encounter when in space include:
Although many think the absence of gravity would be fun, there has been extensive research demonstrating the negative effects of weightlessness on the human body.
Living in zero or negligible gravity for extended periods has a range of health consequences. Many people suffer from a puffy face which many people laugh at, but which actually can signal edema which can have serious consequences. Dizziness is a common problem in low gravity atmospheres. Most seriously, muscle wasting and decalcification of bone occur at relatively fast rates in space. Muscle biopsies from before and after space flight have shown that even when astronauts are doing aerobic exercise five times a week and resistance training three to six times a week, peak muscle strength and overall muscle volume decreased significantly over the course of a six-month mission. Adding other aerobic machines and resistance devices to allow for increased exercise has helped astronauts aboard the International Space Stations somewhat, but there is still some muscle wasting and decalcification that occurs. NASA is considering adding an artificial source of gravity to help with this on future flights although current technology makes this options difficult if not impossible to accomplish today.
2) Radiation - With the absence of Earth’s magnetic field and atmosphere, there is an increased risk to astronauts from radiation from the Sun as well as far off stars and galaxies. Constant exposure to radiation can lead to the development of cancer and even limited
exposure to extremely high levels of radiation, from sources such as solar flares, can lead to radiation poisoning that can be life-threatening.
Although astronauts are protected from radiation through components of the ships hull and their spacesuits, they are aware that these measures can potentially fail during a mishap.
3) Cramped conditions - Living quarters in space are extremely tight, and astronauts have to share them with other crew members for the entire duration of the mission. Common areas are also limited, and most are delegated to the mission and work tasks which the crew often completes as a team. This means that there is almost no alone time, and a general lack of privacy.
4) Constant observation - Astronauts are constantly being monitored for safety reasons as well as to be able to share the mission with the public. Astronauts know that everything they say is not just monitored but is recorded for posterity. Never being able to say or do anything that isn't somehow observed and recorded for the rest of the world can be extremely stressful.
5) Lack of contact with friends and family - Although astronauts prepare for this, they are not expected to withdraw from loved ones on earth, so they can't train for this difficulty. When under a great deal of stress, we often turned to friends or relatives to help us mitigate either through support and empathy or advice and suggestions. The astronauts have only limited contact with loved ones, and on longer missions to farther out in the galaxy such the future Mars mission, there will be no contact possible once they reach a certain distance away from earth.
6) Isolation - While there is a lack of privacy when in space, astronauts also suffer from the effects of isolation and loneliness. Many astronauts have reported the sense of isolation when observing the earth from afar as a small blue ball. When undertaking long missions such as the one proposed to mars, the earth will shrink away to nothing as the ship moves further away so those aboard won't even be able to see it anymore. This sense of being away and apart from every other human being accept fellow crew member can lead to loneliness and depression as astronauts feel like they aren't a part of what is happening on the earth anymore.
7) The Potential for Disaster - Even though astronauts must find ways to prevent themselves from catastrophizing, space is not a habitable place for humans in the absence of protective gear, technology, and artificial atmospheric conditions. Yet all astronauts and space travelers know that something can always go wrong that they do not have the capacity to fix and which could lead to their death. Despite astronauts being extremely well trained to deal with a host of possible problems while in space, they are aware it's impossible to account for or be trained to fix everything that could go wrong. They are also aware that there have been entire crews lost during mission such as when the Columbia blew up less than two minutes after launch.