The Medical Consequences of Human Space Travel to Mars
For the video project, I have decided to investigate the dangers and complications to an astronaut’s health aboard a proposed mission to Mars. This includes the psychological consequences of being on a space ship for months, the risks of cancer and cell damage from being exposed to solar and cosmic radiation, and bone and muscle loss as a result of living in zero gravity. Past and current research about humans in space can aid in my understanding.
One of the most overlooked dangers when it comes to an astronaut’s health is the psychological consequence of a long-term space mission spent in a crammed vessel. Though an astronaut’s day would be very occupied with research, records, and transmission, feelings of loneliness and anxiety are always going to be an underlying response. A study conducted a psychological analysis of 6 males confined in a 520-day Mars mission simulation in a 550 m3 chamber (Basner et al., 2014). Mood states and a series of categorical psychological evaluations in the form of questionnaires were given to the participants weekly. The study found that crew members exhibited depression, insomnia, and stress, among other mental states, leading to an increase in miscommunication and conflicts with mission control. This is why astronauts on the International Space Station are allowed to bring certain forms of entertainment aboard, e.g. Chris Hadfield’s famous cover of ‘Space Oddity’ from the ISS was made with a custom built and approved guitar.
Figure 1: Graph comparing the effectiveness of different shielding materials against Galactic Cosmic Rays and Solar Particle Events. Upper panel shows point dose equivalent per year while the bottom panel shows effective dose equivalent per year, on the y-axes, with aerial-density of the shield on the x-axis.
Probably the most dangerous and preventive aspect of a long-term space mission is the exposure to solar and cosmic radiation. One data value used to measure the affects of radiation is Risk of Exposure-Induced Death (REID), which is a statistical percentage for the risk of fatality from radiation-induced cancer based on an average population. NASA’s precautionary standard for astronauts aboard the ISS is no more than 3% REID, which translates to the risks of 23 out 100 people of an average population (Escobedo and Costello, 2016). Figure 1 compares the effectiveness of various radiation shielding materials, with shield areal-density on the x-axis in g/cm2 and the dose equivalent of Galactic Cosmic Rays (GCR) and Solar Particle Events (SPE) per year on the y-axis (Cucinotta et al., 2005). The graph on the top shows the actual dose equivalent of radiation, called point dose equivalent, on the y axis while the bottom graph shows effective dose, the actual radiation absorbed by tissue and organs. Aluminum, among several materials, is quite successful in blocking SPE, which is why it is the prime shielding material for the ISS and other space vessels. However, all of the materials are relatively insufficient in blocking GCR, which is a major problem.
Lastly, bone loss and muscle atrophy as a result of humans being in a zero gravity environment in space can be detrimental to an astronaut’s health and condition upon reaching Mars and/or returning to Earth. A study measured the effects of bone and skeletal mineral loss in the spine and hip bone of 14 crew members aboard the International Space Station for 4-6 months, comparing the measurements of bone density and volume before and after their missions (Thomas et al., 2004). The crewmembers’ ranges of bone loss were 0.8-0.9% per month in the lumbar spine and 1.2-1.5% in the hip bone. These results are despite exercising routines on the ISS designed to combat, in part, bone and muscle loss, making them alarming figures for a potential mission to Mars which would last multiple months. Muscle atrophy, a common condition for patients confined to one position for extended periods, is quite damaging for astronauts in zero-gravity space, resulting in the loss of muscle mass and strength. A study used Bioartifical Muscle tissue (BAM) tested in both ground (Earth) and flight (microgravity) conditions to determine the in vitro effects of muscle atrophy (Vandenburgh et al., 1999). The study found that in flight conditions for 9-10 days, there was a 10-12% decrease in myofiber (muscle fiber) size as compared to the myofibers grown in normal conditions. These two studies, one conducted on astronauts and the other in vitro, demonstrate the significant physiological effects of bone and muscle loss expected for astronauts in a Mars mission.
Human space travel to Mars is a topic I have always been enthusiastic about, especially since recent insight into Mars’ past and after a serious proposal for a manned mission. Though many people share the dream of being a Mars astronaut for the pioneering value, they may not realize and appreciate the enormous risks an astronaut faces during such a mission and what the chosen class will be signing up for. This is why I believe a video on these risks, including radiation, mental illness, and bone and muscle loss, is so important and informative.
Works Cited
Basner, Mathias, David F. Dinges, Daniel J. Mollicone, et al. “Psychological and Behavioral Changes during Confinement in a 520-Day Simulated Interplanetary Mission to Mars.” PLOS ONE. 9, no. 3 (March, 2014) [Cited 10 September 2016].
Cucinotta, Francis A., Kim, Myung-Hee Y. Kim, Lei Ren. Managing Lunar and Mars Mission Radiation Risks Part I: Cancer Risks, Uncertainties, and Shielding Effectiveness. NASA/TP-2005-213164/PT1. Washington, DC: National Aeronautics and Space Administration, Jul 1, 2005. (20050196720: NTRS)
Escobedo, Victor M. Jr, Kirt Costello. “International Space Station Internal Radiation Monitoring (ISS Internal Radiation Monitoring) – 07.14.16.” National Aeronautics Space Administration. (July 2016) [Cited 10 September 2016].
Lang, Thomas, Adrian LeBlanc, Harlan Evans, et al. “Cortical and Trabecular Bone Mineral Loss From the Spine and Hip in Long-Duration Spaceflight.” Journal of Bone and Mineral Research. 19, In Wiley Online Library. (March, 2004) [Cited 10 September 2016].
Vandenburgh, Herman, Joseph Chromiak, Janet Shansky, et al. “Space travel directly induces skeletal muscle atrophy.” The FASEB Journal. 13, no. 9 (June, 1999) [Cited 10 September 2016].
