http://www.universetoday.com/111462/how-can-we-live-on-mars/
https://medlineplus.gov/radiationexposure.html
http://www.windows2universe.org/kids_space/lifeonmars.html
http://www.swedishepa.se/Environmental-objectives-and-cooperation/Swedens-environmental-objectives/The-national-environmental-objectives/A-Protective-Ozone-Layer/
http://news.nationalgeographic.com/2016/09/elon-musk-spacex-exploring-mars-planets-space-science/#/02-elon-musk-space-x-mars.ngsversion.1475019001760.jpg