David, Leonard. “Commercialization of Space Travel Will Benefit Space Exploration.” Space.com, edited by David Haugen and Zack Lewis, 2009. Opposing Viewpoints in Context, link.galegroup.com/apps/doc/EJ3010356221/OVIC?u=ncmoc11357&xid=91c54456. Accessed Feb. 2017. Gebelhoff, Robert. “The Space Race Is Not Over Yet -- and the Stakes are as High as Ever.” Washington Post - Blogs, 1 Feb. 2016, pp. n/a.SIRS Issues Researcher, http://sks.sirs.com. Hernandez, Cristina. “Astronauts in Mars Shot Would Face Many Health Risks.” Inter Press Service, 2004, sks.sirs.com. Accessed 17 Mar. 2017. Howell, Elizabeth. “How to Train Your Astronaut.” Canadian Geographic, vol. 134, no. 5, Oct. 2014, pp. 34–38. Academic Search Premier, library.ncmissouri.edu:8080/login?url=http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=98790566&site=ehost-live&scope=site. Accessed 30 Mar. 2017. Lind, Michael. “Human Spaceflight Should End.” Salon.com, edited by Margaret Haerens, Dec. 2011. Opposing Viewpoints in Context, link.galegroup.com/apps/doc/EJ3010811209/OVIC?u=chil38234&xid=5de63e3e. Accessed Mar. 2017. Masunaga, Samantha, and Russ Mitchell. “SpaceX to Fly 2 Paying Citizens Around the Moon.” Los Angeles Times, 2017, p. A.1. SIRS Issues Researcher, sks.sirs.com. Accessed 17 Mar. 2017. Preston, Louisa. “Humans Should Colonize Mars.” Physicsfocus.org, edited by Michael Ruth, Sept. 2013. Opposing Viewpoints in Context, link.galegroup.com/apps/doc/EJ3010989211/OVIC?u=chil38234&xid=639d7a55. Accessed Mar. 2017. Rogers, Adam. “Space Tourism Is Not Worth the Human Risk.” Space Tourism Is Not Worth the Human Risk, edited by Michael Ruth, 2014. Opposing Viewpoints in Context, link.galegroup.com/apps/doc/EJ3010989210/OVIC?u=ncmoc11357&xid=0d5049ac. Accessed Nov. 2017. Schwartz, James S.J. “On the Moral Permissibility of Terraforming.” Ethics & the Environment, vol. 18, no. 2, 2013, p. 1. Opposing Viewpoints in Context, link.galegroup.com/apps/doc/A355249397/OVIC?u=chil38234&xid=f998c0a7. Accessed Mar. 2017. Shekhtman, Lauren. “Elon Musk Details Plan for SpaceX Mars Mission. What Would That Look Like?” Christian Science Monitor, Sirs Issue Researcher, 27 Sept. 2016, sks.sirs.com.library.ncmissouri.edu:8080/webapp/article?artno=0000390135&type=ART#cite. Accessed 5 Apr. 2017. Todd, Brian. “Mayo Doc's Stem Cell Experiment Blasts into Space.” Chicago Tribune, 2017, p. n/a. SIRS Issues Researcher, sks.sirs.com. Accessed 5 Apr. 2017. Zhai, Yun Tan. “What Does It Take for 'Normal People' to Go to Space?” Christian Science Monitor, 2016, p. n/a. SIRS Issues Researcher, sks.sirs.com. Accessed 6 Mar. 2017.