http://voyager.jpl.nasa.gov/index.html
http://www.history.com/news/6-fascinating-facts-about-space-probe-voyager-1
http://www.bbc.com/news/science-environment-29341850
https://trmm.gsfc.nasa.gov
https://owlcation.com/stem/NASA-Project-Mercury-Gordon-Cooper-and-Faith-7
https://www.nasa.gov/redplanet/viking.html
http://www.space.com/16769-spaceshipone-first-private-spacecraft.html
https://www.theguardian.com/science/2015/may/09/alexei-leonov-first-man-to-walk-in-space-soviet-cosmonaut
http://www.space.com/16748-international-space-station.html
http://www.history.com/topics/apollo-11
http://www.space.com/6378-nasas-10-greatest-science-missions.html
https://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=1957-001B
http://www.history.com/this-day-in-history/sputnik-launched