1. Originally published as a commentary in Space News (spacenews.com) by H. Benaroya, November 25, 2013. (Courtesy Space News)
2. R.McC. Adams: Why Explore the Universe, 30th Aerospace Sciences Meeting & Exhibit, Reno, January 6–9, 1992.
3. D. Livingston: Is space exploration worth the cost? The Space Review, January 21, 2008.
4. E. Sterner: More than the Moon, washingtontimes.com , April 11, 2008.
5. R. Shapiro: A New Rationale for Returning to the Moon? Protecting Civilization with a Sanctuary, Space Policy , Vol.25, 2009, pp.1–5.