https://spaceref.com/science-and-exploration/armadillo-aerospace-qualifies-for-northrop-grumman-lunar-lander-challenge/
Armadillo Aerospace Qualifies for Northrop Grumman Lunar Lander Challenge - SpaceRef
May 24, 2013 - Space news and reference site.
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https://www.space.com/3989-prize-cup-announces-lunar-lander-challenge-competitors.html
X Prize Cup Announces Lunar Lander Challenge Competitors | Space
Jun 21, 2007 - The X Prize Foundation announced Thursday the name of eight of the nine competitors in this year's Northrop Grumman Lunar Lander Challenge to be held this...
x prize cuplunar lander challengeannouncescompetitorsspace
https://spaceref.com/science-and-exploration/masten-makes-an-attempt-at-northrop-grumman-lunar-lander-challenge-level-1-video/
Masten Makes An Attempt At Northrop-Grumman Lunar Lander Challenge, Level 1 (video) - SpaceRef
May 24, 2013 - Space news and reference site.