The genesis of TESS was as early as 2006, when a design was developed from private funding by individuals, Google, and The Kavli Foundation.[19] In 2008, MIT proposed that TESS become a full NASA mission and submitted it for the Small Explorer program at Goddard Space Flight Center,[19] but it was not selected.[20] It was resubmitted in 2010 as an Explorers program mission, and was approved in 2013 as a Medium Explorer mission.[19][21] TESS passed its critical design review (CDR) in 2015, allowing production of the satellite to begin.[19] While Kepler had cost US$640 million at launch, TESS cost only US$200 million (plus US$87 million for launch).[22][23]