President George W. Bush announced the Vision for Space Exploration on the 14th of January 2004. This announcement occurred months after the Space Shuttle Columbia disaster destroyed hope and safety in human spaceflight.
NASA designed a specific Lunar Architecture to support the return to the Moon by 2020. The first major component was the Lunar Reconnaissance Orbiter which launched successfully in June 2009 aboard an Atlas V rocket.
The Constellation program introduced two distinct rocket systems known as Ares I and Ares V. These vehicles were designed to replace the aging Space Shuttle fleet scheduled for retirement by 2010.
Congress passed a spending bill providing $16.2 billion to kick-start the vision in November 2004. Then-NASA chief Sean O'Keefe called that spending bill a strong endorsement of the exploration goals.
Apollo 11 astronaut Buzz Aldrin voiced criticism in December 2003 stating that sending astronauts back to the Moon felt like reaching for past glory rather than striving for new triumphs. Physicist Robert L. Park argued that robotic spacecraft were doing so well it would be hard to justify human missions.