Best Practices in Spacecraft Development 403 PI-led mission paradigm. Though this approach was commonly used for smaller solar- powered missions, the PKB AO was the first application to a mission of this type. As with other PI-led missions, the selection process was conducted in two steps, beginning with the Step-1 proposals. The New Horizons Step-1 proposal demanded a substantial effort by the entire New Horizons team to produce the document within the two-month schedule. To add to the anguish, in the middle of the proposal preparation, the AO was cancelled based on the new administration's future budgetary plans not to fund it. Within a week, the decision was made to allow the process to proceed despite the fact that there were no plans by the administration to fund the mission. Near the end of the effort, NASA granted an extension of several weeks. On April 5, 2001, the New Horizons Step-1 proposal was delivered to NASA, joining four others in the evaluation. On June 6, 2001, two proposals were awarded funding for the second step of the selection process, the development of the Phase A concept study report. Both New Horizons and the Pluto Outer Solar System Explorer were given 3 months to refine their mission concepts and submit their reports. Following the delivery of the report, each team had nearly a month to prepare oral presentations to the evaluation team. Formal notification of the selection of