Plan B for U.S. Human Space Exploration Program

The Augustine Report recommended the use of commercial launch and propellant depots to improve Program sustainability. Plan A Apollo and Apollo programs provide a basis for sustainability where Apollo was quickly cancelled after the lunar landing but the Shuttle was sustained for 40 years. For an asteroid and lunar missions, commercial launch vehicles with depots showed significant cost improvements that are below current NASA exploration budgets with improvement of mission reliability over NASA baseline architectures and missions.