NASA Associate Administrator for Aeronautics Research Lisa J. Porter answers reporters questions during the fiscal year 2007 news conference, Monday, Feb. 6, 2006, at NASA Headquarters in Washington. NASA Administrator Michael Griffin was joined by the heads of NASA's four mission directorates to explain how the proposed $16.8 billion dollar budget supports the Vision for Space Exploration. The budget represents a 3.2% increase above the fiscal year 2006 appropriated budget. Photo Credit: (NASA/Bill Ingalls)

NASA Associate Administrator for Exploration Systems Scott J. Horowitz answers reporters questions during the fiscal year 2007 news conference, Monday, Feb. 6, 2006, at NASA Headquarters in Washington. NASA Administrator Michael Griffin was joined by the heads of NASA's four mission directorates to explain how the proposed $16.8 billion dollar budget supports the Vision for Space Exploration. The budget represents a 3.2% increase above the fiscal year 2006 appropriated budget. Photo Credit: (NASA/Bill Ingalls)

NASA Administrator Michael Griffin outlines the President's budget for fiscal year 2007 during a news conference, Monday, Feb. 6, 2006, at NASA Headquarters in Washington. Griffin was joined by the heads of NASA's four mission directorates to explain how the proposed $16.8 billion dollar budget supports the Vision for Space Exploration. The budget represents a 3.2% increase above the fiscal year 2006 appropriated budget. Photo Credit: (NASA/Bill Ingalls)

NASA Administrator Michael Griffin outlines the President's budget for fiscal year 2007 during a news conference, Monday, Feb. 6, 2006, at NASA Headquarters in Washington. Griffin was joined by the heads of NASA's four mission directorates to explain how the proposed $16.8 billion dollar budget supports the Vision for Space Exploration. The budget represents a 3.2% increase above the fiscal year 2006 appropriated budget. Photo Credit: (NASA/Bill Ingalls)

NASA Deputy Administrator Shana Dale responds to a reporter's question during a fiscal year 2007 budget press conference, Monday, Feb. 6, 2006, at NASA Headquarters in Washington. NASA Administrator Michael Griffin and the heads of NASA's four mission directorates explained how the proposed $16.8 billion dollar budget supports the Vision for Space Exploration. The budget represents a 3.2% increase above the fiscal year 2006 appropriated budget. Photo Credit: (NASA/Bill Ingalls)

NASA Associate Administrator for Science Mary Cleave answers reporters questions during the fiscal year 2007 news conference, Monday, Feb. 6, 2006, at NASA Headquarters in Washington. NASA Administrator Michael Griffin was joined by the heads of NASA's four mission directorates to explain how the proposed $16.8 billion dollar budget supports the Vision for Space Exploration. The budget represents a 3.2% increase above the fiscal year 2006 appropriated budget. Photo Credit: (NASA/Bill Ingalls)

NASA Administrator Michael Griffin outlines the President's budget for fiscal year 2007 during a news conference, Monday, Feb. 6, 2006, at NASA Headquarters in Washington. Griffin was joined by the heads of NASA's four mission directorates to explain how the proposed $16.8 billion dollar budget supports the Vision for Space Exploration. The budget represents a 3.2% increase above the fiscal year 2006 appropriated budget. Photo Credit: (NASA/Bill Ingalls)

NASA Deputy Administrator Shana Dale introduces NASA Administrator Michael Griffin who outlined the President's budget for fiscal year 2007 during a news conference, Monday, Feb. 6, 2006, at NASA Headquarters in Washington. Photo Credit: (NASA/Bill Ingalls)

NASA Associate Administrator for Space Operations William Gerstenmaier, right, and NASA Associate Administrator for Exploration Systems Scott J. Horowitz talk during the fiscal year 2007 news conference, Monday, Feb. 6, 2006, at NASA Headquarters in Washington. NASA Administrator Michael Griffin was joined by the heads of NASA's four mission directorates to explain how the proposed $16.8 billion dollar budget supports the Vision for Space Exploration. The budget represents a 3.2% increase above the fiscal year 2006 appropriated budget. Photo Credit: (NASA/Bill Ingalls)

NASA Associate Administrator for Space Operations William Gerstenmaier responds to questions during the fiscal year 2007 news conference, Monday, Feb. 6, 2006, at NASA Headquarters in Washington. NASA Administrator Michael Griffin, background right, was joined by the heads of NASA's four mission directorates to explain how the proposed $16.8 billion dollar budget supports the Vision for Space Exploration. The budget represents a 3.2% increase above the fiscal year 2006 appropriated budget. Photo Credit: (NASA/Bill Ingalls)

NASA Administrator Michael Griffin outlines the President's budget for fiscal year 2007 during a news conference, Monday, Feb. 6, 2006, at NASA Headquarters in Washington. Griffin was joined by the heads of NASA's four mission directorates to explain how the proposed $16.8 billion dollar budget supports the Vision for Space Exploration. Seated left to right: Scott Horowitz, NASA Associate Administrator for Exploration Systems, William Gerstenmaier, NASA Associate Administrator for Space Operations, Lisa Porter, NASA Associate Administrator for Aeronautics Research and Mary Cleave, NASA Associate Administrator for Science. Photo Credit: (NASA/Bill Ingalls)

NASA Administrator Michael Griffin, seated center, outlines the President's budget for fiscal year 2007 during a news conference, Monday, Feb. 6, 2006, at NASA Headquarters in Washington. The administrator was joined by the heads of NASA's four mission directorates to explain how the proposed $16.8 billion dollar budget supports the Vision for Space Exploration. The budget represents a 3.2% increase above the Fiscal Year 2006 appropriated budget. Photo Credit: (NASA/Bill Ingalls)