U.S. astronauts should travel to asteroids and other “deep space” destinations in preparation for a mission to Mars rather than fly directly to the planet, members of a presidential panel said yesterday.A flight to Mars, which has been urged by some former astronauts and spaceflight advocates, would be too costly and dangerous, panel members said during a public meeting in Washington.“Technically, economically and in terms of the rewards it produces” deep space is “a reasonable step on the way to Mars,” Norman Augustine, chairman of the committee, told reporters after the meeting. A direct-to-Mars flight “would likely not succeed.”The meeting was the panel’s last public one as it prepares a report with recommendations for President Barack Obama on the space program’s future that is due at the end of this month. Augustine said the committee will give White House officials a preliminary briefing on its findings tomorrow.The committee is focused on four choices, including the deep-space option, a plan that would end U.S. participation in the International Space Station by 2016 and another that would extend U.S. station efforts to 2020. The fourth calls for prolonging the space shuttle program past the current 2010 retirement date.Current budget and future funding estimates for NASA won’t pay for humans to explore space, said former astronaut Sally Ride, a panel member and the first American woman in space. She said that the administration’s plan to return to the moon by 2020 would require more money than is now budgeted.