President Reagan's plan to develop space-based laser weapons able to knock out Soviet missiles in flight is running into some unexpected flak. White House officials had hoped for support from the aerospace industry, which stands to benefit from any infusion of new funds for space programs. But a number of space scientists and industry spokesmen say they're hoping the new missile defense scheme will self-destruct.
The reason: The type of massive research and development program key to any venture into space requires long-range planning and a relative certainty of funding over a 10- to 20-year period. Space scientists warn that setting a new course for US space programs now could drain funds and expertise away from current projects such as the space shuttle. And they add that the Reagan plan could be canceled by succeeding presidents.
If the US shifts course to focus on militarizing space, experts warn, the tremendous effort to catch up with the Soviets in the military space race could force the US into third place behind the Europeans and Japanese in the scientific and commercial space races.
One industry spokesman doesn't expect even the US Air Force to push hard for Reagan's laser-beam dream. ''That would mean they would have to pick up far more of the bill for the space program,'' he says, and that would ''cut into what the Air Force can spend in other areas.''