Edwards Air Force Base, Calif. — With the words, ''Challenger, you are free to take off now,'' President Reagan opened a new chapter of the space shuttle transportation program.
Not two hours after her sister ship Columbia ended her fourth space orbit trip here on the Forth of July, the Challenger made a spectacular takeoff - piggy-backed aboard a 747 airplane - and headed for Cape Canaveral. She will be launched next January.
Neither President Reagan's brief speech nor the long-awaited national space policy statement issued by the White House July 4 indicated a solid financial commitment to the space program.
Nonetheless, Reagan's appearance at Columbia's landing - his first such show of support for the shuttle - was heralded as a boost for the space program.
In particular, NASA officials noted Reagan's reference to looking ''aggressively to the future by . . . establishing a permanent presence in space.''
'' 'Permanent presence' is a reference we believe is a very important one . . . we see it as a strong statement of support for what we're doing,'' Lt. Gen. J. A. Abrahamson, NASA's associate administrator for space transportation systems, told reporters after the Columbia landed to applause and cheers from a flag-waving crowd of 525,000.
Although Mr. Abrahamson acknowledged that the space shuttle will have to fight budgetary battles with other federally funded programs, he said he thought Reagan's Fourth of July appearance would have ''a favorable impact'' on NASA's efforts to obtain future funding.
''If the President is supportive, that's encouraging as we try to develop arguments that show (space shuttle projects) really are good investments on the part of the country,'' he said.
Although Reagan's space policy places heavy emphasis on national security goals, he referred only fleetingly to national security in his speech - dwelling instead on ''pushing back frontiers.''
''The fourth landing of the Columbia is the historical equivalent to the driving of the golden spike which completed the first trancontinental railroad, '' he said. ''It marks our entrance into a new era. The test flights are over, the groundwork has been laid. Now we will move forward to capitalize on the tremendous potential offered by the ultimate frontier of space.''