IT used to be conventional wisdom to say the United States space program lacks well-defined goals while Soviet space planners know where they are going. Now both programs are drifting. This gives a new dimension to the agreement for closer US-USSR space cooperation that emerged from the pre-coup summit.There no longer is a "Soviet" space program or a USSR to deal with. Presumably, the now weaker central authority will carry on the space effort. But no one now knows what its scope and purpose will be. Russian Federation President Boris Yeltsin questions the program's cost. So do many citizens of the republics that will make up the new union. Useful activities, such as maintaining communications and weather satellite networks, will likely continue. But the future of space exploration is uncertain. Dreams of Mars missions now are wishful thinking. Plans for further development of earth-orbital flight are being scaled back. Soviet officials have postponed definition work for an advanced earth-to-orbit space ship. They have scrapped plans to develop a new orbital station along the lines of the United States Freedom design. They are building a modernized version of the present Mir design instead. With uncertainties in both the Soviet and US space endeavors, it's hard to know how the two programs can cooperate usefully. Preexisting agreements are workable. They will likely continue. For example, the Soviet Meteor-3 weather satellite, launched Aug. 15, carries an American instrument to monitor the stratospheric ozone layer. However, the two nations may want to rethink the latest agreement. Its provision for astronaut-cosmonaut exchanges could go forward. But there's a new climate for cooperation in many areas, especially in commercial activities. Soviet space officials now say they will consider any reasonable commercial propositions, including renting out the Mir station. The US should rethink its own space policies in the light of this new reality. What can be done to help American space industry work effectively in the new commercial arena? To what extent can the two manned space flight programs share common goals and facilities? Can there be closer cooperation to share costs and hardware, getting rid of US curbs on such exchanges? There are no easy answers to such questions. Yet they must be faced. A new phase of the space age has been entered, and the hallmark of this phase will be international cooperation in space exploration as well as commercial competition.