WONDERS NEVER CEASE in the television world -- make that read, universe -- as science continues to ply in the sky for new and better ways to make live house calls with electronic services. From VHF to UHF to multi-channel cable, there is always something else on the horizon -- or slightly beyond it, as in the case of direct satellite-to-home broadcasting systems. The latest giant step came Tuesday, when the Federal Communications Commission game a premilinary go-ahead to the Communications Satellite Corporation, better known as Comsat, to beam programs directly from satellites to individual rooftops equipped with special dish-shaped antennas.

By a unanimous vote, the FCC has proposed temporary rules for this service and will start processing applications. Comsat, through a subsidiary, Satellite Television Corporation, plans to provide three channels of programming without commercials for a monthly fee of $14 to $18. Customers will have to install the rooftop dish-antennas and use a converter device to bring the signals onto their TV screens.

But don't invite the neighbors over for a dish of TV quite yet, because even after final FCC approval it will take at least three years to build and launch the necessary satellites. Besides, this system may not prove immediately popular in ubran areas where cable is operating; its biggest demand may be in places that are not now served by cable systems and that get poor reception from regular stations, or in cities that are without cable but whose residents are looking for something different on their screens.

Another applicant planning a similar operation but not offering its own programs is the Direct Broadcast Satellite Corporation of Bethesda. It intends to lease facilities to programmers for what it says will be a relatively low price per hour.

The FCC's action in granting initial approvals is a reasonable acknowledgment of experiments in television transmission, but does not commit the government to anything overly rigid or restrictive. In the long run, both the executive and legislative branches should review the whole matter in greater detail before issuing any hard and fast rules.