The space agency moved last night to reposition the 80-ton Skylab space station to allow flight directors to bring it down over one of the world's oceans when it reenters the Earth's atmosphere.

Commands were to be sent up at 3:47 a.m. today from the Mission Control Center at Houston's Johnson Space Center to pitch Skylab forward so that its huge solar panels will always be pointed at the sun. Skylab then would be assured a steady supply of electricity that could keep its batteries charged during the rest of its lifetime in space.

The maneuver should have been completed by 4:10 a.m., while the space station passed over California on its northeasterly track around the world.

If the space station's batteries can be kept fully charged, flight directors at the Johnson Space Center think they can devise a plan to time its break-up in the Earth's atmosphere so that the debris will come down in an ocean.

Skylab can be moved around in space by using its big gyros or by firing its small jet thrusters. Either way, lots of power is needed to turn the electric motors involved.