CAPE CANAVERAL, Fla. (AP) _ NASA resolved a last-minute wiring problem as the countdown continued toward Friday's liftoff of Atlantis with an Italian satellite that will hurtle through space on the end of a 12-mile cord.

Technicians had to re-enter Atlantis' cargo bay today to lock down six electrical connectors between the shuttle and the platform holding the tethered satellite. Officials could not verify that the work had been done properly and feared the connections might be loose.

Suspicions were raised when two other electrical connectors were found Tuesday to have loose retaining rings.

The work was completed by midday, and the payload bay doors were to be closed by late afternoon.

''I haven't seen anything that would cause us to delay'' liftoff, said NASA payload manager Bob Webster.

The tether between satellite and shuttle is expected to generate 5,000 volts of electricity as the craft sweep through Earth's magnetic field at 17,500 mph.

NASA insists the experiment, while complicated, is safe. But the space agency has little experience in tethered spacecraft and none in electricity- generating tethers. Nor does any other country.

''We look at this as kind of a voyage of discovery, of exploration, sort of like the first time we ever went into space and tried to rendezvous or land on the moon,'' astronaut Jeffrey Hoffman said Tuesday, hours after the countdown began. ''It's a test flight in the very real sense of that word.''

The seven-day mission is scheduled for liftoff at 9:56 a.m. EDT Friday. Forecasters said there was 95 percent chance of good launch weather.

Atlantis' seven-member crew is to unreel the satellite from the shuttle midway through the flight. The spherical satellite, supplied by the Italian Space Agency, is 5 feet in diameter and weighs 1,140 pounds.

For 30 hours it will fly above Atlantis, connected by a copper and fiber cord. U.S. and Italian researchers want to see how a tethered satellite can be controlled and how well the system produces electricity.

If the experiment works, tethers could be used to power spacecraft and explore parts of the atmosphere too high for instrument-laden balloons but too low for free-flying satellites.

The shuttle also holds a European Space Agency scientific satellite that will be released 18 hours into the flight.

It will be retrieved by another shuttle crew next spring so scientists can analyze samples of crystals, seeds, spores and eggs after months in space.

Atlantis' crew consists of five Americans, an Italian and a Swiss.