A stuck power cable delayed the satellite's release for at least two hours before Nasa said the problem had finally been solved. Ground-controllers and the crew sent repeated computer commands and slackened tension on the satellite's spool of thin wire in their efforts to disconnect the cable, which provides power and communications from the shuttle to the satellite.
The Atlantis crew was scheduled to unreel the 1,100lb (500kg) sphere on a flexible wire-and-fibre tether about as thick as a shoelace.
Scientists want to see whether the cable, stretched through the Earth's electrically charged ionosphere, can generate electricity. Such cables might some day power a space station and even propel spacecraft, scientists say. As Atlantis orbited 184 miles above Earth, the tether was expected to ripple, sway like a pendulum, bounce like a yo-yo and swing in circles like a skipping- rope. If the shuttle gets into danger, the crew can activate explosives to cut the satellite loose and fly away.
'We expect to see some things about flying satellites attached to tethers that nobody's really thought about,' said the commander, Loren Shriver, who spent two years training for all the flying manoeuvres he may have to make to steady the tether.
'Or at least if they've thought about them, it's hard to describe the kind of motion that we might see.'
Nasa expects the cord to produce up to 5,000 volts of electricity as it cuts across Earth's magnetic field at 17,500mph. The current should flow from the satellite to the shuttle.
Meanwhile, the first satellite released by Atlantis' astronauts, owned by the European Space Agency, remained stuck in a precariously low orbit. The uninsured dollars 213m (pounds 111m) Eureca satellite, released on Sunday, was 276 miles above Earth.
Ground-controllers had fired thrusters to boost it to a 320-mile-high orbit, but stopped because the satellite appeared to be tilted the wrong way. Controllers at the European Space Agency may fire the thrusters again in a few days, said Daria Robinson, a spokeswoman for the agency.
On its present course, Eureca and its load of crystals, seeds, shrimp eggs and bacteria spores would eventually plunge through the atmosphere and burn up. Shuttle astronauts are scheduled to pick up the satellite next spring if it can be boosted to the right orbit.Reuse content