Shuttle ready for repair mission

Atlantis sits ready on the launch pad

The Space Shuttle Atlantis is ready to begin the countdown towards launch on Monday, on a mission to service the International Space Station (ISS).

STS -101

Launch - 2115 BST, 24 April

ISS Docking - 1535 BST, 26 April

ISS Undocking - 0851 BST 2 May

Landing - 1742 BST, 4 May

Orbit Altitude - 300 km

There had been uncertainty after an incorrect reading on a hydraulic power drive on the shuttle's rudder. The rudder is vital for landing and so the unit was replaced with one taken from the shuttle Columbia.

Tests on the drive have now been completed and it is "ready for flight", said Nasa.

The mission, STS-101, will boost the orbit of ISS and replace its batteries. ISS is gradually losing altitude as the result of increased solar activity.

Main engine No.1 is tested

The launch is scheduled for 2115 BST (2045 GMT), though the launch window is just five minutes.

Atlantis will dock with the ISS and the seven-member crew will unload more than a tonne of cargo. They will also perform several maintenance tasks onboard to prevent ISS from falling into disrepair before its assembly continues later this year.

The crew also will conduct one spacewalk to perform work on the exterior of the station.