Mission controllers will decide whether to land the space shuttle Endeavour later on Wednesday after bad weather on Tuesday caused more delays.

The orbiter could land at the Kennedy Space Center at 1553 BST or at 1727 BST.

If conditions are not right for either of those two opportunities, the vehicle has three chances to land at the alternative site at Edwards Air Force Base in California, the first of which is at 1858 BST.

Endeavour has enough fuel and supplies to stay in orbit until Thursday.

Endurance record

The continued delay lengthens the new US space endurance mark set by returning astronauts Carl Walz and Dan Bursch. They have spent more than six months on the International Space Station.

This is still well short of the world record set by Russian Valery Poliakov in the mid-1990s. He served on the Mir platform for 437 consecutive days.

Walz and Bursch, together with their Russian commander Yury Onufrienko, form the outgoing Expedition Four crew on the ISS. Endeavour brought up their replacement, Expedition Five.

This latest crew, which includes Peggy Whitson, Valery Korzun and Sergei Treschev, will study the effects of prolonged spaceflight on human muscles and carry out other medical experiments.

Endeavour's mission also continued construction work on the space platform. Astronauts Philippe Perrin, of France, and Franklin Chang-Diaz, of the US, performed three spacewalks.

One of their tasks was to repair a wrist-joint on the station's robotic arm. They also installed a platform that allows the arm to move around the exterior of the ISS.