The launch of the US space shuttle Endeavour has been postponed for a fourth time due to poor weather conditions. The decision was taken less than one hour before the planned lift-off, when the astronauts were already in place in the aircraft.

Saturday's launch was scrapped because of lightning strikes and two earlier attempts were cancelled because of technical problems. The next launch attempt is scheduled for Monday evening US local time.

Endeavour will have seven astronauts on board, as well as reserve parts for the International Space Station and the third part of a platform. This will be added to the ISS to enable experiments that call for direct contact with space to be carried out.

photo: International Space Station (flickr/ Top TechWriter.US)