Two astronauts will make a hastily-planned spacewalk to try to fix an ammonia leak in the International Space Station’s power system.

Nasa said today it had delayed the launch of space shuttle Discovery while it runs tests to determine whether newly-installed valves would cause serious damage if they broke during lift-off.

A TELECOMS entrepreneur blasted off yesterday on a Russian rocket bound for the international space station, achieving her dream of becoming the world’s first paying female space tourist.