The launch of the US space shuttle Endeavour has been put back again so that NASA can assess possible damage from lightning strikes.Blast off has now been scheduled for Sunday. Last month NASA was forced to cancel two launch attempts because of potentially dangerous fuel leaks. This time however officials are confident the delay is only a minor hitch. Mike Moses, Shuttle Launch Integration Manager, said: “We use these multiple sensors to kind of help us narrow down what we think was induced to the vehicle out there at the pad. The lightning protection system is really good, and it definitely does its job. We are just being extra cautious, I guess is a good way to say it.” Endeavour and its seven strong crew are due to spend 16-days in orbit. The mission aims to install an external research platform on the International Space Station. However, NASA is running out of time to finish the station before the shuttle fleet retires in 2010.