Endeavour Launch Postponed

It looks like the space shuttle Endeavour will have to wait for its final flight. NASA announced that the launch was postponed for at least 48 hours due to an issue with the Auxillary Power Unit 1 heaters. It was shaping up to be a dramatic launch, with the largest crowds expected to attend since the launch of Apollo. President Obama and his family were expected to join the crowd, as was Rep. Gabrielle Giffords, whose husband, Mark Kelly, is leading the Endeavour's last mission. Giffords, who was shot in the head earlier this year, had already flown to Florida.