NASA has postponed the launch of space shuttle Endeavour by 24 hours, following the discovery of an technical problem with the Auxilliary Power Unit.

The delay was announced as the shuttle commander Mark Kelly and his crew were on their way to the launch pad, The Associated Press reports. NASA reports that two heaters on an anxiliary power unit were not working. The AP says engineers could not figure out the problem and NASA decided to scrub the 3:48 p.m. ET flight.

President Obama had planned to be on hand for the launch, but had not yet arrived.

(Sources: USA Today / Fox News)