Posted: Wed, Mar 14, 2007, 7:27 PM ET (2327 GMT)
The upcoming launch of the heavy version of the Delta 4 on its first operational mission has been delayed until some time this summer in order to repair cracks on its Cape Canaveral launch pad. The Delta 4 Heavy was scheduled to lift off next month to place the DSP 23 missile warning satellite into orbit. However, Air Force officials said Wednesday they were now targeting summer as the next possible launch date. Aviation Week reported last weekend that a liquid oxygen leak during a recent fueling test caused structural damage to a metallic launch table at the pad. The incident is still under investigation. The launch will be the first operational mission for the Delta 4 Heavy, the most powerful EELV variant. The Delta 4 Heavy first flew in December 2004, carrying a test payload; that satellite ended up in a lower-than-planned orbit because of a propellant flow problem in the launch vehicle.

Related Links:

•  Wall Street Journal article (subscription required)
•  Aviation Week article