Delta II is a rocket used to launch various projects into space. The Delta series of rockets were first designed and made by McDonnell Douglas. This company joined with Boeing in 1997. Delta II rockets have been made since 2006 by United Launch Alliance, which is a joint company owned by Boeing and Lockheed Martin to supply launch rockets to the US government. Boeing Launch Services supplies Delta II rockets to private companies.
The Delta II rockets were based on the Thor rockets built in the 1950's. These were used to carry Inter Continental Ballistic Missiles. The first Thor was launched on January 26, 1957. The Delta II rocket was first launched on February 14, 1989. The rocket was developed after the explosion of the Space Shuttle Challenger in 1986. The US Air Force needed another way to launch its GPS satellites. As of 2011, there have been 128 Delta II launches from both Cape Canaveral Air Force Station and the Vandenburg Air Force Base. Only two launches have been unsuccessful. In August 1995, a rocket motor failure meant the Koreasat 1 was put into a lower orbit, and in January 1997 Delta 241 carrying a GPS satellite exploded 13 seconds after taking off.
- Graham, William (October 28, 2011). "Delta II successfully launches NPP satellite on behalf of NASA and NOAA". nasaspaceflight.com. http://www.nasaspaceflight.com/2011/10/live-delta-ii-launch-npp-satellite-nasa-and-noaa/. Retrieved November 6, 2012.