Liftoff at long last

Liftoff. On the seventh try in eight days, NASA has launched its tandem Cloudsat and CALIPSO missions. The Delta 2 rocket roared off pad 2 at Vandenberg Air Force Base in California at 6:02 a.m. after suffering a string of delays from support plane availability to weather over the last week. The mission was long delayed before that by a Boeing rocket worker strike in late 2005.

Once in orbit, these two satellites will team up to study the mysteries of clouds and aerosols. The data they collect will help scientists learn about Earth's weather and air quality. The two satellites will join three others, flying in formation, called the A train. Among other things, the A train constellation is expected to improve our knowledge about climate change.