A rocket carrying an Italian Earth-observation satellite blasted off Friday evening from the California coast.

The Delta rocket II lifted off around 7:30 p.m. and made an arc south over the dark Pacific Ocean as it headed toward orbit.

The payload was the third part of a four-satellite system called COSMO-SkyMed -- short for Constellation of Small Satellites for Mediterranean Basin Observation -- developed under an agreement between the Italian Space Agency and Italy's defense ministry.

The satellites use radar to create images for civil protection, defense, science and commercial purposes.

Col. David Buck, the mission's spacelift commander, said both sides overcame a language barrier to successfully launch the rocket.

"People don't always think about it, but this is rocket science, and our airmen and industry partners make it look easy," he said.

The first two satellites were launched last year from Vandenberg, 130 miles west of Los Angeles, and the system became operational in August.

It has already supplied images of such disasters as Myanmar's Cyclone Nargis and China's spring earthquake that have been used by international organizations in planning aid, according to the Italian Space Agency.

The third satellite is expected to increase the number of images from the current capacity of 900 a day to 1,350 a day. The fourth satellite in the billion-euro system should be launched in early 2010.