CAPE CANAVERAL -- It has been a hectic first six months of the year for the Atlas and Delta families of rockets, flying a combined 7 times so far in 2014. Here is a look at the year to date for United Launch Alliance and the four Atlas missions and three by Delta:

Vehicle: Atlas 5-401
Payload: TDRS-L
Date: Jan. 23, 2014
Site: Cape Canaveral, Fla.

The Tracking and Data Relay satellite-L was successfully delivered into orbit to reinforce NASA's space-based tracking and communications network. Advancing from the days of ground stations providing sporadic coverage of man's early exploits in space to the creation of an orbiting satellite network for constant communications, the next bird in the third generation of NASA's tracking stations in the sky roared off the launch pad on Jan. 23.

Vehicle: Delta 4-Medium+ (4,2)
Payload: GPS 2F-5
Date: Feb. 20, 2014
Site: Cape Canaveral, Fla.

Igniting a surge of three Global Positioning System satellite launches in the next five months, a Delta 4 rocket blazed a trail of fire and light into the Florida sky Feb. 20. The new bird -- known as GPS 2F-5 -- will become a primary broadcasting satellite in the constellation.

Vehicle: Atlas 5-401
Payload: DMSP F19
Date: April 3, 2014
Site: Vandenberg Air Force Base, Calif.

A new global weather observatory for the U.S. armed forces was lofted into orbit aboard its Atlas 5 booster rocket from California on April 3 to provide tactical forecasts to military operations. The $518 million spacecraft will help guide some of the most important decisions in the armed forces, from flight patterns to troop movements.

Vehicle: Atlas 5-541
Payload: NROL-67
Date: April 10, 2014
Site: Cape Canaveral, Fla.

Setting sail at mid-day on a marathon trip to orbit, an Atlas 5 rocket launched a classified spacecraft for the National Reconnaissance Office on April 10. The clandestine launch appeared to deploy an intelligence-gathering spacecraft directly into geosynchronous orbit.

Vehicle: Delta 4-Medium+ (4,2)
Payload: GPS 2F-6
Date: May 16, 2014
Site: Cape Canaveral, Fla.

A replacement Global Positioning System spacecraft for the world's best-known satellite constellation ascended into orbit aboard a Delta 4 rocket in a spectacular sendoff at sunset May 16. It was a direct insertion ascent, putting the $245 million Global Positioning System 2F-6 payload into the navigation network three hours and 15 minutes after blastoff.

Vehicle: Atlas 5-401
Payload: NROL-33
Date: May 22, 2014
Site: Cape Canaveral, Fla.

Completing a pair of missions in one week's time, a feat also performed last month, United Launch Alliance sent an Atlas 5 rocket soaring May 22. This classified mission for the National Reconnaissance Office appeared to launch a data-relay satellite into geosynchronous transfer orbit.

Vehicle: Delta 2-7320
Payload: OCO 2
Date: July 2, 2014
Site: Vandenberg Air Force Base, Calif.

Streaking back into action after a two-and-a-half-year hiatus, a Delta 2 rocket launched NASA's Orbiting Carbon Observatory No. 2 to watch the Earth breathe from space. It is the agency's first spacecraft dedicated to measuring carbon dioxide in Earth's atmosphere, a critical new data-gathering project for scientists and policy-makers,