Atlas V rocket launch try

The United Launch Alliance booster rocket lifted off at 4:44:57 p.m. EST (2144:57 GMT) from Cape Canaveral  to place the Orbital ATK-owned resupply ship into its preliminary 143-statute-mile orbit.

Orbital ATK also intends to launch its fifth resupply mission atop an Atlas V from Cape Canaveral. When the launch was moved to today, the weather forecast improved to a 40 percent chance of acceptable conditions at launch time.

"It's our first time launching the enhanced Cygnus which allows us to carry a lot more cargo to the ISS".

Mission Description:Cygnus is a low-risk design incorporating elements drawn from Orbital ATK and its partners' existing, flight-proven spacecraft technologies.

The rocket holds 7,400 pounds of supplies, all packed into a capsule named Cygnus after the swan constellation. US astronauts Scott Kelly and Kjell Lindgren would use the station's robotic arm to grab the Cygnus and berth it.

"The mission is critical because it's our first mission returning to delivering cargo to the International Space Station after the mishap from the ORB-3 mission". "Cygnus will spend more than a month attached to the space station, before its destructive re-entry into Earth's atmosphere, disposing of about 3,000 pounds of trash". Launch failures have sidelined both of NASA's commercial suppliers; United Launch Alliance's trusty Atlas V was called into service to get the supply chain moving again.

The California-based space transport company SpaceX now has an agreement with the American space agency, which is valued at $1.6 billion, to launch around 12 unmanned ISS missions using its Falcon 9 spacecraft and Dragon capsule. That's the reason for the rocket's debut today as a launch vehicle for space station resupply.

The Cygnus that launched Sunday is carrying several experiments on board, including a life sciences research module the size of a locker, a research project to evaluate flame-resistant and flame-retardant textiles in microgravity, an exploration of gas and liquid movement, and two different systems for networking small satellites or modular pieces into a larger whole. The station typically stocks about six months of provisions, and two different craft, one from Japan and one from Europe, have docked in the meantime and brought some supplies.

The successful launch shortly before sunset was cheered as a sign that the company had rebounded from its failure past year. In October 2014, a Cygnus shipment was lost when Orbital's Antares rocket failed due to flaws in one of its Russian-made engines.