Orbital ATK resumes US cargo missions to ISS months after rocket explosions

A private US cargo spaceship was launched to the International Space Station (ISS) on Sunday afternoon, months after two US commercial shipments were destroyed in launch explosions. A live broadcast by NASA TV showed Orbital ATK's Cygnus blasted off atop a United Launch Alliance Atlas V rocket as planned at 4:44 p.m. EST (2144 GMT) from Cape Canaveral Air Force Station in Florida. The launch of Cygnus spacecraft has been delayed three times this week due to bad weather, including thick clouds and high winds, but Sunday's launch appeared to go smoothly. "Beautifully. All systems nominal. Next stop: @Space_Station," Orbital ATK tweeted. "On a side note: we're finally done worrying about the wind." This marked the Virginia-based company's fourth operational mission to the ISS for the US space agency NASA under the Commercial Resupply Services (CRS) contract as well as the debut of the enhanced Cygnus, which has about 3,500 kilograms of cargo on board. The earlier version of the spaceship could carry only about 2,000 kilograms of cargo. Orbital ATK is one of the two commercial companies hired by NASA after the space shuttles were retired to fly cargo to the ISS. Its third CRS mission using the company's own Antares rocket was destroyed in a launch explosion in October last year. The other company, SpaceX, was recovering from a similar launch explosion in June this year as well. At a prelaunch news conference earlier this week, Kirk Shireman, NASA's ISS program manager, called the explosions "growing pains" in what he said was "a transition period." "Commercial space is going to happen," Shireman said. "It is inevitable. It is occurring right now. It is our future." The NASA official put 2015 as "a difficult year" for the ISS as a result of the two US cargo delivery failures as well as the loss of a Russian cargo spacecraft in April, revealing that the orbiting lab has basically toilet supplies through February next year and that food supplies would also run out on April 12. "So we're looking forward to having those supplies being replenished" by Orbital ATK's latest cargo resupply mission, he said. Shireman stressed that NASA wanted to "have a regular cadence of resupply flights" over the next year as both Cygnus and SpaceX's Dragon resumed cargo missions to the ISS. If all goes as planned, Cygnus will arrive at the ISS on Wednesday for an expected two-month visit. Orbital ATK has three CRS missions scheduled in 2016 to support ISS cargo needs. A second Cygnus launch using the Atlas V rocket will take place next spring from Florida, followed by the return of operations to NASA's Wallops Flight Facility in Virginia in mid-2016 where the company will continue CRS missions atop the upgraded Antares rocket.