WASHINGTON — An Atlas 5 successfully launched a Cygnus spacecraft April 18 carrying three and a half tons of cargo for the International Space Station.
The United Launch Alliance Atlas 5 401 lifted off on schedule at 11:11 a.m. Eastern from Space Launch Complex 41 at Cape Canaveral, Florida, after a countdown free of any major issues. The Cygnus spacecraft separated from the Centaur upper stage 21 minutes after launch in low Earth orbit.
“Everything looks very nominal,” said Vern Thorp, program manager for commercial missions at ULA, in an interview on NASA Television shortly after spacecraft separation. The Atlas performed “slightly above nominal” on the flight, he said, and the Centaur upper stage placed the Cygnus into the planned orbit.
The Cygnus, flying on a mission designated OA-7, is carrying 3,459 kilograms of cargo for the ISS. That cargo includes a mix of crew supplies, vehicle hardware and science investigations. The Cygnus will arrive at the station and be berthed by the station’s robotic arm early April 22.
That scientific payload includes an Advanced Plant Habitat, an upgraded version of a zero-gravity greenhouse that will be used for bioscience experiments and studies for future long-duration missions where crews will grow their own food. Another experiment will test the effectiveness of antibody-drug conjugates against cancer cells. The microgravity environment of the station allows the cancer cells to grow in three dimensions to better test the effectiveness of the treatment.
The Cygnus is also carrying 38 cubesats. Most of those cubesats will be later deployed from the ISS, but four will be released from the Cygnus itself after it departs the station in July, moving to a higher altitude to extend those satellites’ orbital lifetimes. Of the satellites, 28 are from a European project called QB50 that will use the satellites to study the Earth’s thermosphere. They will be joined by an additional eight cubesats launching later this year on an Indian Polar Satellite Launch Vehicle.
The launch is the third time that Orbital ATK has used an Atlas 5 to launch a Cygnus spacecraft. Two prior launches, in December 2015 and March 2016, were purchased by Orbital ATK after the October 2014 failure of the company’s Antares rocket carrying another Cygnus spacecraft. Last November, the company announced it would launch a third Cygnus on an Atlas 5 in order to maximize the payload it could carry to the station to meet NASA’s needs.
“Because there was a slightly increased demand for cargo to the station sooner rather than later, and Atlas had a vehicle available and additional upmass available, we talked to NASA and decided jointly to go ahead with the Atlas,” said Frank Culbertson, president of Orbital ATK’s Space Systems Group, at a NASA press conference April 17 at the Kennedy Space Center.
Orbital plans to launch the remaining four Cygnus missions on its current Commercial Resupply Services contract on Antares rockets, with the next coming as soon as this summer. Orbital ATK has a follow-on cargo contract from NASA for missions to the ISS starting in 2019, with the option of using either Antares or Atlas 5 rockets for those missions.
Orbital ATK named this Cygnus spacecraft the S.S. John Glenn, after the Mercury 7 astronaut and former senator who passed away in December. Culbertson, a former astronaut, recalled watching Glenn’s February 1962 spaceflight while in school. “That my earliest inspiration of actually thinking maybe someone in this country could grow up to be an astronaut,” he said. “I’m sad that he’s gone, but he’s lived a really full life and he’s provided inspiration to a couple of generations of American men and women.”