Antares launch
An Orbital ATK Antares rocket lifts off from Wallops Island, Virginia, Nov. 12, carrying a Cygnus cargo spacecraft. Credit: SpaceNews/Jeff Foust

Updated at 11:10 a.m. Eastern with details from post-launch briefing.

WALLOPS ISLAND, Va. — An Orbital ATK Antares rocket successfully launched a Cygnus cargo spacecraft packed with supplies and equipment for the International Space Station Nov. 12.

The Antares lifted off from Mid-Atlantic Regional Spaceport here at 7:19 a.m. Eastern, at the end of a five-minute window. At a post-launch press conference, Kurt Eberly, deputy program manager for Antares at Orbital ATK, said that was because of an issue with the process of chilling one of the RD-181 main engines during pre-launch preparations.

The five-minute slip had another benefit as well. “It gave the range some more time to clear out some boats that were trending towards the hazard area,” he said. Controllers scrubbed a previous launch attempt Nov. 11 when an aircraft entered the range.

The Antares had an “over-performance” on this launch, placing Cygnus into a slightly higher orbit than planned, but one that doesn’t affect plans for the Cygnus to arrive at the ISS early Nov 14.

Eberly said this additional performance, which also was noted on the rocket’s previous flight in October 2016, could allow the Antares to carry slightly heavier payloads on future missions. “We’re going to be adjusting our models, and when we do that, we’ll be able to bank a little bit more margin,” he said, which could be used for Cygnus based on internal discussions and those with NASA.

The Cygnus, on a mission called OA-8, is carrying more than 3,300 kilograms of cargo, including crew supplies, station hardware and scientific investigations. “We have Cygnus completely packed full of cargo on this mission,” said Dan Hartman, deputy ISS program manager at NASA, said at a pre-launch briefing Nov. 10.

The Cygnus spacecraft, named “S. S. Gene Cernan” after the Apollo 17 astronaut who passed away earlier this year, will remain at the station only a few weeks, with the arm unberthing the Cygnus, after filling it with cargo for disposal, on Dec. 3.

NASA will wait to release Cygnus for a day, however, using the spacecraft for tests of a docking system for future commercial crew vehicles. “We just want to get a little bit more characterization of our ISS GPS performance during that operation,” Hartman said.

Cygnus will then be released by the robotic arm on Dec. 4, the same day as SpaceX is scheduled to launch a Dragon cargo spacecraft to the ISS. Hartman said that while the station could accommodate both Cygnus and Dragon simultaneously, SpaceX’s previous analyses for its upcoming mission assumed Cygnus would not be there. “That’s primarily what’s driving” the early departure of Cygnus.

After leaving the station, but before its mission-ending destructive reentry, Cygnus will fly to a higher altitude and then deploy 14 cubesats mounted in dispensers on the exterior of the spacecraft’s service module. Those cubesats include eight Lemur satellites for Spire, a company that operate a constellation of ship-tracking and weather satellites, as well as technology demonstration cubesats for NASA and The Aerospace Corporation.

This mission is the fourth time that NanoRacks has flown cubesats in external dispensers on a Cygnus, said Henry Martin, mission manager at NanoRacks, at a Nov. 10 pre-launch briefing, but on previous flights weren’t able to fill all the dispensers. “It’s totally full” on this flight, he said.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...