Northrop Grumman is set to launch the penultimate flight of its current Antares rocket configuration — with Russian engines and a Ukrainian first stage structure — to begin a resupply mission Sunday delivering more than four tons of cargo to the International Space Station.
The current configuration of the Antares rocket, known as the Antares 230+, will be retired next year to allow Northrop Grumman and partner Firefly Aerospace to develop a new U.S.-made booster to replace the Ukrainian/Russian design for future space station cargo flights.
Northrop Grumman’s 18th resupply mission to the space station is set to begin with a blastoff from Virginia’s Eastern Shore at 5:50:16 a.m. EST (1050:16 GMT) Sunday, the opening of a five-minute launch window. Two Russian-made RD-181 engines will power the 139-foot-tall (42.5-meter) rocket off of pad 0A at the Mid-Atlantic Regional Spaceport in Virginia, co-located with NASA’s Wallops Flight Facility on the Atlantic coast.
The official launch weather forecast calls for an 80% chance of favorable conditions for launch before sunrise Sunday.
The kerosene-fueled RD-181 engines will throttle up to generate 864,000 pounds of thrust and burn for 3 minutes and 18 seconds, steering the Antares rocket southeast from Virginia on a path to line up with the space station’s orbital track. The Ukrainian-built first stage will jettison a few seconds after engine cutoff, followed by jettison of the rocket’s nose cone at T+plus 3 minutes and 54 seconds, and ignition of the U.S.-made upper stage solid rocket motor at T+plus 4 minutes and 7 seconds for a nearly three-minute burn.
The rocket will place Northrop Grumman’s Cygnus cargo freighter into orbit nearly seven minutes after launch. The supply ship will separate from the Antares upper stage at T+plus 8 minutes and 52 seconds, allowing the Cygnus spacecraft to open its fan-shaped solar arrays and begin a pursuit of the space station.
Assuming an on-time launch Sunday, the Northrop Grumman cargo ship will arrive at the station early Tuesday. NASA astronaut Nicole Mann will operate the station’s robotic arm to capture the Cygnus spacecraft and place it on a berthing port at the orbiting lab’s Unity module for a nearly three-month stay.
The mission is designated NG-18, and will mark the 18th Cygnus spacecraft fly to the space station. Northrop Grumman has a multibillion-dollar cargo resupply contract with NASA covering Cygnus missions through NG-25.
But Northrop Grumman is transitioning away from two of its major suppliers after supply chain strains caused by Russia’s invasion of Ukraine earlier this year. NPO Energomash, a Russian rocket engine builder, manufactures the RD-181 engines used on the Antares 230+ rocket’s first stage. And the first stage structure itself is designed and built by Ukrainian companies Yuzhnoye and Yuzhmash.
“We’ve had great support from those three suppliers,” said Kurt Eberly, Northrop Grumman’s director of space launch programs. “Things are working very well technically on the vehicle and programmatically we got great support from them. I just wish it could have continued, but also this is an opportunity for us to transition to what we think is going to be a more competitive vehicle.”
In August, Northrop Grumman and Firefly Aerospace announced a partnership to develop a new U.S.-built Antares first stage booster powered by seven Miranda engines developed by Firefly. That rocket, called Antares 330, is scheduled to debut in late 2024.
Northrop Grumman had two engine sets and two Antares first stage boosters in the United States when Russian invaded Ukraine in February, enough to cover the company’s needs for the NG-18 and NG-19 missions. After the launch of NG-19 on the final Antares 230+ rocket, currently scheduled for March, Northrop Grumman will launch the next three Cygnus cargo missions on SpaceX Falcon 9 rockets from Cape Canaveral in 2023 and 2024.
Falcon 9 rockets already launch SpaceX’s own resupply missions to the space station with the Dragon spacecraft. Unlike the Dragon, the Cygnus supply ships will launch covered by the Falcon 9’s payload fairing. Eberly said in August that Northrop Grumman booked the NG-20, NG-21, and NG-22 launches with SpaceX using the company’s own internal funding.
Officials hope the Antares 330 rocket will be ready to resume space station cargo launches from Virginia in late 2024 for the NG-23, NG-24, and NG-25 missions, the final three cargo flights on Northrop Grumman’s current contract with NASA.
Northrop Grumman and Firefly officials hope to attract more business for the Antares 330 rocket beyond space station cargo launches. The companies also plan a new rocket design currently called the Medium Launch Vehicle, or MLV, that will replace the Antares 330. The new MLV will have a liquid-fueled upper stage to replace the solid-fueled motor used on the Antares 230+ and Antares 330.
Eberly said the configuration of the Antares 330 with seven main engines is “compatible” with future attempts to perform propulsive landings with the booster.
“We’re building in the capability to do reuse later in that development,” Eberly said. “We’ll start out with an expendable version, and we’ll bring in the reuse later, is the plan.”
In a pre-launch press conference Saturday, Eberly said the fallout from Russia’s military attack on Ukraine has not impacted any of the preparations for the NG-18 mission.
“We do all the work on all the hardware … and we had all the hardware here prior to the launch of NG-17 for the NG-18 and NG-19 missions,” Eberly said. “So really it’s been unaffected.”
Ground teams assembled the Antares rocket’s first and second stages, then installed the Cygnus payload and nose cone inside a horizontal integration facility at Wallops. Northrop Grumman rolled the rocket to pad 0A on Wednesday at the Mid-Atlantic Regional Spaceport, a facility run by the Virginia Commercial Space Flight Authority.
After guiding the Antares rocket up the ramp at pad 0A, ground teams engaged a hydraulic lift to raise the launcher vertical later Wednesday to begin a series of preflight checks. A combined systems test was completed Thursday to verify interfaces between the Antares rocket, the Cygnus cargo carrier and the NASA-operated range at Wallops.
Workers then lowered the Antares rocket back to a horizontal position and moved a mobile clean room over the top of the launcher’s payload shroud. Technicians opened the top of the fairing to access the forward hatch of the Cygnus spacecraft for loading of time-sensitive cargo and experiments early Saturday.
The Antares team closed the Cygnus hatch, re-installed the top of the Antares payload fairing, and raised the rocket vertical again Saturday in time to commence the five-hour launch countdown at 1:50 a.m. EDT (0550 GMT) Sunday, Eberly said.
The change from daylight saving time to standard time at 2 a.m. will occur during the Antares countdown. The launch team will oversee final activation, readiness checks and filling of the Antares rocket’s first stage with kerosene and liquid oxygen propellants before liftoff.
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