Orbital ATK resupply the ISS

Orbital ATK launch of a Antares 230 Rocket
Orbital ATK launch a cargo resupply mission to the ISS on an Antares Rocket from Wallops. Credit: Orbital ATK Flickr.

On May 21st 2018, Orbital ATK’s Antares launch vehicle orbited the companies Cygnus OA-9 cargo hauling spacecraft. Launched from the little known NASA Wallops Island in Virginia, it took off from pad 0A at 08:44 UTC. OA-9 took 3,250 kg of cargo to the international space station, along with several cubesats that with deployer hardware added roughly 120 kg. This launch was in honour of J.R.Thompson, former Orbital Science CEO, who passed away in 2017.

Antares 230 waitjng
Antares 230 rocket waiting to launch from NASA Wallops Island. Credit: Space Launch Schedule

It was the third flight of the Antares 230 variant, a redesigned vehicle powered by two Energomash RD-181 engines instead of the AJ-26 engines that powered the first five Antares flights. The change was made after one of the AJ-26 turbopumps failed and triggered a destructive explosion above the pad in 2004. Cygnus OA-9 was the sixth enhanced Cygnus with a stretched cargo module, but only the third to fly on Antares, Atlas 5 launched the other three.#

ISS Cargo waiting
The OA-9 Cygnus cargo waiting to me mated with the rest of the rocket at Orbital ATK. Credit: Orbital ATK Flickr.

According to Orbital ATK, Cygnus  OA-9 weighed 6,173 kg at launch, matching OA-8 payload for heaviest launched by an Antares rocket. The RD-181 engines produce a total of 392 tonnes of thrust at liftoff, that powers the 293 tonne rocket into the sky. Built in Ukraine (former Soviet design), the first stage burned for 211 seconds. After first stage shutdown it seperated and coasted “up hill” for 37 seconds before the Orbital ATK Castor 30XL second stage motor ignited to produce 51 tonnes of thrust for 160 seconds. The payload fairing separated 12 seconds before second stage ignition. Cygnus separated into a 198 x 317 km x 51.63 deg orbit about 9 min 6 sec after liftoff.

OA-9 loading cargo
Orbital ATK loading cargo into the Cygnus OA-9 second stage. Credit: Orbital ATK Flickr.