Aerospace and defence company Northrop Grumman has launched the 12th Cygnus cargo mission to the International Space Station (ISS) for Nasa.

The company’s Antares rocket carrying its Cygnus cargo spacecraft lifted-off from the Mid-Atlantic Regional Spaceport Pad 0A on Wallops Island, Virginia, at Nasa’s Wallops Flight Facility.

Known as NG-12, the mission delivered cargo under a Commercial Resupply Services-2 (CRS-2) contract.

Weighing approximately 3,729kg, NG-12 was the heaviest delivery made by Cygnus and Antares so far.

The rocket designed for this mission featured an upgraded Stage 1 core. It has lighter composite structures complemented by an enhanced second-stage motor.

Northrop Grumman flight systems vice-president and general manager Scott Lehr said: “With these upgrades, we are able to offer Nasa more cargo capacity for their CRS-2 missions by increasing the performance of Antares. We are also providing more flexibility for the final cargo load.

“As a commercial partner to Nasa, we are dedicated to providing the best value to our customer in support of their critical missions.”

Northrop Grumman will also operate two Cygnus spacecraft at the same time. The NG-11 Cygnus spacecraft was launched in April.

According to Northrop Grumman, Cygnus was to be exposed to a late load of critical cargo 24h before lift-off.

This would allow Cygnus to safely transport time-sensitive payloads, such as the live rodents to the space station.

Northrop Grumman space systems vice-president and general manager Frank DeMauro said: “Northrop Grumman is honoured to continue providing cargo logistics services to the space station under Nasa’s second commercial resupply services contract as a trusted partner.

“The Cygnus spacecraft continues to provide critical services to the orbiting laboratory while demonstrating a number of innovative capabilities, and our recent partnership with the Eastern Virginia Medical School is just one of the ways we’re expanding our programme.”