The first flight of the newly updated Antares rocket — the premiere vehicle of private spaceflight company Orbital ATK — will take place sometime in July, the company announced today according to Space News. The flight will send cargo and supplies to the International Space Station, as part of Orbital's commercial partnership with NASA. It also marks the first launch of the Antares after a previous version of the vehicle exploded during a space station resupply mission in October 2014.
Orbital has spent nearly two years redesigning the Antares
Since the accident, Orbital has spent nearly two years redesigning the Antares. The biggest change has been replacing the engines in the rocket. Originally, the Antares flew on two AJ26 engines, refurbished Soviet-era engines manufactured by US company Aerojet Rocketdyne. But Orbital claims the engines were responsible for the accident and decided to replace them. An investigation by Orbital found that a defect in the turbopumps of one of the AJ26 engines caused an explosion that ultimately destroyed the rocket. That puts the blame on Aerojet for not making the engines correctly.
Not everyone is in agreement about what caused the accident, though. Aerojet claimed that the explosion was actually caused by foreign debris found in the engine, according to Reuters. And an investigation by NASA couldn't conclusively say if the explosion was caused by defective turbopumps or foreign debris. Regardless, Orbital still decided to replace the AJ26 engines with RD-181s — engines developed by Russian company NPO Energomash.
While Orbital replaced the Antares engines, the company had to rely on help from the United Launch Alliance to help fulfill its contractual obligations to NASA. Orbital is required to periodically resupply the International Space station through 2024 — a condition of its commercial resupply contract with the space agency. For its past two resupply missions, the company launched its Cygnus cargo capsule on top of ULA's Atlas V rockets. Both launches successfully transported the Cygnus to the ISS.
Now with the debut of the Antares, Orbital will be back to launching resupply missions with its own rockets. First, the company plans to conduct a static test fire of the Antares rocket in May; the vehicle's engines will be ignited while the rocket is restrained to see if everything is working properly. If that goes well, then Orbital will be on track for its July launch.