On October the 22nd the Antares rocket that was scheduled to bring the Cygnus Orb-3 to ISS on its CRS-3 mission, exploded just after take off.
This Antares 130 is a upgraded version of the Antares and the first one of this type to fly.
The first stage is powered by two AJ-26 engines, which are modified NK33 engines originally developed in the 1960’s by the Russian’s for there unsuccessful N1 moon rocket.
The second stage is fitted with a Castor 30XL solid fuel engine made by Thiokol how also produced the Space Shuttle boosters.
The probable cause of the crash is a problem with the one of the AJ26 motors of the first stage, or the fuel system. The video clearly shows a destructive explosion in the aft section of the first stage. After the explosion the Antares falls back to the ground and crashed right into it’s launchpad. The 240 ton propellant ignites, as does the the solid fuel from the second stage, which burns for serval minutes with bright flames.
Cygnus Orb-3 was an unmanned mission heading for ISS with 900 Kg of scientific cargo, which got destroyed in the fire.
Orbital Sciences, how build the Antares rocket and the Cygnus cargo vessel, is one of the two parties that fly cargo to ISS under the Commercial Resupply Services contract.