( CNN ) -- Decades-old Russian engines are believed to have caused the Antares rocket 's failure to launch properly , Orbital Sciences Corp. 's CEO David Thompson said Wednesday . `` Current evidence strongly suggest that one of the two AJ26 main engines that powered Antares ' first stage failed about 15 seconds after ignition , '' Thompson said in a conference call with investors . Last week , a company spokesman said the unmanned rocket , which exploded in a fireball at NASA 's Wallops Flight Facility in Virginia , was deliberately destroyed after it became apparent there was a problem . The turbo pump in one of the engines likely failed , Thompson said Wednesday . Orbital will likely stop using these engines , he said , since they have proven to be unreliable . The Antares rocket and Cygnus cargo spacecraft had been set to carry roughly 5,000 pounds of supplies and experiments to the International Space Station . Despite what Thompson described as a `` setback , '' the company plans to stay on track with its $ 1.9 billion NASA contract delivering cargo to the space station , he said . Orbital hopes to launch its Cygnus spacecraft using third-party rockets , he said . There are three companies in the running : two from the United States and one from Europe . Thompson would not reveal which companies , but said a decision is expected within a month . SpaceX and United Space Alliance , the two likely U.S. companies -- operate regular launches at Cape Canaveral Air Force Station in Florida . Orbital Sciences , SpaceX and the Russians ' Soyuz all regularly fly cargo and supplies to the six astronauts and cosmonauts stationed on the space station . While using another company 's launch vehicle , Orbital will concentrate on replacing the 1970s-era Russian engines by 2016 . Thompson thanked NASA for its support . `` We look forward to working closely with them to quickly recover from last week 's setback , '' he said .
Evidence indicates an engine failed 15 seconds after ignition , Orbital 's CEO says . The turbo pump in one of the engines likely failed , he says . Comment: