Antares rocket explosion cause sought in US

The builders of an unmanned supply rocket which exploded on the way to the International Space Station have vowed to find the cause of the failure.

Antares, built by Orbital Sciences Corp, combusted seconds after leaving a launch pad in the US state of Virginia.

The company has warned locals near the crash site to avoid hazardous wreckage.

Crews have accessed the Nasa facility to search for debris, which may shed light on the incident. The investigation could take weeks.

"We will not fly until we understand the root cause," said Frank Culbertson, executive vice-president of Orbital Sciences, adding the top priority now was repairing the launch pad as "quickly and safely as possible".

Mr Culbertson told the BBC the mission's range safety officer had initiated a command to destroy the rocket, after a major, yet-unidentified failure occurred 15 seconds into the flight.

"Whenever a rocket either goes off course or appears to not be functioning properly, in the interest of public safety they'll destroy the rocket itself with an explosive charge," he said.

One line of inquiry will be the rocket's AJ-26 engines. They were refurbished Soviet-era power units originally developed to take cosmonauts to the moon in the late 1960s.

The rocket, launched from Wallops Flight Facility, was due to carry nearly 5,000lb (2,200kgs) of supplies to six astronauts aboard the International Space Station (ISS).

It included equipment for astronauts to conduct tests on blood flow to the human brain and to analyse meteors.

There was also equipment for experiments to examine the growth of pea shoots in orbit and how the body's immune system reacts to space travel.

More than 1,300lb (600kg) of food was on board, including pre-packaged meals and freeze-dried crab cakes.

The flight - expected to be the third contracted mission with Nasa - was initially planned for Monday but was delayed due to a yacht in the surrounding danger zone.

Meanwhile, the Russian Space Agency launched its own supply rocket to the ISS early on Wednesday. It arrived successfully six hours later with a reported three tonnes of food aboard.

Following the failed launch of Antares, Nasa's station programme manager Mike Suffredini told US media that all of the lost materials will be sent to the ISS at a later date. The six-person crew has enough supplies to last into next spring, he added.