Orbital-3,[6][7] also known as Orb-3, was an attempted flight of Cygnus, an automated cargo spacecraft developed by United States–based company Orbital Sciences, on 28 October 2014.

In an Orbital Sciences tradition, this Cygnus spacecraft was named S.S. Deke Slayton after one of NASA's original Mercury Seven astronauts and Director of Flight Operations, who died in 1993.

The vehicle began falling back to the launch pad and the Range Safety Officer engaged its flight termination system just before impact.

[8][13] Initial review of telemetry data found no abnormalities in the pre-launch, the launch sequence, and the flight, until the time of the failure.

[10][17] Subsequent investigation found that the LOX turbopump had exploded, which in turn, caused a shock wave that severed surrounding propellant lines and started a fire from leaking fuel.

The fire damaged various components in the thrust section leading to the engines gradually being shut down, although a specific reason for the failure could not be determined.

The Cygnus cargo vehicle carried 2,215 kg (4,883 lb) of supplies and experiments meant for the International Space Station.

[19] After the accident they stated that this would not set them back due to their approach to space involving many satellites in various constellations.

Although NASA and Orbital Sciences agree that the turbopump failed, they differ as to the root cause (machining or debris).