At the time there was video footage of the explosion. Now, NASA has released a series of captivating photos of the event on the agency's Flickr stream. The images are strangely beautiful -- and it helps to know that no one was killed or hurt by the explosion, according to the NASA report (PDF) on the launch.
This shot shows the takeoff before anything went wrong.
According to the report, the explosion came about because a liquid oxygen turbopump (a pump driven by a turbine) in the main engine failed. The independent investigators who produced the report found that there was twisting in the pump that caused friction that created enough heat to cause ignition of the fuel.
Although the investigators couldn't figure out what caused the turbopump to fail, they offered three possible explanations.
The first is "inadequate design robustness" of the part, meaning that it is simply designed in such a way that it's susceptible to oxygen fires and failures.
The second is that foreign object debris (FOD) could have gotten into the engine and messed with the pump. But the report says that while titanium and silica were found in the engine after the crash, "there were not gross-levels of FOD present within the system."
The final possible reason for the part failure was "manufacturing or other workmanship defect," as the investigation did find "the presence of a defect on the turbine housing bearing bore that was not consistent with baseline design requirements." The report says that the defect got introduced during the machining of the part.
When it became clear that there was something wrong with the launch, NASA technicians instituted a destruct command to the Flight Termination System, which in effect blew up the rocket and its cargo to minimize the damage it would cause when it crashed to the ground.
The resupply mission was put together by space-gear manufacturer Orbital ATK and consisted of one of its Antares rockets along with its unmanned Cygnus spacecraft loaded with about 5,057 pounds (2,296 kilograms) of pressurized cargo. The launch was Orbital ATK's third cargo delivery mission to the ISS as part of a $1.6 billion contract with NASA.
Although this particular launch ended in disaster, NASA is still working with Orbital ATK on resupply missions to the ISS.
Two of the company's Cygnus space capsules will launch atop Atlas V rockets made by United Launch Alliance -- one on December 3 and another in March 2016, according to Space.com. That will be followed by another Cygnus/Antares pairing to launch out of NASA's Wallops Flight Facility on Wallops Island, Virginia, in May or June.