It was on June 28th that a SpaceX Falcon-9 rocket exploded seconds after lift-off from Cape Canaveral. A preliminary investigation, overseen by the Federal Aviation Authority, NASA and the US Air Force, into the loss has determined that a broken metal strut was the probable cause.
CEO Elon Musk, at a press briefing in California on July 20th, told journalists that 3000 channels of second-by-second telemetry had been examined, as well as recovered debris and video evidence.
Musk said that SpaceX had examined thousands of these struts and found a few which failed at much lower forces than expected, and that there were faults with the grain structure of some of the struts.
“Preliminary analysis suggests the overpressure event in the upper stage liquid oxygen tank was initiated by a flawed piece of support hardware (a “strut”) inside the second stage,” said the official SpaceX statement. “Several hundred struts fly on every Falcon 9 vehicle, with a cumulative flight history of several thousand. The strut that we believe failed was designed and material certified to handle 10,000 lbs of force, but failed at 2,000 lbs, a five-fold difference. Detailed close-out photos of stage construction show no visible flaws or damage of any kind.”
“Despite the fact that these struts have been used on all previous Falcon 9 flights and are certified to withstand well beyond the expected loads during flight, SpaceX will no longer use these particular struts for flight applications. In addition, SpaceX will implement additional hardware quality audits throughout the vehicle to further ensure all parts received perform as expected per their certification documentation.”
SpaceX stressed that these conclusions are preliminary. “Our investigation is ongoing until we exonerate all other aspects of the vehicle, but at this time, we expect to return to flight this [autumn] and fly all the customers we intended to fly in 2015 by end of year.”
The next official launch is a satellite for the USA’s National Oceanic & Atmospheric Administration, and was slated for August 9th. This is now delayed to at least September, and the consequential ‘knock-on’ will further delay key commercial clients such as SES, who will lose revenues from such delays. Musk told journalists that he had spoken to each of his customers last week. SES might well update the market when they release their quarterly results on July 24th.