Almost exactly a year after STS-51-C, Space Shuttle "Challenger" was destroyed with all hands on board during the STS-51-L mission including Ellison Onizuka, a crew member on both flights. As part of the investigation into the disaster, it was reported to the Rogers Commission that during the launch of STS-51-C, the worst solid rocket booster (SRB) blow-by effects of any mission prior to STS-51-L occurred, indicating conclusively that the Viton O-rings were not sufficiently sealing the hot gases inside the combustion chambers of the SRBs while firing. After they were recovered post-flight, the O-rings in both the right and left SRBs showed some degree of charring, but analysis of the center field joint of the right SRB showed an unprecedented penetration of the primary O-ring and heavy charring on the secondary O-ring.