Space Shuttle Challenger disaster

The Challenger space shuttle disaster of January 28, 1986 was determined to be the cause of the O-ring seal failure.A key factor was the cold weather leading up to the launch.Caltech physics professor Richard Feynman demonstrated this on television by dropping a small O-ring into icy water and later demonstrating its lost flexibility in front of an investigating committee.

The material of the failed O-ring was specified by Morton-Thiokol, the contractor for the shuttle motors.When an O-ring cools below its glass transition temperature,Tg, it loses its elasticity and becomes brittle.What's more, when an O-ring cools close to (but not above) its Tg, the cold O-ring, once compressed, will take longer than normal to return to its original shape.O-rings (and all other seals) work by creating positive pressure against a surface, preventing leaks.On the night before the launch, extremely low air temperatures were recorded.Therefore, NASA technicians checked; the ambient temperature was within launch parameters and the launch sequence continued.However, the temperature of the rubber O-ring is still significantly lower than that of the surrounding air.While investigating the launch footage,Feynman observed a small deflation event of the solid rocket booster at the junction of the two sections in the moments before the disaster. This was due to a failed O-ring seal.The escaping hot gases hit the external fuel tank and the entire vehicle was destroyed as a result. 

After the accident, rubber manufacturers have made changes.Many O-rings are now batch and treat date coded, as is done in pharmaceutical production, to precisely track and control dispensing.For aerospace and military applications, o-rings are often individually packaged and marked with material, cure date, and batch information.O-rings can be recalled from shelves if needed.In addition O-rings and other seals are regularly tested for quality control batches by the manufacturer and often multiple times for quality assurance by distributors and end users.As for the boosters themselves, NASA and Morton-Thiokol redesigned them with a new joint design that now contains three O-rings instead of two, and the joint itself has an onboard heater for when the temperature drops to 50 Use below °F.The heater can be turned on (10°C). O-rings haven't had a problem since Challenger, and they played no role in the 2003 Columbia space shuttle disaster.

Future

O-rings are one of the simplest yet most critical precision mechanical components ever created.However, there is a new Advancements may alleviate some of the critical seals of O-rings.There is a cottage industry of elastomer consultants who help design O-ring-free pressure vessels.Nanotechnology rubber is one such new frontier.Currently, these advances have increased the importance of O-rings.Since O-rings involve the fields of chemistry and material science, any progress in nano-rubber will affect O-ring manufacturers.Elastomers are already available filled with nanocarbon and nanoPTFE and molded into O-rings for high performance applications.For example, carbon nanotubes are used in static dissipative applications, and nano-polytetrafluoroethylene is used in ultrapure semiconductor applications.The use of nano-PTFE in fluoroelastomers and perfluoroelastomers can improve wear resistance, reduce friction, reduce permeability, and can be used as a cleaning filler.The use of conductive carbon black or other fillers can exhibit the useful properties of conductive rubbers, namely protection against arcing, static sparking, and bulk charge buildup within the rubber that can cause it to behave like a capacitor (static dissipative).By dissipating these charges, these materials, including doped carbon black and rubber with metal-filled additives, reduce the risk of fire, which can be used in fuel lines.