The morning of January 28, 1986 was particularly cold in the US. Icicles formed on the space shuttle launch pad, and people waiting for the launch were dressed in heavy coats and scarves - an unusual sight for tropical Florida.The pressure was on NASA to make the space shuttle fulfil its promise of being a space taxi - one of the goals NASA promised when it was first designed. The schedule for 1986 originally listed 12 flights. colombia had already flown its mission, after numerous delays and now Challenger waited on the launch pad, also delayed. The pressure was on to launch.Several engineers raised concerns over the low temperature at Kennedy Space Center and what effect it would have on the space shuttle, particularly the rubber O-rings in the SRBs. No one had tested the O-rings at such low temperatures. However management needed to get the mission underway, as soon as possible. The night before, the decision was made to go ahead with the launch.As the SRBs ignited, the hot gases inside immediately caused the O-rings to expand in the casing joints to prevent flame leaking out sideways. Because the rings were frozen, during this launch they took a fraction of a second longer to expand. One set of O-rings on the right hand SRB immediately burnt away, releasing a puff of black smoke immediately after lift-off.The join held, possibly due to burnt material blocking the exit of exhaust through the side. But as the shuttle passed through max-Q (maximum aerodynamic pressure), the 'material' was shaken out and flame leaked out the side of the SRB. The gap in the casing opened further, eventually causing the bottom of the booster to break free from the external tank. In an instant, the nose of the SRB punctured the external tank causing liquid hydrogen and liquid oxygen to burst out of their pressurised tanks and immediately ignite in a ball of flame.The force of the explosion blew away the SRBs, which continued to travel on an uncontrolled path. The orbiter broke into many sections and plummeted to the ocean, 16 kilometres below. Had the astronauts survived the explosion, it is unlikely they would have survived without oxygen or the impact of hitting the water.
Back row, left to right, Ellison S. Onizuka, Sharon Christa McAuliffe, Greg Jarvis, Judy Resnik.Front Row, left to right, Pilot Mike Smith, Commander Dick Scobee, Ron McNair.
