A cloud of fire engulfed the space shuttle just 73 seconds after liftoff, at an altitude of some 46,000 feet (14,000 meters). It looked like an explosion, the media called it an explosion and even NASA officials mistakenly described it that way initially. But later investigation showed that in fact, there was no detonation or explosion in the way we commonly understand the concept.

A seal in the shuttle’s right solid-fuel rocket booster designed to prevent leaks during liftoff weakened in the frigid temperatures and failed, and hot gas began pouring through the leak. The fuel tank itself collapsed and tore apart, and the resulting flood of liquid oxygen and hydrogen created the huge fireball believed by many to be an explosion.

A seal in the shuttle’s right solid-fuel rocket booster designed to prevent leaks from the fuel tank during liftoff weakened in the frigid temperatures and failed, and hot gas began pouring through the leak. The fuel tank itself collapsed and tore apart, and the resulting flood of liquid oxygen and hydrogen created the huge fireball believed by many to be an explosion.

After the collapse of its fuel tank, the Challenger itself remained momentarily intact and actually continued moving upwards. Without its fuel tank and boosters beneath it, however, powerful aerodynamic forces soon pulled the orbiter apart. The pieces—including the crew cabin—reached an altitude of some 65,000 feet before falling out of the sky into the Atlantic Ocean below.

It’s likely that the Challenger’s crew survived the initial breakup of the shuttle but lost consciousness due to loss of cabin pressure and probably died due to oxygen deficiency pretty quickly. But the cabin hit the water’s surface (at more than 200 mph) a full 2 minutes and 45 seconds after the shuttle broke apart, and it’s unknown whether any of the crew could have regained consciousness in the final few seconds of the fall.

Though popular wisdom about the 30-year-old tragedy holds that millions of people watched the Challenger’s horrific fate unfold live on television—in addition to the hundreds watching on the ground—the fact is that most people watched taped replays of the actual event.

All major networks carrying the launch cut away when the shuttle broke apart, and the tragedy occurred at a time (11:39 a.m. Eastern Time on a Tuesday) when most people were in school or at work. CNN broadcast the launch in its entirety, but cable news was a relatively new phenomenon at the time, and even fewer people had satellite dishes.

Though the general public may not have been watching live, NASA had arranged a satellite broadcast onto TV sets in many schools because of McAuliffe’s role in the mission, and many of the schoolchildren who watched remember the disaster as a pivotal moment in their childhoods.

NASA officials apparently felt intense pressure to push the Challenger’s mission forward after repeated delays, partially due to difficulties getting the previous shuttle, Columbia, back on the ground. But the rumors that pressure was exerted from above, specifically from the Reagan White House, in order to connect the shuttle or its astronauts directly in some way with the State of the Union seem to have been politically motivated and not based on any direct evidence.

In the aftermath of the tragedy, Reagan postponed his annual message to the nation (the first, and so far only, time in history a president has done so) and addressed the nation about the Challenger instead. Widely regarded as one of the best speeches of his presidency, the 650-word address ended with a moving quote from the poem “High Flight,” by the American pilot John McGee Jr., who was killed while flying for the Royal Canadian Air Force in World War II.

Of the Challenger astronauts, Reagan said: “We will never forget them, nor the last time we saw them, this morning, as they prepared for their journey and waved goodbye and ‘slipped the surly bonds of earth’ to ‘touch the face of God.’”

Within a day of the shuttle tragedy, salvage operations recovered hundreds of pounds of metal from the Challenger. In March 1986, the remains of the astronauts were found in the debris of the crew cabin. Though all of the important pieces of the shuttle were retrieved by the time NASA closed its Challenger investigation in 1986, most of the spacecraft remained in the Atlantic Ocean.

A decade later, memories of the disaster resurfaced when two large pieces of the Challenger washed up in the surf at Cocoa Beach, 20 miles south of the Kennedy Space Center at Cape Canaveral. NASA believed the two barnacle-encrusted fragments, one measuring more than 6 feet wide and 13 feet long, were originally connected, and that they came from the shuttle’s left wing flap.

After being verified, the newly found parts were placed in two abandoned missile silos with the other shuttle remains, which number around 5,000 pieces and weigh in at some 250,000 pounds.