Challenger's Final Flight - The disaster, second by second

On Jan. 28, 1986 — 40 years ago Wednesday — America watched in horror as the nation’s first civilian space traveler and six NASA astronauts died in the explosion of the shuttle Challenger.

A Problem Unnoticed At Liftoff

Liftoff

Challenger lifts off from Cape Canaveral at 11:38 a.m. EST, two hours behind schedule. One of the issues NASA officials had dealt with was the weather: Temperatures at Cape Canaveral are so low that O-ring seals in the solid rocket boosters could fail, some engineers say.

0.7 Seconds

Puffs of black smoke — visible only by automatic launch cameras — indicate hot gasses are burning through an O-ring seal in Challenger’s right booster. Within seconds, the puffs disappear as the faulty O-ring manages to seal itself.

7.7 Seconds

Challenger clears the tower and begins to roll to place the orbiter below the fuel tank as the stack arcs over the Atlantic. This is normal.

19.0 Seconds

“Looks like we’ve got a lot of wind here today,” says pilot Michael Smith via the cockpit intercom. Commander Dick Scobee agrees.

27.0 Seconds

Challenger’s three main engines throttle down to 94% as the shuttle approaches maximum aerodynamic pressure. Smith notes via intercom that the shuttle has reached 10,000 feet and half the speed of sound.

35.4 Seconds

The three main engines throttle down to 65% as planned.

37.0 Seconds

Challenger passes through the first of several wind shears — extremely high winds — that jostle the shuttle and begin to work open the damaged booster joint.

51.9 Seconds

Onboard flight computers instruct Challenger’s main engines to throttle back up to 104% as planned.

14 Seconds That Bring Disaster

58.8 Seconds

A small plume of flame and smoke bursts through the side of the right side solid fuel booster’s 3/8th-inch-thick steel outer casing and quickly grows.

1 Minute, 0 Seconds

Data automatically radioed from Challenger to mission control shows the internal pressure in the right side booster dropping.

1 Minute, 4.7 Seconds

The escaping flame melts a hole in the external fuel tank. Liquid hydrogen in the tank begins feeding the growing fire. The main engine nozzles swivel, compensating for the increasingly unbalanced thrust and struggling to keep the shuttle on course.

1 Minute, 6.8 Seconds

Pressure in the shuttle’s external liquid hydrogen tank begins to drop, indicating a leak. Smith has a gauge but it’s unlikely he notices — the leak happened so suddenly and the fire is rapidly spreading.

1 Minute, 8.0 Seconds

Ground controllers haven’t yet spotted any anomalous readings. From his console at Mission Control in Houston, astronaut Dick Covey calls: “Challenger, (you are) go at throttle up,.” “Roger, go at throttle up,” Scobee replies, even as his spacecraft is breaking up.

1 Minute, 12.3 Seconds

The flame burns through the strut attaching the solid rocket booster to the external fuel tank. The booster swivels into and punctures the tank, releasing large amounts of liquid hydrogen propellant. The plume of fire, now quite large, rapidly grows into a fireball.

1 Minute, 13.0 Seconds

By this point, the main engine nozzles have started swinging rapidly enough for the crew to feel abnormal motion.

Liquid oxygen pressure falls in the turbopump inlets.

Apparently, Smith, the pilot, has found the gauge showing falling pressure.

His comment is caught on the cabin intercom recorder: “Uh oh.”

Stunned Silence in Mission Control

1 Minute, 13.2 Seconds

An explosion created by the broken fuel tank engulfs Challenger and the ship breaks apart. It’s traveling at just under twice the speed of sound, 8.7 miles above the Atlantic.

Several large pieces of the orbiter fly away intact, including the crew cabin. They arc upward until, gradually losing momentum, they begin to fall to Earth. The solid rocket boosters cork-screw through the sky.

1 Minute, 39 Seconds

Stunned mission controllers in Houston track the falling pieces of Challenger and to look for additional data to determine what happened.

1 Minute, 50 Seconds

The Air Force range safety controller sends a signal that destroys the errant solid fuel boosters.

1 Minute, 56 Seconds

Mission Control spokesman Steve Nesbitt in Houston announces over the public affairs circuit: “Flight controllers here are looking very carefully at the situation. Obviously, a major malfunction.”

3 Minutes, 25 Seconds

The first pieces of debris can be seen via tracking cameras, splashing into the Atlantic.

3 Minutes, 58 Seconds

Challenger’s crew compartment smashes into the Atlantic at 200 mph. It will later be found on the ocean floor, 100 feet below the surface.