How Did Space Shuttle Challenger EXPLODE?

The Space Shuttle, designed to provide NASA with a cost-effective, reuseable service into space. As it enters its fifth year of service, not a single astronaut has been lost. But on a cold January morning, this perfect record will be shattered, and a shadow cast over every future launch.

On the 28th January 1986 at Cape Canaveral, Florida, USA, Space Shuttle Challenger is undergoing preparations for liftoff.
It will be the 25th mission of the programme, and the 10th flight of this specific Shuttle.
Introduced in 1981, the Space Shuttle programme was conceived as a successor to the large, costly, single-use rockets previously employed. The reuseable Shuttles promise to lower the cost of launching crews into space, allowing for frequent and reliable transportation of people and cargo to low Earth orbit.
Shuttle missions have been responsible for launching numerous satellites, probes, and even the Hubble Space Telescope.
The shuttle itself is comprised of the Orbiter Vehicle, which is a delta wing design, measuring 56 meters in length, with three rocket engines in the rear, which help power it during liftoff. It has a central payload bay for carrying its cargo, and located at the front is the cockpit, which typically houses a crew of 7 astronauts.
Attached to the orbiter, is a large orange external fuel tank, filled with liquid fuel for the Shuttle’s main engines. Once its fuel is expended, it is jettisoned, and breaks up in the atmosphere. This is the only part of the launch vehicle that is not re-used.
And attached to the external tank, are a pair of Solid Rocket Boosters, or SRBs for short. These provide the additional thrust needed to escape Earth’s atmosphere.
The SRBs provide the bulk of the thrust required during launch, and contain solid-fuel. They are composed of a nose cone, four main segments connected together at joints; in between these joints are o-rings which prevent the ignited fuel from escaping. Attached at the bottom are a rocket nozzle, connected to a solid-propellant-motor; one for each booster.
On landing, after re-entry, The orbiter vehicle will glide to the ground and land like a traditional aircraft.
This Shuttle, named “Challenger”, is the second oldest of the fleet, and the so-called “leader”, being the most used at the time.

This mission, named STS-51-L, will see Challenger and its crew perform a routine satellite deployment, as well as observe Halley’s Comet for 6 days.
But that’s not all; as this will also be the first “Teacher in Space Project” flight, where one of thousands of applicants has been chosen to be the first civilian to fly on a Space Shuttle mission. It was introduced to increase public interest in NASA and spaceflight, as well as help inspire younger generations to pursue careers in mathematics and science.
The teacher selected is Christa McAuliffe, and she will join the rest of the crew - Commander Francis Scobee, Pilot Michael Smith, Mission Specialist Ellison Onizuka, Mission Specialist Judith Resnik, Mission Specialist Ronald McNair, and Payload Specialist Gregory Jarvis.

The morning of the 26th of January had seen record-low temperatures for the area overnight, and the launch pad and shuttle are covered in ice. Despite being delayed for 2 hours to allow the ice to melt, this liftoff will be the coldest on record.
Adding to this, a nearby flight had that morning reported a strong crosswind over the launch site.

At 11:38am, Space Shuttle Challengers engines ignite, and the vehicle begins its climb towards space.
Thousands of onlookers spectate the awesome sight, including many in schools across the US, where classrooms allow the students to watch the launch live on TV.
Initially, while still in the thicker air closer to Earth, after initial liftoff, the throttle is rolled back to a lower setting of 65% due to the aerodynamic forces acting on the vehicle. If they go too fast at this stage, the stress will be too much to handle.
When they reach the suitable altitude where the air is thinner, creating less drag on the shuttle, the go-ahead from control to “go at throttle up” will be issued; this means it’s safe to increase throttle to the power required for the ship to achieve the velocity needed to escape Earth’s gravity.
Shortly before the command is given, Challenger is buffeted by a crosswind, rocking the shuttle back and forth for a few seconds; it is noticeable, but nothing the ship’s structure can’t handle. The Pilot comments to the Commander “Looks like we've got a lotta wind here today."
At 11:39 and 8 seconds, CAPCOM gives the go-ahead.
“Challenger, go at throttle up”