34 years ago, America watched the space shuttle Challenger explode killing everyone on board

Tuesday marked the 34th anniversary of one of the deadliest space disasters in NASA history. January 28, 1986—a day meant to be a historic victory for America turned into a tragedy of unfathomable proportions when the space shuttle Challenger broke apart moments after launch, killing all 7 crew members on board. The launch and subsequent explosion were watched live by students across the nation via the special satellite broadcast NASA had set up for schools, unwittingly making them witnesses to the space agency's first in-flight fatalities.

According to CNN, it was later determined that the tragedy was caused by dangerously cold temperatures that morning combined with a design flaw. The external fuel tank collapsed due to a leak in the shuttle's right solid rocket booster joint, releasing liquid hydrogen and liquid oxygen propellants. This gave way to a giant fireball, causing what looked like a giant explosion that tore the Challenger apart. The shuttle broke apart 73 seconds after launch at approximately 11:40 am ET on that fateful day, falling approximately 46,000 feet to the Atlantic Ocean. 

The Challenger disaster grounded NASA's space shuttle program for nearly three years. According to Robert Cabana, former NASA astronaut, and director of the Kennedy Space Center, it also prompted the space agency to change its culture after learning that engineers had raised concerns about the launch the night before. Allan McDonald, director of the Space Shuttle Solid Rocket Motor Project for the engineering contractor Morton Thiokol, reportedly refused to a launch recommendation for the Challenger over safety concerns as he suspected that below-freezing temperatures might impact the integrity of the solid rockets' O-rings.

Among the seven brave men and women killed in the explosion was Christa McAuliffe, a high-school teacher from New Hampshire. She'd been selected for the mission as part of the Teachers in Space program and was set to be the first civilian and teacher in space. Taking to Twitter on the occasion of the 34th anniversary of the disastrous Challenger launch on Tuesday, New Hampshire Sen. Jeanne Shaheen commemorated the life of McAuliffe. 34 years later, the loss of Christa McAuliffe and the crew of Space Shuttle Challenger continues to be felt across the country. Christa was a trailblazer who sought to educate and enlighten her students and those across the nation, she tweeted.

McAuliffe joined commander Francis R. Scobee; pilot Michael J. Smith; payload specialist Gregory Jarvis; and mission specialists Ronald McNair, Ellison Onizuka, and Judith Resnik to make up the crew of Mission STS-51L. Addressing the nation from the Oval Office the evening of the failed launch, President Ronald Reagan said, "Ladies and gentlemen, I'd planned to speak to you tonight to report on the state of the Union, but the events of earlier today have led me to change those plans. Today is a day for mourning and remembering. Nancy and I are pained to the core by the tragedy of the shuttle Challenger. We know we share this pain with all of the people of our country. This is truly a national loss."

"We mourn seven heroes: Michael Smith, Dick Scobee, Judith Resnik, Ronald McNair, Ellison Onizuka, Gregory Jarvis, and Christa McAuliffe. We mourn their loss as a nation together. For the families of the seven, we cannot bear, as you do, the full impact of this tragedy. But we feel the loss, and we're thinking about you so very much. Your loved ones were daring and brave, and they had that special grace, that special spirit that says, 'Give me a challenge and I'll meet it with joy.' They had a hunger to explore the universe and discover its truths. They wished to serve, and they did. They served all of us," Reagan continued.

Speaking directly to the nation's children, he said, "I know it is hard to understand, but sometimes painful things like this happen. It's all part of the process of exploration and discovery. It's all part of taking a chance and expanding man's horizons. The future doesn't belong to the fainthearted; it belongs to the brave. The Challenger crew was pulling us into the future, and we'll continue to follow them." To honor the fallen crew, their families and friends came together to establish the Challenger Center with the aim of helping children learn about science and space. "That's really the legacy I think of Challenger -- that mission, that focus on outreach and education," former astronaut Capt. Kenneth S. Reightler remarked. "I think (the Challenger crew members) would be very, very proud."