What space shuttle exploded on take off, on January 28, 1986, and which two female astronauts died on board?

On January 28, 1986, the nation watched in horror as the Space Shuttle Challenger broke apart just 73 seconds after liftoff. The disaster was ultimately traced to the failure of an O-ring seal in the right solid rocket booster. Unusually cold temperatures on launch day had compromised the seal, allowing hot, pressurized gas to escape and lead to a catastrophic structural failure that cost the lives of all seven crew members.

Among the crew were two remarkable women. Judith Resnik was an accomplished astronaut and engineer on her second spaceflight, having already become the second American woman to travel to space in 1984. She was joined by Christa McAuliffe, a high school social studies teacher from Concord, New Hampshire. McAuliffe had been selected from more than 11,000 applicants to be the first participant in the Teacher in Space Project.

McAuliffe's mission was to conduct lessons from orbit, and her presence brought immense public attention to the flight. Millions of Americans, including many schoolchildren, were watching the launch live. The tragedy became a defining moment for a generation and prompted a nearly three-year halt in the shuttle program while NASA underwent a significant overhaul of its safety protocols and management culture.