The first fatal accident in the history of U.S. space flight occurred on January 27, 1967, during preparations for the first manned mission of the Apollo space program. A flash fire broke out in the command module of Apollo 204 during a simulated launch at Cape Canaveral Air Force Station in Florida, killing astronauts Virgil “Gus” Grissom, Edward White and Roger Chaffee of asphyxiation. A stray spark started the fire in the pure oxygen environment inside the module, and design flaws in the hatch door made it impossible to open in time to save the astronauts. In the aftermath of the accident, NASA officially designated the mission as Apollo 1.

Just three months after the Apollo 1 fire, Russian cosmonaut Vladimir Komarov became the first fatality in space flight when Soyuz 1, the first Soviet space vehicle aimed at eventually reaching the moon, crashed into Earth on April 24, 1967. Soyuz 1 was still in the experimental stage at the time of the mission, and problems began almost immediately after it entered orbit, some nine minutes after launch. One of the solar panels failed to deploy, which cut the power supply and interfered with the spacecraft’s controls. The mission was aborted, but after a difficult reentry into Earth’s atmosphere, the Soyuz 1 parachutes failed to deploy correctly, and Komarov was unable to escape before the spacecraft crashed violently to the ground in southeastern Russia.

Eager to outstrip their counterparts in the U.S. space program after the success of the moon landings, the Russians launched the world’s first space station, Salyut-1, in April 1971. That June, three cosmonauts aboard Soyuz 11 spent three weeks conducting experiments and observations at the space station, earning hero status back at home. Upon their return trip on June 30, the spacecraft made a normal reentry and a perfect (automatic) landing. But when the ground team opened the hatch, they found all three cosmonauts unresponsive. A faulty air vent had opened when the orbital and descent modules of Soyuz 11 separated, and the cabin had depressurized; the cosmonauts, none of whom were wearing space suits, likely suffocated to death 30 minutes before landing. As a legacy of the Soyuz 11 disaster, the Soviet and U.S. space programs would pass requirements ensuring their cosmonauts and astronauts wear space suits during any phases of a mission where depressurization could possibly occur.

On the bitterly cold morning of January 28, 1986, the space shuttle Challenger broke apart 73 seconds after its launch from Cape Canaveral, crashing into the Atlantic Ocean from an altitude of some 50,000 feet. All seven astronauts aboard were killed including Christa McAuliffe, a high school teacher who had been selected as part of a national “Teacher in Space” initiative. An investigation later found that NASA had known that extreme cold temperatures could result in damage to the spacecraft’s rubber O-rings—which separated its rocket boosters and prevented fuel leaks—but elected to go ahead with the launch anyway, prompting widespread outrage and the temporary suspension of the space shuttle program.

After a 16-day mission, the veteran space shuttle Columbia (which made the shuttle program’s first flight in 1981) was reentering the Earth’s atmosphere ahead of a planned landing at Cape Canaveral when tragedy struck: The shuttle’s orbiter broke into pieces, raining debris over eastern Texas and killing all seven astronauts aboard. A small piece of insulating foam had broken loose from a fuel tank during launch and pierced Columbia’s left wing, but because the foam had detached during earlier shuttle launches without incident, NASA officials didn’t think it was a problem. Upon reentry, however, hot gases and smoke penetrated the damaged wing, causing it to break off and the rest of the shuttle to disintegrate. The Columbia disaster marked the beginning of the end of the U.S. space shuttle program; NASA would retire its last space shuttle in 2011.