Apollo 13 Accident

If the oxygen tanks within Apollo 13's service module had been damaged earlier in the mission, the three astronauts would have been lost.

If the oxygen tanks within Apollo 13's service module had been damaged later in the mission, the three astronauts would have been lost.

As it happened ... the astronauts had about a 90% chance of being lost when the oxygen tanks were actually damaged.  Concentrated team work on the ground, and in space, made the 10% chance really count.

This image, from NASA, depicts the three parts of the Apollo 13 spacecraft:

• The Service Module - where the accident occurred;

• The Command Module - "Odyssey," Apollo 13's main space capsule; and

• The Lunar Lander - "Aquarius," which became Apollo 13's "life boat" (also, during various Apollo time periods, known as the "Lunar Module" and "Lunar Excursion Module," or LEM).

Because the astronauts had not-yet descended to the Moon, the Lunar Lander was still fully equipped with supplies.  When the Moon landing was aborted, the astronauts "moved into" Aquarius until it was time to return to Earth.

Typically, during an Apollo Moon Mission, the Lunar Module was jettisoned onto the Moon's surface.  With Apollo 13, however, Aquarius was released to burn-up in space. It had no ability to withstand the forces of re-entry.

For much of the return trip to Earth, the astronauts towed the service module so it could help to protect Odyssey's heat shield.  About four hours before Odyssey re-entered Earth's atmosphere, Apollo 13's crew disengaged the Service Module, setting it adrift. 

For the first time, Jim Lovell - Commander of Apollo 13 - was able to see the Service Module's damage.  He was stunned, telling Mission Control, in Houston:

There's one whole side of that spacecraft missing.

Click on the top image for a better view.