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Moons of our Solar System
Moons of our Solar System

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3.2 Apollo 13

The third crewed mission that was intended to land on the Moon was Apollo 13, launched on 11 April 1970. While still on their way to the Moon, about 300 000 km from Earth and almost 56 hours into their mission, the crew heard an explosion coming from one of the oxygen tanks inside the service module. This prompted one of the most famous Apollo quotations, uttered by astronaut Jack Swigert: ‘Houston, we’ve had a problem here’.

The fuel cells which powered the spacecraft needed oxygen to combine with hydrogen to generate electricity and water; with the ruptured oxygen tank losing its contents to the vacuum of space, the main power supply to the command module soon ran out, leaving only the limited-supply back-up batteries to provide power. The crew were forced to shut down the main command module and instead rely on the lunar module, which was able to act like a lifeboat.

With the planned Moon landing now out of the question and the spacecraft rapidly approaching lunar orbit, the crew and mission controllers back on Earth faced a stark choice: either opt for a direct return to Earth, which would mean jettisoning the crew’s only source of life-supporting resources – the lunar module; or try to use the Moon’s gravity to ‘fling’ the damaged spacecraft back towards Earth. Although it would mean travelling further away from Earth first, passing behind the Moon, the latter option was chosen.

With dwindling oxygen supplies and reduced power, which left the inside of the spacecraft at a chilly 4 °C for the duration of the return flight, Apollo 13 limped back to Earth, safely splashing down in the Pacific Ocean on 17 April 1970.

As the crew had proved, returning to Earth could be a perilous experience.

View of Apollo 13 astronauts changing one of the modified LiOH cannisters.
Figure 15 View of Apollo 13 astronauts changing one of the modified LiOH cannisters.

See also: Apollo 13: Houston, We’ve Got a ProblemVideo player: 31347_4_20_nasa_documentary_govarchivesarc1155023.m4v

[Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] . This film depicts attempts to return the crewmen of the Apollo 13 mission safely to earth following an explosion onboard the service module. The film emphasises the Mission Control and spacecraft teamwork that overcame the life-or-death problems of Apollo 13, as well as the worldwide reaction to the crisis. Listen out for the famous quotation by Jack Swigert at 4:43 into the video. Warning: this video is 150mb in size. For this reason, we recommend that you access the link over a WiFi connection rather than a 3G or 4G connection, which could prove costly depending on your mobile data tariff.