This month marks the 53rd anniversary of the Apollo 13. Read on to learn all about this mission – what it set out to do, and what went wrong – in this extract from Night Sky Almanac 2023.
The ill-fated Apollo 13 mission was launched from the Kennedy Space Center in Florida on 11 April 1970. The intention was for the spacecraft to be placed into orbit around the Moon and for a landing to take place in the Fra Mauro region, believed to contain material displaced by the impact that created the Mare Imbrium. (The next flight, Apollo 14, did successfully land at the Fra Mauro region.) The three-man crew were James Lovell (Commander), John Swigert (Command Module Pilot), and Fred Haise (Lunar Module Pilot). Swigert was to remain in lunar orbit, while Lovell and Haise descended to the surface in the Lunar Module, to carry out their exploration and experiments there.
In the event, the spacecraft was approximately two-thirds of the way towards the Moon, when on April 14, a routine operation caused one of the two oxygen tanks on the Service Module to rupture, resulting in the loss of oxygen from both tanks. This led to the famous statement, initially from Swigert and then Lovell: ‘Houston, we’ve had a problem here ...’. The rupture led, not only to a loss of vital oxygen, but also to a loss of power from the Service Module’s fuel cells, which drew oxygen from the two tanks. The Command Module, where the astronauts would normally spend their time, lost power (normally supplied by the Service Module), and oxygen. The Service Module itself was seriously damaged, although the extent of the damage was not evident until the Service Module was jettisoned, shortly before re-entry into Earth’s atmosphere, and the crew were able to see and take photographs of the destruction.
The decision was taken to use the Lunar Module, which was fully supplied with oxygen and power, as a ‘lifeboat’, despite it being designed to support two men for two days, rather than three men for four days. The Lunar Module was dormant for most of the flight, so the decision was taken to ‘power up’ the Module. Because of the location of the mishap, it was not possible to perform the ‘direct abort’ path that had been planned for any earlier emergency. It would be necessary for the flight to make a loop around the Moon before heading back to Earth. To do so, changes had to be made to the control systems, so that the engine of the Lunar Module could make the necessary adjustments to the flight path to put the spacecraft on a return trajectory to Earth. These changes were successfully implemented.
Various modifications were made to the Lunar Module to enable it to support the three men for four days. The modifications were successful, despite the crew having to live under extremely uncomfortable conditions, with a lack of power, cold temperatures, high humidity and a shortage of drinking water.
One critical point was to adapt the carbon-dioxide scrubber system to remove excess carbon dioxide from the air. This used lithium hydroxide canisters. Although a certain (very small) percentage of carbon dioxide is required for efficient human respiration, an excess may lead to unconsciousness or even death. There were lithium hydroxide canisters in the Command Module, but they were of the wrong shape to fit the system in the Lunar Module. Luckily, an improvised solution was found, although this involved the use of plastic covers from flight manuals and other items, all held together with duct tape. Fortunately, the improvised solution worked, and carbon dioxide levels fell immediately.
The damaged Service Module was jettisoned, with the Lunar Module being undocked somewhat later, before atmospheric re-entry. The Command Module re-entered the atmosphere as planned, and splashed down in the South Pacific on April 17. The three crew members had been safely returned to Earth.
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