LM abort modes

In the continuing spirit of NASA’s defence-in-depth philosophy, a series of PADs were read up to the crew that not only told them exactly when they were going to start their descent to the surface, but also what to do in the event of an abort being necessary at various times before, during and after the descent – in case the radio link were to fail and prevent the provision of the information at the time of the energency. As the programme progressed and planners made their procedures more elaborate, these PADs increased in complexity. All these PADs were based around a single event, powered descent initiation (PDI) which was the moment the main engine

was ignited to start to slow the spacecraft and take it out of orbit and on to the surface. Some PADs told the crew what to do if the landing was aborted before PDI, others were relevant if PDI did not occur. Yet more had details of the bums to make if an abort were required during the descent – one relevant to the first six minutes, the other relevant to an abort between six minutes and touchdown. All these PADs were copied down by the LMP onto forms in the checklist.

With all the preparations done, they were nearly ready to go to the Moon and pick up some rocks.