6.5 Were the astronauts lifted by wires when they fell?

IN A NUTSHELL: No. The astronauts do appear to get back up with incredible ease when they fall, as if they were assisted by invisible wires, but this ease is due to the fact that the astronauts on the Moon weighed less than 30 kilograms (66 pounds), and their movements seem odd because their heavy spacesuit and backpack displaced their center of gravity considerably upwards and backwards.

THE DETAILS: On the Moon, the Apollo astronauts weighed one sixth of their Earth weight due to the lower lunar gravity. Their backpack and spacesuit weighed a total of approximately 81 kilograms (180 pounds) on Earth, which became a mere 13.5 kilograms (30 pounds) on the Moon. Their body weight was likewise reduced.

In other words, on the Moon a fully suited astronaut weighed a total of about 30 kilograms (66 pounds). Getting up after a fall, therefore, was trivial in terms of effort. Doing it without toppling over again, however, was challenging.

The way the astronauts regained their footing looks unusual because in addition to being in one-sixth gravity they were carrying a backpack (known as PLSS) which was quite heavy in proportion to their body weight (more precisely, its mass was considerable if compared to the mass of their body). Their PLSS weighed 26 kilograms (57 pounds) on Earth and 4.3 kilograms (9.5 pounds) on the Moon – one third of their body weight – and therefore displaced their center of gravity upwards and backwards. That’s why they were always leaning forwards: to compensate for the heavy load on their backs.

Figure 6-15. An astronaut picks himself up by pushing with this arms after falling forwards.


Moreover, the wire theory fails because the Apollo TV footage includes unbroken sequences that last tens of minutes, during which the astronauts change direction and position repeatedly. How would the wires not get tangled up? There's also the problem that the TV coverage includes many wide shots, which would require extremely long wires to keep the control rig and winch out of frame.