MOST of us know the speed of light, but few of us ever consider the speed of time. Obvious it might be, but the speed of time is one second, per second. You can be forgiven though, for thinking otherwise, especially when considering that the penultimate voyage to land humans on the moon occurred 40 years ago!
Apollo 16 took off for the moon from the Kennedy Space Centre in Florida, fittingly, on April 16, 1972. Despite many of us being old enough to have been around when this flight to our nearest celestial neighbour was launched, it's a safe bet that most of us don't remember it. By the time we got to this, the fifth manned flight to land on the moon, it had all become a little humdrum, and most of us mainly remember the very first one. Only those with a profound interest in space flight or the Apollo Program would be able to tell you, that astronauts John Young and Charlie Duke descended to the surface in the Lunar Module called "Orion", whilst Ken Mattingly remained in lunar orbit and waited for their return to the Command Module named "Casper".
Young and Duke called the moon home for near enough to three days, or 71 hours if you want to be exact. They took with them a lunar rover for travel to remote sites for gathering samples. In pursuit of this they put 26.7 kilometres on the rover's odometer, meaning they went quite some distance from "Orion" on their field trips. At one point while travelling downhill, they set a speed record for the lunar buggy of 17.1 kmh! They carried with them oxygen tanks with enough capacity to last for nearly eight hours. In all they returned 95.8 kilograms of lunar samples.
The previous Apollo missions had in the main landed in areas of the moon that were "maria", or seas – the reasonably flat areas that we perceive as dark markings with the naked eye when we look at the moon from earth. These basalt plains were created by lava welling up from the lunar interior, possibly following large impacts, whilst a molten core still existed on the moon. In order to sample material that was older than this, it was imperative that Apollo 16 landed in the highlands and an area west of Mare Nectaris was selected. The material they brought back to earth was essential in gaining a complete understanding of lunar geology.