Locomotion – Lunar Surface Terrain
Section 5.5.5, Page X
The surface of the moon is over three billion years old. Over that time, asteroid and
meteor collisions left impact craters everywhere. The base of the lunar sea is mostly
rolling lunar regolith. There are not many large rocky formations like up in the highlands.
Lunar regolith is a very find and dry powder. The individual grains cannot be seen by a
human eye. The regolith has a small electric charge which causes it to stick to almost
anything it touches. The Apollo 12 astronauts found it all over the inside of their lander
and all over their suits and tools after external exploration. The adhesive dust might coat
the shell of the space ball however dust mitigation techniques to solve this problem are
discussed in section 5.5.1.
The craters on the moon range from millimeters in diameter to tens of meters in other
places. A comparison shown in figure 1 between the Apollo 12 crew and Lunar Orbiter 3
and 4 gives a nearly linear probability of finding craters of a given size over the moon’s
surface.Shoemaker At our landing site, there are four large craters bigger than 50 meters in
diameter. There will be a few craters greater than 4 meters in diameter however most of
the craters that the space balls encounter are between 0.02m to 4 m in diameter.
Fig, Section5.5.5.1: Probability of crater by diameter.
(Shoemaker)
Author: Cory Alban
Locomotion – Lunar Surface Terrain
Section 5.5.5, Page X
To avoid getting stuck in a crater, the lunar lander takes a 360 degree panorama after
touchdown and sends the pictures to mission control. From the panorama and existing
satellite maps we choose the best path of travel from the craft to avoid large craters.
Smaller craters are less hazardous. The speed of the space ball will be enough to carry the
ball over small craters without getting stuck.
Each crater impact sends bits of moon rock and debris across the surface of the moon.
Data collected from Apollo 11 and Apollo 12 missions as well as from the Surveyor 3
site shows a nearly linear probability of encountering debris objects as a function of the
debris size.Shoemaker The linear relationship is shown below in figure 2. The majority of
rocks the space ball encounters are of equal or smaller diameter as the ball itself.
Fig, Section5.5.5.2: Debri encounter probability
(Shoemaker)
In the event of a collision with a rock, the space ball is designed to withstand a full speed
impact with large objects. The space ball runs up and over any objects that are smaller
than the outer shell.
Author: Cory Alban