Location
Cocoa Beach, Florida
Start Date
3-4-1967 12:00 AM
Description
For certain combinations of lighting and viewing conditions, the lunar landing site will be void of visible details because of the strong back scattering photometric properties of the lunar surface. This washout happens at zero phase angl e (i.e., the angle 9etween the source and the viewer). The effect has been observed from the earth and has been confirmed by Surveyor I pictures.
To demonstrate this effect, photographs of a scale model of a lunar surface dusted with copper oxide under various lighting and viewing angles were made. Copper oxide was chosen because its reflection properties are similar to those of a lunar surface. Each picture is identified on the CuO photometric function chart. Those pictures showing good terrain detail correspond to the high contrast region on the chart. It is shown that a substantial improvement of the astronaut's viewing conditions could be achieved with descent trajectories whose viewing angles are greater than the sun angles or trajectories in which the sun is off to one side.
The uncertainty of the lunar photometric function as compared to the photometric function of the model used for simulation is shown to be significant and the need for an accurate determination of a lunar photometric function is pointed out.
Lighting conditions for a Lunar Landing Mission
Cocoa Beach, Florida
For certain combinations of lighting and viewing conditions, the lunar landing site will be void of visible details because of the strong back scattering photometric properties of the lunar surface. This washout happens at zero phase angl e (i.e., the angle 9etween the source and the viewer). The effect has been observed from the earth and has been confirmed by Surveyor I pictures.
To demonstrate this effect, photographs of a scale model of a lunar surface dusted with copper oxide under various lighting and viewing angles were made. Copper oxide was chosen because its reflection properties are similar to those of a lunar surface. Each picture is identified on the CuO photometric function chart. Those pictures showing good terrain detail correspond to the high contrast region on the chart. It is shown that a substantial improvement of the astronaut's viewing conditions could be achieved with descent trajectories whose viewing angles are greater than the sun angles or trajectories in which the sun is off to one side.
The uncertainty of the lunar photometric function as compared to the photometric function of the model used for simulation is shown to be significant and the need for an accurate determination of a lunar photometric function is pointed out.
