Category

Determining Lunar Surface Properties from Craters

Introduction

By studying the topography of craters, try to determine how they were formed

　The surface of the Moon and many planetary satellites are covered with a large number of impact craters. These features were produced the impact of small celestial bodies such as meteorites.
In this experiment, images of craters on the lunar surface acquired from Apollo missions are analyzed to determine crater topography.
　Analysis of photographs allows a more detailed determination of crater topography to be made than by simply observing the Moon's surface through a telescope. By studying these images it is possible to determine the relative ages of different surface features.

Experimental Method

Things to Prepare

　Writing materials; tracing paper; printouts of the Apollo images of the lunar surface below (click on an image to view a full-size version)

The upper three images are of a valley in the Mare Crisium
	Apollo17-M0286	Apollp17-M0289	Apollo16-M0293
The lower left and centre images show lava features in the Oceanus Procellarum, and the lower right image displays Aiken crater on the Moon's far side.
Apollo17-M0293	Apollo16-M2837	Apollo17-M0286

Tracing Surface Features

　Copy some of the surface features from the photographs using tracing paper.
　Determining how these features were formed will require a lot of thought.

Experimental Results

NASA National Space Science Data Centre
Apollo17-M0286 Metric Photography
Image processing by Satoshi Nomati, teacher at Kakuda High School, Miyagi Prefecture

Craters identified in the image were outlined in pink on the tracing paper.

Discussion

Which Crater is Older?

　By examining the topography of the two craters shown on the right, determine which was formed first.　
　Where the craters overlap, can you see which one was formed on top of the other?
　Trace their outlines with pink and blue to determine which is the older crater.

NASA National Space Science Data Centre　Apollo17-M0293 Metric Photography
Image processing by Satoshi Nomati, teacher at Kakuda High School, Miyagi Prefecture

The Blue Crater is Younger

　It is easy to show this if you try drawing the pink and blue craters yourself.

If we assume that the pink crater is older...		If we assume that the blue crater is older...
１．The pink crater forms first		１．The pink crater forms first
２．Then the blue crater forms on top		２．Then the pink crater forms on top
３．The blue crater obliterates part of the rim of the pink crater		３．The pink crater obliterates part of the rim of the blue crater

　The way in which craters are formed on top of each other helps us learn about the cratering process.
　Studies of overlapping craters allow us to determine their relative ages.