NASA STEM ACTIVITY

IMPACT CRATERS

BACKGROUND

The Artemis 3 mission will land the first woman and 

next man on the southern pole of the Moon. Our 

orbiting platform, Gateway, will give us the opportunity 

to land in almost any location we choose using an 

ascent/descent vehicle that will be docked with the 

station. The location on the “bottom” of the Moon, 

along with the high rims of the craters, make it possible 

for there to be permanently shadowed regions that 

contain water and ice. Traveling to this region will help 

us identify areas rich in water and other resources, and 

how to best use those materials available to us on the 

lunar surface. 

CHALLENGE

In this activity, you will model and measure aspects 

that affect the appearance of impact craters. 

MATERIALS • Marbles or other objects such as steel shot, ball 

bearings, golf or wooden balls

• A high-walled pan. Pans should be plastic, 

aluminum or cardboard. Do not use glass. Pans 

should be at least 7.5 cm deep. Basic 10"x12" 

aluminum pans or plastic tubs work fine, but the 

larger the better. A larger pan may allow you to 

drop more marbles before having to resurface the 

target materials.

• Any dry powdery material that can look like the 

Moon's surface. It is important that the materials 

allow you to create different kinds of layers, and 

to use contrasting colors. 

• Ruler or measuring tape

• Digital or food scale

• Newspaper or other covering to protect floors 

(if inside)

LUNAR SURFACE MATERIALS

 All purpose flour: Reusable in this activity and 

can be preserved in a covered container. 

 Baking soda: Reusable in this activity, even if 

colored, by adding a clean layer of new white 

baking soda on top. Keeps indefinitely in a 

covered container. Baking soda mixed (1:1) with 

table salt also works.

 Corn meal: Reusable in this activity but probably 

not recyclable. Keeps only in freezer in an airtight 

container. 

 Sand and/or corn starch: Mixed (1:1), sand 

must be very dry. Keeps only in freezer in airtight 

container. 

 Dry tempera paint, powdered drink mix, cocoa 

powder, or glitter: Sift on top using screen or 

flour sifter. A contrasting color to the base 

materials gives striking results. 

National Aeronautics and

 Space Administration
PREPARING YOUR LUNAR TEST SURFACE 

Look at craters in pictures of the Moon or other planetary bodies. Brainstorm. 

How do you think craters were formed?

What do you think affected the appearance and size of the craters and ejecta? 

Crater images can be found in NASA’s searchable image catalog at: 

www.nasa.gov/multimedia/imagegallery/index.html

1. Spread newspapers under the pan(s) to catch spills or consider doing the 

activity outside. Replace the paper when you switch impactors. 

2. Fill the pan with your chosen material to about 2.5 cm and smooth the 

surface so it settles evenly.

3. Sprinkle a fine layer of a dark, contrasting material evenly until it 

completely covers the surface. 

4. Practice dropping the impactors before you record the data. It’s best to 

record data before trying to remove the impactor. 

CRATERING PROCESS

1. Measure the mass of each impactor. Record the mass on the data chart.

2. Drop impactor #1 from a height of 30 cm onto the prepared surface.

3. Measure the diameter and depth of the resulting crater.

4. Note the presence of ejecta (rays). Count the rays, measure and 

determine the average length of all the rays.

5. Record measurements and any other observations you have about the 

appearance of the crater on the data chart. Complete three trials and 

compute the average values.

6. Repeat steps 2 through 5 for impactor #1, increasing the drop heights to 

60 cm, 90 cm and 2 meters. Complete the data chart for these as well. 

7. Now repeat steps 1 through 6 for two more impactors. Use a separate 

data chart for each impactor.

8. Graph your results by creating two graphs. 

9. Graph #1: Average crater diameter vs. impactor height or velocity. 

10. Graph #2: Average ejecta (ray) length vs. impactor height or velocity. 

Tip: On the graphs you can use different symbols (e.g., dot, triangle, 

plus, etc.) for different impactors, to make your data easier to read.

2.5 cm base layer Thin contrasting 

layer
LEARNING ABOUT MOON CRATERS

The circular features so obvious on the Moon’s surface are impact craters formed when impactors smashed into the 

surface. The explosion and excavation of materials at the impacted site created piles of rock (called ejecta) around the 

circular hole as well as bright streaks of target material (called rays) thrown for great distances.

Two basic methods forming craters in nature are:

1) impact of a projectile on the surface and:

 2) Collapse of the top of a volcano creating a crater termed caldera. By studying all types of craters on Earth and by 

creating impact craters in experimental laboratories geologists concluded that the Moon's craters are impact in origin.

The factors affecting the appearance of impact craters and ejecta are the size and velocity of the impactor, and the 

geology of the target surface. By recording the number, size, and extent of erosion of craters, lunar geologists can 

determine the ages of different surface units on the Moon and can piece together the geologic history. This technique 

works because older surfaces are exposed to impacting meteorites for a longer period of time than are younger 

surfaces.

WHAT TO LOOK FOR

Typical characteristics of a lunar impact crater are labeled on this photograph of Aristarchus, 42 km in diameter, located 

West of Mare Imbrium.

Floor

Ejecta

Raised rim

Wall

Rays

Central uplifts

• Floor: Bowl shaped or flat, characteristically below 

surrounding ground level unless filled in with lava.

• Ejecta: Blanket of material surrounding the crater 

that was excavated during the impact event. 

Ejecta becomes thinner away from the crater.

• Raised rim: Rock thrown out of the crater 

and deposited as a ring-shaped pile of debris 

at the crater’s edge during the explosion and 

excavcation of an impact event.

• Walls:Characteristically steep and may have giant 

stairs called terraces.

• Rays: Bright streaks starting from a crater 

and extending away for great distances. See 

Copernicus crater for another example.

• Central uplifts: Mountains formed because of 

the huge increase and rapid decrease in pressure 

during the uplifts impact event. They occur 

only in the center of craters that are larger than 

40 km diameter. See Tycho crater for another 

example.

www.nasa.gov NP-2020-04-2885-HQ