Name: _____________________________________________ Period: _______ Date: ______________ Impact Craters Lab Goal: To find a relationship between a projectile and the crater it leaves behind. Background Many of the features we see gracing the Moon’s surface are ‘impact craters’ formed when impactors smashed into the lunar surface. The resulting explosion and excavation of material at the impacted site creates piles of rock (called ejecta) around the circular hole as well as bright streaks of target material (called rays) thrown for great distances. Two common methods of craters formation 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. 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. Impact craters are not unique to the Moon. They are found on all the terrestrial planets (Mercury, Venus, Earth and Mars) and on many moons of the outer planets. On Earth, impact craters are not as easily recognized because of weathering and erosion. Famous impact craters on Earth are Meteor Crater in Arizona, U.S.A.; Manicouagan in Quebec, Canada; Sudbury in Ontario, Canada; Ries Crater in Germany, and Chicxulub on the Yucatan coast in Mexico. Characteristics of Impact Craters Typical characteristics of an impact crater are: Floor: bowl shaped or flat, characteristically below surrounding ground level unless filled in with lava. Ejecta rays: blanket of material surrounding the crater that was excavated during the impact event. Ejecta becomes thinner away from the crater. Bright streaks starting from a crater and extending away for great distances. See Copernicus crater for another example. 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 excavation of an impact event. Walls: characteristically steep and may have giant stairs called terraces. Central uplifts: mountains formed because of the huge increase and rapid decrease in pressure during the impact event. They occur only in the center of craters that are larger than 40 km diameter. Name: _____________________________________________ Period: _______ Date: ______________ Materials: □ □ □ □ □ □ □ 1 tray of sand 1 15cm Ruler 1 golf ball 1 Baseball 1 tennis ball 1 softball 1 marble □ □ □ Safety goggles are required for this lab, sand in eyes can cut/damage your eyes. Clean up any spills immediately, sand on tile is slick and a tripping hazard Use all tools the way they are meant to be used Safety: Question: How does the size, density and composition of a projectile affect the size of crater upon impact? Hypothesis: _________________________________________________________________________________________ _________________________________________________________________________________________ _________________________________________________________________________________________ Procedure: 1. Measure the diameter(cm) and mass(g) of each projectile. Calculate the circumference and density of each object. Item Marble Ping pong Ball Golf Ball Tennis Ball Baseball 2.1cm3 33.51cm3 40.76cm3 146.46cm3 230.08cm3 Diameter in cm Circumference in cm C = 3.14 * Diameter Mass in grams Volume Density Mass ÷ Volume 2. 3. 4. 5. Stand on the table, hold the projectile over the tray of sand on the floor. Drop it. Do not throw it. Carefully remove the projectile and measure and record the Diameter of the crater(cm) left behind. Use the ruler to smooth over the sand. Repeat the test 3 times for each object, record all data on your data sheet Name: _____________________________________________ Period: _______ Date: ______________ Data Sheet: Impact Craters Lab Projectile and Crater Data: Crater Diameter (cm) Projectiles Drop 1 Marble Drop 2 Drop 3 Drop 1 Ping Pong Ball Drop 2 Drop 3 Golf Ball Drop 1 Drop 2 Drop 3 Drop 1 Baseball Drop 2 Drop 3 Drop 1 Tennis Ball Drop 2 Drop 3 Average Crater Diameter (cm) Name: _____________________________________________ Period: _______ Date: ______________ Plot your Data: Projectile Circumference vs Crater Diameter Use the graph below to plot your projectile circumference (y axis) versus average crater circumference (x axis) Name: _____________________________________________ Period: _______ Date: ______________ Plot your Data: Projectile Mass vs Crater Diameter Use the graph below to plot your projectile density (y axis) versus average crater circumference (x axis) Name: _____________________________________________ Period: _______ Date: ______________ Conclusion: 1. What conclusions can you make about projectile size and crater size? Refer to the graph you made. 2. What conclusions can you make about projectile mass and crater size? Refer to the graph you made. 3. Was your hypothesis correct or not? Explain. 4. What experiments or tests would you like to run next to learn more?