I. Introduction: Is there a difference between the size of the crater and the ejecta blanket? This question could lead to many different discoveries. When you think about the thousands of craters on mars, every single one of them will be different than another. With each crater you have to consider how it was created (meteoroid impact, volcanic eruption, or gas explosion) and then consider how large each impact or explosion was. Studying the distance the ejecta was launched you could determine the force of the explosion or impact. From there you could even find the size of meteoroid. Hypothesis: The bigger the crater, the bigger the ejecta blanket; therefor, the smaller the crater, the smaller the ejecta blanket. II. Background: General Definitions: Crater- circular bowl shaped depression on a surface such as Earth or Mars. Ejecta matter thrown out of a crater by an erupting volcano or during meteorite impact. Ejecta Blanket- is a generally symmetrical apron of ejecta that surrounds a crater.
Craters have been changed or modified along with their ejecta blankets because of many different environmental factors due to the erosion caused by wind, water, and lava. A crater may have a smooth floor, partially filled with sediment or material. Other impacts may have a ridged floor due to the impact where the matter leaves bubbled out traces of the planetary crust. Middle-aged craters are usually known as modified because they have had more time to erode. These have an appearance that is noticeable due to their broken rims, but are not completely destroyed like older craters also called destroyed craters. We did not study destroyed craters due to the excessive erosion and their tendencies to be nearly completely filled with sediment, so we only researched preserved and modified craters. Craters are caused by meteor collision, or from volcanic magma, and gas explosions. On Earth most meteors burn up in the atmosphere as shooting stars, before they collide with the surface of our planet at the speed of sound. Notably on Earth there have only been one-hundred and sixty impact craters recognized due to the natural factors of the planet that strip away the evidence left behind of the crater. Frankly most craters are never detected due to these factors of rain, wind, lava, plants, and animals. There have only been about 160 terrestrial impact craters that have been recognized on Earth. Due to the factors that scrape away evidence of a crater, some are never detected. Impact craters give several typed of evidence about planets. They excavate and expose material. Their central peaks expose material originally about one-tenth of the crater diameter below the surface. For example, Pieter s (1982) found that the central peak of the lunar crater Copernicus has a spectrum not seen in other lunar areas, and he interpreted it as olivine-rich, up thrust material from a 10-k, deep crustal layer. A blanket of debris surrounding an impact crater is composed of material ejected from the crater during its formation, and is laid down with stratigraphy inverted from that of the bedrock typically a star-shaped distribution of ejecta around the crater rim. In addition to rock fragments excavated from the crater, and melted material, surface material from outside the crater may be incorporated by base surge erosion or excavated by secondary craters caused by large ejected blocks.
III. Experimental Design/Methods: We used the THEMIS camera system from the Mars Odyssey Spacecraft. Specifically the Visible Imagine System. Our focusing on craters and ejecta blankets was with the intention of determining if there is any relation in the size of each. All images that were explored were located within the -45 to 45 latitude. With 30 images we used JMARS and explored images. Aspects of the images that we documented were the following: image ID, latitude and longitude, type of crater. Measurements of the images that we documented were the following: recorded measurements diameter left to right of the crater, diameter top to bottom of the crater, area of the crater, area of the crater and ejecta blanket. Also we noted any additional information of special interest. IV. The Data: We used the themis image camera attached to the bottom of the Odyssey space craft orbiting around mars to view and even take our own picture of a location on mars. We found approximately thirty themis images that fit our criteria in order to gather information to format our research question. We used features that contained a crater and an ejecta blanket. Such as in themis image V2665027, V26717030, and some that did not have a themis idea number. We displayed our information in tables, charts, and graphs: Sample of a crater and ejecta blanket
IV. Analysis Plan Image ID (V# or I#) Lat. Long. Diameter Left to Right Diameter Top to Bottom Area of Ejecta Blanket & Crater Area of crater Type of Crater V2665027 43.4 359 1.17 1.10 9.286 0.94 Modified Additional Info of Interest None 2 359 4.05 3.76 6.02 1.1 Modified V26717030 0.341 119.3 1.16 1.17 2.17 1.118 Preserved None 9 358 2.34 2.21 5.59 1.83 Modified None 40.6 359 1.54 0.84 25.06 2.24 Modified Area of Crater vs. Area of Ejecta Blanket
Distance Across The Crater Left To Right vs. Top To Bottom Map showing location of Craters Analyzed http://mola.gsfc.nasa.gov/images/mercat_med.jpg Red marker is the targeted location
Types Of Craters V. Discussion: The table above shows how we recorded the information we gathered. We recorded the image ID, latitude, longitude, diameter left to right, diameter top to bottom, area of ejecta blanket & crater, area of crater, type of crater, and any additional information. This help us organize all the data we gathered. Each graph represents something different. The bar graph shows out of the craters we used how many were preserved and modified. The first scatter plot graph represents the area of the crater vs. the area of the ejecta blanket. This graph shows that the ejecta blanket always has a larger area then the crater. The second scatter plot graph shows the correlation of the diameter of the crater from top to bottom and left to right. This correlation shows that all of our craters and almost perfectly circular. The map above shows all the creators we looked at on JMARS. All the blue dots we marked on the map are craters with ejecta blankets that we recorded the data of. The one red dot on the map is the image we as a class selected to get a picture of which had never had a picture taken of before.
There could be errors in our number and the fact that craters are constantly being changed on mars by the natural effects such as: wind, lava, or other meteor impacts. We also rounded or numbers which could throw are values off some. VI. Conclusion: Our research question was to determine whether there is a relationship between the size of the crater and the size of the ejecta blanket. We concluded that there is a correlation between the size of the crater and its ejecta blanket. Our hypotheses is that the larger the crater the larger the ejecta blanket and the smaller the crater the smaller the ejecta blanket. According to our research we learned that the larger the area of our crater the larger the areas of the ejecta blanket likewise, the smaller the area of the crater the smaller the area of the ejecta blanket will be. So within our research we proved that our hypothesis was correct in the since that the ejecta blanket was approximately three times the size of the crater. We can expand on our project in that we can observe more craters, and we can also expand on the fact that depending on the surface of the area it can determine the size of not only the crater but also the ejecta blanket. We would like to acknowledge that if we did not have Dr. Buckner as a teacher we would have never heard of this project, and we would like to thank Ms. Jessica for helping us in this project from the start to finish.
VII. References http://seismo.berkeley.edu/~rallen/eps122/reading/hartmanndatingwithcraters.pdf http://news.discovery.com www.enchantedlearning.com/subjects/astronomy/meteor/ http://education.natioanlgeographic.com/education/encyclopedia/crater/ http://marsed.mars.asu.edu/files/msip_resources/mars%20image%20analysis%202012.pdf