Lab09-Identifying Surface Features from Space_21S(1) (1)

National Aeronautics and Space Administration Lab 9: Identifying Surface Features from Space Objective This activity will help you understand how to identify features on the surface of our planet and other objects in our solar system. This task will be accomplished by observing images taken from space. The images of Earth you will observe in this activity are credited to astronauts from the International Space Station or Space Shuttle, using hand-held cameras. Identifying surface features using images from space requires making attentive observations, being descriptive, and using prior knowledge about Earth to determine what is being shown in the images. In addition, you will need to explain what processes were involved in creating the features. You will then apply that knowledge to identify features on the surface of Mars. Background Information NASA explores planetary bodies, including Earth, to better understand the solar system in which we live. Various types of spacecraft and scientific instruments are used to explore and gather data. Scientists use the data returned from these spacecraft to make observations which they record, analyze, and interpret. One technique or process of gathering data from a distance using spacecraft, or even aircraft, is called remote sensing. Remote sensing allows us to gather data of a location we might not be able to visit in person. One application of remote sensing is using images to identify geologic features on Earth and different planets. The first part of this activity allows you to explore and discover visible features in astronaut photography acquired from space. There is a database of over 900,000 images available for the public to view images from space, available at the Gateway to Astronaut Photography of Earth website, http://eol.jsc.nasa.gov ; the images in this activity are a small subset of that collection. The activity builds on your prior knowledge about Earth and takes you through a procedure wherein you can recognize visible features of Earth and associate those features with a geologic process that occurs on the Earth’s surface. Planetary scientists who make observations of geologic features on Earth need to have useful ways to describe those features. This becomes especially important as they compare geologic features on Earth to features being observed on other planets. Below is a list of characteristics scientists often use to describe geologic features in images based on their observations. Descriptor characteristics: 1. Size: Features can be described in terms of actual or relative size. For a detailed planetary comparison study, image scales and actual sizes of features becomes necessary. If the exact size of a feature is not known, relative or comparative sizes of features within the same image can be described. In this lesson we will focus on relative sizes. Useful descriptors: larger than, longer than, smaller than, shorter than, narrow, wide, thick, thin, tall, short, etc.

National Aeronautics and Space Administration 2. Shape: Features can be described in terms of geometric shape. Useful descriptors: roundish, oblong, square, etc. 3. Texture: Features can be described as having a certain texture. Useful descriptors: smooth, rough, jagged, scalloped, smeared, etc. 4. Position / orientation: Features can be described in terms of their location relative to other features in an image. Useful descriptors: on top of, next to, below, under, slanted, parallel, perpendicular, etc. In this lab activity, you’ll be observing features formed by four major processes that shape the surfaces of solid objects in the solar system: wind ( aeolian processes), water ( fluvial processes), volcanic activity, and impacts . Aeolian processes: features created by or associated with the effects of wind. A planetary body needs to have an atmosphere in order to have aeolian processes. • Sand dune: a mound of sand formed by windblown sand sized particles. There are different sand dune ‐ types or shapes such as barchan (crescent-shaped), longitudinal, and star. • Wind streak : a feature formed when wind blows sand or dust sized particles off the surface (erosional) or ‐ onto the surface (depositional). • Yardang: a sharp ridge or multiple ridges oriented in the same direction formed by sand sized particles ‐ eroding exposed rock. Fluvial processes: features created by or associated with flowing water. A planetary body needs to have a certain balance between atmospheric pressure and temperature in order to have water flow on the surface. • Channel: a feature often created by the flow of water. Can vary in size and shape depending on local geology and steepness of topography. In flatter areas they meander into a snake like shape. Can include ‐ the following features: smooth margins, meanders, oxbow lakes (created when a meander is cut off and forms a U shaped body of water), streamlined islands, levees, bars, and banks. ‐ • Valley / drainage network: a set of channels formed by water draining downslope creating a network of small channels or tributaries that merge to form progressively larger channels. These features most often have a branch-like appearance. • Delta: a feature formed by the deposition of sediment that builds up where the mouth of a river flows into another body of water, such as a lake or sea. Volcanic processes: features created by or associated with volcanic activity. A planetary body needs to have a hot interior in order to have active volcanic processes. • Volcano: a raised structure that includes an opening in the crust of a planet where hot molten rock (magma) and gases escape from below the surface. • Central vent or caldera: a circular depression generally at the top of a volcano where magma and gas escape to the surface. These terms are closely related. When a magma chamber is empty enough for the central vent to collapse it is referred to as a caldera. May be oblong in shape. • Volcanic deposits (lava flows, ash flows): as hot magma reaches the surface and flows out onto the surface, it is called a lava flow. Lava flows have jagged margins. Ash flows or plumes come from more explosive eruptions and include tephra (ash, cinders, or volcanic bombs) and gas released into the atmosphere and/or on the surface.

National Aeronautics and Space Administration Impact processes: features created by or associated with a meteorite striking the surface. The thickness of an atmosphere plays a role in the size and number of impactors that strike the surface. Planetary bodies with active geologic processes can cause impact craters to erode or get filled in. • Impact crater: a circular hole (depression) in the surface formed by the result of a meteorite striking the surface at a high velocity. • Note: Sometimes a central peak or uplift is visible in the center of an impact crater. This feature is an exposed set of uplifted rocks that show evidence of fracturing and shock that occurs during impact. Not all craters have this feature. Identification Criteria of Features on Earth You will now make observations of astronaut photographs of Earth. Your logged observations of these images will help you learn to identify specific features associated with different geologic processes (aeolian, impact, fluvial, and volcanic). The Earth Feature Cards you will examine include images grouped by process. As you make observations, think about how each feature is formed and be prepared to select and create identification criteria for each feature in the tables below. 1. Individually, make observations of the geologic features visible in the images on the feature chart. 2. In the tables below, type one X for each row to indicate which criterion best describe each geologic feature. 3. Add additional descriptions that can be used as other identification criteria for each feature if you wish (the “Other” criteria are optional). 4. Discuss your answers with your team members to make sure everyone has the same answers. Aeolian processes – features created by or associated with the effects of wind Identification criteria Sand dunes Wind streaks Yardangs Look like smears across the surface Have a ripple-like appearance Look “cut into” the surface forming criss-crossing or parallel lines Sand-sized particles closely grouped together on the surface in piles, lines, or C shapes Look like a series of grooves scratched into the surface Look like a faint mixture of light or dark smudges on the surface Other:

National Aeronautics and Space Administration Impact processes – features created by or associated with a meteorite striking the surface Identification criteria Impact crater Circular feature that sometimes has a raised rim and a smooth, flat floor Flat, roundish feature that looks eroded and is sometimes filled in or outlined by water Other: Fluvial processes – features created by or associated with the effects of water Identification criteria Channel Drainage network Delta Feature has a dendritic pattern similar to the vein-like pattern in a leaf Long, extended feature that curves or meanders through an area; sometimes has two or three smaller channels connected to it Long, winding feature that sometimes contains features such as U- shaped oxbow lakes, meander scars, or teardrop-shaped island(s) Has a fan-like or triangular shape Sometimes looks like a triangle or bird’s foot where sediment is built up and deposited Numerous small channels or tributaries that feed into larger channels or valley Other: Volcanic processes – features created by or associated with volcanic activity Identification criteria Volcano Central vent / caldera Lava flow Looks similar to an impact crater and is circular in shape An entire structure that includes a circular opening at the top and has flanks or sides An entire structure that may look raised and have a cone or done or steeple-like shape Channel-like flow or finger-y appearance with uneven edges Single or multiple circular depressions at the center or top of volcano Flow-like material that appears darker or lighter than the surrounding surface Other: