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Looking for Young Features on Europa
an image analysis simulation

Teachers, your students can study the most recent pictures of Europa taken by the Galileo spacecraft. Using a Color Macintosh or Mac clone, free software, lesson, and images, your students will simulate the scientific adventure of peering at new worlds. Learners will simulate the work of project scientists, investigating geological features of the Jovian moon Europa. Science students will evaluate one image to determine the relative geological age of discreet features in one region of Europa. This qualitative analysis will lead student investigators to experience science using scientific tools.

Note for Windows 3.1 and Windows 95 users- Scion Corporation is making NIH Image work on Wintel Computers. The program is called Image PC. Recently out of alpha and into beta version 1 testing, it is available at http://www.scioncorp.com.

PC users be aware of the following 3 facts:

  1. This lesson was created and tested on Macs.
  2. All beta software is buggy and may cause your machine to crash. Tracking and reporting your crashes to Scion will improve the product.
  3. Let me know if you successfully used this lesson on a Wintel computer.

Scott Coletti (scolett@quest.arc.nasa.gov)
Creator of this activity

Table of Contents

How to Download the Lesson Package

Setting up the Mac Desktop for a Quick Start

Why Image Analysis in Education

Summary of Digital Imaging

Lesson Brief

Lesson Plan

Learner Handout (4 pages)



Before downloading this TIFF lesson image make sure to download the application (NIH Image). Once you have installed NIH Image in your computer, set Netscape to use NIH image to view TIFF files. You set Netscape to use NIH Image by doing the following:

  1. Go to Options in the command line.
  2. Select the menu item General Preferences in Options Menu.
  3. Select Helper card and scroll down until you can select the extension "TIFF".
  4. Click the browse button until you find the application NIH Image in your computer. Select NIH Image in the dialog box, set the file type to "TIFF" and click apply.
  5. Make sure to select Launch application or save file from the action options in the Netscape dialog box, depending on how much memory you have.

The Lesson Image-Image Title: Prominent Doublet Ridges on Europa

The Anticipatory Set Image-Planetary image of Europa in natural and false color


When I introduce a new lab to my students, I often use the Mac alias capability for ease of use.

To create Aliases of any file take the following steps:

  1. Click one time on any file to select.
  2. Go to the word File in the Command line.
  3. Go to the menu Item in File called Make Alias. and let go)

In this lesson I created an alias of both the Full Europa/PICT and the Doublet/TIFF/grid/amber/9.x images. I drag those 2 Aliases to the bottom of the Desktop. I have kids double click on the Alias of the image for the anticipatory set. The Mac automatically launches ClarisWorks and loads the image to the screen. When done with the anticipatory set the kids just quit ClarisWorks and double click the lesson image Alias to automatically launch NIH Image.


Remember the old Chinese proverb...something about hearing and forgetting, seeing and learning, doing and remembering? Well, Image Analysis in Education covers two of the three...the two that count the most.

The comical retort "Do I need to draw you a picture?" is an appropriate example of a natural tendency of our species to be primarily visual. We start in kindergarten with the calendar: day, date, and pictures of brown leaves decorating October. Hey, it works, so we do it.

Who of us involved in teaching has not struggled to make difficult concepts simple and easy to understand. And who, involved in this struggle has not turned time and again to visualizing information as an obvious solution: a solution that offers a way to see the unseen. This seeing the unseen is a fundamental tenet of Imaging in education.

The primary grades are full of visual information conveyances: big books, flash cards, multiplication tables and this-is-the-way-to-throw-the-ball, junior; in the middle school years: the skeleton in the lab closet, the Mercator effect, atoms (when will it be gluons?), stars and planetary mobiles, cell models, and catapult contests so students can see Newton's law at work. It is no secret to great teaching that to see an object does wonders for the transfer of ideas.

The concept of visualizing information is not new to teachers. This is the point I want to hammer home: visualizing information is a normal way for the species to go about the business of discovery.

Imaging in Education, the subject I am introducing, simply adds to the teachers tool box the capabilities of the computer to manipulate images in the service of understanding. This image manipulation makes invisible information visible.


Computers can only see what they see as numbers and computer images are no more than a string of numbers. Those numbers control what the computer displays on a screen. The numerically-controlled computer shoots electrons at the back of the screen where several colors of phosphor are painted. The phosphor gets excited by the electrons and in the excitement becomes luminous. If it is a red phosphor, it glows red; green glows green; and blue, blue. Through various technologies, these three dots of color together can be seen as any color of the rainbow. Each dot has a fancy computer name. The dots are called Pixels. Pixel stands for Picture Element. Most computers can send at least 256 colors to each dot (pixel) on the screen. It is the manipulation of these dots that we call digital imaging. In fact the free program used to analyze this lessons image acts on the pixels on the computer screen.

Let me introduce you to this free software that works on the Apple Macintosh computer,called NIH Image. It does one job brilliantly. Its mission in life is to help humans analyze pixels, one at a time, a group of 9, or an array of 300,000. It slices; it dices. It can graph, plot, measure, and create data sets (which you can export to your favorite spreadsheet for graphing, by the way). Among other functions, NIH Image can magnify the image, edit, enhance, apply a new coat of colors and teach an old dog new tricks.



In this lesson I will introduce you to 4 tools in the NIH Image programs tool box. The tools are:

Grabber Hand
Magnifying Glass
Color Tables
Look Up Table Tool


The image used in this lesson is indeed beautiful. Much has been and is being discovered by analyzing the original data of this image. The copy we work with clearly shows various features and their local relationships. Using image analysis allows students to make qualitative observations. (for the technically minded this image is provided in a TIFF file format after conversion from the JPEG file. The full digital images necessary for scientific analysis will be released for analysis within one year after receiving each orbits last data.


Right now our species has a satellite named Galileo orbiting the Jovian System 500 million miles away. It took almost seven years for Galileo to travel from Earth to where it now circles the large gas giant. Galileo's mission: to send back observations of the planet and its moons.

Galileo's Solid State Imaging camera can "see" wavelengths that run from 416 to 989 microns (blue to near infrared).

Galileo sends back its precious information in a journey that, at the speed of light, only takes about one class period to get from Jupiter to Earth. Arriving home, the data are picked up by a global system of antennas called the deep space network. The data stream is sent to NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California . Once at JPL the information from the sapcecraft is validated and calibrated for distribution.

On Feb 20 Galileo flew by one of the most intriguing of Jupiter's 16 natural satellites, Europa. Pictures of this moon's surface taken from only 370 miles away showed features ranging from as small as a van to the size of a city building. These pictures will expand the coverage and resolution from our past imaging attempts of Europa with Voyager I and II.


When Galileo Galilei first turned a telescope to look at Jupiter, he saw four "wandering stars" orbiting the planet. Of these four, Europa is the second moon out from Jupiter. It measures about the same size as our moon in diameter, yet it is the smallest of Jupiter's 4 main moons (or what are now known as the Galilean satellites). By viewing Europa with infrared sensors it is possible to detect water in the form of ice on its surface.

The geology of this moon appears to be shaped, in part, from the movement of material that has been forced up from below the surface. The surface may be geologically young (perhaps only a few tens of millions of years old) Indications that material has been upwellings from the interior is helping scientists to figure out what lies under Europa's surface.

Europa is an icy, slushy moon, torn by global forces related to tidal surges and swells in response to Jupiter's gravitational pull. The icy moon is also ripped at by the supplemental tidal forces of the other Galilean moons Ganymede (the third moon), Callisto (the fourth moon) and Io (the first moon).

Planet-wide compressional and/or extensional movement is revealed in surface features. Geological activity in the form of what scientists call "ice volcanoes" appears to have sent material up through trenches,thousands of miles long, which riddle this moon's surface with a seemingly chaotic network of cracks. These ridges are the dominant feature, appearing as light and dark bands traversing the face of this moon. All of Europa's geological activity has created a relatively smooth surface where no elevation extends higher than a couple thousand feet. An elevation that would only warrant use of the term "hill" here on Earth (by comparison, the tallest mountain on Earth, Mauna Kea, is over 33,476 feet in elevation from sea floor to peak). This billiard ball-smooth moon is five times brighter then our own lunar landscape.

While the dominant feature on Europa is light and dark banding, other features have also been identified by planetary geologists. These features include impact craters, domes, crisscrossing lines, mottled terrain, disrupted terrain, gray bands, bright patches (high albedo areas), small knobs, raised platforms and dark patches referred to as "freckles".

The Hubble Space Telescope has imaged a tenuous atmosphere on Europa. Scientists theorize that all the forces acting on this moon are raising gaseous water from its surface.

Europa Quick-Look Statistics

Discovery:                             Jan 7, 1610 by Galileo Galilei
Diameter (km):                         3,138km
Mass (kg):                             4.8e22 kg
Mass (Earth = 1)                       0.0083021
Surface Gravity (Earth = 1):           0.135
Mean Distance from Jupiter (km):       670,900km
Mean Distance From Jupiter (Rj):       9.5 Rj
Mean Distance from Sun (AU):           5.203AU
Orbital period (days):                 3.551181days
Rotational period  (days):             3.551181days
Density (gm/cm^3)                      3.01 gm/cm^3
Orbit Eccentricity:                    0.009
Orbit Inclination (degrees):           0.470degrees
Orbit Speed (km/sec):                  13.74km/sec
Escape velocity (km/sec):              2.02 km/sec
Visual Albedo:                         0.64
Surface Composition:                   Water ice


After reading through Europa Brief for Learners in the Learner Handout my 8th. graders had a good understanding of what they were looking at; half the 7th. graders however, did not. I used the following demonstration to help the next class understand what they were looking at.

First I gathered up the following materials: an old newspaper, pieces of Yarn of various thicknesses and colors, and some red and blue water base poster paint. With the paper on the floor and a puddle of blue paint here and there, I began throwing yarn on the news print explaining as I went along how various geological features might be shaped. The blue paint puddles represent material that has come from underneath the surface. The red paint splattered last, onto the newspaper and yarn represents material that has come back down to the surface after being lofted in the air by some event.



Students analyze an image of Europa classifying surface features by relative age


Planetary Geology and the Scientific Process


Middle School


Mac-proficient science teacher with some experience (or help) using the World Wide Web.


Given the Image titled Prominent Doublet Ridges on Europa (Image catalog #PIA00542), a Mac, the program NIH Image and the lesson package titled Finding Young Features on Europa, the learner will analyze the image, making qualitative statements of the relative geological features of one discrete region of the Jovian satellite Europa.


All students on task 95 percent of contact time.

Many verbalizations of excitement and interest

Learner-generated statement that ages geological features (from youngest to oldest) demonstrating an understanding of possible planetary geological forces at work.

Mastery of vocabulary by use of word bank demonstrated by naming features.

Observation of Image navigation and feature location using coordinate system.


Color Mac running system 7.0.1 or newer, with a minimum of 3 Mb of available RAM. Minimum 12 inch monitor with the ability to display 256 colors (8 bit).

Web access to pick up all materials.

Software (NIH Image 1.61)

Image Processing for Teachers download site-



National Institute of Health download site-


The Lesson Image

-Image Title: Prominent Doublet Ridges on Europa

Before downloading this TIFF lesson image make sure to download the application (NIH Image). Once you have installed NIH Image in your computer, set Netscape to use NIH image to view TIFF files. You set Netscape to use NIH Image by doing the following:

  1. Go to Options in the command line.
  2. Select the menu item General Preferences in Options Menu.
  3. Select Helper card and scroll down until you can select the extension "TIFF".
  4. Click the browse button until you find the application NIH Image in your computer. Select NIH Image in the dialog box, set the file type to "TIFF" and click apply.
  5. Make sure to select Launch application or save file from the action options in the Netscape dialog box, depending on how much memory you have.


The Anticipatory Set Image
-Planetary image of Europa in natural and false color



  • 2.25 hours total prep for beginners
  • 45 minutes to down load everything
  • 15 minutes to install program
  • 15 minutes to print
  • 60 minutes of learning curve for beginners (Reading the material and doing the lesson beforehand)


  • 80 minutes total contact
    • (about two periods for 8th graders on grade)
    • (about three periods for 7th graders on grade, with spring like weather, on Valentines day, just before ski week ;-)
  • 05 minutes to open Anticipatory Set image, enjoy and close.
  • 05 minutes Step 1-Open Lesson Image and pass out Learner Handout
  • 10 minutes Step 2-Play with tools for lesson
  • 10 minutes Step 3-Annotate Europa Brief for Learners
  • 10 minutes Step 4-Teacher Demonstration
  • 10 minutes Step 5-Discuss grid, Identify, draw and write up oldest feature
    1st Class contact over
  • 20 minutes Step 6-Identify, draw and write up features
  • 10 minutes Step 7-Class, group, individual discussion/writing of evidence for various events


Bring up the full planetary image of Europa in natural and false color on the computer monitor (or print a few color copies). Read Lesson Brief-Europa or improvise ;-)


The learning experience will be constructive and hands on. Cross ability help among students is encouraged.


10 minutes Step 8-Discuss/write/share/debate closure question


Learner Handout, discussion and ability to state case for aging features.


Learner Handout
Page # of 2


The Youngest feature of Europa: an image analysis simulation

an image of the surface of Europa

Galileo's closest encounter with the Jovian moon Europa will happen on Feb 20th, 1997. Galileos on board camera will send back pictures from only 370 miles above Europas surface. We need to look for features that would suggest presence of a liquid water. A first step in your imaging training might be to figure out the relative age of the features in this current image that was taken on Dec. 19, 1996. How old are these features? If they are only the oldest features, then that might mean that any subsurface liquid might be long gone. If they are among the youngest features, that might mean that there is still some subsurface liquid. So, let's find out which features are the youngest. One interesting question can be asked as you age these features: Will certain features be consistent with the existence of subsurface liquid water where we can invest future scientific resources for further investigation?

Step 1) Double click on the image icon called Doublet Ridges at the bottom of the desktop.

(You are looking at a picture of the Jovian moon Europa)

Page 2 of 4

Step 2) Use the magnifying glass and the grabber hand to take a good long look at the image-

  • The magnifying glass will let you see close up (this is called Zoom In) wherever you click on the image. To reset the magnification back to normal, double click the magnifying tool. To zoom out one step at a time hold the option key down as you click the tool (notice the plus sign changes to a minus sign when you hold the option key down and click). The grabber hand lets you move the image around.

Step 3) Read the following Europa Brief for Learnersabout the image. As you read, take notes along the right margin of your handout.

Europa Brief for Learners

This image of Jupiter's satellite Europa was obtained from a range of 7364 miles (11,851 km) by the Galileo spacecraft during its fourth orbit around Jupiter. This orbit was Galileos first close pass of Europa. The image spans 30 miles by 57 miles (48 km x 91 km) and shows features as small as 800 feet (240 meters) across (a little smaller than the size of a football field). The sun illuminates the scene from the right. The large circular feature in the upper left of the image could be the scar of a large meteorite impact. Clusters of small craters seen in the right of the image may mark sites where debris lofted (thrown up) from this impact fell back to the surface. Prominent doublet ridges over a mile (1.6 km) wide cross the plains in the right

Page 3 of 4

part of the image; younger ridges overlap older ones, allowing the sequence of formation to be determined. Gaps in ridges are where new surface material has obliterated older preexisting terrain.

When discussing the image with your fellow investigators it will help if everyone knows that the origin (x=0, y=0) is in the lower left corner. For convenience call the square at the corner of origin (1,1) and each square up and over to the right in sequence. The thumbnail at the beginning of the learner handout is set up already.


Watch as your teacher demonstrates how events and geological features may cover each other, creating, destroying, and altering the surface of Europa.

Step 5) To start your search for the youngest feature in this image, investigators need to know where in the image a feature or evidence of an event can be found. The first step is to locate the feature on the image. Label the grid below as the thumbnail image on page 1 is already labeled.

a rectangle made of forty eight rectangles four by eight

Page 4 of 4

Step 6) Now that you have a way of locating features on the grid, you can name the major features, identifying them in relationship to each other, oldest to newest. Use the word bank below to describe what you see on the entry line below. You need to also draw each feature on the grid above

a rectangle divided into four triangles

Planetary science word bank- Impact, Crater, Debris, Slush, Dome, Reflection (Albedo), Radiate, Mottled, Terrain, Crisscross, Knobs, Platform, Freckled (low albedo), Brightness, Erupting, Geysers, Freeze, Tectonic, Force, Tidal, Fault, Parallel, Fracture, Event, Geology, Europa, Jupiter, Artifact, Meteor.

Step 7) What evidence of major geological event/s stands out in this image?

Step 8) How did you go about deciding the relative age of each feature?


As fascinated as I am with how digital imaging tools work. And how they can effectively accelerate and compress learning, I have been brief in conveying what the teacher needed to know to use this lesson. If you are inclined to this same fascination, check out the following resources:

Computer Graphics
Donald Hearn, M Pauline Baker
Copyright  1986
Prentice-Hall, Inc.

Envisioning Information
Edward R. Tuft
Copyright  1990
Published by Graphics Press

Scientific Visualization:
Advances and Challenges
Edited by L Rosenblum, R A Earnshaw, et al
Copyright  1994
Academic Press Inc.

The Image Processing Handbook 2nd. Ed.
Russ, C. John
Copyright  1995
Published by CRC Press Inc.

The Visual Display of Quantitative Information
Edward R. Tuft
Copyright  1983
Published by Graphics Press

Also you can visit the world leader in imaging in education.   Go to the
Image Processing for Teachers Web site http://ipt.lpl.arizona.edu/

The men and women who invented and maintain NIH Image at the National
Institute of Health (NIH)  take no less then 3 pages describing the
glorious capabilities of NIH Image.  There is also links to other imaging

If you thirst for more understanding of the difference between beautiful
pictures (eg,GIF,JPEG) and images with scientific merit (eg, TIFF, PDS,
FITS, DEM) your journey can start by joining the folks at the Image
Processing for Teachers (IPT), or joining  their email list

Other Resources used to create this introductory image lesson

Jet Propulsion Labs (JPL)

Online From Jupiter 97

Science 10-18-96
V274, pgs.309-464

Image Processing for Teachers

National Institute of Health: Home for NIH Image.



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