The
   Potato
      Asteroid

Objective

The objective is to carefully measure the size and shape of an "asteroid" potato.  Students and cadets are required to use their imagination to observe and record precise calculations.  A potato is used because of its irregular shape.  The collected data can be compared to known data about actual asteroids.

Time Requirement

About an hour

Materials

Each student will need the following:

• Potato
• Metric Ruler
• Art Paper
• Pencil
• A dunking Measuring Cup (may be shared)
• A large metric measuring cup or graduated cylinder - marked in Milliliters (may be shared)
• A Scale in Ounces (may be shared - Metric is preferred)
• String
• Water
• Calculator
• Colored Markers

Background

• Between the orbits of Mars and Jupiter, the observer will find literally thousands of small planets known as asteroids.   When these chunks of debris enter our atmosphere, and hopefully burn up, they are known as meteorites.  Sometimes when asteroids in the Mars/Jupiter orbit collide, they break orbit and move elsewhere, often towards Earth.  One asteroid, known as Gaspra, became the first to be photographed close up by the Jupiter bound spacecraft Galileo.  Another asteroid, observed by Galileo, was found to have its own tiny moon.   It is called IDA, a name that honored the state of Idaho.  Ida is shaped much like a typical Idaho potato and, using your imagination, this activity will set about investigating the asteroid "lookalike".  Ida is 52 kilometers long (approximately 32 miles) and appears to have a magnetic field.  Its moon is known as Dactyl.
  
• Recently, another NASA spacecraft entered obit around the asteroid named EROS.  This NASA project is known as the Near Earth Asteroid Rendezvous (NEAR).  The NEAR website is updated frequently with new information collected by the NEAR project.  Follow this link to NEAR (Note: this link will leave this site) to view recent data.   There are larger photos there that can be printed, or if your unit has access to the internet they can be observed on-line.  Some teaser images of Eros from the NEAR website are presented below:
  

  Asteroids Mathilde at left, and Eros at Right	Eros in Color (Is that a potato, or what?)

 

Procedure

1. Each student should first sketch their asteroid potato.  Have them draw in shadows to create an appearance of the overall contour as seen in the NASA images.
2. Each cadet should give their asteroid a name and refer to it by this name throughout this exercise.
3. The asteroid potato should be weighed and the data recorded.
4. Wrap a string around the length and width of the asteroid potato and then measure the length of the string to get length and width circumferences.  Record the data.
5. It's time to check volume.  Fill the dunking cup completely full of water.  Pour all of the water into the measuring cup.   Have all of the cadets record the initial amount of water in the dunking cup.
6. Pour all of the water back into the dunking cup.
7. Make sure that the cup is completely full for each cadet at this step.  Have the cadet carefully dunk the potato in the measuring cup so that it is completely below the surface of the water.  Hold it down with a pinky if needed.  (This will make a mess, but that's part of the fun!)
8. Remove the potato, and record the amount of water left in the cup by pouring the remaining water into the measuring cup.   Subtract the amount left from the amount that was originally in the cup.  That is the volume of the asteroid.  Record the data.
   
   A sample Asteroid Data Fact Sheet is presented below.  You may be able to cut and paste this table from the web page, or you may make your own.  Each student should record their observations on the fact sheet.

Cadet Name:		Asteroid Name:
A	Circumference Length:	(in centimeters)
B	Circumference Width:	(in centimeters)
C	Weight:	(grams?  Ounces?)
D	Starting Water:	(ml)
E	Remaining Water:	(ml)
F	Fluid Volume of the Potato:	(subtract E from D)
	("F" is also volume in cubic Centimeters!)

Discussion

Challenge the students with the question "How would scientists measure an asteroid using different methods?"   Also ask "What can we learn from studying asteroids?"  Another good question is what observations can we perform with a potato that would be very difficult to do in space?

 

This activity was inspired by Dr. Lynn Bondurant, Education Programs Officer at NASA/Lewis Research Center in Cleveland, Ohio

Adapted from: Aerospace 2000, Volume 5
Published by the Aerospace Education Training Directorate
National Headquarters, Civil Air Patrol.