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Cooking With Kuiper: The Instruction Set

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(update:  2/18/2015)

Time to build a comet!

If you have adult or older-student assistants, ask them to take charge of crowd control; that is, keeping the audience from crowding around the demonstration. Everyone will get to see the comet! Spare a minute for a brief lecture on the hazards of dry ice. You may have participants who know that dry ice can “burn”, but not all will understand that idea at first. However, no one wants to get hurt. Mention that you will be protecting your hands with gloves and your eyes with safety goggles (or safety-rated eyeglasses).

Supplies for Comet Making (Just Add a Cooler-Full of Dry Ice)

Supplies for Comet Making (Keep your cooler-full of dry ice in a safe spot.)

Participation opportunities include: helping move the materials and equipment to a mess-tolerant location, measuring ingredients, and smashing dry ice. The trauma of allotting slots to help out is one important reason to try the exercise at least twice. (Crowd-control tip: sometimes it helps to announce “I’ll only choose helpers from those who do not raise hands and call out to volunteer.”)  As a first step, take one of your plastic bags and cut it open along one side, then use it to line your mixing bowl.  Take 2 other bags and put one inside the other to make a double-thickness bag.

In the first stage,  your chosen helpers will take turns measuring all the “safe” ingredients into the bag-lined mixing bowl.  Working with the dry ice needs closer control, so keep your supply of CO2 off to one side for now.  As you introduce each ingredient, explain why it’s being included.  You can use the short explanations provided here as a starting point, adding your own facts or curriculum tie-ins, but remember to keep it brief or you’ll lose your audience’s attention.

Let’s start with water: most comets are composed primarily of water ice. During the early formation of the solar system, the planets were bombarded by comets—so some of the water you will use in this experiment may have actually originated in the Kuiper Belt!  (For a popular-science overview, check out this article from Time Magazine.)  Your helper will add 2 cups of water.

Next, add sand or gravel: most comets incorporate at least some rocky material.  Have your helpers measure out about 2 Tablespoon (TB) of grit.

Next, you’ll add ammonia: real comets typically contain NH3, the active ingredient in this cleaning solution.   (Regrettably, few, if any, comets show up to help when it’s time to clean house.)  If you’re using a squirt bottle to store the solution, your helper just needs to add one “squirt” of ammonia solution.  Otherwise, your helper should measure in 1 Tablespoon.

A Dirty Soup of Rocks, Water, and Organics

A Dirty Soup of Rocks, Water, Ammonia, and Organics

And, for our last step before major excitement sets in, stir in a touch of ice-cream topping: these contain organic molecules, which are a normal component of comets. The organic molecules in real comets are not this delicious–they include hydrogen cyanide and formaldehyde–but comets often contain complex and interesting compounds such as amino acids.   Researchers at NASA’s Ames Research Center have shown that amino acids from comets striking Earth long ago during the Solar System’s early eons would not only survive impact but would form even more important compounds for life under the heat of impact.   So it may be that we are here to enjoy ice cream (and sugary toppings) thanks to ancient comets.   Let your helper squirt in one squeeze-worth (it will be about a tablespoon).

Now, finally, it is time to add the dry ice.  Comets contain significant quantities of frozen gases, especially carbon dioxide, which just happens to be the gas that we call “dry ice” when frozen.  This stage of your demonstration is a two-step process. First, you will put on safety goggles and work gloves and use the hammer to tap off about 2 pounds of dry ice (1/4 to 1/3 of your supply).  Place the chunks into the doubled plastic bag and twist the opening closed.  Then, and only then, one lucky volunteer will be asked to don a set of goggles and, once protected, may proceed to smash the contained dry ice with the hammer.

Crushing Dry Ice with Flat Side of Hammer

Crushing Dry Ice with Flat Side of Hammer

Have your crusher use a two-handed grip (this helps deflect the temptation to also handle the bag of dry ice and also limits the range of motion, protecting bystanders from the crusher’s swing) and turn the hammer sideways, to smash with a broader surface area.

Once that stage is completed, ask the crusher to rejoin the group.  Make sure that the wooden stirring spoon is at hand and that you are still wearing your work gloves and goggles. Then open the bag and quickly scoop out roughly two cups of crumbled dry ice.

2 Cups of Ice-Cold CO2

2 Cups of Ice-Cold CO2

Give the mixture a stir and then swiftly add the dry ice, stirring vigorously. There will be some dramatic vaporization of CO2 and in moments the dry ice will freeze the water solution to a slushy slurry. Quickly wrap the plastic bag around your slushy mass and—keeping those gloves on—form the contents into a snowball, using firm pressure to shape the contents.

Comet's In the Bag

Comet’s In the Bag

You will feel the mass harden as you form your iceball. At that point, it is time to unwrap the comet and reveal it to your onlookers. You will have something that looks surprisingly like the common description of a comet—“a dirty snowball”.  You may even want to use your snowball-making skills to firm up the comet a bit once you remove it from the bag–remember to keep your gloves on!

Forming Up the Proto-Comet

Firming Up the Comet

Your finished comet

Your finished comet

Set the comet aside on a cold-safe surface, in a location where the eventual water-ice-melt will not damage anything. The comet will continue to outgas CO2 vapor. If you are working outdoors, any breeze will push this plume into a fair imitation of a comet’s tail.

Gases (CO2) immediately begin to sublime from the comet's surface

Gases (CO2) immediately begin to sublime from the comet’s surface

Your experiment team will undoubtedly want to repeat this process. A typical group of students will demand about four comets. After 2 or 3 builds, it will be time to set up fresh plastic bags for mixing and crushing.  If the group is larger, find ways for students to share participation tasks. For instance, two students can take turns as dry-ice crusher, two can each measure one cup of water into the mix, and so on.  As you proceed, instead of repeating the descriptive information yourself, invite the students to call out more of what they remember about the components represent.

Comet, Starting in "Dirty Snowball"

Here’s one small starter comet, let’s call this one “Dirty Little Snowball”

 

These model comets will last a long time, up to a few hours depending on their size and the conditions.  You can explain that the comets which get our attention are much larger–Comet Halley is estimated to be about the size of Manhattan Island–and between visits to the inner Solar System, they orbit back to where it is too cold for water, ammonia, or CO2 to be anything other than solids.  By no means do you need to make any effort to create spherical, smooth comets.  In fact, as you create successive comets, allow them to be different, irregular, and, well, messy.  Here are a few samples from a few of my comet-making sessions:

That's one frosty, rocky, comet:  "Before"

That’s one rocky comet, frosted with ice crystals of H2O and CO2

 

 

That's one slimy, partly-dissociated comet

Here’s a comet with conspicuous dark patches

That's one tall, cone-shaped comet

That’s one tall, frosty, cone-shaped comet

 

 

 

 

 

 

 

If your schedule permits, allow some time to pass and return to look at the comets after they have lost more material, as if you are checking in on a comet as it approaches the sun and some of its ice has been drawn off under the combined forces of the sun’s radiation and the solar wind…forming the comet’s tail.

Holey Comet, Batman!

Holey Comet, Batman!

Cooking with Kuiper: Project Supply Chart

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All Lined Up for Comet Building

All Lined Up for Comet Building

(Update:  2/18/2015)

As mentioned in the notes for project leaders, it’s best to repeat the procedure at least twice–three times if the class is large, to ensure that everyone has a chance to participate in the “safe” portions of the activity and to produce a variety of comets to observe.

Purchase dry ice in advance by as much as a day (purchase at the higher end of the quantity range if you need to store it overnight) and  store wrapped in insulating material, but not  tightly sealed.  (Frozen CO2 will sublime to gas and can even explode a container that is sealed too tightly.)  A small non-airtight cooler tucked into another lightly-closed, non-airtight cooler works fine, especially if wrapped in a blanket and stored in a cool location.

For the ice-cream topping, choose a small bottle with a squirt-style top full of caramel- or chocolate-flavor syrup for ice-cream sundaes.  Do NOT purchase hard-shell toppings;  stick to sticky sugar syrups.  Be prepared to fend off requests to sample the syrup.

For ammonia, do not use pure ammonia;  simply choose a basic non-sudsy ammonia-based cleanser.  A “sport-top” (squirting-style) water bottle about half-full of ammonia works well and keeps the ammonia away from hands, eyes, and clothing.  However, be sure to clearly label the bottle with the contents.

For trash bags, choose a good, sturdy brand.  They’ll take significant abuse!

Please note carefully that most equipment is required to be either plastic or wood.

  Per comet

For about 3-4 comets, allowing for waste and failures

 

Estimated cost

(2015 prices)

Good sturdy “tall kitchen” garbage bag, cut down one long edge to make a liner for the bowl 1

2

(have a second on hand in case the original tears)

$0.50

($12 for box of 45)

Additional “tall kitchen” garbage bags

3

Open the bags and layer them one inside the other, to create a triple-thick bag

6

Have a second layered set of 3 bags on hand in case of tears

$1.50

($12 for box of 45)

Large plastic mixing bowl, 2-cup plastic measuring cup, tablespoon measure, large wooden spoon

1 of each

Reminder:  for safety, use plastic containers and a wooden spoon

1 of each Bring from home or borrow from volunteers
Water 2 cups

2 quarts on hand

(store in a pitcher for measuring out in 2-cup quantities)

n/a
Sand or fine gravel 2 tablespoons ½ cup zero
Ammonia 

One squirt (about 1 tablespoon)

 

½ cup

$1.50

($10 for 28-ounce bottle)

Ice-cream topping

One squirt (about 1 tablespoon)

 

About ½ cup (Bring at least a 4-ounce container of syrup.) $6.50
Dry ice 2 cups of dry ice, after crushing. About 7-10 pounds of dry ice. $15($1.50 per pound)
Safety goggles

1 pair, adult size

1-2 pair, adult or child size (depending on student age)

1 pair, adult size

1-2 pair, adult or child size (depending on student age)

If not available in classroom—one-time purchase for reuse in many projects. $5 each

 

Heavy work gloves 1 pair, to fit Project Leader 1 pair, to fit Project Leader Use own gloves or borrow from volunteer (a new pair would cost about $10-12)
Total Cost: $39.50

For an easy-to-print version:  Just Supplies Cooking with Kuiper

Cooking With Kuiper: Notes for Project Leaders

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(update:  2/18/2015)

Last week on the tvweb, this happened: astronomer Derrick Pitts turned up once more on “The Late Late Show”.  And even though science-loving Craig Ferguson has moved on to new horizons, Director Pitts stayed and showed Guest Host Wayne Brady how to make a comet.  So I looked back at my entries for this project and realized they need some updates, and particularly some visuals. Have patience–it’s a multi-entry blog feature, so look for two more entries for the complete Updated Edition of “Cooking With Kuiper.”

The Kuiper Belt–that donut-shaped aggregation of hundreds-of-thousands of rocky objects orbiting beyond Neptune–is one of the most interesting regions of the Solar System just now.  Just last year, NASA’s Deep Impact explorer hurled a probe into the surface of Comet Tempel 1, flinging up a curtain of debris to reveal more about the comet’s composition.

Deep Impact's probe sent back this image just before striking Comet Tempel 1 (Image: NASA/JPL-Caltech/UMD)

Deep Impact’s probe sent back this image just before striking Comet Tempel 1 (Image: NASA/JPL-Caltech/UMD)

NASA’s New Horizons mission is due to arrive in July 2015 at Pluto–the most famous Kuiper Belt object–to observe the newly-redesignated dwarf planet and its five moons and then head out to explore.  You can check in on the progress of the mission at NASA’s home for New Horizons.  There is a general agreement among astronomers that the comets which return again and again (periodic comets)  began in the Kuiper belt.

In this project, we’ll be building a model of a comet using household supplies to represent most of the comet’s components and dry ice to capture the icy-cold environment of the Kuiper Belt.   While most Messy-Monday projects are entirely hands-on this particular activity is meant as a demonstration with controlled audience participation.  Some students may be careful enough to work with dry ice…but too many are not, and the step at which the dry ice is added can be dynamic and unpredictable.

A study of comets draws in much of what students should know about their planetary system and extends that knowledge into new and intriguing areas.  Students in intermediate grades probably know the basics of comets…that they come from the far reaches of the solar system, that they have tails, and that a comet crashing into the earth makes a cool disaster movie.  They might be surprised to know that scientists still want to find out more about comets, because all we know about comets so far is from watching them on their travels through the solar system.  Just a few months ago, the Rosetta spacecraft launched in 2004 by the European Space Agency actually landed a robotic explorer named Philae on Comet Churyumov-Gerasimenko, so why not launch an investigation into the nature and structure of comets by building our own lumpy, irregular, gas-spewing comets?

This activity is best paired with at least one hands-on activity centering on comets.   The second activity in this series combines a crafting-style model construction project and a cometary motion simulation game.  Other resources can provide other activities.  For instance, students can make a flip-book illustrating a short-period comet’s behavior as it travels from the orbit of Neptune to the sun and back.  And users of Pixel Gravity can run a simulation of the comet impact which led to the demise of the dinosaurs.

In the next installment, we’ll assemble a supply list for this project.  I recommend you  plan to build at least two comets, to let more kids participate and also to illustrate just how different two comets can be.

 

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