270984648_f59dfe953b_zThe recent anniversary of the Challenger explosion has brought back memories of when I was young and dreamed of being an astronaut just like Sally Ride. I studied the constellations and even met some of the Apollo astronauts at the Morehead Planetarium.  While I did become a scientist and worked briefly at a radio observatory, I never did make it into space.  But I still like to watch the rocket launches and even launch a rocket or two of my own.  There is no thrill like watching a rocket shoot into the sky and imagining where it could go if it could just break free of our gravity.

There are several types of rockets that you can make at home (there’s a list below) but the easiest and most reliable is the Film Canister Rocket.

What you need

Film Canister (if you can’t find one, the mini M&M tubes work as well)
Effervescent tablet such as Alka Seltzer
Plate (if you are doing this inside which is NOT recommended unless you have VERY high ceilings)
Toilet paper tube (optional)
Index cards, styrofoam egg carton scissors and glue (optional)

What to do
Read these directions before you start because once you load your rocket you need to work fast!

  1. Find a place to launch your rocket.   Outside is best since this rocket really flies much higher than most ceilings and leave a fizzy, watery mess behind. If you are going to launch indoors you can put your rocket on a plate to catch the ejected fuel.
  2. (Optional) You may want to put a nose cone and fins on your rocket. Index cards work well for a nose cone but I suggest cutting fins out of a Styrofoam egg carton so that they will be waterproof.   Attach each of these with glue. You can also use a rubber band to attach an astronaut (Benny?) to the outside of the rocket (aka film canister)
  3. Put a quarter of an effervescent tablet in the rocket.
  4. Pour a tablespoons of water into the rocket – at least enough to cover the tablet and no more than half full. QUICKLY put the cover on the rocket and make sure it is on tightly.
  5. Place the rocket in your launch area UPSIDE DOWN. This means the cover should be on the ground.
  6. This is the hard part. Wait. In about 10 seconds you will hear a pop and your rocket will shoot up in the air!

Note: It can take up to 30 seconds for the rocket to launch. Resist the urge to pick up your rocket or put any part of your body (especially your face!) above the rocket. You could get hurt. If you hear a hissing noise this means the lid was not on tightly and the gas (aka fuel) is leaking out. You can open up your rocket, clean it out and start over. If the rocket doesn’t launch after a full minute you can do the same.

What happens?
When you add water to the effervescent tablet it starts to dissolve. The tablet is made of citric acid (this is the acid found in lemons and oranges) and sodium bicarbonate (you might know this as baking soda). When these two chemicals mix they react to create create carbon dioxide gas inside your rocket. (This is the same reaction as vinegar – aka acetic acid – and baking soda that you might be familiar with.)

As more and more gas is created the pressure builds up inside the rocket. When the cover can’t hold anymore it is popped out and all the gas goes rushing out with a large force and a large POP! If the cap is on the bottom and the gas is pushed down, according to Newton’s 3rd Law, an equal and opposite force will push your rocket up.

This is exactly how real rockets work! Except they use slightly more powerful fuel than baking soda and acid. If your want to learn more, NASA has a whole page about rocketry.

Take your rocket to the next level. You could even use it as your science fair project. Here are some ideas for questions to explore.

  • Can you figure out a way to measure how high your rocket flies?
  • Try hot and cold water. Does the temperature affect how quickly your rock launches or how high it flies?
  • How big a piece of tablet creates the quickest or highest launch?
  • What is the ideal combination of water and tablet for the highest launch? Or for the quickest launch?
  • What affect does adding a nose cone or fins have to the fight of your rocket? Can you angle the fins so that your rocket spins? Are four fins better than three?
  • Do other containers work better? Try a playdough container, plastic egg or anything else you can think of.

More Rockets
If you’ve mastered the film canister rocket and are ready for a bigger challenge, here are some more rockets you can create at home.

Water Bottle Rockets
Water bottle rockets use the exact same principle as the film canister rockets. One big difference is that you have a bigger rocket – a 20 oz up to a 2 liter bottle.   And instead of using a chemical reaction to create gas you will use a bicycle pump to force air into the bottle. You can make your own launcher () or buy one. I’ve tried a couple and recommend the Aquapod.

Stomp Rocket
You can buy stomp rocket toys most anywhere or you can make your own.  A stomp rocket works the same as a water bottle rocket except you are pushing the air into the rocket with a big stomp of your foot and launching it immediately. These rockets are fun to play with but usually don’t go very high.

Matchbox Rocket
When you are ready to use a fuel that burns instead of gas pressure you can create these small matchbox rockets. Make sure you have a grown up help you since there is a danger of getting burned or starting a fire.

Solid Fuel Rockets
When you are ready for the big time try building a solid fuel rocket. You can buy kits to build these at home but it is a good idea to have help from a grown up.  You can also find a local rocketry club to learn more about rockets and attend group launches.

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