Distance Learning Module: Core Samples
Rock and soil samples reveal a lot about the chemistry, physical structure, and ability to support life on a planet, moon, or asteroid.
Can you complete this engineering challenge to design a device that takes core samples of a potato “asteroid”?
Background Information
Geologists, archaeologists, and other scientists take core samples to learn about the composition of many materials on Earth. A core sample is a section of a substance (usually rock or soil) which is obtained by drilling, or boring, into the surface and pulling out a piece of the interior for study. Surface materials can change when they are exposed to wind and water, so cores taken from below the surface give scientists more reliable samples for analysis. This photo shows core samples of rock collected by a mining company.
In space, rock and soil samples reveal a lot about a planet’s, moon’s, or asteroid’s chemistry, potential to support life, and geologic history. When space programs like NASA can’t send a person into space to do the job, they use mechanical rovers to collect samples. A rover is a type of vehicle that can drive over land that’s rocky, dusty, sandy, or rough.
Today we’re going to imagine taking core samples from an asteroid: one of the many small, rocky bodies that orbit the sun and lie between Mars and Jupiter. Asteroids range in size from less than a kilometer (half a mile) to nearly 800 kilometers (500 miles).
Design your own core sampler
For this activity, we challenge you to design a device that will take a core sample from a potato. The potato will act as an “asteroid,” and you’re designing a drill that can be used by an imaginary rover. It’s harder than it looks!
Materials
Paper cup
Sturdy adhesive tape (masking, duct, painter’s, etc.)
Popsicle sticks (craft sticks)
Rubber bands
Small binder clips
Scissors
Potato slices (can substitute another fruit or veggie of similar texture/firmness)
Sharpened pencil
Skewer (optional)
Ballpoint pen that can be disassembled (optional)
Procedure
Start by pushing a plastic straw through a potato slice with your bare hands. Pull the segment of potato out of the interior of the straw: this is a core sample!
Did this process work? What made it difficult to take a sample this way?
Design and build a frame for your corer:
Use a sharpened pencil or skewer to make a hole in the bottom of your cup.
Slide the plastic straw through this hole—you will manipulate the straw from the top of the cup, and the device will take samples from the bottom.
Use popsicle sticks and tape to create a frame that will hold the straw upright in the center of the cup, so that it can move freely up and down through the hole in the cup’s bottom. There are no wrong answers: this is all about creating and testing your own unique design!
Hint: you can stabilize the straw by taking apart a ballpoint pen, feeding the plastic body (tube) portion into the hole in the bottom of your cup, and placing the straw inside of the tube—so that the pen body helps to guide the straw’s movement.
Design and build a plunger for your corer:
Use popsicle sticks, tape, and binder clips to design a plunger for your device. This is the part of the corer that will pull the straw back and then drive it into the potato’s surface.
Attach the plunger to your plastic straw, and then feed the straw back through the hole in the bottom of the cup. Your device now consists of two pieces: a plunger attached to the straw sampler, and a frame that holds the sampler mechanism upright and allows it to move up and down.
Use rubber bands to hook your device’s plunger portion to the frame portion.
Test your device:
Now place your corer on top of a potato slice. Pull the plunger upward, then let it go.
What happened? Did it take a core sample of the “asteroid”? Was this more effective than trying to take a sample by hand?
What’s happening?
When you stretch the rubber bands, they build up potential (stored) energy.
When you release the rubber bands, the potential energy changes to kinetic (motion) energy.
When the straw hits the potato, the kinetic energy changes to mechanical energy and does work. The more potential energy the plunger has, the more deeply the straw can penetrate and do more work.
Evaluate and tweak your design:
If your corer still does not work the way you’d like, play around with the design and see which factors make it more effective.
Adding binder clips to the plunger adds more weight, or mass, to that portion of your device. With more weight, there is more potential energy when the plunger is pulled back against the rubber bands—so the plunger can do more work.
You can also increase the force of the plunger by adding more rubber bands, or pulling the rubber bands back farther.
If the straw tip bends or breaks, try snipping off the broken end or use a new straw. You can even put a sharp skewer into the inside of the straw, to help penetrate the potato’s surface as the plunger makes contact.
What other factors make your device stronger/more stable/more effective at penetrating the potato’s surface?
The sky is the limit! Keep changing the elements of your device until you have perfected the design to your liking.
Learn More
Osiris Rex is a spacecraft that launched in 2016 to study a near-Earth asteroid called Bennu. It uses a tool similar to your corer to take core samples. The samples are set to return to Earth in 2023.
asteroid bennu (image credit: NASA/Goddard/University of Arizona)
In July 2020, NASA will launch the Mars 2020 mission. During this mission, the Perseverance rover will collect rock and soil samples of the surface of Mars, using a coring device on the end of a robotic arm. Click here to watch a NASA animation of how the rover will collect, store, and transport samples.
detail of the PERSEVERANCE rover, with focus on the robotic arm (image credit: nasa)
