Mars Thermos (Rana Khan, Lilach Cary)
Author(s)
Rana Khan, Lilah Cary (adapted from JPL Activity)
Overview
Student teams use the engineering design process and everyday materials to design an insulator that will keep a small amount of water from rapidly changing temperature. This activity incorporates both science and engineering process skills. Students will design and build an insulator and use it to conduct a scientific experiment, complete with control. Students learn the application of heat transfer and basic thermodynamics, while practicing their data collections and analysis mathematics skills.
The goal of this activity is to keep cold water cold and warm water warm. Students must decide how much water is optimal for the experiment and they must keep this water from changing temperature more than 5 degrees F in 10 minutes.
NGSS Engineering Standards
MS-ETS1-1
Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions.
MS-ETS1-2
Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.
MS-ETS1-3
Analyze data from tests to determine similarities and differences among several design solutions to identify the best characteristics of each that can be combined into a new solution to better meet the criteria for success.
MS-PS3-3
Apply scientific principles to design, construct, and test a device that either minimizes or maximizes thermal energy
Materials needed
Thermometers (Ideally 2 per team. Inexpensive digital kitchen (meat) thermometers may be purchased online--read reviews for accuracy, durability, and waterproof capabilities--or any classroom-safe thermometers may be used.
Stopwatches (1 per team)
Graduated cylinders (1 per team)
Plastic cups (2 per team. Cappuccino cups or Dixie cups are about the right size. If there's more than 100 mL of water, the temperature won't change as quickly.)
Insulating materials (bubble wrap, paper, cloth, sand, water, foil, Styrofoam, etc.)
Tape (masking, packing, or duct)
Paper towels (for cleaning up spills)
Pitcher (for ice water)
Ice
Water
Insulated commercial thermos or carafe (for warm water)
Electric tea kettle or hot plate and pot (for heating water)
Copies of Mars Thermos Experiment Record
Pencils
Teacher Tips
Management
Suggested team size: two to three students
Pre-Activity Set-Up
Heat water to no warmer than 120°F and place it in a well-insulated commercial thermos or carafe. Keep it in a safe location away from student access.
Fill the pitcher with ice and pour water over the ice to fill the pitcher. Mix, and allow the water to become ice cold.
Make sure paper towels are readily accessible to all teams in case of spills.
To expedite the experiment, set up on control (un-insulated) set of cups for which you (or a designated student) will record temperatures.
Cold Water Experiment Tips
This experiment works best when the temperature in your classroom is moderate (not on a cold winter day when the heater is broken).
Use ice to pre-cool the water only. DO NOT transfer any ice to student cups.
Hot Water Safety and Experiment Tips
Water used should NEVER be more than 120°F for students. See scald table below.
Time/Temperature Relationship in Scalds
Table courtesy of Shriners Burn Institute
Scalds can cause serious injury. If in doubt about your students' ability to follow propert safety precautions, perform the cold water portion of the experiment only.
Use an electric teapot to heat water safely away from students and mix with cooler water in a commercial insulated thermos to the appropriate temperature (120 degrees F) and then pour for students. Note: BE CAUTIOUS of using a microwave oven to heat the water--scalds can happen very easily by way of super-heating.
Instruct students to start their measurements immediately upon receiving their water samples.
This experiment works best when the temperature in your classroom is moderate.
Background
Very little atmosphere exists on Mars, so temperatures fluctuate through a very wide range. In winter, near the poles, the temperature can be as low as -125°C (-195°F). A summer day on Mars may get up to 20°C (or 70°F) near the equator, but at night, the temperature can plummet to about -73°C (-100°F). These are serious extremes for both robots and human beings!
Robots carry sensitive on-board science and computer equipment that must remain somewhat warm in order to properly function. Anyone living on Mars--even for a short time--will have to deal with this temperature variation and be protected properly from its damaging effects. Just think about the number of layers you wear when going outside on a very cold winter's day.
Spacecraft and humans traveling into extreme temperature environments must be surrounded by protective layers to keep them at a fairly constant temperature. Engineers need to design protective blankets and spacesuits to prevent heat from being transferred to, or transferred away, from our spacecraft and bodies. How might we insulate spacecraft and ourselves from the wide variations of temperature in the Martian environment?
Thermal engineering has to include important design elements so spacecraft can remain protected as temperatures rapidly change--at high speeds, day and night conditions, and on different surface.
Procedure
Introduce the activity by explaining the objective: Teams of 2-3 must keep water from changing temperature more than 5°F in 10 minutes. They must work under the following constraints:
Each material is given a monetary value. Students must not spend more than $500,000 on their design. (Make each piece of an item worth around $100,000.
Size: When sending equipment into space, it needs to be able to fit into a spacecraft to be delivered to their target location. The thermos built must be able to fit into a shoebox (supply a shoebox to be used as measurement).
Mass: In order to transport equipment in space, the mass of the equipment is another consideration that must be made. Students building their thermos must ensure that the mass remains under 1 kg (prior to being filled with water).
Students are competing to create a device that not only can hold its temperature, but is also the most compact, least massive, and cheapest design. Students can compete in any and all of these categories.
Emphasize hot water safety protocols.
Discuss the definitions and real-world applications of heat, temperature, equilibrium, and thermal energy transfer.
Have students write definitions of these terms on their copies of the Mars Thermos Experiment Record.
Ask students to predict how the temperature will change in each cup of water and use the terms defined in Step 4 to write their hypothesis.
Instruct students on the use of thermometers and have them announce, compare and record the temperature of the room in degrees Fahrenheit.
Ask each group to decide how much water they should use in each cup. Ask them to write their justification for their chosen amount. Students should use their prior knowledge and thought processes to consider that a greater amount of water will change temperature slower than a smaller amount of water.
Have student teams use graduated cylinders to obtain ice water (with no ice) and hot water (no warmer than 120 degrees F) samples, place the samples in their control cups and perform the control experiment.
Have students investigate the insulative properties of the materials available and then design and build a Mars Thermos for the cold and hot cup. Remind them to make sure they are able to easily obtain temperature measurements.
Have teams perform the experiment with their Mars Thermos designs, then graph their data.
Have teams share performance data with the class.
Have teams design a second set of Mars Thermoses, improving upon their original design, then redo the experiment.
If time allows, have students vary the amount of water used in the two designs to determine the impact the amount of water has on the experiment.
Lab Form
Graph the results from your experiment using the data from either Trial 1 or Trial 2. Time is the independent variable in this experiment. You, as the experimenter, decide when to take temperature readings. The independent variable is plotted on the x-axis. The temperature of water is the dependent variable in this experiment. The temperature of water depends on the time it was measured. The dependent variable is plotted on the y-axis. Label the y-axis and plot your data using dots. Connect your dots to make a line. Draw two lines in two different colors to distinguish the data from each cup using google sheets.
How to graph using google sheets
Questions
Do you think the temperatures in the cup will reach equilibrium with the air in the room? Explain.
Yes, over time the water in the cup will reach equilibrium with the air in the room. According to the first law of thermodynamics, energy is conserved and transferred until they are in balance.
In what situations on Earth are insulation and limiting thermal transfer important?
The gases in our atmosphere provide our planet with insulation, which allows us to sustain living conditions on Earth, like temperatures that are necessary to sustain life.
Living in areas with more extreme temperatures requires insulation: polar bears and whales, for example, have blubber and fat to keep them warmer and help them maintain homeostasis.
The water temperature would change more rapidly on Mars because Mars doesn't have a strong atmosphere to hold in the Sun's heat the way that it does on Earth.
Photos
Would the water temperature change more slowly or more rapidly on Mars?
