Gaining Traction on Mars Activity

Introduction

NASA has been exploring Mars to make discoveries for the benefit of all humanity and to develop technologies that will help humans explore even further into the solar system. To achieve this, NASA has sent rovers like Curiosity and Perseverance to traverse its surface and collect data. However, gaining traction on Mars has some challenges. Mars’ atmosphere is much thinner than Earth’s, which affects the performance of materials used for rover wheels and traction systems. Landing on Mars in August 2012, the NASA Mars Science Laboratory rover Curiosity exemplified these challenges. Curiosity was engineered to study Mars’ atmosphere, climate, and geochemistry in areas such as Gale Crater and Mount Sharp. Although the mission was planned for two years, Curiosity was designed to potentially last up to 14 years. NASA scientists have discovered that Curiosity’s wheels are deteriorating faster than expected, especially the middle ones, highlighting that rubber, typically used in Earth’s tires, is not feasible to work in the Martian environment due to its atmosphere and extremely low temperatures. Rover wheels must be durable enough without adding excessive weight, which would require more fuel for launch and space travel constraints. This is why Curiosity uses lightweight aluminum wheels. In this activity, participants will work in teams to design and test various wheels in Martian simulant soil to discover the most efficient and cost-effective prototype.

In this activity, participants will design and test various wheel prototypes on a simulated Martian surface to determine which is the most cost-effective.

Grade Range: 6-12

Time Needed: 120 Minutes

Materials List

Ensure that educators have: 

• • Small, electrically driven four wheeled vehicle, preferably four-wheel drive. This can be a purchased toy or made from common robotics kits
  • 1 underbed storage box (41 Qt)
  • 1 50 lb. bag of play sand per group (3-4 Students)
  • Various objects to modify wheels, such as straws, tape, toothpicks, glue, cardboard, etc.
  • Blank paper for brainstorming
  • Optional: 3D printed wheels file
    • TPS Medium GTOM Wheel Double Trapezoid 4.00 6.00 3.75 5.75 7 
    • TPS Small GTOM Wheel Double Trapezoid 3.75 5.75 3.50 5.50 7 
    • TPS Large GTOM Wheel Double Trapezoid 4.25 6.25 3.75 5.75 7 

Safety

Ensure that students:

• • Are aware of their surroundings and carefully move throughout the room when necessary.
  • Use caution and wear eye protection when building and testing the wheels.
  • Practice safe cutting techniques and scissor handling when building and testing.

Activity Procedure

Investigation Preparation

Step 1: Prepare the test vehicle(s):

The test vehicles should be electrically driven and four-wheel drive. A single vehicle with removable wheels can be used for the entire class if each team has their own set of four wheels that they can modify. Separate vehicles can also be used for each team if they are identical. If building a test vehicle from a classroom robot kit, the files for 3D printed, smooth, low traction wheels are located on the activity’s webpage. Teams can either make physical alterations to their smooth wheels or make changes to the 3D files and print their altered wheels.

Step 2: Preparing the test bed:

Prepare the test bed by pouring play sand into the storage tote and leveling it. Have several thin, sturdy objects on hand (such as books or wood blocks) to place under one end of the test bed to adjust its angle of incline.

Assign Teams and Roles

Consider assigning roles and tasks to individuals within the team. Example of roles for each team:

• • Design engineer — sketches, outlines, patterns, or plans the ideas that the team generates.
  • Technical engineer — assembles, maintains, repairs, or modifies the mechanical or electrical components of the system.
  • Operations engineer — sets up and operates the system to complete a process or test.
  • Technical writer — records and organizes information and data and prepares documentation to be published.

Introduce the Challenge

The facilitator should:

Show an image of shoe soles to the participants. Ask which shoes they think are best for hiking on a rocky trail. Which shoes would slide easily on a smooth floor? Why?

After discussing the image, have participants compare their own shoe soles to the ones in the image. Which soles do their shoes most closely resemble? Participants with smoother shoe soles have likely experienced more slipping and sliding than those with more rugged shoe soles. This is caused by varying degrees of traction.

Provide context for this activity using the background information from above.

Distribute sketch paper to each team.

Demonstrate the test vehicle crossing the test bed to the participants. Begin by setting up the test bed as a level plane, then increase the angle of the test bed by placing objects under one end. Continue to increase the angle of the test bed until the test vehicle begins to struggle to climb in the sand due to a loss of traction in the wheels. Measure the amount of time it takes for the test vehicle to make it from the bottom to the top of the test bed at this angle and record it as the baseline time that the participants are challenged to beat with their wheel designs.

Explain the challenge to the participants:

• • Each team will use the available materials to modify and test rover wheels on a simulated Mars surface.
  • Rover wheel designs are tested by attaching them to the test vehicle in the test bed. The back wheels must touch the wall to start.
  • Next, the vehicle is timed until it touches the opposite wall with the front wheels.
  • Designs are evaluated for the fastest time and the least amount of wheel damage.
  • At the end of the challenge, teams will share their experience and results with the other participants.

Completing the Challenge

Participants should be responsible for researching and reviewing background information, brainstorming possible approaches, and selecting the best option based on defined criteria and constraints. Once this part is completed, teams must develop a plan, create a prototype, and test it. Throughout the process, they should reflect on outcomes, incorporate feedback, and, if needed, make improvements to the prototype based on what they have learned before communicating their findings and solutions.

Challenge Questions

• • What challenge is our team being asked to complete?
  • What supplies are available to us?
  • What criteria must be met? (Things our team must do)
  • What are our constraints? (Things we are not allowed to do)
  • How will we measure success?
  • How will we divide our team into roles and responsibilities?
  • What ideas do we have to accomplish the task?
  • Why do we think this will work?

Share

Prepare to present your team’s design to the rest of the class. Be sure to include the following:

• • The roles of each of your team members.
  • Your team’s initial ideas and designs.
  • Any challenges you had while modifying your wheels.
  • The results of your first test.
  • How you improved your design and the subsequent results.
  • What you learned from the challenge.
  • What ideas you liked from other teams’ designs.

Bonus Challenge

Continue to increase the angle of the test bed to find the team that can climb the steepest slope with their wheel designs.

Career Connection

Advanced manufacturing mixes innovation and technology to improve designs and inventions. This type of career includes subject areas such as engineering, artificial intelligence, and robotics. In this activity, participants will explore innovations and advancements in robotic development. The career field of robotics includes numerous aspects such as programming, production, mechatronics (combining mechanical, electrical, and computer engineering), as well as smart manufacturing in a safe and efficient manner.

Other Resources

The Amazing Adventures of AstroBiobot
NASA Glenn’s Shape Memory Alloy Tires: Part 1
NASA Glenn Research: Reinventing the Wheel

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