1. Technological Design © 2013 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Technological Design STS-118 Design Challenge Lunar Plant Growth Chamber Teacher Resource 3.2

2. STS-118 Unit: Big Idea The Engineering Design Process is a comprehensive, valuable tool that can be used to provide solutions to complex challenges on Earth and beyond. © 2013 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Technological Design

3. Lesson 3: Big Idea The design of technological devices requires the consideration of limitations, trade-offs, and many iterations before a final design can be selected. © 2013 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Technological Design

4. Identify Criteria and Constraints Helps to specify subsystems Affects final design and development Subsystems include: Water and nutrients Air circulation Heating and cooling Lighting Radiation protection © 2013 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Technological Design

5. Active Subsystems Are mechanical/electrical devices needed? Pumps Fans Lights Heaters Recorders © 2013 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Technological Design

6. Energy Sources Power needed for active subsystems Batteries Photovoltaic cells Radioisotopic thermoelectric generators Fuel cells © 2013 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Technological Design

7. Controls Feedback devices Sensors Timers Brains Microprocessors Switches Example: window fan with thermostat © 2013 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Technological Design

8. Passive Subsystems Feedback devices not required Example, air moving by convection currents in a gravity environment © 2013 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Technological Design

9. Optimization Ongoing process of designing Dependent on criteria and constraints May require subsystem redesign Models and prototypes allow testing for quality and efficiency © 2013 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Technological Design

10. System Stability Influenced by all components in the system Complex systems have many layers of controls and feedback loops Results in more ways things can go wrong Components detect, back up, bypass, compensate for minor failures Example: Three fuel sensors in the space shuttle external tank © 2013 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Technological Design