When NASA’s Solar Probe Plus launches in 2015, it will need to withstand temperatures of 2,600 Fahrenheit as it orbits four million miles from the sun’s center and samples the edge of the corona, the sun’s atmosphere.
The Solar Probe Plus will take measurements and photographs in hopes of answering two questions: Why is the sun’s corona so much hotter than its visible surface? How is the solar wind accelerated?
To get this close to the sun, the unmanned probe must be carefully designed for this environment of high heat and radiation. The current design features a carbon-carbon frame layered around foam and a sunshield to help keep the instruments in the space probe as cool as possible.
1. Ask students to imagine that they are going to a trip to the desert. Give students 30 seconds to make a list of the supplies and clothing they would want to take with them. Discuss some of the possibilities. Now ask students to imagine that they are going on a trip to the sun. Again give students 30 seconds to make a list of the supplies and clothing they would want to take with them. Discuss the students’ responses.
2. The sun is our closest star, yet there is much we don’t know about it because its high temperature makes it difficult to get close. Pass out copies of “Just Ask: Probing the Sun ... How Close Can We Get?” (http://www.pbs.org/newshour/rundown/2010/12/just-ask-flying-into-the-sun.html).
As students read, ask them to underline information about the mission goals and the current space probe design. Discuss the article. What variables are important to consider when designing a spaceship that will go close to the sun? How close has a spacecraft gotten to the sun? How close will the Solar Probe Plus get to the sun? What is the goal of the mission? What is the space probe’s current design?
3. Tell students that they have been asked to improve upon the current probe design. Show students an artist’s interpretation of the probe from the Solar Probe Plus Fact Sheet (http://solarprobe.jhuapl.edu/common/content/SolarProbePlusFactSheet.pdf). The probe must be engineered to keep the instruments on board at room temperature even as the temperatures around the probe exceed 2,600 Fahrenheit (1427 Celsius).
Experimenting with Heat
1. Tell students that before they can decide on their spacecraft design, they must first know more about heat and heat transfer.
2. Before class, prepare two identical beakers of water. One should contain very hot water. The other should hold very cold water. Place both in a place where they can be easily seen but not touched.
3. Ask students to devise a plan to determine which glass holds the hot water and which hold the cold water without getting close to the beakers. Give students a few minutes to brainstorm with a partner. Ask for suggestions.
4. Drop a few drops of food coloring into each glass (from a distance above). Point out that in one glass the food coloring is spreading quickly and in the other it is spreading very slowly. Ask if this observation can help identify which cup is hot and which is cold.
5. Explain that when a substance is hot, the atoms in the substance are moving faster than when the substance is cold. Therefore, the molecules in the hot water are moving and vibrating more than those in the cold water. This pushes around the dye causing it to spread out more quickly in the hot water. When the atoms in a “hot” area hit atoms in a cooler area, they pass this energy along causing the heat to spread.
6. Pass out the Worksheet 1 – Understanding Heat Transfer. Divide students into teams of 4. Each group will need: a hot plate, a 500 mL glass beaker, a metal spoon, a plastic spoon, a glass rod, a wooden spoon, glitter, a tea candle, and matches. Ask students to work through the lab to learn about the different ways heat travels.
Redesigning the Probe
1. Discuss the lab. Review the concepts of convection, conduction, and radiation.
2. Remind students that they will be using this information to improve the design for the Solar Probe Plus.
3. Divide students into groups of two. Pass out Worksheet 2 – Probe Design. Students will need connection to internet.
4. Ask students to work through the worksheet to design their own space probe.
1. Divide the class into competing groups. Ask students to use recycled materials to build a thermos to keep water hot. The groups will compete to see which team’s thermos keeps water hot the longest.
2. Living things depend on energy from the sun. Research the sun. How does the sun produce this energy? What does the inside of the sun look like? What substances make up the sun? How does the heat move from the center of the sun to the planets? Write up your research.