Behind the Mission to Mercury

What You Need


  • Sketch paper and pencils for each student
  • Model materials such as: clay, paper clips, paper cups, cardboard, wire, glue, aluminum foil, plastic (or Glad) wrap, etc. Really any supplies will work, but be sure there are enough for eight small models.
Behind the Mission to Mercury


To assess the goals, benefits, success, and limitations of technology (instruments) on a space mission.


Science for All Americans states, "We use technology to try to change the world to suit us better." The changes range from mere survival to human aspirations. This lesson takes a look at how technology helps society realize its aspirations through space exploration. It also takes a step back to look at the planning involved in testing and assessing the technology for such a mission.

The lesson revolves around the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft mission to Mercury. Students will read about the real mission first and discuss the instruments and spacecraft. They will touch on how one can take measures before a mission to ensure success in both design and the mission itself.

The development starts with an interactive called Make a Mission, which asks students to prepare a spacecraft for a mission to the planet Mercury. This interactive emphasizes cost and design constraints.

The assessment is a culmination of what students have learned throughout the lesson. Students are assigned to a task force. Each team takes on the planning and design of an instrument. They need to look at, and plan for, the big picture of a mission—from sketches and goals of the instrument to the success and goals of the mission. This portion of the lesson also recommends that students build models to check the design of their instrument.

Perhaps the best way to become familiar with the nature of engineering and design is to do some. By participating in such activities, students should learn how to analyze situations and gather relevant information, define problems, generate and evaluate creative ideas, develop their ideas into tangible solutions, and assess and improve their solutions. To become good problem solvers, students need to develop drawing and modeling skills along with the ability to record their analysis, suggestions, and results in clear language. (Benchmarks for Science Literacy, p. 48.)

Though this lesson stands on its own, it would complement other science studies in the areas of space science, geology, design, and technology.

Planning Ahead

You and your students may want to read:

  • Why Mercury?, part of the MESSENGER site. It gives a good overview of the planet.
  • Nature of Technology is an essay from chapter 3 of Science for All Americans that covers the importance of technology.


Have students go to the Behind the Mission to Mercury student esheet. There, they will be instructed to read about the Mission to Mercury at Mercury the Mission. After that reading, they should click on Mercury: The Key to Terrestrial Planet Evoltuion and finally, Spacecraft Design. These pages show a menu running down the left side of the page. If time allows, students should be encouraged to read more about MESSENGER by clicking on different menu items.

After they are finished reading, put the MESSENGER Mission into the larger context of space exploration by asking these questions:

  • How will this mission help us learn about earth and the solar system as a whole? 
    (The main focus is to learn about the planet itself and its makeup, but students should be able to delve into deeper reasoning. For example, solving mysteries about Mercury will help us learn about the other planets in our solar system, including Earth and how it may have formed and evolved. Students may or may not see the importance of the bigger picture, but either way it should be touched on before getting into the details of this lesson.)

Now discuss the mission itself:

  • What are the goals of the MESSENGER Mission?
    (The scientific goals of the mission are to investigate six key scientific questions about Mercury's characteristics and environment with a set of miniaturized space instruments. The six questions are: (1) Why is Mercury so dense? (2) What is Mercury's geologic history? (3) What is happening to Mercury's core? (4) What is the nature of Mercury's magnetic field? (5) What are the unusual materials at Mercury's poles? (6) What is the nature of Mercury's atmosphere?)
  • When scientists and engineers did the initial planning for this mission, what do you think they had to take into consideration?
    (From the readings alone, students should be able to come up with several answers. Here are some ideas: (1) Where Mercury is and how the conditions of the planet may dictate what kind of research can be done. For instance, we can put robots on Mars, could we put them on Mercury? (2) The design of the spacecraft and the instruments on board. How do the size and mass affect the mission as well as the cost? (3) In order to make the mission efficient, gravity assistance is used. (4) Cost.)

Once students are done brainstorming, focus the conversation on design. Introduce these ideas/questions:

  • Consider the X-Ray Spectrometer. Do you think that the people planning this mission had to consider how much money it would cost to build it?
    (Yes, is the obvious answer, but this question gives you an opportunity to establish that projects like MESSENGER always have a budget. When the Mars Missions are mentioned in the news, often the amount of money the missions cost is mentioned as well.)
  • What if you only had a certain amount of money, and you had to spend less on the X-Ray Spectrometer or on other instruments? What are some considerations when making your choice?
    (Here you may want to go off track a little to make the point and direct the conversation to real-life examples. Do students ever have to make decisions about purchases because of cost? If so, what are the tradeoffs? Perhaps most students can relate to a good pair of jeans or sneakers [but let students choose any items they wish to discuss…all count]. Discuss if the designs and/or durability are compromised with cost. With clothes, some students may go for name brands, which may not necessarily mean that they are comfortable, or will last longer. With, say a good pair of sneakers for a specific sport, like running, spending more may result in better comfort. The variations are endless. The point is to have students consider whether or not it pays to spend more, and that they may need to consider different aspects of an item when purchasing. There are no right or wrong answers for this discussion.)
  • How could you find out about the life and quality of the instrument, before it is built?
    (This may not be intuitive to students. It will depend on how technologically savvy they are. For instance, some students may know what computer simulations are, but some may not. In a basic sense, you want to be sure that students at least know that things should be tested in order to assess their performance. Brainstorm different ways for testing. Even take some of the real-life examples they've just discussed and talk about how they could be tested. For instance, how could running shoes be tested? The benchmark mentions small-scale models, computer systems, and parts of the system thought to be least reliable.)
  • What are other limitations for all of the instruments for this mission?
    (Because of the fuel expense and the size of the spacecraft, size and weight are definite limitations.)
  • What is the point of testing the performance of an instrument before the mission?
    (Discuss how failure of an instrument could result in failure of a mission. How can this be prevented?)


Students should continue to follow the instructions on the Behind the Mission to Mercury student esheet. The first part of the Development of the lesson is an interactive, called MESSENGER: Mission to Mercury. Students will plan which pieces of scientific equipment they will need on board the spacecraft in order to complete the goals of a mission successfully. The equipment must not only fit on the spacecraft, but the cost of the equipment must also fall within a specified budget. Students are asked to stop for discussion after part one.

Ask students:

  • Why are the instruments an important factor in meeting the goals of the mission?
    (In general, learning about Mercury could not be achieved without the instruments. Specifically, instruments will take pictures, measure chemicals and elements, search for magnetic regions, learn about the geology, measure gases in the atmosphere, and measure energy and particles in the magnetic fields. Students may bring up other ideas from the MESSENGER Mission and that is fine, as long as the importance of the instruments is understood.)
  • What are some of the goals of the mission and how specifically did you meet them?
    (The goals are to collect different data sets, which are achieved by the use and success of the instruments.)
  • What constraints did you notice when planning for this mission?
    (The two main constraints for this interactive are cost and design. See if students can further their earlier thoughts from the Motivation. Were they surprised about the limitations of space and money? Do they have any ideas about overcoming these limitations?)
  • Were there tradeoffs when trying to make the mission work?
    (Tradeoffs is an important topic that hasn't been discussed yet. There are tradeoffs with every project. For this one, staying within the budget may mean doing the mission differently. Try to explore other tradeoffs that students may expect when planning a mission to a planet.)

For part two of the Development, assign teams the task of proposing, testing, and designing an instrument for the Mercury Mission. There are general directions for students on the student esheet. Students also should use the Proposal Guidelines for Mercury Mission Instruments student sheet to help guide them in this part of the lesson. Prior to sending them back to their esheet, however, you will need to divide your class into eight groups and assign each group an instrument from the list below. Each team will be asked to propose and create blueprints for an instrument.

  • Mercury Dual Imaging System (MDIS)
  • Gamma-Ray and Neutron Spectrometer (GRNS)
  • Magnetometer (MAG)
  • Mercury Laser Altimeter (MLA)
  • Mercury Atmospheric and Surface Composition Spectrometer (MASCS)
  • Energetic Particle and Plasma Spectrometer (EPPS)
  • X-Ray Spectrometer (XRS)
  • Radio Science (RS)

You should stress that even though these instruments exist with specific goals for the real mission, students should be as creative as possible. They are free to add to the goals of the instrument or even change the instrument in any way. As long as the instrument helps the overall mission, they should not feel constrained in any way to do exactly what the mission instruments do.


Students are asked to reflect back on the lesson and answer these questions:

  • What are some of the consequences that came about due to choices that you made during any part of the lesson (in other words, either during the interactive or during the proposal writing)?
  • What are some of the things scientists and engineers must think of when designing an instrument for a space mission?
  • When planning for a mission, what are some of the ways the team can ensure a successful mission?

These questions are written directly from each of the benchmarks focused on in this lesson, however the answers should not read like the benchmarks. They should demonstrate that the student has a full understanding of the readings, and a better understanding of what it takes to plan for a mission to space. Students could feasibly write a page on each question. You should see that your students' thoughts have progressed from the initial Motivation questions.


Exploration for advanced students:
One of the considerations when planning MESSENGER was the path the spacecraft would take to Mercury and Mercury's position, or location, when the spacecraft would reach the planet. The major axis of Mercury's elliptical orbit about the sun precesses by 37 seconds of arc per century. This was explained by Einstein's general theory of relativity as a consequence of the curvature of spacetime near the sun generated by the sun's mass. Corrections to the path of MESSENGER will have to take this spacetime curvature into account. The following site, Orbits in Strongly Curved Spacetime, describes this phenomenon.

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