Choosing a Topic:

The theme of the paper is Planetary Exploration. The assignment is to write a proposal for exploration of a planetary body in the Solar System by an unmanned spacecraft. Your spacecraft may include a "probe" or "lander" (instruments sent to the atmosphere or surface of the planetary body) or "orbiter" (instruments that stay in orbit around the planetary body, and make measurements from there). The exploration must focus on a particular aspect of the planetary body, for instance, atmospheric composition, or potential for life, or the history of impact craters. You may choose one of the following suggested topics or you may define a new one. If you wish to choose a topic that is not on this list, the topic must be approved in advance by your TA. Acceptable topics are restricted to features within our Solar System. Topics related to the Sun itself are not relevant - Remember the theme is Planetary Exploration (including satellites, rings, and other planetary objects).

Suggested Mission Objectives: The "Mission Objective" is a statement of the scientific and technical goals of the mission. A variety of different missions are suggested below. These suggested missions are organized by topic (for instance, planetary atmospheres) and by planetary body (for instance, Jupiter). As you read more about the topic you chose, you will find that some missions require sending instruments into contact with the atmosphere or surface (probes) while some observations are better accomplished from the vantage point of space (orbiters).
    The topics and questions listed below are provided to jump-start your thinking.  You can find other topics and under-answered questions in your textbook or on a variety of websites. 

I. Missions involving weather and atmospheres:

Suggested possible destinations for one of these missions: Jupiter, Saturn, Uranus, Neptune, Mars, Venus, Triton, or Titan.

Determine the structure and composition of a planetary object's atmosphere:

• How do the temperature and pressure vary with depth?
• What is the composition of the atmosphere?
• Are there any clouds, and if so, what are they like?
• How many cloud layers exist?
• Where are the clouds located?
• What is the size and density of the cloud particles?
• Measure winds in the atmosphere:
• How deep within the atmosphere do winds exists?
• How fast are the winds blowing?
• Is there lightning in the planetary atmosphere?
• How energetic is it?
• At what level in the atmosphere does it occur?
• How frequently does lightening occur?

II. Missions involving current or past geologic activity on the surface of a planetary object such as volcanoes, faulting, mountain-building, or erosion.

Good possible destinations for one of these missions: Mars, Venus, Europa, Io, Ganymede, Miranda, Titan, Enceladus, Pluto.

• Is there current or recent volcanic activity on the planet?
• Can lava flows be identified from space?
• What is the distribution of lava flows?
• What type of volcanic activity is seen (explosive, basaltic, etc.)?
• Are volcanic gases evident in the atmosphere?
• Is the planetary body tectonically active?
• Are faults observed?
• If so, are they currently active?
• Do earthquakes occur on this planetary body?
• Are rift zones observed? Do they extend across large regions of the planet?
• What is the distribution of impact craters on the surface of the planetary object? (Mercury would also be a good destination for this mission)
• Are there more craters in some regions than others?
• How often are large craters vs. small craters found?
• What is the morphology of craters on this surface?
• Have the craters been modified since formation? If so, how?
• What do these observations say about the geologic history?
• What is the chemical composition of the surface of the planet?
• Depending on the planetary body being studied, important questions can include:

  Is there water (in liquid or ice form) on the surface?

  What are the rocks or ice composed of?

  What is the concentration of heat producing elements (Uranium, Potassium, Thorium) in the rocks or ice?

  Is there evidence for erosion on the surface?

  Are wind streaks visible? If so, where?

  Are dunes observed?

  Is there evidence for surface water in the past? Was it everywhere?

  Have landslides occurred?

III. Missions involving the origin of life:

Best possible destinations for one of these missions: Mars, Europa, Titan

• Could the soil (if any) sustain life (past or present)?
• What is the soil composition in one or more locations on the surface?
• What is the best place to land on Mars to determine the possibility of past life?
• Are complex, organic molecules currently present in the soil?
• Is there a source of water and energy to sustain life?
• Is water present in liquid form, or was it in the past? If so, where?
• Is the any evidence for submarine volcanic activity? (this is relevant to Jupiter's moon, Europa).
• What is the composition of the atmosphere, if any?
• Are complex organic molecules found there?
• Is water present?

IV. Missions involving interaction among planetary bodies:

Best possible destination for one of these missions: Rings of Saturn, rings of Uranus, Asteroid Belt, Pluto and its moon Charon.

Rings

• What is the structure of the rings?
• Search for the small moons called "shepherding satellites" that are thought to create the gaps in rings (shepherding satellites have been identified for some, but not all, of the gaps in Saturn's rings)
• What is the composition of the ring particles?
• What is the size distribution of ring particles?
• Do the composition and size distribution of particles vary among different rings
• Where are braided structures observed?
• Do they change through time?

Investigate the geology of one of the larger asteroids. Good candidates for a close approach or lander include: Ceres, Vesta, Pallas, Davida, Gaspra (Gaspra was already approached and photographed by the Galileo spacecraft), Braille (Braille has recently been visited by Deep Space 1), or Eros (first reached on Valentine's Day, 2000 and landed upon in early 2001).

• What is the composition of the surface rocks of the asteroid?
• Are impact craters observed on the asteroid? If so, what is the morphology of the craters?
• What is the mass of the asteroid (can be determined from its gravitational pull on the spacecraft). What does the mass indicate about the composition of the asteroid?
• Is the asteroid similar to meteorites which have fallen to Earth? If so, which type of meteorite?

Investigate the composition and interaction of Pluto, the most remote planet, and its moon, Charon.

• What are the surface compositions of Pluto and Charon? Are they similar or different?
• Do the surfaces show evidence for recent or current geological activity?
• Does either object have an atmosphere? If so, what is it composed of?
• How does the orbit of Charon about Pluto affect each of these planetary objects?
• What is the rate of spin of the two objects (the length of a Pluto-day and a Charon-day)?

V. Missions involving magnetic fields

Best locations: Jupiter, its moons Io or Ganymede, or Saturn, Uranus, or Neptune

• Characterize the magnetic field of the planetary body
• What is the strength of the magnetic field?
• Is the magnetic field centered in the middle of the planet?
• Does the magnetic field vary with time?
• In the case of Jupiter's moons, is the magnetic field of the moon altered by the strong magnetic field of nearby Jupiter?
• How can the nature of the magnetic field be used to infer the structure of the interior of the planetary body?

VI. Missions involving comets:

Best locations: A rendezvous with any good-sized comet in the inner solar system.

• What is the nucleus of the comet like?
• What is the composition of the comet?
• What is the density of the comet nucleus?
• What is the shape of the comet?
• How large is the nucleus?
• What is the tail of the comet like?
• What is its overall composition?
• Are complex, organic molecules present in the comet tail?
• How does the tail form?

Once you have chosen a destination and a mission objective, you must explain how the mission will go about achieving that objective. You will need to read about what is currently known about the proposed destination, and what questions remain unanswered. What measurements must be made to answer the questions posed? For instance, to measure atmospheric pressure would require a barometer. The type of spacecraft sent must be picked (orbiter vs. probe). For instance, to characterize cloud layers in the atmosphere of Jupiter, an atmospheric probe might be required. To map active volcanoes on Jupiter's moon Io, on the other hand, an orbiting spacecraft might provide a more comprehensive view. Furthermore, you'll need to send along an instrument package to achieve your mission objectives. A review of available instrumentation can be found at scientific instruments.

If you find out in your research that NASA already has a mission planned that is similar to your proposed mission, then don't ignore it. Describe briefly the goals of NASA's mission, then design yours so that it becomes complimentary to the NASA mission. How will the measurements, observations and objectives of your mission increase our knowledge beyond that of the primary mission by NASA? (We'll permit a certain amount of overlap between your mission and that of NASA.)