Crash Landing! Teacher Answer Key
This activity was designed to create an open-ended discussion of what makes a planet
habitable. There are no definitive answers to this part of the activity; however, there are
some selections that are better than others. For the terrestrial organisms that are more
familiar to us, cases can be made for choosing Planet 3, Planet 4, and even Planet 2.
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Planet 4 is probably the best choice. It is fairly cold, but has oxygen present in the
atmosphere, indicating that it may have life already in residence. Planet 4 has
ozone, and therefore offers protection from UV radiation.
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Planet 3 is on the warm side, but has oceans of liquid water, which give it an
Earth-like appearance.
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Planet 2 is too small to maintain much of an atmosphere, but has a habitable
temperature and polar ice caps that indicate there might be a source of water.
For the extremophiles, the cases made will be a little different.
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Cases could be made for the moons of Planets 5 and 7, since they have extreme
environments that seem similar to the Earth environments of the extremophiles.
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Planets 3 and 4 are reasonable choices for the extremophiles as well, since the
presence of tectonic activity allows for the possibility that hydrothermal vents
exist on the planets.
Planet 4, in general, appears to be suited to all of the organisms in this activity, and many
groups will likely choose this planet. But, encourage students to use all they have learned
in the module to think about the planets, and about what might make one a better choice
than another.