In situations where it is not possible to return samples to Earth for analysis, the presence of extraterrestrial life may be uncovered by making spectroscopic measurements. As described in Book 8, study of the atmospheres of ‘rocky' exoplanets is ideally what is required. Although this is not yet possible, as of 2010, results have been obtained from the direct imaging of an exoplanet known as HR 8799 c. Spectroscopic data obtained from the planet's atmosphere are shown in Figure 1 and give an impression of the kind of information that scientists have to work with.
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HR 8799 c spectrum
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Figure 1 Spectroscopic data obtained from the direct imaging of exoplanet HR 8799 c.
(i) Explain how spectroscopy could be used by astronomers to assess the habitability of exoplanets and how it might be used to decide whether or not they could have an active biosphere. (70-100 words)
(ii) State which region of the electromagnetic spectrum includes the range of wavelengths plotted on the x-axis of Figure 1 and explain why it would be preferable to site the telescope needed to make the measurements at very high altitude or in space. (Two or three sentences)