From observations before Mars Express we knew that the Martian atmosphere is about one hundred times less dense than the Earth’s at ground level, that it’s composed almost entirely of carbon dioxide (CO2) with trace to small amounts of other gases, and that atmospheric temperatures range from 298 K (+25°C) at the equator to 140 K (-130° C) at the winter pole. We also know that the atmosphere contains a lot of dust. But there were many gaps in our knowledge, like how temperature and pressure vary with altitude, what the global circulation patterns are, how the composition of the atmosphere varies with time and place, and what all the trace constituents are. We also don’t know for sure how much dust there is in the atmosphere, how it’s transported there, what it’s made of and how it affects the Martian weather. PFS is helping find the answers to some of these outstanding questions.
PFS Scientific principles
PFS identifies complex molecules from the wavelengths the molecules absorb from sunlight and from the infrared radiation (heat) they emit, taking measurements over the wavelength range 1.2-45 µm and making it best suited for identifying molecules in the atmosphere. PFS is complementar to OMEGA that has a similar principle over a narrower range of wavelength but qith a better spatial resolution, which makes it good for imaging the composition of the surface.
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