Planetary Science

With the discovery of an elusive band of infrared emissions spectra in Venus' atmosphere, astronomers now have a tool to monitor key species associated with "nightglow" in planetary environments.

Emissions from numerous chemical species create a pervasive atmospheric nightglow that surrounds Venus, as well as Earth and Mars. The glow is generated in part by ultraviolet emissions accompanying the recombination of nitrogen and oxygen to form nitric oxide.

Scientists have known from lab experiments that a characteristic group of near-IR emissions, which provide additional data, must also accompany the UV emissions created during NO production. But the near-IR emissions have been difficult to detect in planetary atmospheres.

Now, a sensitive instrument aboard the European Space Agency's Venus Express spacecraft has detected these near-IR emissions, which come not only from NO but also from molecular oxygen (Proc. Nat. Acad. Sci. USA, DOI: 10.1073/pnas.0808091106).

Antonio García Muñoz of Australian National University, in Canberra, and colleagues say this new realm of potential spectral exploration could prove profoundly useful to planetary scientists.

The researchers believe that the ability to observe near-IR spectra will make it possible to simultaneously monitor NO and O₂ and their transport throughout the planet's atmosphere. This could "help refine global circulation models of the venusian atmosphere," notes Brian Sharpee, an astronomer at Stanford Research Institute, in Menlo Park, Calif.