October 10, 2014

SPICAV results

Venus observed from its surface to the high atmosphere

A new episode of active volcanism on Venus?

Graph of sulphur dioxide abundance
Graph of sulphur dioxide abundance
Copyright : E. Marcq et al. (Venus Express) ; L. Esposito et al. (earlier data)

For decades, planetary scientists have debated whether Venus possesses active volcanoes. The latest twist to the tale is provided by data sent back from ESA's Venus Express orbiter, revealing unexplained major changes in the amount of sulphur dioxide gas above the planet's dense cloud layer.
By studying the SPICAV data, a team of scientists from France and Russia has discovered an unusual change in the amount of sulphur dioxide (SO2) gas in the upper atmosphere.
The SPICAV data show that the concentration of SO2 above the main cloud deck increased slightly to about 1000 parts per billion by volume (ppbv) between 2006 and 2007, but then steadily decreased over the next five years, reaching only 100 ppbv by 2012. This is very reminiscent of a pattern observed by Pioneer Venus during the 1980s, the only other multi-year dataset of SO2 measurements.

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Tenuous ozone layer discovered in Venus' atmosphere

 ESA/AOES Medialab
This artist's impression of planet Venus highlights the spots where the molecule ozone (O3) has been detected in the planet's atmosphere. The discovery relies on observations performed with the SPICAV instrument on board ESA's Venus Express. Credits: ESA/AOES Medialab

Using observations of Venus performed with an instrument on ESA's Venus Express scientists have detected, for the first time, a tenuous layer of ozone in this planet's atmosphere. Located at an altitude of about 100 km, the layer is a thousand times less dense than the one found, at a lower altitude, in the Earth's stratosphere, but both are dominated by very similar chemical reactions. The discovery poses new challenges to the characterisation of planetary atmospheres, especially in the quest for biomarkers on extrasolar planets.

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