JOINT PRESS RELEASE: ESA/EPSC-DPS JOINT MEETING 2011
ISSUED 13:15 CEST ON THURSDAY 6TH OCTOBER
Ref. PN: EPSC11/11
ESA finds that Venus has an ozone layer too
ESA’s Venus Express spacecraft has discovered an ozone layer high in the atmosphere of Venus. Comparing its properties with those of the equivalent layers on Earth and Mars will help astronomers refine their searches for life on other planets. The results are being presented today at the Joint Meeting of the European Planetary Science Congress and the American Astronomical Society's Division for Planetary Sciences.
Venus Express made the discovery while watching stars seen right at the edge of the planet set through its atmosphere. Its SPICAV instrument analysed the starlight, looking for the characteristic fingerprints of gases in the atmosphere as they absorbed light at specific wavelengths.
The ozone was detectable because it absorbed some of the ultraviolet from the starlight.
Ozone is a molecule containing three oxygen atoms. According to computer models, the ozone on Venus is formed when sunlight breaks up carbon dioxide molecules, releasing oxygen atoms.
These atoms are then swept around to the nightside of the planet by winds in the atmosphere: they can then combine to form two-atom oxygen molecules, but also sometimes three-atom ozone molecules.
“This detection gives us an important constraint on understanding the chemistry of Venus’ atmosphere,” says Franck Montmessin, who led the research.
It may also offer a useful comparison for searching for life on other worlds.
Ozone has only previously been detected in the atmospheres of Earth and Mars. On Earth, it is of fundamental importance to life because it absorbs much of the Sun’s harmful ultraviolet rays. Not only that, it is thought to have been generated by life itself in the first place.
The build-up of oxygen, and consequently ozone, in Earth’s atmosphere began 2.4 billion years ago. Although the exact reasons for it are not entirely understood, microbes excreting oxygen as a waste gas must have played an important role.
Along with plant life, they continue to do so, constantly replenishing Earth’s oxygen and ozone.
As a result, some astrobiologists have suggested that the simultaneous presence of carbon dioxide, oxygen and ozone in an atmosphere could be used to tell whether there could be life on the planet.
This would allow future telescopes to target planets around other stars and assess their habitability. However, as these new results highlight, the amount of ozone is crucial.
The small amount of ozone in Mars’ atmosphere has not been generated by life. There, it is the result of sunlight breaking up carbon dioxide molecules.
Venus too, now supports this view of a modest ozone build-up by non-biological means. Its ozone layer sits at an altitude of 100 km, about four times higher in the atmosphere than Earth’s and is a hundred to a thousand times less dense.
Theoretical work by astrobiologists suggests that a planet’s ozone concentration must be 20%of Earth’s value before life should be considered as a cause.
These new results support that conclusion because Venus clearly remains below this threshold.
“We can use these new observations to test and refine the scenarios for the detection of life on other worlds,” says Dr Montmessin.
Yet, even if there is no life on Venus, the detection of ozone there brings Venus a step closer to Earth and Mars. All three planets have an ozone layer.
“This ozone detection tells us a lot about the circulation and the chemistry of Venus’ atmosphere” says Håkan Svedhem, ESA Project Scientist for the Venus Express mission.
“Beyond that, it is yet more evidence of the fundamental similarity between the rocky planets, and shows the importance of studying Venus to understand them all,.”
Contact for further information:
ESA Science and Robotic Exploration Communication Officer
Tel: +31 71 565 6799
Mob: +31 61 594 3 954
LATMOS – UVSQ/CNRS/IPSL, France
Tel: +33 1 80 28 52 85
ESA Project Scientist Venus Express
Notes for Editors:
F. Montmessin, et al., “A layer of ozone detected in the nightside upper atmosphere of Venus”, Icarus, 216, Issue 1, November 2011, pp82-85, DOI: 10.1016/j.icarus.2011.08.010
EPSC-DPS JOINT MEETING 2011
The EPSC-DPS Joint Meeting 2011 represents the first cooperation between the European Planetary Science Congress (EPSC) organised by the Europlanet Research Infrastructure and the Division for Planetary Sciences of the American Astronomical Society. The meeting is being organised in association with the European Geosciences Union and with the support of the Université de Nantes. More than 1800 abstracts for oral presentations and posters have been submitted for the meeting.
EPSC-DPS 2011 provides a platform for the worldwide planetary sciences community to exchange and present results, develop new ideas and network. It has a distinctively interactive style, with an extensive mix of talks, workshops and posters, intended to provide a stimulating environment for the community to meet. The meeting covers the entire scope of the planetary sciences.
Details of the congress can be found at the official website:
A session overview is available at:
The Europlanet Research Infrastructure is a major (€6 million) programme co-funded by the European Union under the Seventh Framework Programme of the European Commission.
Europlanet’s Networking Activities provide European planetary scientists with the opportunity to define key science goals, and to exchange ideas and personnel. Europlanet provides TransNational Access to leading laboratory and field site facilities tailored to the needs of planetary research for Planetary Sciences, developing them further through highly focused Joint Research Activities. It is building a Virtual Planetary Observatory where all types of planetary data can be accessed.
The Division for Planetary Sciences (DPS) of the American Astronomical Society (AAS) is the largest organization of professional planetary scientists in the world. The DPS was formed in 1968 as a sub-organization within the AAS devoted to solar system and extrasolar planet research. Today it is the largest special interest Division of the AAS.
DPS Website: http://dps.aas.org/