ESA Portal - 2010 Apr 08
[youtube]http://www.youtube.com/watch?v=p3Wsxtnl ... r_embedded[/youtube]ESA’s Venus Express has returned the clearest indication yet that Venus is still geologically active. Relatively young lava flows have been identified by the way they emit infrared radiation. The finding suggests the planet remains capable of volcanic eruptions.
It has long been recognised that there are simply not enough craters on Venus. Something is wiping the planet’s surface clean. That something is thought to be volcanic activity but the question is whether it happens quickly or slowly? Is there some sort of cataclysmic volcanic activity that resurfaces the entire planet with lava, or a gradual sequence of smaller volcanic eruptions? New results suggest the latter.
NASA-Funded Research Suggests Venus is Geologically Alive
NASA JPL 2010-121 - 2010 Apr 08
For the first time, scientists have detected clear signs of recent lava flows on the surface of Venus.
The observations reveal that volcanoes on Venus appeared to erupt between a few hundred years to 2.5 million years ago. This suggests the planet may still be geologically active, making Venus one of the few worlds in our solar system that has been volcanically active within the last 3 million years.
The evidence comes from the European Space Agency's Venus Express mission, which has been in orbit around the planet since April 2006. The science results were laid over topographic data from NASA's Magellan spacecraft. Magellan radar-mapped 98 percent of the surface and collected high-resolution gravity data while orbiting Venus from 1990 to 1994.
Scientists see compositional differences compared to the surrounding landscape in three volcanic regions. Relatively young lava flows have been identified by the way they emit infrared radiation. These observations suggest Venus is still capable of volcanic eruptions. The findings appear in the April 8 edition of the journal Science.
This video still shows the volcanic peak Idunn Mons in the Imdr Regio area of Venus
(at 46 degrees south latitude, 214.5 degrees east longitude). (NASA/JPL-Caltech/ESA)
Indications of volcanic activity on Venus
DLR Portal - 2010 Apr 08
Fresh Signs of Volcanic Stirrings Are Radiating From VenusDLR scientists evaluate data from the VIRTIS infrared spectrometer
Although some uncertainty remains, the most recent infrared data from VIRTIS (Visible and Infrared Thermal Imaging Spectrometer) seem to confirm it. "We are pretty sure that Venus still has volcanic activity," say Jörn Helbert and Nils Müller from the DLR Institute of Planetary Research (Institut für Planetenforschung) – members of the VIRTIS team.
The European Space Agency's (ESA) Venus Express orbiter has been circling the planet, which is constantly obscured by thick cloud cover, since 11 April 2006. The spacecraft travels around the planet in an elliptical orbit at an altitude that varies from 300 to 66 000 kilometres. It carries VIRTIS, the only instrument that can look through the atmospheric windows onto the surface of Venus and record its infrared radiation patterns at a variety of heights.
- Science 9 April 2010: Vol. 328. no. 5975, p. 157, DOI: 10.1126/science.328.5975.157-a
In a paper published online this week in Science, researchers report new evidence that Venus is still reshaping its surface—as well as cooling its interior—through volcanic outpourings like Hawaii's or Iceland's. One contingent of planetary scientists has long held that most of the venusian surface renewed itself half a billion years ago in a single volcanic paroxysm and has been nearly dormant since, but the Science authors argue that Venus also resembles Earth in steadily resurfacing itself.
- Science DOI: 10.1126/science.1186785
The questions of whether or not Venus is geologically active and how the planet has resurfaced over the last billion years have major implications for interior dynamics and climate change. Nine "hot spots," areas analogous to Hawaii with volcanism, broad topographic rises, and large positive gravity anomalies suggesting mantle plumes at depth, have been identified as possibly active. This study uses variations in thermal emissivity of the surface by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on the ESA Venus Express spacecraft to identify compositional differences in lava flows at three hot spots. The anomalies are interpreted as a lack of surface weathering. We estimate the flows to be younger than 250 ky, and probably much younger, indicating that Venus is actively resurfacing.