Monday, February 15, 2016
Evidence Found For Volcanoes On Venus
Graphic showing three outlines "hot spots" identified in infrared from European Space Agency's Venus Express spacecraft. gives evidence of ongoing volcanic activity.
The planet Venus, Earth's nearest solar system neighbor (closest approach at 28 million miles), has not been hospitable to Earth spacecraft. Several Russian Venera probes, in fact, lasted barely more than an hour after dispatching images. The conditions, a crushing atmospheric pressure and temperatures hot enough to melt lead (450C) were the contributing factors.
More recently other craft, which didn't land, have met with more success in their investigations. In 2006, for example, the European Space Agency's Venus Express visited the planet and used measurements of thermal radiation emitted from the surface to compile a topographic map. On account of the planet's atmosphere being so thick with greenhouse gases (mainly CO2) it was found that temperature fluctuations in the lower regions were minimal (temperature can also serve as an indicator of altitude since more fluctuations will be found where the greenhouse gas density is less dense).
Previous analyses by the ESA craft have disclosed evidence of tectonic and volcanic activity but had not confirmed whether the planet remains active today. However, new research published by Shalygin et al, Geophysical Research Letters, 2015, appears to show evidence for current and ongoing volcanic activity.
The ESA team used a camera adjusted to absorb infrared radiation (wavelength of 1.01 micrometers) from the dark side of the planet. These emissions were monitored from the surface and evidence for volcanic activity found. In particular, four "hot spots" - temperature anomalies - were identified over the course of 316 observational sessions that generated 2,463 images of the Ganis Chasma region.
By monitoring the precise locations and shapes of the bright spots as the spacecraft orbited, the team was able to conclude that the signal was coming from the planet's surface as opposed to its atmosphere. According to Shalygin et al, volcanic activity could be creating the hot spots - predicted to be between 520 C and 830 C, ranging in area from 1 to 200 square kilometers.
The team's findings are reinforced by the fact that the observed temperature anomalies all occurred in Ganis Chasma, an area of Venus' surface suspected to contain a range of geological activities. These include phenomena such as: faults, mantle upwelling and lithographic extension (a tectonic plate process) - which are the same mechanisms leading to volcanism on Earth.
The ESA team suspects the eruptions on the Venusian surface are somewhat contained by the planet's surface pressure which is 100 times that of our own. Because of the inordinately high pressure, volcanic eruptions are not so much explosive events like Mt. Saint Helens on Earth as slow, oozing effusions. Somewhat like the massive flows of hot mud out of the fumaroles at Yellowstone only thousands of times greater.
Note that such research is not at all detached and irrelevant but provides a deep insight into the geodynamics of our solar system. The more we learn about the other terrestrial type planets, including Venus and Mats, the more we stand to learn about the origin of our own.