NASA-Funded Research Suggests Venus is Geologically Alive
WASHINGTON -- 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.
"The geological history of Venus has long been a mystery," said Sue
Smrekar, a scientist at NASA's Jet Propulsion Laboratory in Pasadena,
Calif., and lead author of the paper describing the work. "Previous
spacecraft gave us hints of volcanic activity, but we didn't know how
long ago that occurred. Now we have strong evidence right at the
surface for recent eruptions."
The volcanic provinces, or hotspots, on which Smrekar and her team
focused are geologically similar to Hawaii. Scientists previously
detected plumes of hot rising material deep under Venus' surface.
Those plumes are thought to have produced significant volcanic
eruptions. Other data from the planet suggest that volatile gases
commonly spewed from volcanoes were breaking down in its atmosphere.
The rate of volcanism will help scientists determine how the interior
of the planet works and how gases emitted during eruptions affect
climate.
Something is smoothing Venus' surface because the planet has only
about 1000 craters, a relatively small amount compared to other
bodies in our solar system. Scientists think it may be the result of
volcanic activity and want to know if it happens quickly or slowly.
The Venus Express results suggest a gradual sequence of smaller
volcanic eruptions as opposed to a cataclysmic volcanic episode that
resurfaces the entire planet with lava.
Smrekar and her team also discovered that several volcanic features in
the regions they studied show evidence of minerals found in recent
lava flows. These mineral processes correspond to the youngest
volcanic flows in each region, giving scientists additional support
for the idea they formed during recent volcanic activity. On Earth,
lava flows react rapidly with oxygen and other elements in the
atmosphere when they erupt to the surface. On Venus, the process is
similar, although it is more intense and changes the outer layer more
substantially.
Scientists call Venus Earth's sister planet because of similarities in
size, mass, density and volume. Scientists deduce that both planets
shared a common origin, forming at the same time about 4.5 billion
years ago. Venus also is the planet on which the runaway greenhouse
effect was discovered. The planet is cloaked in a much less friendly
atmosphere than Earth. It is composed chiefly of carbon dioxide,
which generates a surface temperature hot enough to melt lead and a
surface pressure 90 times greater than that on Earth.
The small group of worlds in our solar system known to be volcanically
active today includes Earth and Jupiter's moon Io. Crater counts on
Mars also have suggested recent lava flows. Scientists are studying
evidence of another kind of active volcanism that involves
ice-spewing volcanoes on other moons in our solar system.
NASA sponsored Smrekar's research. The European Space Agency built and
manages Venus Express.
To view the spacecraft data and images, visit:
http://www.nasa.gov/topics/
Source: NASA
