New Evidence Suggests Venus Is Volcanically Active（在线收听）

New Evidence Suggests Venus Is Volcanically Active

Scientists say examinations of old images provide new evidence that the planet Venus is volcanically active.

The finding is based on radar images captured more than 30 years ago by the U.S. space agency NASA's Magellan spacecraft.

NASA calls Magellan one of the agency's "most successful deep space missions." The spacecraft became the first to capture images of the whole surface of Venus during a five-year mission that began in 1989. It also made other discoveries about the planet.

Scientists reported the new findings about Venus in a study in the publication Science.

The area of Venus the team studied had long been thought to be volcanically active. But the latest study suggests the new examination of images provided the first direct evidence of more recent volcanic activity on the planet.

The researchers looked at images that Magellan captured in the 1990s. The images showed volcanic openings on the surface of Venus that appeared to change shape and size in less than a year, the team reported.

It is important for scientists to study active volcanoes in an effort to understand more about what is happening below the planet's surface, NASA said in a statement. Volcanic activity can greatly affect how a planet grows and develops over time.

Robert Herrick is a research professor at the University of Alaska Fairbanks. He is also a leader of a team preparing for an upcoming NASA mission to Venus. The mission, involving an orbiter called VERITAS, is expected to launch within 10 years.

NASA says the orbiter will study Venus from the surface to core in an effort to understand this rocky planet about the same size as Earth.

Herrick said in a statement that NASA's planned VERITAS mission is what led him to look for recent volcanic activity based on the old Magellan images from the 1990s.

The changes the team discovered were found in an area of Venus called Alta Regio. The area sits near the planet's equator and contains two of the planet's largest volcanoes.

The researchers said radar images taken by the Magellan spacecraft showed that a volcanic vent on the surface about 1.6 kilometers wide had expanded and changed shape over an eight-month period in 1991. The vent sits on Maat Mons, the planet's highest volcano.

An image from February 1991 showed the vent as a circular formation covering about 2.6 square kilometers. An October 1991 image showed the vent with an irregular shape covering about 3.9 square kilometers.

Herrick said the images provide new evidence of volcanic changes on the planet's surface. He said they clearly demonstrate that the volcanic vent got larger and looks to have changed from a circular shape to nearly flat.

Herrick added that examinations of the images suggest a large amount of magma entered an area underneath the vent in a rocky collapse. The result, he said, was the formation of a wide, irregular area likely created by volcanic activity. Herrick said the area "still has an active lava lake in it when the second image is taken."

Scott Hensley is a senior research scientist specializing in radar sensing technology at NASA's Jet Propulsion Laboratory in California. He told the Reuters news agency it is possible the vent collapse was not linked to active volcanism. But he thinks that in this case, volcanic activity is the best explanation for the changes seen in the old images of Venus' surface.

The new findings were made possible because of progress made in recent years in imaging examination technologies.

The data suggests there are volcanic eruptions on Venus about every few months. That is similar to some volcanoes here on Earth in places like Hawaii, the Canary Islands and Iceland, Herrick said.

Words in This Story

mission – n. a flight by an aircraft or spacecraft to perform a specific task

core – n. the center of a planet

vent – n. a hole in something that lets air and other materials in

manual – n. using your hands to do something

erupt – v. to suddenly throw out smoke, fire and melted rocks