VOA科学技术2024--New Study Examines Whether Venus Had Liquid Water

（单词翻译）

A new study suggests that Venus likely never had water flowing on its surface. The research was based on data related to the chemical makeup¹ of the planet's atmosphere.

Scientists have long considered whether Venus once held liquid water, even possibly large oceans. Such research was based on the fact that Venus is like our own planet in many ways. It is a rocky planet similar in structure and size to Earth and is also our closest planetary neighbor.

But the latest study provides evidence that Venus has likely always been the hot, extremely dry planet it remains² today. Researchers from Britain's University of Cambridge led the study. It recently appeared in the publication Nature Astronomy.

The researchers' data examinations led them to conclude that both the surface and interior of Venus remain dry. The team said the strongest evidence that Venus once had large amounts of water would be the discovery of some water inside the planet today. But the study provided no evidence of that.

Since water is considered an important element for supporting life, the researchers also suggest that Venus was likely never habitable, or able to support life.

The lead writer of the study was Tereza Constantinou, a doctoral student at the University of Cambridge's Institute of Astronomy. She told Reuters news agency, "We suggest that a habitable past would be associated with Venus' present interior being water-rich, and a dry past with Venus' present interior being dry."

The researchers explained they attempted to measure the current destruction rate of molecules³ in water, carbon dioxide and carbonyl sulfide in Venus' atmosphere. The state of the planet's atmosphere is linked to volcanic⁴ activity, the team said.

"Volcanism, through its supply of gases to the atmosphere, provides a window into the interior of rocky planets like Venus," the researchers wrote in a statement. "As magma rises from the mantle⁵ to the surface, it releases gases from the deeper portions of the planet.

Volcanic explosions, or eruptions⁶, can provide information on the amount of water contained deep below a planet's surface, the scientists said.

On Earth, for example, volcanic eruptions mostly release steam, a vapor⁷ created when water gets heated. Measurements of volcanic gases on Earth have shown they release about 60 percent water vapor.

But the researchers said their examinations suggested volcanic gases released on Venus were less than 6 percent water vapor. This persuaded the team to conclude that the planet's interior - the source of the magma that releases volcanic gases - must be very dry.

The team noted⁸ that scientists have had two leading theories on the history of water on Venus. The first is that the planet had a moderate climate for billions of years, with liquid water flowing over areas of the surface. Over time, widespread volcanic activity likely led to extreme heat and dry conditions that made the water disappear.

The second theory imagined Venus as being very hot from the beginning, preventing liquid water from ever forming on the surface.

Constantinou said, "Both of those theories are based on climate models, but we wanted to take a different approach based on observations of Venus' current atmospheric⁹ chemistry." She added that the team did not find evidence that any chemicals being removed from the atmosphere were later being restored.

This provides strong evidence that Venus has a very dry interior today, the scientists concluded. "The atmospheric chemistry suggests that volcanic eruptions on Venus release very little water, implying that the planet's interior...is equally dry," Constantinou said.

She added that her team "would have loved to find that Venus was once a planet much closer to our own." However, Constantinou noted the finding suggests that researchers should center their searches "on planets that are mostly likely to be able to support life - at least life as we know it."

I'm Bryan Lynn.

Bryan Lynn wrote this story for VOA Learning English, based on reports from Reuters and the University of Cambridge.

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Words in This Story

magma - n. hot liquid rock found just below the surface of the Earth

mantle - n. a layer of something that covers a surface

vapor - n. many small drops of liquid that form in the air

approach - n. the way something is done

imply - v. to communicate an idea or feeling without saying it directly