VOA慢速英语2021--“地球的哪个邻居可能有生命？”（在线收听）

A new study says life in the clouds of Venus is unlikely.

Scientists from Europe and the U.S. say there is not enough water in the planet's clouds to support life as we know it.

The team started studying the possibility of life in Venus' clouds after a surprise announcement in September of last year. At that time, a team of scientists said they used telescopes to find evidence of the chemical phosphine in the thick clouds covering the planet. Phosphine is a poisonous gas. But on Earth, it is only associated with life.

The organizers of the study and other experts agreed that the presence of phosphine was not proof of life. Their findings, however, suggested that organisms could exist in the thick, sulfuric acid-filled clouds of Venus.

But researchers of the recent study used observations from spacecraft. They found that the amount of water in Venus' atmosphere is more than 100 times too low to support life like Earth's.

John Hallsworth is a microbiologist at Queen's University Belfast in Northern Ireland. He said the amount of water is very low and "an unbridgeable distance from what life requires to be active."

His team studied the most dry-tolerant and also the most acid-tolerant microbes on Earth. The team then decided that the microbes could not survive on Venus.

The latest findings suggest Venus is unlikely to have water-based organisms like ones on Earth. But the researchers identified another planet with enough water in its clouds and the right temperatures to support life – Jupiter.

"Now I'm not suggesting there's life on Jupiter and I'm not even suggesting life could be there," Hallsworth told reporters. The team said it was not sure if the nutrients necessary for life existed in Jupiter's atmosphere. "But still, it's a profound and exciting finding and totally unexpected," Hallsworth said.

Hallsworth and NASA astrobiologist Chris McKay wrote about their findings in Nature Astronomy, published in late June. They said further studies will be needed to learn whether microbial life might exist deep in the clouds of Jupiter.

As for Venus, three new spacecraft will be going there within the next 10 years. NASA is sending two spacecraft next year and the European Space Agency is also sending one. Hallsworth and McKay do not believe their findings about Venus are likely to change.

"It's unfortunate because I'm very interested in searching for life on other worlds and I would love to think that Venus is habitable," McKay said.

The scientists who wrote the earlier study suggested there might be life in the clouds of Venus because they found evidence of phosphine gas. On Earth, the gas is linked with life.

Sara Seager is an astrophysicist at Massachusetts Institute of Technology (MIT) and was part of the September team. She said, "We are not trying to push Venus as a definitely habitable world. So far...Venus is inhabitable!" Seager added that she supports doing careful research "in case there is life on Venus."

Any life in Venus' clouds - if it exists – might be totally unlike anything on Earth. It might have changed to be able to live in the planet's extremely hot and severe conditions, scientists say.

"If there is life in the clouds of Venus, then this has to be 'Life as we do not know it,' said astrobiologist Janusz Petkowski, who works with Seager at MIT. Petkowski wondered, "The question is how different that life can be?"

Words in This Story

associated – adj. connected or linked with something else

sulfuric acid – n. a very strong kind of acid

tolerant – adj. able to allow or accept something that is harmful or unpleasant

habitable – adj. suitable or fit to live in

profound – adj. very great

astrobiologist – n. a person who studies the possible origin, distribution, evolution, and future of life in the universe, including that on Earth, using a combination of methods from biology, chemistry, and astronomy