VOA慢速英语2021--美航天局宣布将执行两项探索金星的任务

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NASA to Return to Venus with Two New Missions

The U.S. space agency NASA has announced plans to launch two new missions to the planet Venus.

The missions will mark a return to U.S. exploration of Venus after many years. Two new robotic spacecraft are to be designed and built to study the planet with the highest temperatures in our solar system.

NASA chose American company Lockheed Martin to create and operate both spacecraft. The company will receive $500 million for each mission through NASA's Discovery Program. The spacecraft are expected to launch between 2028 and 2030.

One mission, called DAVINCI+, is designed to measure the planet's dense¹, cloudy atmosphere to understand how it formed and developed, a NASA statement said. It also aims to capture the first high-quality pictures of geological structures on Venus. Some are similar to ones on Earth.

After arriving at Venus, the DAVINCI+ spacecraft will send a probe into the planet's atmosphere. It will then use its instruments to measure levels of gases and other elements, temperature and pressure, Lockheed Martin said.

The other mission, VERITAS, will map the surface of Venus to learn about "the planet's geologic² history and understand why it developed so differently than Earth," NASA said. When the VERITAS orbiter arrives at Venus, it will use a method called "aerobraking" to place itself "into an optimal³ science position in the planet's orbit," Lockheed Martin said. It will then use imaging equipment to capture data about the planet's geology.

Venus is Earth's closest planetary neighbor and the second closest planet to the sun. It is similar in structure to Earth, but a little smaller. Venus rotates in the opposite direction as Earth and most other planets. Also, its rotation⁴ is very slow.

The air on Venus is so dense and pressurized that it behaves more like a fluid than a gas near the surface. The planet has extremely high winds that push clouds completely around the planet every five days.

Such extreme conditions make it difficult for spacecraft to survive in Venus' atmosphere or on its surface. But scientists are very interested in learning more. Some believe Venus may have had ancient seas that could have made it habitable before unknown forces destroyed them.

"It is astounding⁶ how little we know about Venus," NASA scientist Tom Wagner said in a statement. He added that the new missions can provide fresh data on the planet's thick atmosphere, which is made up mostly of carbon dioxide. "It will be as if we have rediscovered the planet," Wagner said.

James Garvin is the chief scientist for NASA's Goddard Space Flight Center in Maryland. He said in a statement he considers Venus important to understanding "climate change, the evolution of habitability and what happens when a planet loses a long period of surface oceans."

The first spacecraft to explore Venus was NASA's Mariner⁷ 2 in 1962. It passed within about 34,000 kilometers of the planet. NASA says Mariner 2 successfully recorded the planet's temperature for the first time. It measured the Venus surface temperature to be about 465 degrees Celsius⁸.

The United States and the former Soviet⁹ Union sent several spacecraft to Venus from the 1960s to the 1980s. The former Soviet Union is the first and only country to successfully land a spacecraft on the surface of Venus. The first landing was the Soviet explorer Venera 7 in 1970. The Soviet spacecraft lasted less than two hours in the extreme environment.

In 1989, NASA used a space shuttle to send its Magellan spacecraft into orbit around Venus. The European Space Agency also put a spacecraft into orbit around Venus in 2006. And, a Japanese spacecraft called Akatsuki was launched in 2010 and is currently orbiting Venus.

Words in This Story

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

geology – n. the study of rocks and soil and the physical structure of the Earth

probe – n. a vehicle used to examine or observe something closely

optimal – adj. the best of most effective possible in a particular situation

rotate – v. to turn or cause something to turn in a circle

habitable – adj. able to support life

astound⁵ – v. to surprise of shock someone very much

evolution – n. a gradual process of change and development