新研究表明火星存在大型地下海洋

A new study provides evidence that Mars contains a large ocean deep beneath its surface.

The finding is based on data collected by the InSight Lander, a robotic explorer operated by the American space agency NASA. InSight, which landed in 2018, was designed to capture data from within the planet's interior. The lander ended its operations on Mars in late 2022.

For the current study, researchers used seismic data collected by InSight. The team examined the data to study Martian quake activity. Seismic activity on Mars happens in the form of “marsquakes.” NASA says InSight had recorded more than 1,300 marsquakes.

The device InSight uses to measure ground movements is called a seismometer. NASA specially designed the lander and its instruments to be extremely sensitive for the Martian environment. The seismic data suggests liquid water exists deep beneath the ground where InSight operated from.

Since water is considered necessary to support life, scientists say the presence of it on Mars leaves open the possibility that some form of life might exist, or existed there in the past.

Numerous past studies have also provided evidence that liquid water could exist on Mars. Scientists have already uncovered evidence that about 3 billion years ago, the surface of Mars likely had an active system of lakes, rivers and oceans

Mars is believed to have lost its surface water as its atmosphere thinned. This likely turned the planet into the dry, dusty world it is today. Scientists have theorized that much of the ancient water escaped out into space or remained buried under the surface.

Water below Martian crust

Vashan Wright is an assistant professor of Geophysics at the University of California San Diego's Scripps Institution of Oceanography. He helped lead the research. Wright told The Associated Press the data suggests liquid water sits between 11 to 20 kilometers down in the Martian crust. He added that the water likely moved down from the surface billions of years ago when water is believed to have flowed freely on Mars.

The researchers combined computer models with the seismic data collected by InSight to reach their findings. They said the data showed the water is likely contained in a deep layer of igneous rock beneath the Martian surface. Igneous rock is formed from magma, a very hot liquid rock that has cooled.

Wright and his team recently reported their results in a study published in Proceedings of the National Academy of Sciences.

In a statement to Reuters news agency, Wright said, "On Earth what we know is where it is wet enough and there are enough sources of energy, there is microbial life very deep in Earth's subsurface." He added that the data suggests "the ingredients for life as we know it” may exist in the Martian subsurface.

The researchers said the InSight lander operated around the planet's Elysium Planitia area, near the equator. They believe the area is representative of the rest of Mars. The study suggests enough water exists below the surface to form a planet-wide ocean about 1 to 2 kilometers deep.

Better understanding of Martian water cycles

There is currently no way to confirm the study's suggested existence of liquid water because it sits so far beneath the Martian surface. Such a confirmation would require large drills and other specialized equipment.

But Wright said in a statement that for now, researchers can use the newly examined data to gain a better understanding of Martian water cycles. This can help scientists improve their knowledge about the planet's climate as well as the development of the Martian surface and interior. Wright noted the latest findings could also help guide researchers in where to look for further evidence of possible life forms on Mars.

"I'm inspired and I hope the public is also inspired," Wright said about the study results. "Humans can work together to put instruments on a planet... and try to understand what's going on there."

I'm Bryan Lynn.

Bryan Lynn wrote this story for VOA Learning English, based on reports from The Associated Press, Reuters, UC Berkeley News and Proceedings of the National Academy of Sciences.

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interior – n. the inside part of something

seismic – adj. relating to or caused by an earthquake

crust – n. a hard, dry layer of the surface of something

layer – n. an amount of something covering a surface

ingredient – n. a part of something that makes it successful

drill – v. to use a tool or machine to make holes in a hard substance

cycle – n. a series of events that happen in a particular order and are often repeated

inspire – v. to make someone feel that they want to do something and can do it