Week Five:火星探險

Mars Rover Finds Changing Rocks, Surprising Scientists

As NASA’s Curiosity rover treks up a three-mile-high mountain on Mars, the rocks are changing. That says something about how the planet’s climate and environment changed more than three billion years ago — but scientists are not sure what.

Since it landed more than three years ago in a 96-mile-wide depression known as Gale Crater, Curiosity has made a number of discoveries, notably that the crater once held lakes of fresh water. For most of that time, the rocks it encountered were generally basaltic, a volcanic composition typical on Mars.

“Now in the recent few months, that has changed,” Ashwin R. Vasavada, the project scientist for the mission, said at a news conference on Thursday at a meeting of the American Geophysical Union in San Francisco, where researchers were presenting some of their newest results.

They have surprising clues but no definitive story, yet.
Each layer of sedimentary rock tells something about the geological conditions at the time the rock formed, meaning that Curiosity, which arrived at the base of the mountain in September 2014, is in a sense moving forward through the geological history of Mars as it climbs.

What has caught the attention of Dr. Vasavada and his colleagues lately is silica, a class of minerals made of silicon and oxygen. The evidence points to the action of liquid water even after the lakes disappeared.

“Groundwater passed through the rock multiple times, leaving different chemical signatures behind,” Dr. Vasavada said.

Basalt is generally half silica. Curiosity has been examining two rock units: one a mudstone of lake bed deposits, among the oldest rocks the rover will examine, and the other a sandstone of coarse grains that were blown in and draped onto the mountain. “It probably is among the youngest rocks we’ll encounter on the mission,” Dr. Vasavada said.

In the mudstone and the sandstone, Curiosity found much higher levels of silica, up to 90 percent more than it had observed previously in basaltic rocks.

“All of this we’re just beginning to piece together and understand,” Dr. Vasavada said.

After arriving at a spot the scientists named Marias Pass, an intersection between the older mudstone and younger sandstone near the base of the mountain, Curiosity spied a patch of light-toned bedrock, part of the mudstone. It fired a laser to vaporize the rock in several places; the instrument identifies the constituent elements from the colors of light given off. Then Curiosity drove off to do more science elsewhere.

Back on Earth, scientists analyzing the data realized this was something different: It turned out to be the first of the high-silica rocks.

http://www.nytimes.com/2015/12/18/science/mars-rover-finds-changing-rocks-surprising-scientists.html?_r=0



Structure of the Lead：
WHO-  NASA’s Curiosity rover
WHERE- MARS
WHAT- Finds Changing Rocks
WHEN- not given
HOW- Surprise

Keywords：
basaltic 玄武
mudstone 泥岩
vaporize 蒸發
drove off  擊退
high-silica 高硅

week four 長江船難

Death toll grows in Yangtze River tragedy

June 3, 2015 12:00AM ET Updated 2:28AM ET

Hopes dimmed Wednesday for rescuing more than 400 people still trapped in a capsized river cruise ship that overturned in stormy weather, as hundreds of rescuers searched the Yangtze River site in what could become the deadliest Chinese maritime accident in decades.

Chinese state broadcaster CCTV reported that 18 bodies had been pulled from the boat, which was floating with a sliver of its hull jutting from the gray river water about 36 hours after it capsized. A total of fourteen people have been rescued, but the vast majority of the 456 people on board, many of them elderly tourists, were unaccounted for.

The Yangtze disaster could have a higher death toll than the 304 people killed when a ferry sank in South Korea in April 2014. Most of those killed in that incident were children on a school trip.

State television carried pictures of rescuers, some standing on the upturned hull of the shallow-draft, multi-decked Eastern Star cruise ship, working through the night. So far their efforts have yielded few successes, with only 14 people found alive.

Among the few rescued was an elderly woman who had been trapped in an air pocket in the ship, which capsized on Monday night during a freak tornado on the river, a rare occurrence in a country where twisters are uncommon.

Tour guide Zhang Hui said in an interview with the state-run Xinhua News Agency from his hospital bed that he grabbed a life jacket with seconds to spare as the ship listed in the storm, sending bottles rolling off tables as it suddenly turned all the way over.

Zhang, 43, said he drifted in the Yangtze all night despite not being able to swim, reaching shore as dawn approached.

“The raindrops hitting my face felt like hailstones,” he said. “‘Just hang in there a little longer,’ I told myself.”

Weather continues to hamper rescue efforts, as showers, thunderstorms and strong winds are expected to continue in the area for the next day or so.

The Yangtze search area has been expanded up to 135 miles downstream, state television said, suggesting that many bodies could have been swept far away from where the ship foundered in the rain-swollen river.

Relatives, angry at what they perceive as a lack of information, have scuffled with officials in Shanghai, where many of the tourists started their journey by bus after booking the trip through an agency based in the city.

People questioned whether the captain did enough to ensure the passengers' safety and demanded answers from local officials in unruly scenes that drew a heavy police response. The ship's captain and chief engineer, were in police custody, CCTV said. 

Early on Wednesday, about two dozen affected family members, some crying and others shouting "help us," marched down streets in entral Shanghai towards the main government office watched by police.

A passenger manifest carried by state media showed those on board the Eastern Star ranged in age from three to more than 80. There were 456 people on board when the ship capsized. Official state media originally reported there were 548 people aboard.

Premier Li Keqiang, who rushed to the scene to oversee rescue efforts, called for “regular and transparent updates” on the rescue and investigation. However, state broadcaster CCTV announced Wednesday morning that it was suspending live broadcasts from the disaster site for technical reasons.

It did not elaborate. International media workers have also been kept away from the immediate area surrounding where workers are searching for bodies.

The Chinese military has taken the lead in rescue operations with teams working in round-the-clock shifts. They were exploring the possibility of drilling holes through the ship to reach possible survivors, or to refloat the vessel — a challenging endeavor.

An initial investigation found the ship was not overloaded and had enough life vests for its passengers.

The Eastern Star, which had the capacity to carry more than 500 people, was heading to the southwestern city of Chongqing from Nanjing, capital of Jiangsu province. When the ship capsized, it was about halfway through an 11-day cruise, winding upstream with stops at scenic and historic sites.

The popular route often includes a stop at the Three Gorges Dam, which the Eastern Star had yet to reach, and the Fengdu Ghost Town, which got its reputation from a local folklore. Tourists can also walk within an ancient city called Jingzhou with city walls and battlefields that are described in the Chinese literary classic “Romance of the Three Kingdoms.”

Maritime accidents of this magnitude are uncommon in China, where major rivers are popular routes for tours and cruises.

The incident comes after China has beefed up maritime safety regulations in recent years, with authorities becoming even more stringent after last year's South Korean ferry disaster that killed more than 300 people, industry insiders said.

The Eastern Star, owned by the Chongqing Eastern Shipping Corp., passed inspections by the authorities in the central province of Chongqing last month, unnamed officials at the Nanjing Maritime Bureau told the official People’s Daily. It was not checked at the Nanjing port as ships like it are usually inspected every three months.  

http://america.aljazeera.com/articles/2015/6/3/death-toll-grows-in-in-yangtze-river-tragedy.html

Structure of the Lead：

WHO-Tour guide Zhang Hui, rescuers, victims

WHEN-not given

WHAT-more people died in Yangtze River tragedy

WHY-stormy weather

WHERE-Yangtze River

HOW-not given

Keywords：

1. dim 黯淡

2.  maritime 海上

3.  yield 產生

4. unruly 不羈

5. beefed up 加強