日批在线视频_内射毛片内射国产夫妻_亚洲三级小视频_在线观看亚洲大片短视频_女性向h片资源在线观看_亚洲最大网

US EUROPE AFRICA ASIA 中文
World / US and Canada

NASA is back at Mars

(Agencies) Updated: 2014-09-22 11:10

NASA is back at Mars
[Infographic/Agencies]

CAPE CANAVERAL, Fla - A NASA robotic spacecraft fired its braking rockets on Sunday, ending a 10-month journey to put itself into orbit around Mars and begin a hunt for the planet's lost water.

After traveling 442 million miles (71 million km), the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft fired its six rocket thrusters, trimming its speed from 12,800 mph (20,600 kph) to 10,000 mph (16,093 kph).

The 33-minute engine firing left MAVEN in the clutches of Mars' gravity as it flew over the planet's north pole and slipped into a looping 236-mile by 27,713-mile (380-km by 44,600-km) high orbit.

"I don't have any fingernails anymore, but we made it," Colleen Hartman, NASA deputy director for science at Goddard Space Spaceflight Center in Greenbelt, Md., said during a NASA Television broadcast of MAVEN's arrival.

Flight control teams burst into cheers and applause as radio signals from MAVEN confirmed it was in Mars orbit at 10:25 p.m. EDT/0225 GMT.

Over the next several weeks, MAVEN will lower its altitude until it reaches its 93-mile by 3,900-mile (150-km by 6,200-km) operational orbit.

MAVEN will study how the solar wind strips away atoms and molecules in the planet's upper atmosphere, a process that scientists believe has been underway for eons.

"By learning the processes that are going on today we hope to extrapolate back and learn about the history of Mars," MAVEN scientist John Clarke, with Boston University, said in an interview on NASA Television.

Scientists strongly suspect that Mars was not always the cold and dry desert it is today. The planet's surface is riddled with what appear to be dry riverbeds and minerals that form in the presence of water.

But for water to pool on the planet's surface, its atmosphere would have had to be much denser and thicker than it is today. Mars' atmosphere is now about 100 times thinner than Earth's.

Scientists suspect Mars lost 99 percent of its atmosphere over millions of years as the planet cooled and its magnetic field decayed, allowing charged particles in the solar wind to strip away water and other atmospheric gases.

Learning about how Mars lost its water is key to understanding if the planet most like Earth in the solar system ever could have supported life.

The $671-million MAVEN mission is scheduled to last one year. The spacecraft joins two other NASA orbiters, two NASA rovers and a European orbiter currently working at Mars.

A seventh Mars probe owned by India is scheduled to arrive on Wednesday.

 

Trudeau visits Sina Weibo
May gets little gasp as EU extends deadline for sufficient progress in Brexit talks
Ethiopian FM urges strengthened Ethiopia-China ties
Yemen's ex-president Saleh, relatives killed by Houthis
Most Popular
Hot Topics

...
主站蜘蛛池模板: 成人影片在线免费观看 | 欧美 日本 国产 | 久久精品一二三区 | 午夜小网站 | 三级理伦| 看全色黄大色大片 | 精品国产999久久久免费 | 蜜臀av网站 | 黄色在线视频网站 | 日韩免费在线观看 | 成人片在线播放 | 欧美精品免费一区二区三区 | 五十路av| 亚洲自拍中文字幕 | 亚洲精品网站在线观看 | 极品盗摄国产盗摄合集 | 国产成人精品久久久 | 在线观看免费黄色片 | 欧美在线一区二区三区四区 | 四虎传媒| 国产一区二区成人 | 一区二区视频网站 | 亚洲综合色在线 | 日韩在线天堂 | www.色视频 | 久热精品视频在线播放 | 国产精品视频一区二区三区不卡 | 国精产品久拍自产在线网站 | 亚洲色在线视频 | 午夜av免费在线观看 | 中文字幕在线视频免费观看 | 亚洲国产无 | 色呦呦中文字幕 | 欧洲精品 | 精品久久伊人 | 亚洲天堂av网站 | 在线看片网站 | 亚洲一区欧美一区 | 国产精品综合 | 国产精久久久 | 一区二区三区国产在线 |