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NASA spacecraft launched to mysterious and rare metal asteroid_我的网站

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一 | CAPE CANAVERAL, Fla. -- NASA’s Psyche spacecraft rocketed away Friday on a six-year journey to a rare metal-covered asteroid.Most asteroids tend to be rocky or icy, and this is the first exploration of a metal world. Scientists believe it may be the battered remains of an early planet's core, and could shed light on the inaccessible centers of Earth and other rocky planets.SpaceX launched the spacecraft into an overcast midmorning sky from NASA’s Kennedy Space Center. Named for the asteroid it’s chasing, Psyche should reach the huge, potato-shaped object in 2029.“It's so thrilling,” said Laurie Leshin, director of NASA’s Jet Propulsion Laboratory. Added Arizona State University's Jim Bell, part of the Psyche team: “What a great ride so far.”An hour later, the spacecraft separated successfully from the rocket's upper stage and floated away, drawing applause from ground controllers.After decades of visiting faraway worlds of rock, ice and gas, NASA is psyched to pursue one coated in metal. Of the nine or so metal-rich asteroids discovered so far, Psyche is the biggest, orbiting the sun in the outer portion of the main asteroid belt between Mars and Jupiter alongside millions of other space rocks. It was discovered in 1852 and named after Greek mythology’s captivating goddess of the soul.“It’s long been humans’ dream to go to the metal core of our Earth. I mean, ask Jules Verne,” lead scientist Lindy Elkins-Tanton of Arizona State University said ahead of the launch. “The pressure is too high. The temperature is too high. The technology is impossible,” she said. “But there’s one way in our solar system that we can look at a metal core and that is by going to this asteroid.”Astronomers know from radar and other observations that the asteroid is big — about 144 miles (232 kilometers) across at its widest and 173 miles (280 kilometers) long. They believe it’s brimming with iron, nickel and other metals, and quite possibly silicates, with a dull, predominantly gray surface likely covered with fine metal grains from cosmic impacts.Otherwise, it’s a speck of light in the night sky, full of mystery until the spacecraft reaches it after traveling more than 2 billion miles (3.6 billion kilometers).Scientists envision spiky metal craters, huge metal cliffs and metal-encrusted eroded lava flows greenish-yellow from sulfur — “almost certain to be completely wrong,” according to Elkins-Tanton. It's also possible that trace amounts of gold, silver, platinum or iridium — iron-loving elements — could be dissolved in the asteroid's iron and nickel, she said. “There's a very good chance that it’s going to be outside of our imaginings, and that is my fondest hope," she said.Believed to be a planetary building block from the solar system’s formation 4.5 billion years ago, the asteroid can help answer such fundamental questions as how did life arise on Earth and what makes our planet habitable, according to Elkins-Tanton.On Earth, the planet's iron core is responsible for the magnetic field that shields our atmosphere and enables life.Led by Arizona State University on NASA’s behalf, the $1.2 billion mission will use a roundabout route to get to the asteroid. The van-size spacecraft with solar panels big enough to fill a tennis court will swoop past Mars for a gravity boost in 2026. Three years later, it will reach the asteroid and attempt to go into orbit around it, circling as high as 440 miles (700 kilometers) and as close as 47 miles (75 kilometers) until at least 2031.The spacecraft relies on solar electric propulsion, using xenon gas-fed thrusters and their gentle blue-glowing pulses. An experimental communication system is also along for the ride, using lasers instead of radio waves in an attempt to expand the flow of data from deep space to Earth. NASA expects the test to yield more than 10 times the amount of data, enough to transmit videos from the moon or Mars one day.The spacecraft should have soared a year ago, but was held up by delays in flight software testing attributed to poor management and other issues. The revised schedule added extra travel time. So instead of arriving at the asteroid in 2026 as originally planned, the spacecraft won’t get there until 2029.That’s the same year that another NASA spacecraft — the one that just returned asteroid samples to the Utah desert — will arrive at a different space rock as it buzzes Earth.___The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Science and Educational Media Group. The AP is solely responsible for all content.。游客挤爆国大校园，针对这一问题，国大校方、学生会和学生在8月21日举行对话会，探讨解决方案。在对话会后，校方提出几项长期措施。学生带团前须向校方报名预留名额学生在带团前，必须预先向校方报名预留名额。为管理进入校园的人流量，校方将每天只提供有限的名额。

二 | 团队学生必须严格遵守大学的校园参观指南、参观礼仪，以确保国大的其他日常活动不受影响。带团学生必须佩戴学生导览员的证件，便于校方识别。

三 | 带旅行团参观的学生导游需向校方注册明年1月开始，国大要求在校园内带旅行团参观的学生导游向校方注册，接受与国大学生大使同样的培训，并获得学生讲解员证书后才可以带团。根据新加坡法律，没有新加坡旅游局颁发的有效导游证而提供导游服务是违法行为。因此校方强烈建议，所有在校园内组织旅游团的学生主动向校方登记。如果发现无证导游在校内进行导游活动，将向有关部门举报，而进行无预约导览活动的国大学生将受到纪律处分。将改进访客入校系统国大也要求所有旅游巴士入园前必须登记，每日可入园的旅行巴士名额有限。

四 | 参观国大博物馆以及参加官方活动的旅游巴士入园也须登记。日前，国大校车被当成公交车另外，国大也将改进访客进入校园的系统，让到大学的访客和大学的合作伙伴、服务供应商等能够顺利进入校园设施。这类访客主要包括会议和课程的参与者、研究和教学合作者、行业协会和附属机构、校友等。新系统预计明年1月启用。图书馆恢复门禁从8月14日起，国大所有的图书馆都恢复门禁，与此同时，校方正在寻求更好的解决方案，以确保不会影响国大师生使用图书馆的体验。新加坡国大试行新规应对游客大量涌入：中午禁入食堂、校园导览计划如果有去国大游玩的游客请注意以上新规，同时也不要把不文明行为带入大学学府。也希望国大开始实施的这一系列措施，能有效缓解游客过多的问题，对学生们的影响降低。