NASA·每日一图

This illustration imagines the view from NASA’s Cassini spacecraft during one of its final dives between Saturn and its innermost rings, as part of the mission’s Grand Finale. Cassini made 22 orbits that swooped between the rings and the planet before ending its mission on Sept. 15, 2017, with a final plunge into Saturn. #TBT Image Credit: NASA/JPL-Caltech 这张图描绘了美国宇航局的卡西尼号飞船在土星和它的内环之间最后一次俯冲时的景象，这是此次任务的最后一部分。卡西尼号完成了22次绕环飞行和绕行的轨道，直到2017年9月15日结束任务，并最终坠入土星。 #TBT 影像来源：NASA/JPL-Caltech

Like a wisp of electric green smoke, the aurora australis seemingly intersects with the Earth’s airglow as the International Space Station orbited above the Indian Ocean halfway between Australia and Antarctica. Ever-shifting displays of colored ribbons, curtains, rays, and spots, auroras are most visible near the North (aurora borealis) and South (aurora australis) Poles as charged particles (ions) streaming from the Sun (the solar wind) interact with Earth’s magnetic field. Auroras happen when ions in the solar wind collide with atoms of oxygen and nitrogen in the upper atmosphere. The atoms are excited by these collisions, and they typically emit light as they return to their original energy level. The light creates the aurora that we see. The most commonly observed color of aurora is…

Japan’s resupply ship, the H-II Transfer Vehicle-9 (HTV-9), is pictured attached to the International Space Station’s Harmony module. Stowed inside the Japanese space freighter is the HTV-8 cargo pallet that was brought up to the station on a previous resupply mission. The pallet contains old nickel-hydrogen batteries for disposal that were disconnected from the station during a series of spacewalks at the end of 2019. Carrying four tons of supplies, water, spare parts and experiment hardware for the Expedition 63 crew aboard the International Space Station, HTV-9 launched from Tanegashima Space Center in southern Japan on Wednesday, May 20 at 1:31 p.m. EDT (2:31 a.m. Thursday, May 21, Japan time). Image Credit: NASA 如图所示，日本的再补给船H-II运载器-9 (HTV-9)连接到国际空间站的和谐舱。装载在日本太空飞船里的是在先前的补给任务中被带到太空站的HTV-8货盘。该货盘装有待处理的旧镍氢电池，这些镍氢电池在2019年底的一系列太空行走中已与该站断开连接。 HTV-9于美国东部时间5月20日周三下午1点31分(日本时间5月21日周四凌晨2点31分)从日本南部的种子岛航天中心发射升空，为国际空间站的第63号远征队宇航员带去四吨物资，水，零件和实验硬件。 影像来源：NASA

Much of Mars is covered by sand and dust but in some places stacks of sedimentary layers are visible. In this image, exquisite layering is revealed emerging from the sand in southern Holden Crater. Sequences like these offer a window into Mars’ complicated geologic history. Holden Crater was once a candidate landing area for the Curiosity, Mars Science Laboratory, and is still an intriguing choice today. Image Credit: NASA/JPL-Caltech/University of Arizona 火星的大部分地区被沙尘覆盖，但在一些地方可以看到成堆的沉积层。在这张图片中，霍尔顿陨石坑南部的沙子上呈现出精致的分层。像这样的科学为了解火星复杂的地质历史提供了一个窗口。 霍尔顿环形山曾经是“好奇号”火星科学实验室的候选着陆区域，今天仍然是一个有趣的选择。 影像来源：NASA/JPL-Caltech/University of Arizona

Almost like snowflakes, the stars of the globular cluster NGC 6441 sparkle peacefully in the night sky, about 13,000 light-years from the Milky Way’s galactic center. Like snowflakes, the exact number of stars in such a cluster is difficult to discern. It is estimated that together the stars have 1.6 million times the mass of the Sun, making NGC 6441 one of the most massive and luminous globular clusters in the Milky Way. NGC 6441 is host to four pulsars that each complete a single rotation in a few milliseconds. Also hidden within this cluster is JaFu 2, a planetary nebula. Despite their name, planetary nebulas have little to do with planets. A phase in the evolution of intermediate-mass stars, planetary nebulas last for only…

Lightning flashes from a storm cloud to strike the ground. Such bolts represent only a small part of the overall phenomenon of lightning. The most powerful activity occurs high above the surface, in Earth’s upper atmosphere. Up there, lightning creates brief bursts of gamma rays that are the most high-energy naturally produced phenomena on the planet. Researchers recently measured these high-energy terrestrial gamma-ray flashes, or TGFs, using instruments on the International Space Station. The work helps reveal the mechanism behind the creation of the bright flashes we call lightning. The instruments are part of the Atmosphere-Space Interactions Monitor (ASIM), an Earth observation facility on the outside of the space station used to study severe thunderstorms and their role in Earth’s atmosphere and climate. This photo…

The samples Apollo 11 brought back to Earth from the Moon were humanity’s first from another celestial body. NASA’s upcoming Mars 2020 Perseverance rover mission will collect the first samples from another planet (the red one) for return to Earth by subsequent missions. In place of astronauts, the Perseverance rover will rely on the most complex, capable and cleanest mechanism ever to be sent into space, the Sample Caching System. In this image taken on May 20, 2020 at the Kennedy Space Center, engineers and technicians insert 39 sample tubes into the belly of the rover. Each tube is sheathed in a gold-colored cylindrical enclosure to protect it from contamination. Perseverance rover will carry 43 sample tubes to the Red Planet’s Jezero Crater. Image Credit:…

A small glacier in the Arctic region of Norwegian archipelago Svalbard, as photographed by NASA’s Airborne Tropical Tropopause Experiment (ATTREX). This is one of the seven regions where ice loss is accelerating, causing the depletion of freshwater resources. Seven of the regions that dominate global ice mass losses are melting at an accelerated rate, a new study shows, and the quickened melt rate is depleting freshwater resources that millions of people depend on. The impact of melting ice in Greenland and Antarctica on the world’s oceans is well documented. But the largest contributors to sea level rise in the 20th century were melting ice caps and glaciers located in seven other regions: Alaska, the Canadian Arctic Archipelago, the Southern Andes, High Mountain Asia, the Russian…

On Saturday, May 30, 2020, a SpaceX Falcon 9 rocket carrying the company’s Crew Dragon spacecraft launched on NASA’s SpaceX Demo-2 mission to the International Space Station and made its way into the history books. The Demo-2 mission is the first launch with astronauts of the SpaceX Crew Dragon spacecraft and Falcon 9 rocket to the International Space Station as part of the agency’s Commercial Crew Program. The test flight serves as an end-to-end demonstration of SpaceX’s crew transportation system. Behnken and Hurley launched at 3:22 p.m. EDT on Saturday, May 30, from Launch Complex 39A at the Kennedy Space Center. A new era of human spaceflight is set to begin as American astronauts once again launch on an American rocket from American soil to…

A SpaceX Falcon 9 rocket carrying the company’s Crew Dragon spacecraft launched from Launch Complex 39A on NASA’s SpaceX Demo-2 mission to the International Space Station with NASA astronauts Robert Behnken and Douglas Hurley onboard, at 3:22 p.m. EDT on Saturday, May 30, 2020, at NASA’s Kennedy Space Center in Florida. The Demo-2 mission is the first launch with astronauts of the SpaceX Crew Dragon spacecraft and Falcon 9 rocket to the station as part of the agency’s Commercial Crew Program. The test flight serves as an end-to-end demonstration of SpaceX’s crew transportation system. A new era of human spaceflight is set to begin as American astronauts once again launch on an American rocket from American soil to low-Earth orbit for the first time since…