There were not one, but two asteroid encounters this weekend
There were not one, but two asteroid encounters this weekend
这个周末，不仅是一次，而是有两次小行星探测任务
As the United States of America celebrated its 250th birthday on terra firma with fireworks displays this weekend, two Asian countries made some splashes of their own farther from Earth. 当美国在这个周末于陆地上燃放烟花庆祝其建国 250 周年之际，两个亚洲国家在远离地球的太空中也掀起了属于自己的波澜。
On Sunday, an aging Japanese spacecraft named Hayabusa2, which completed its initial sample-return objective more than half a decade ago, found success with an extended mission that saw the vehicle fly by a peanut-shaped asteroid named Torifune. 周日，日本一艘名为“隼鸟 2 号”（Hayabusa2）的老牌航天器成功完成了一项扩展任务。该航天器在五年多前就完成了最初的样本返回目标，此次它成功飞掠了一颗名为“鸟船”（Torifune）的花生状小行星。
Hours later, the Chinese space agency released images from a spacecraft, Tianwen-2, arriving at its target asteroid following a journey of 1 billion km. At this small asteroid, the Chinese spacecraft will attempt to retrieve samples and return them to Earth late next year. 几小时后，中国航天机构发布了“天问二号”探测器传回的图像，该探测器在经过 10 亿公里的飞行后抵达了目标小行星。中国航天器将在这颗小行星上尝试采集样本，并计划于明年晚些时候将其送回地球。
Torifune flyby
“鸟船”飞掠任务
The Japanese space agency’s Hayabusa2 mission launched back in December 2014 and made a rendezvous with a near-Earth asteroid named 162173 Ryugu in June 2018. After gathering samples, the spacecraft burned its ion propulsion engines to return to Earth, and during a flyby in late 2020 it released a small return capsule. Scientists recovered 5.4 grams of asteroid material from the capsule. 日本宇宙航空研究开发机构（JAXA）的“隼鸟 2 号”任务于 2014 年 12 月发射，并于 2018 年 6 月与近地小行星“龙宫”（162173 Ryugu）会合。在采集样本后，该航天器启动离子推进器返回地球，并于 2020 年底在飞掠地球时释放了一个小型返回舱。科学家们从该舱中回收了 5.4 克小行星物质。
By this point, however, Hayabusa2’s efficient propulsion system still had nearly half of its xenon propellant remaining—approximately 30 kg of the 66 kg it began its mission with. So Japanese engineers and scientists plotted out an operations plan that would extend over the next decade and visit two more asteroids. It flew by the first of these on Sunday, a 450-meter-long asteroid designated as 98943 Torifune. 然而，此时“隼鸟 2 号”高效的推进系统仍剩余近一半的氙推进剂——在任务开始时的 66 公斤中还剩下约 30 公斤。因此，日本工程师和科学家制定了一项跨越未来十年的运行计划，旨在访问另外两颗小行星。周日，它飞掠了其中的第一颗，即编号为 98943 的“鸟船”小行星，其长度为 450 米。
Observations began about two weeks ago and culminated in a flyby during which the spacecraft passed within about 800 meters of the asteroid. “These observations continued until immediately before the closest approach to Torifune but could not be conducted after the spacecraft had passed the asteroid,” JAXA, the Japanese space agency, said in a news release early Monday. “At present, only part of the data acquired by the scientific instruments has been transmitted to Earth. The remaining data will be transmitted to the ground during future operations.” 观测工作在大约两周前开始，并在飞掠期间达到高潮，航天器距离小行星最近处仅约 800 米。日本航天机构 JAXA 在周一早间的新闻发布会上表示：“这些观测一直持续到最接近‘鸟船’之前，但在航天器飞过小行星后无法进行。目前，科学仪器获取的数据仅有一部分传回地球。其余数据将在未来的运行中传回地面。”
The successful operations set the stage for the final encounter planned by Hayabusa2, a tiny near-Earth object believed to be just 11 meters across. This flyby of 1998 KY26 would occur sometime in July 2031 if the spacecraft proceeds nominally. 此次任务的成功为“隼鸟 2 号”计划中的最后一次探测奠定了基础，目标是一个直径仅 11 米的微小近地天体。如果航天器运行正常，这次对 1998 KY26 的飞掠预计将在 2031 年 7 月的某个时间进行。
Aloha Kamoʻoalewa
“卡莫瓦”探测任务
Also this weekend, the China National Space Administration announced that its Tianwen-2 spacecraft had reached within 20 km of another near-Earth asteroid designated 469219 Kamoʻoalewa. This is another relatively small asteroid, with a diameter of only about 20 meters. The spacecraft made its arrival on July 2. 同样在这个周末，中国国家航天局宣布，“天问二号”探测器已抵达距离另一颗近地小行星“卡莫瓦”（469219 Kamoʻoalewa）20 公里范围内。这是另一颗相对较小的小行星，直径仅约 20 米。该探测器于 7 月 2 日抵达目标。
As part of its announcement, China released a somewhat fuzzy image of the asteroid, which loosely resembles the shape of an arrowhead. The probe’s arrival marks the beginning of more detailed scientific operations, the Chinese space agency said, to better characterize the asteroid’s shape, material composition, rotational properties, and more. 作为公告的一部分，中国发布了一张略显模糊的小行星图像，其形状隐约像一个箭头。中国航天机构表示，探测器的抵达标志着更详细科学探测工作的开始，旨在更好地表征该小行星的形状、物质成分、自转特性等。
The asteroid is also known as a “quasi moon” because it rotates ahead of Earth in a similar orbital period of 365 days. It is leading Earth, and at its closest approach comes within about 4.6 million km (more than 10 times the Earth-Moon distance). It is not gravitationally bound to Earth, however. 这颗小行星也被称为“准卫星”，因为它以 365 天的相似轨道周期在地球前方运行。它位于地球前方，在最接近时距离地球约 460 万公里（超过地月距离的 10 倍）。不过，它并不受地球引力束缚。
After characterizing the nature of the asteroid, Tianwen-2 will attempt to gather samples. A return to Earth is tentatively scheduled for November 2027. If all goes well, after the release of a sample capsule, Tianwen-2’s mission will also be extended. China has announced preliminary plans for the spacecraft to then travel to and orbit an intriguing asteroid named 311P/PanSTARRS. This asteroid has “tails,” and so it may be a comet. 在完成对小行星性质的表征后，“天问二号”将尝试采集样本。返回地球的时间暂定于 2027 年 11 月。如果一切顺利，在释放样本舱后，“天问二号”的任务也将得到扩展。中国已宣布初步计划，让该航天器随后前往并环绕一颗名为 311P/PanSTARRS 的有趣小行星。这颗小行星拥有“尾巴”，因此它可能是一颗彗星。