This week, astronomers are seeing double. Just a day after Japan’s spacecraft flew by a strange, two-lobed asteroid named Torifune, China’s space agency announced that its own robotic envoy had arrived at another space rock — an angular, compact object named 469219 Kamoʻoalewa.

本周，天文学界好事成双。日本的航天器飞掠一颗名为“鸟船”(Torifune)的奇特双叶小行星仅一天后，中国国家航天局宣布，其探测器已经抵达了另一颗太空岩石——一个名为“振荡天星”(469219 Kamoʻoalewa)的有棱角的紧凑天体。

China’s spacecraft, Tianwen-2, has been hunting down its target — a so-called quasi-moon — ever since it launched from Earth in May 2025. Finally, after a 400-day voyage around the solar system, it got within 12 and a half miles of the asteroid’s surface, allowing the spacecraft to take its first detailed photograph.

中国的航天器“天问二号”自2025年5月从地球发射升空以来，就一直在追踪其目标——一颗所谓的准卫星。最终，在围绕太阳系进行了为期400天的航行之后，它进入了距离该小行星表面约20公里的范围内，并拍摄到第一张详细照片。

Pointy, asymmetric and just 60 feet in length, Kamoʻoalewa looks very different from the far more rubbly and rotund asteroids that various uncrewed spacecraft have visited in recent years.

振荡天星呈尖锐状、不对称且长度仅约18米，这与近年来各种无人航天器探访过的那些表面更为松散、圆润的小行星看起来大相径庭。

“Kamo‘oalewa looks amazing, like nothing we’ve seen floating in space before,” said Sabina Raducan, a researcher at the International Space Science Institute in Bern, Switzerland.

位于瑞士伯尔尼的国际空间科学研究所研究员萨比娜·拉杜坎表示：“振荡天星看起来太不可思议了，跟我们以前见过的太空漂浮物截然不同。”

Its craggy, diminutive nature suggests a dramatic origin story — perhaps a high-speed collision between two large asteroids. “It could be a remnant of a catastrophic event,” said Cristina Thomas, a planetary scientist and planetary defense researcher at Northern Arizona University.

这种多岩石、体积微小的特性暗示了一个极具戏剧性的起源故事——也许是两颗大型小行星之间的一场高速碰撞。“它可能是一场灾难性事件的残余物，”北亚利桑那大学的行星科学家兼行星防御研究员克里斯蒂娜·托马斯说道。

As a quasi-moon, Kamo‘oalewa loops around and keeps in lock-step with Earth, but it’s not a genuine moon because it’s gravitationally tied to the sun. It poses no danger to us, but quasi-moons like Kamo‘oalewa offer clues as to how asteroids that started life between Mars and Jupiter ended up at Earth’s doorstep — something that scientists concerned about potentially killer asteroids are keen to learn more about.

作为一颗准卫星，振荡天星绕着地球转圈并与地球保持步调一致，但它并不是一颗真正的卫星，因为在引力上它与太阳绑定在一起。它对我们不构成危险，但像振荡天星这样的准卫星为我们提供了线索，帮助我们了解最初在火星和木星之间诞生的小行星是如何来到地球附近的——这是关注潜在毁灭性小行星的科学家们渴望更多了解的东西。

Tianwen-2 won’t just admire this asteroid from afar. After conducting science observations from above, it will swoop down and collect some pristine asteroid matter from Kamoʻoalewa before returning it to Earth in late 2027.

“天问二号”不会只是从远处欣赏这颗小行星。在从上方进行科学观测之后，它将俯冲而下，从振荡天星收集一些原始的小行星物质，然后再于2027年底将其送回地球。

“The sampling is definitely going to be challenging,” Dr. Raducan said. But if China pulls it off, it will become the third nation to lift material directly from an asteroid, after Japan and the United States.

“采样绝对将是一项具有挑战性的任务，”拉杜坎说。但如果中国成功办到，它将成为继日本和美国之后第三个直接从小行星上采集到物质的国家。

Tianwen-2, whose name is often translated to “Questions to Heaven,” traveled 620 million miles through space to rendezvous with the asteroid, which is “about the length of a bowling lane,” Dr. Thomas said. “Kamo‘oalewa is the smallest object that humans have visited with a spacecraft.”

托马斯表示，“天问二号”在太空中航行了10亿公里才与这颗小行星交会，而这颗小行星的“长度大约与一条保龄球道相当”。“振荡天星是人类利用航天器探访过的最小的天体。”

加拿大-法国-夏威夷望远镜的MegaCam相机在2016年4月28日拍摄的振荡天星相对于背景恒星移动的延时图像。

Based on Tianwen-2’s first photo, the asteroid resembles a rocky splinter. “It looks exactly like an intact shard that we get from impact experiments in laboratory,” Dr. Raducan said.

根据“天问二号”的第一张照片，该小行星酷似一块岩石碎屑。“它看起来完全就像我们在实验室撞击实验中获得的一块完整碎片，”拉杜坎说。

Scientists briefly wondered if Kamo‘oalewa might be a chunk of our own moon, created by an asteroid impact millions of years ago.

科学家们一度猜想，振荡天星是否可能是月球的一块碎片，是由数百万年前的一次小行星撞击所产生的。

That theory has fallen out of favor. Scientists found that it’s much more likely that Kamo‘oalewa started out as an object in the main belt of asteroids just beyond Mars.

这一理论如今已被抛弃。科学家们发现，振荡天星更有可能最初是作为火星之外主小行星带里的一个天体而存在的。

A recent, preliminary examination of Kamo‘oalewa using the remarkably perceptive James Webb Space Telescope also revealed it to be a very reflective object, and not something darker and moon-like. This survey also uncovered hints that its surface composition is akin to a rare type of meteorite known as an aubrite.

最近，利用敏锐度惊人的詹姆斯·韦布空间望远镜对振荡天星进行的初步检验还表明，它具备高反射率，不是月球那种相对黯淡的天体。这项调查还发现了一丝迹象，表明其表面成分类似于一种被称为顽火无球陨石(aubrite)的罕见陨石类型。

Aubrites are particularly exciting because they might come from a massive, smashed-up asteroid-like object that had its own active geologic processes, including those that made magma, rocky layers and perhaps even a metal core — almost like a miniature planet. It’s possible that Kamo‘oalewa may be the remains of something similar.

顽火无球陨石尤其令人兴奋，因为它们可能来自一个被撞碎的巨大、类似于小行星的天体，该天体自身曾拥有活跃的地质过程，包括那些产生岩浆、岩石层甚至可能是金属核心的过程——几乎就像一个微型行星。振荡天星有可能是某种类似天体的残余物。

For now, nobody can be certain as to what exactly Kamo‘oalewa may be. “It takes coordinated efforts across several disciplines to find the story that can explain everything best,” said Benjamin Sharkey, a planetary scientist at the University of Maryland.

目前，没有人能确切判定振荡天星究竟是什么。“需要跨越多个学科的协同努力，才能拼凑出最合理的解释，”马里兰大学的行星科学家本杰明·沙尔基说道。

But, if all goes according to plan, we’re about to find out the truth. Sometime in the next few months, Tianwen-2 will plunge toward Kamo‘oalewa and attempt to extract some of its rocky debris in one of several ways, including using jets of gas to agitate the surface grains into a container, and anchoring itself to the asteroid before drilling into it. Should it succeed, the spacecraft will depart Kamoʻoalewa with the goods in April 2027.

但是，如果一切按计划进行，我们即将查明真相。在接下来几个月的某个时候，“天问二号”将向振荡天星俯冲，并尝试以几种方式中的一种提取其岩石碎屑，包括利用气体喷射将表面颗粒激荡到一个容器中，以及在对其进行钻探之前将自身锚定在该小行星上。如果成功，该航天器将于2027年4月带着收获物离开振荡天星。

But the asteroid won’t make it easy for China.

但这颗小行星不会让中国轻易得手。

When the United States and Japan brought asteroid samples to Earth, the samples were pebbly objects barely held together by their own gravity. While interacting with them had their own spaceflight challenges, scooping them up into a storage capsule wasn’t too difficult.

当美国和日本将小行星样本带回地球时，样本都是仅凭自身引力勉强聚集在一起的碎石堆天体。虽然与它们接触有着自身在航天飞行方面的挑战，但将它们铲入储存舱并不是太困难。

Kamo‘oalewa, however, may be a solid, rigid rock. “It’ll be the first time we visited something like that,” said Andy Rivkin, a planetary scientist and planetary defense researcher at Johns Hopkins Applied Physics Laboratory in Laurel, Md.

然而，振荡天星可能是一块坚硬、刚性的岩石。“这将是我们第一次探访这样的东西，”位于马里兰州劳雷尔的约翰斯·霍普金斯大学应用物理实验室的行星科学家、行星防御研究员安迪·里夫金表示。

The quasi-moon’s Hawaiian name means “wobbling celestial object.” As it swivels around once every 28 minutes, it’s more like a rapidly moving spinning top — something that could imperil Tianwen-2’s touchdown.

这颗准卫星的夏威夷语名字意为“摇摆的太空天体”。由于每28分钟就会自转一圈，它更像是一个快速移动的陀螺——这可能会危及“天问二号”的着陆。

And the fact that Kamo‘oalewa is so tiny means that Tianwen-2 — which, weighing around two tons, is no pipsqueak — could have an outsize effect on the asteroid itself. “The hope is that while drilling, the spacecraft doesn’t push the asteroid on a different orbit,” Dr. Raducan said, “given that their relative sizes are so similar.”

并且，振荡天星极其微小这一事实意味着，重量大约为两吨、绝非小家伙的“天问二号”可能会对该小行星本身产生巨大的影响。“希望是在钻探时，航天器不会将该小行星推向不同的轨道，”拉杜坎说，“因为它们的大小相对来说是接近的。”