Mars spacecraft images pinpoint comet 3I/ATLAS's path with 10x higher accuracy. This could help us protect Earth someday

火星航天器图像以10倍更高的精度确定彗星3I/ATLAS的运行轨迹。这未来可能有助于我们保护地球。

The path of comet 3I/ATLAS through the solar system has been predicted with an accuracy 10 times greater than previous estimates, thanks to images taken by a European Space Agency spacecraft orbiting Mars. Though 3I/ATLAS poses no threat of striking Earth, the breakthrough could have important implications for defending Earth against other comets and asteroids someday.

借助欧洲航天局绕火星运行的航天器所拍摄的图像，彗星3I/ATLAS在太阳系中的运行轨迹预测精度比之前的估计提高了10倍。尽管3I/ATLAS不会对地球构成撞击威胁，但这一突破未来可能对防御其他彗星和小行星、保护地球具有重要意义。

The ExoMars Trace Gas Orbiter (TGO) spacecraft observed 3I/ATLAS between Oct. 1 and Oct. 7 as it passed relatively close to Mars, with the comet's closest approach bringing it to within 18 million miles (29 million kilometers) of the Red Planet on Oct. 3. Up until September, calculations of the location and trajectory of 3I/ATLAS relied on observations made by Earth-based telescopes. Scientists did expect a modest improvement in the accuracy of locating 3I/ATLAS with the addition of Mars-based data, but this addition actually yielded a tenfold improvement.

“ExoMars微量气体轨道器（TGO）航天器于10月1日至10月7日期间对3I/ATLAS彗星进行了观测，当时该彗星正相对接近火星。10月3日，这颗彗星与这颗红色星球（火星）的最近距离达到1800万英里（2900万公里）。截至9月，对3I/ATLAS彗星位置和轨迹的计算都依赖于地球基望远镜的观测结果。科学家们原本预计，加入火星基数据后，对3I/ATLAS彗星定位的精度会有一定程度的提升，但实际上，这一数据的加入使得定位精度提高了十倍。”

"The Mars probe got about 10 times closer to 3I/ATLAS than telescopes on Earth, and it observed the comet from a new viewing angle," the European Space Agency (ESA) wrote in a statement. "The triangulation of its data with data from Earth helped to make the comet’s predicted path much more accurate. Because 3I/ATLAS is passing through our solar system fast, traveling with speeds up to 155,000 miles per hour (250,000 kilometers per hour), it will soon vanish into interstellar space, never to return. The improved trajectory allows astronomers to aim their instruments with confidence, enabling more detailed science of the third interstellar object ever detected."

欧洲航天局（ESA）在一份声明中写道：“这台火星探测器（对3I/ATLAS彗星）的观测距离比地球望远镜近约10倍，并且从一个全新的观测角度对该彗星进行了观测。它的数据与地球数据进行三角测量（结合），有助于使这颗彗星的预测运行轨迹精确得多。由于3I/ATLAS正快速穿越我们的太阳系，其运行速度高达每小时15.5万英里（每小时25万公里），它很快就会消失在星际空间中，再也不会返回。（对其轨迹的）改进使得天文学家能够有把握地瞄准他们的仪器，从而能够对这颗有史以来探测到的第三个星际天体开展更详细的科学研究。”

To image 3I/ATLAS, ExoMars TGO turned one of its instruments, CaSIS (Colour and Stereo Surface Imaging System), which usually surveys the surface of the Red Planet in high resolution, toward the stars. The planetary defense team at ESA's Near-Earth Object Coordination Center accounted for the location of the ESA spacecraft around Mars to ensure it captured footage of 3I/ATLAS.

为了对3I/ATLAS彗星成像，ExoMars TGO（火星微量气体轨道器）将其搭载的CaSIS（彩色立体表面成像系统）仪器转向星空。该仪器通常用于以高分辨率勘测火星（红色星球）表面。欧洲航天局近地天体协调中心的行星防御团队考虑了欧洲航天局航天器在火星轨道上的位置，以确保其捕捉到3I/ATLAS彗星的影像。

This special consideration was necessary because observations of comet/asteroid trajectories are usually made using observatories in a fixed location, such as by Earth-based telescopes, or from orbit around Earth, such as the James Webb Space Telescope (JWST).

这种特殊考量是必要的，因为对彗星/小行星轨迹的观测通常是通过固定位置的天文台进行的，例如地基望远镜，或是通过绕地球轨道运行的设备，比如詹姆斯·韦伯太空望远镜（JWST）。

Accounting for ExoMARS TRO's special location, exact position around Mars, and the speed at which it orbits the Red Planet, the planetary defense team, with aid from ESA flight dynamics and science and instrument teams, was able to use data from the spacecraft to calculate the future locations of 3I/ATLAS, or its "ephemeris."

考虑到ExoMars TGO（火星微量气体轨道器）的特殊位置、围绕火星的精确轨道位置，以及它绕这颗红色星球运行的速度，行星防御团队在欧洲航天局飞行动力学团队、科学团队和仪器团队的协助下，得以利用该航天器的数据计算出3I/ATLAS彗星未来的位置，即其“星历表”。

The data collected by ExoMars TRO represents the first time that astrometric data, or measurements of the position of a celestial object, have been collected and submitted to the Minor Planet Center (MPC) by a spacecraft orbiting another planet. The MPC is a hub of asteroid and comet observations from a range of observations, radar stations, and spacecraft.

ExoMars TGO收集的数据，是首次由绕另一颗行星运行的航天器收集并提交给小行星中心（MPC）的天体测量数据（即对天体位置的测量数据）。小行星中心是汇集来自各类天文台、雷达站和航天器的小行星与彗星观测数据的枢纽。

That is a big deal for planetary defense.

这对行星防御来说是一件大事。

"ESA routinely monitors near-Earth asteroids and comets, calculating orbits to provide warnings if required," the space agency wrote. "As this 'rehearsal' with 3I/ATLAS shows, it can be useful to triangulate data from Earth with observations from a second location in space. A spacecraft may also happen to be closer to an object, adding even more value."

欧洲航天局（ESA）在一份声明中写道：“欧空局例行监测近地小行星和彗星，计算其轨道，必要时发出预警。正如对3I/ATLAS彗星的这次‘演练’所展示的，将地球观测数据与太空中第二个位置的观测数据进行三角测量（结合）是有用的。航天器也可能恰好更接近目标天体，从而带来更大价值。”

This isn't the last time that 3I/ATLAS will be observed by a distant spacecraft, either. The interstellar comet is currently being sped by JUICE (Jupiter Icy Moons Explorer), which is bound for the Jovian system. Catching 3I/ATLAS immediately after its closest approach to the sun, JUICE is likely to get the best view of 3I/ATLAS during the interstellar comet's active phase as radiation from the sun is causing it to expel material.

这也不是3I/ATLAS彗星最后一次被遥远的航天器观测到。这颗星际彗星目前正处于“木星冰卫星探测器（JUICE）”的观测范围内，该探测器正前往木星系统。在3I/ATLAS彗星最接近太阳后，JUICE 立即对其进行观测，有望在这颗星际彗星的活跃期获得最佳观测视角——此时太阳辐射正促使它喷出物质。

However, because this spacecraft is currently on the other side of the sun from Earth, the JUICE observations of 3I/ATLAS won't be available to scientists until Feb. 2026.

然而，由于该航天器目前位于地球的太阳对面一侧，科学家们要到2026年2月才能获取JUICE对3I/ATLAS彗星的观测数据。