China’s Tianwen-1 Orbiter Captures First Close-Up of 3I/Atlas

China’s Tianwen-1 Mars orbiter has made a significant breakthrough by becoming the first spacecraft to capture and release a close-up image of the interstellar object known as 3I/Atlas. This achievement positions China ahead of NASA and other global space agencies in the ongoing exploration of interstellar phenomena. The object is only the third confirmed visitor from outside the solar system, making these images a remarkable scientific milestone.

The photograph was taken on October 3, 2023, from approximately 30 million kilometres away. Notably, the equipment used for this capture was originally designed for mapping the Martian surface rather than for deep-space observation. While NASA has also conducted observations of 3I/Atlas, China was the first to produce and publicly share detailed visual captures, showcasing its capabilities in space exploration.

Technical Challenges and Scientific Insights

The China National Space Agency (CNSA) reported that Tianwen-1 successfully captured the images despite the challenges posed by the object’s extreme faintness, which is estimated to be between 10,000 and 100,000 times dimmer than Martian surfaces. The agency highlighted that the images reveal “distinctive features of a comet,” including a bright central nucleus surrounded by a hazy coma of dust and gas. This observation contradicts claims made by Harvard astrophysicist Avi Loeb, who suggested alternative explanations for the object’s structure.

NASA’s Hubble Space Telescope has also observed 3I/Atlas, noting a similar teardrop-shaped cloud trailing from its icy core. Initial estimates of the nucleus size suggest it could measure up to 5.6 kilometres in diameter, although NASA has indicated that it may be significantly smaller. This smaller size raises questions about its origin and composition, adding to the intrigue surrounding the object.

The Tianwen-1 science team began planning the observation in early September, taking into account the object’s high speed and faint brightness. Adjustments were made to the tracking algorithms and exposure techniques to maintain a stable lock on the rapidly moving target. As a result, the images will support further analysis of the object’s trajectory and material composition.

Broader Implications for Interstellar Research

The CNSA stated that the data gathered from these observations will contribute to the understanding of how interstellar objects form in other planetary systems before being ejected into open space. This insight is particularly valuable as scientists seek to comprehend the dynamics of our universe.

Tianwen-1 is part of China’s broader ambition in space exploration, which aims to establish the country as a leading force in planetary science. The mission has already successfully deployed a rover on the Martian surface and is now contributing to deep-space observation efforts. Following Tianwen-1, China’s Tianwen-2 mission, launched earlier this year, is expected to return samples from a near-Earth asteroid by 2026.

3I/Atlas travels on a hyperbolic trajectory, confirming its entry into the solar system from interstellar space. Previously, only two other such visitors have been documented: Oumuamua in 2017 and Borisov in 2019. Some researchers, including Loeb, have posited that the object’s movement exhibits “anomalous characteristics,” potentially indicating non-natural origins. However, NASA’s lead scientist for small solar system bodies has firmly rejected this notion, asserting that the object behaves consistently with known comets.

With this new close-up image of 3I/Atlas, scientists now have the opportunity to compare it with known comets and asteroids from different star systems. This comparison will help determine whether its materials formed around our Sun or emerged from a completely different stellar environment, further enriching our understanding of interstellar objects.