Scientists outline mission to chase down interstellar comet

Researchers in the United States have drawn up a mission plan to intercept a comet arriving from outside the solar system, in what they say could offer extraordinary insights into how planets and stars form.

A study by the Southwest Research Institute (SwRI) in Texas shows that a spacecraft launched from Earth could carry out a high-speed flyby of one of these rare visitors, capturing data on its composition, structure and atmosphere.

Interstellar objects are bodies formed in distant star systems that are flung across space and occasionally pass through our neighbourhood. The first to be detected was 1I/‘Oumuamua in 2017, followed by comet 2I/Borisov in 2019 and most recently 3I/ATLAS this year. Scientists expect many more will be found in the coming decade with the aid of next-generation telescopes such as the Vera Rubin Observatory in Chile.

“These objects offer humanity its first chance to closely explore material forged around other stars,” said Dr Alan Stern, planetary scientist and associate vice president at SwRI. “A flyby mission could transform our understanding of how solid bodies form across the galaxy.”

The institute’s study used 3I/ATLAS as a test case and concluded that the proposed spacecraft could have intercepted it. Because of their extreme speeds and hyperbolic paths, orbiting such objects is currently impossible, but SwRI scientists say a head-on flyby is both feasible and affordable.

Matthew Freeman, project manager for the study, said the encounter would deliver “groundbreaking” observations. Data collected could reveal the comet’s physical properties, origins, and the behaviour of its coma, the envelope of gas and dust that escapes from its surface.

To explore trajectory options, the team built software to generate synthetic populations of interstellar objects and calculate low-energy flight paths. Dr Mark Tapley, SwRI’s orbital mechanics expert, found that the trajectory to 3I/ATLAS was within reach of the spacecraft design. “The encouraging thing about 3I/ATLAS is that it shows such missions are achievable with existing technology,” he said.

The mission concept could be proposed to NASA in the future. If approved, it would mark the first time a spacecraft has directly studied an object from beyond the solar system.