Publications on our interstellar guest 3I/ATLAS continue, as they should- we have only months before it passes behind the Sun. Publications on the arXiv platform:
arXiv:2507.14916
Yang, B. Meech, K. J. Connelley, M. et al. Spectroscopic Characterization of Interstellar Object 3I/ATLAS: Water Ice in the Coma
Submitted 20 July, 2025; originally announced July 2025.
arXiv:2507.07312
Alvarez-Candal, A. Rizos, J. L. Lara, L. M. et al. X-SHOOTER Spectrum of Comet 3I/ATLAS: Insights into a Distant Interstellar Visitor
Submitted 21 July, 2025; v1 submitted 9 July, 2025; originally announced July 2025.
arXiv:2507.15755
Yaginuma, A. Frincke, T. Seligman, D. Z. et al. The Feasibility of a Spacecraft Flyby with the Third Interstellar Object 3I/ATLAS from Earth or Mars
Submitted 21 July, 2025; originally announced July 2025.
Yet again, please consider these openly-distributed papers to be, at best, drafts of peer-reviewed journal papers, and at worst, future journal rejects. In this particular case, Yang et al. and Alvarez-Candal et al. are doing what some snicker as ‘squiggly line interpretation’. For a demonstration of that snickering, you only need to see the mess made when astronomers claimed the detection of life-marker chemicals in an exoplanet, K2-18b:
Madhusudhan, N. Sarkar, S. Constantinou, S. et al. 2023 Carbon-bearing Molecules in a Possible Hycean Atmosphere ApJL 956 L13 acf577
Madhusudhan, N. Constantinou, S. Holmberg, M. 2025 New Constraints on DMS and DMDS in the Atmosphere of K2-18 b from JWST MIRI ApJL 983 L40 adc1c8
The threshold for “detection” (yes, exact quote) is more than a bit arbitrary, and the fact that 3I/ATLAS is within our Solar System, not another system, is only a bit helpful. The object 3I is still far (near Jupiter), its coma is weak, and these comet emissions should be quite faint. Of course, we’re talking about an interstellar object here, so one possibility is that this is some exceptional visitor. But it’s not for a single paper to claim that; we’ll see if other groups can confirm or deny.
As for missions to 3I, we’ve already mentioned that. The propulsive capability needed from an Earth launch is staggering, even assuming a space probe was already built and ready to go. Yaginuma et al. proceed to a new brainstorm: using a craft, now at Mars, and thrusting it out of orbit, onto a 3I-intercept trajectory. Note, however, the authors won’t name any such Mars orbiter, much less recommend a policy change for it. They do, though, repeat that Vera Rubin will spot more interstellar objects.