The Feasibility of a Spacecraft Flyby with the Third Interstellar Object 3I/ATLAS from Earth or Mars

TL;DR

This paper assesses the feasibility of spacecraft flybys of the interstellar object 3I/ATLAS from Earth or Mars, analyzing transfer trajectories, required delta-V, and mission timing to inform potential observation strategies.

Contribution

It provides detailed calculations of transfer trajectories and delta-V requirements for missions to 3I/ATLAS from Earth and Mars, highlighting feasible mission scenarios and operational challenges.

Findings

Mars launches in mid-2025 require lower delta-V (~5 km/s) for early October flybys.

Earth launches post-discovery need high delta-V (~24 km/s), making them more challenging.

Flyby speeds pose observational and engineering challenges for mission success.

Abstract

We investigate the feasibility of a spacecraft mission to conduct a flyby of 3I/ATLAS, the third macroscopic interstellar object discovered on July 1 2025, as it traverses the Solar System. There are both ready-to-launch spacecraft currently in storage on Earth, such as Janus, and spacecraft nearing the end of their missions at Mars. We calculate minimum $\Delta V$ single-impulse direct transfer trajectories to 3I/ATLAS both from Earth and from Mars. We consider launch dates spanning January 2025 through March 2026 to explore obtainable and hypothetical mission scenarios. Post-discovery Earth departures require a challenging $\Delta V\gtrsim24$ km s$^{-1}$ to fly by 3I/ATLAS. By contrast, Mars departures from July 2025 - September 2025 require $\Delta V\sim5$ km s$^{-1}$ to achieve an early October flyby -- which is more feasible with existing propulsion capabilities. \added{We further calculate the phase angle and flyby velocity for these trajectories, noting that the resulting flyby speeds would impose significant observational and engineering challenges that a mission would need to overcome.} We discuss how existing spacecraft could be used to observe 3I/ATLAS and how spacecraft at other locations in the Solar System could be repurposed to visit future interstellar objects on short notice.