Intercepting Interstellar Objects

TL;DR

This paper evaluates how the CI rapid-response flyby framework can underpin future ISO exploration by arguing for a prepositioned, wait-in-space mission architecture capable of in situ measurements of interstellar visitors. It details CI's multi-spacecraft payload and the essential role of a neutral mass spectrometer alongside remote sensing to characterize nucleus, gas, and dust, while proposing a scalable path to an ISO mission with realistic $Δv$ budgets and inner-Solar-System encounter geometries. The work highlights the scientific potential of direct sampling of extrasolar material to test planet formation theories and the universality of ices and minerals, and emphasizes UK leadership and capability development to realize such missions in the 2025–2035 planning horizon. Overall, the approach offers a concrete, technically feasible route to achieving the first in situ study of an ISO, with clear implications for mission design, international collaboration, and the astronomical discovery pipeline from LSST.

Abstract

We describe how the ESA Comet Interceptor mission, which is due to launch in 2028/29 to a yet-to-be-discovered target, can provide a conceptual basis for a future mission to visit an Interstellar Object. Comet Interceptor will wait in space until a suitable long period comet is discovered, allowing rapid response to perform a fast flyby of an object that will be in the inner Solar System for only a few years; an enhanced version of this concept could realistically provide the first in situ investigation of a visitor from another star system.

Figures (2)

• Figure 1: Comet Interceptor spacecraft and instruments (ESA).
• Figure 2: Accessible regions for CI comet encounters, relative to Earth, for different $\Delta v$ (0.75 or 1.5 km/s) and time of flight (ToF) trajectories (from 2021AcAau.188..265S).