A paper in Advances in Space Research, “Interstellar Now! Missions to and Sample Returns from Nearby Interstellar Objects” (full text [PDF]), explores the feasibility of fly-by, rendezvous, and sample return missions to interstellar objects such as the recently discovered 1I/'Oumuamua and 2I/Borisov and the suspected captured interstellar asteroid 514107 Kaʻepaokaʻawela, which is in a retrograde orbit around the Sun synchronous with Jupiter. It concludes that in many cases, particularly when the object is discovered before perihelion, that a probe which could be launched by a Falcon Heavy or SLS would be able to investigate such objects using technologies such as a Solar Oberth maneuver, solar sail, or nuclear thermal propulsion could investigate such objects at close range. Sample missions plans are included. Here is the abstract:
The recently discovered first high velocity hyperbolic objects passing through the Solar System, 1I/'Oumuamua and 2I/Borisov, have raised the question about near term missions to Interstellar Objects. In situ spacecraft exploration of these objects will allow the direct determination of both their structure and their chemical and isotopic composition, enabling an entirely new way of studying small bodies from outside our solar system. In this paper, we map various Interstellar Object classes to mission types, demonstrating that missions to a range of Interstellar Object classes are feasible, using existing or near-term technology. We describe flyby, rendezvous and sample return missions to interstellar objects, showing various ways to explore these bodies characterizing their surface, dynamics, structure and composition. Interstellar objects likely formed very far from the solar system in both time and space; their direct exploration will constrain their formation and history, situating them within the dynamical and chemical evolution of the Galaxy. These mission types also provide the opportunity to explore solar system bodies and perform measurements in the far outer solar system.