First European Interstellar Symposium 2024

Background

It is frequently believed that the space between the stars is empty. The interstellar community is firmly grounded in this belief and is predominantly focused on missions to other star systems. Today, we know that the space between the stars is not empty but is populated by a plethora of objects. While interstellar dust has been known for many decades, more recently, larger objects have been discovered, such as interstellar objects and nomadic worlds.

Objective

We present a variety of mission architectures to interstellar objects and nomadic worlds and thereby explore propulsion technology – trip time limits over a variety of distance requirements.

Methods

We use the Optimum Interplanetary Trajectory Software (OITS) to find optimal trajectories for various interstellar objects along. Furthermore, we use Technology Readiness Levels (TRL) for comparing propulsion system performance with maturity.

Results

We find that chemical propulsion in combination with a solar Oberth manoeuvre and/or flybys (in particular the Passive Jupiter Gravity Assist (PJGA)) reaches its limits at a distance of roughly 500 AU, if the maximum trip time is set at about 80 years. For reaching nomadic worlds, which may have average distances of 10^3 to 10^4 AU, precursor versions of interstellar-capable propulsion systems are needed, such as laser sails and fusion propulsion.

Conclusions

We conclude that existing propulsion systems, combined with flyby maneuvers are viable for reaching interstellar objects up to hundreds of AU distance, which is in a similar range as the putative Planet Nine. However, nomadic worlds (hundreds of km in diameter) are likely only reachable via interstellar-capable propulsion systems. The presented results have important implications for future propulsion system roadmaps, which should also focus on the development of interstellar-capable propulsion systems.