space Practical Magic

We’ve figured out how to turn a passing comet into an interstellar spaceship using just four small engines.

March 19, 2026

Original Paper

A Minimal Four-Thruster System for Comet-Based Interstellar Navigation

Bo Pieter Johannes Andrée

arXiv · 2603.16981

The Takeaway

Instead of building massive ships from scratch, we could 'hitch a ride' on comets already leaving our solar system. By placing four jets in a specific pattern, we could use the comet's own rotation and ice-fuel to steer it like a massive cosmic sailboat toward other stars.

From the abstract

Interstellar comets arrive with key ingredients for deep-space platforms already in place: volatile inventories convertible to propellant, natural rotation providing continuous attitude variation, and hyperbolic trajectories that carry them through the inner Solar System and back out to interstellar space. Rather than constructing spacecraft from scratch, we ask what \emph{minimal modification} is required to steer such a body along a controlled trajectory. The answer is surprisingly modest. By