Stellar Gravitational Lens Engineering for Interstellar Communication and Artifact SETI

TL;DR

This paper explores the engineering challenges and feasibility of using stellar gravitational lenses as interstellar communication relays, including long-term stability, perturbation management, and SETI search strategies around the Sun.

Contribution

It provides a detailed analysis of the engineering requirements, perturbation mitigation, and potential SETI applications of stellar gravitational lens relay systems.

Findings

Relativistic perturbations can be countered with modern propulsion over centuries.

Certain nearby stars are suitable for extraterrestrial stellar relay placement.

Long-term stability of gravitational relays is feasible with active adjustments.

Abstract

Several recent works have proposed "stellar relay" transmission systems in which a spacecraft at the focus of a star's gravitational lens achieves dramatic boosts in the gain of an outgoing or incoming interstellar transmission. We examine some of the engineering requirements of a stellar relay system, evaluate the long-term sustainability of a gravitational relay, and describe the perturbations and drifts that must be actively countered to maintain a relay-star-target alignment. The major perturbations on a relay-Sun-target alignment are the inwards gravity of the Sun and the reflex motion of the Sun imparted by the planets. These approx. m/s/yr accelerations can be countered with modern propulsion systems over century-long timescales. This examination is also relevant for telescope designs aiming to use the Sun as a focusing element. We additionally examine prospects for an artifact SETI search to observe stellar relays placed around the Sun by an extraterrestrial intelligence and suggest certain nearby stars that are relatively unperturbed by planetary systems as favorable nodes for a stellar relay communications system.