Comment to: The interaction of relativistic spacecrafts with the interstellar medium

TL;DR

This paper critiques a previous analysis of relativistic spacecraft interactions with interstellar medium, emphasizing the importance of correct modeling of gas interactions to accurately assess risks from dust and gas.

Contribution

It provides a corrected treatment of the Szenes model for gas interactions, challenging prior conclusions about the relative threat of dust versus gas to relativistic spacecraft.

Findings

Proper modeling alters the perceived threat levels from gas and dust.

Dust remains a significant hazard for relativistic spacecraft.

Corrected analysis impacts spacecraft shielding strategies.

Abstract

Recently, Hoang et al. (arXiv:1608.05284) reported analysis of the interaction of relativistic spacecrafts with interstellar medium (ISM, i.e. gas atoms and dust particles) relevant for the Breakthrough starshot initiative (https://breakthroughinitiatives.org/Initiative/3). The main conclusion is that dust pose much greater threat to the starship than gas atoms. However, analysis used to treat interaction of the spaceship with gas atoms is based on the incorrect use of the Szenes model. Only by proper treatment of the Szenes model can be found if the conclusion remains valid - or not. In the following, the main comments we have raised about the paper are listed. Present text is based on the v2 version of the above mentioned paper [0] that was accepted for publication in Astophysical Journal.