# Fast litho-panspermia in the habitable zone of the TRAPPIST-1 system

## TL;DR

This study shows that litho-panspermia could occur extremely rapidly in the TRAPPIST-1 system, with material transfer between planets happening within a century, much faster than in our Solar System.

## Contribution

The paper introduces a simulation-based analysis demonstrating that impact ejecta can transfer between habitable planets in TRAPPIST-1 within a century, highlighting a potential for rapid biological material exchange.

## Key findings

- Approximately 10% of ejecta reach another habitable planet within 100 years.
- Transfer times are shortest for ejection velocities near planetary escape velocity.
- Litho-panspermia in TRAPPIST-1 is 4-5 orders of magnitude faster than in the Solar System.

## Abstract

With several short-period, Earth-mass planets in the habitable zone, the TRAPPIST-1 system potentially allows litho-panspermia to take place on very short timescales. We investigate the efficiency and speed of inter-planetary material transfer resulting from impacts onto the habitable zone planets. By simulating trajectories of impact ejecta from their moment of ejection until (re-)accretion, we find that transport between the habitable zone planets is fastest for ejection velocities around and just above planetary escape velocity. At these ejection velocities, ${\sim}10\%$ of the ejected material reaches another habitable zone planet within $10^2\mathrm{~yr}$, indicating litho-panspermia can be 4 to 5 orders of magnitude faster in TRAPPIST-1 than in the Solar System.