Continuing the discussion from So about panspermia…:
Much ungrounded speculation on other threads on panspermia. The are excellent papers available that provide more rigorous answers.
Modelling panspermia in the TRAPPIST-1 system
The recent ground-breaking discovery of seven temperate planets within the TRAPPIST-1 system has been hailed as a milestone in the development of exoplanetary science. Centred on an ultra-cool dwarf star, the planets all orbit within a sixth of the distance from Mercury to the Sun. This remarkably compact nature makes the system an ideal testbed for the modelling of rapid lithopanspermia, the idea that micro-organisms can be distributed throughout the Universe via fragments of rock ejected during a meteoric impact event. We perform N-body simulations to investigate the timescale and success-rate of lithopanspermia within TRAPPIST-1. In each simulation, test particles are ejected from one of the three planets thought to lie within the so-called ‘habitable zone’ of the star into a range of allowed orbits, constrained by the ejection velocity and coplanarity of the case in question. The irradiance received by the test particles is tracked throughout the simulation, allowing the overall radiant exposure to be calculated for each one at the close of its journey. A simultaneous in-depth review of space microbiological literature has enabled inferences to be made regarding the potential survivability of lithopanspermia in compact exoplanetary systems.
They find, for example,
Given the sizeable range of [radiation] experienced by our test particles, it would be justifiable to assume that at least some journeys must be survivable.
Also take a look at this article. There are, also, other pretty good articles out there on this topic.
Enhanced interplanetary panspermia in the TRAPPIST-1 system
The search for extraterrestrial life is one of the most exciting frontiers in present-day astronomy. Recently, the TRAPPIST-1 star was discovered to host seven rocky planets with masses and radii similar to those of the Earth, of which at least three of them may be capable of supporting life. Our paper addresses the possibility that life on one of these planets can spread to others through the transfer of rocky material. We conclude that this process has a high probability of being operational, implying that this planetary system may possess multiple life-bearing planets. Thus, our work has profound theoretical and observational consequences for future studies of the TRAPPIST-1 system and the likelihood of life in our galaxy.