Bacterial morphologies in carbonaceous meteorites and comet dust

TL;DR

This paper reviews evidence of microbial fossils in meteorites and comet dust, supporting the theory that comets may have played a role in spreading life through panspermia.

Contribution

It presents new morphological and chemical analyses of comet dust and meteorite fossils, strengthening the case for extraterrestrial microbial life and cometary panspermia.

Findings

Identification of organic-walled hollow spheres in comet dust

Detection of siliceous diatom skeletons similar to those in meteorites

Support for the hypothesis that comets may carry microbial life

Abstract

Three decades ago the first convincing evidence of microbial fossils in carbonaceous chondrites was discovered and reported by Hans Dieter Pflug and his collaborators. In addition to morphology, other data, notably laser mass spectroscopy, confirmed the identification of such structures as putative bacterial fossils. Balloon-borne cryosampling of the stratosphere enables recovery of fragile cometary dust aggregates with their structure and carbonaceous matter largely intact. Scanning electron microscope studies of texture and morphology of particles in the Cardiff collection, together with Energy Dispersive X-ray identifications, show two main types of putative bio-fossils - firstly organic-walled hollow spheres around 10 microns across, secondly siliceous diatom skeletons similar to those found in carbonaceous chondrites and terrestrial sedimentary rocks and termed "acritarchs". Since carbonaceous chondrites (particularly Type 1 chondrites) are thought to be extinct comets the data reviewed in this article provide strong support for theories of cometary panspermia.