Darwin's Dust and the Search for Signs of Past Life on Mars

HANS MOOSMÜLLER, Desert Research Institute

     Abstract Number: 215
     Working Group: Planetary Aerosols: From Earth to Exoplanets

Abstract
When Charles Darwin undertook his famous voyage around the world on the HMS Beagle, his first landing was on the Cape Verde Islands on 16-Jan-1832. Upon arrival, Darwin encountered a dust storm and collected samples of dust deposited on board the Beagle. He sent the samples to Professor Christian Ehrenberg, who found that “this dust consists in great part of infusoria [diatoms] with siliceous shields.” Darwin concluded from the samples and meteorological conditions that the dust originated from ancient African freshwater lakes more than 600 km away. Therefore, Darwin had remotely detected signs of past life in Africa.

The current search for signs of past life on Mars is focused on using a rover to obtain and examine local soil samples from the delta of an ancient river, where life may have occurred. Currently, soil samples are being stored, for retrieval during the planned Mars Sample Return (MSR) mission, for further examination on Earth. However, very recently it has become clear that MSR may be delayed until 2040 with a greatly increased budget (≈$10G). Therefore, NASA is searching for alternative MSR concepts, and alternative ways of looking for signs of past life on Mars may also be of interest.

Inspired by Darwin’s observations of signs of life in mineral dust aerosols on Earth, one may imagine a different paradigm for searching for signs of past life on Mars, based on the examination of mineral dust. Mars aerosols are completely dominated by mineral dust continuously cycled, that is entrained and deposited, all over Mars. Therefore, it would be possible to obtain and examine mineral dust from the entire Martian surface at a single surface sampling location. Such examination of deposited mineral dust for signs of past life could utilize optical and/or electron microscopy without need for MSR.