Darwin’s Dust and the Search for Signs of Ancient Life on Mars

HANS MOOSMÜLLER, Desert Research Institute

     Abstract Number: 498
     Working Group: Bioaerosols

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 near the island of Santiago. Darwin collected samples of dust deposited on board the Beagle and send the samples to Professor Ehrenberg (University of Berlin, Germany), who found that “this dust consists in great part of infusoria with siliceous shields [i.e., shields of diatoms], and of the siliceous tissue of plants.” Darwin concluded from the samples, the wind direction, and the general meteorological conditions during wintertime that the dust originated from ancient freshwater lakes in Africa, more than 600 km away. Therefore, Darwin was able to observe remotely that life had existed in Africa at some time. Similar conclusions can be made from examination of African dust transported to the Caribbean or the Amazon.

The current search for signs of ancient life on Mars is focused on using a rover to examine local soil samples from the delta of an ancient river, where life may have occurred. In addition, soil samples are stored, for retrieval during a planned sample return mission, for further examination on Earth. 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 ancient life on Mars, based on the examination of mineral dust. Mars aerosols are completely dominated by mineral dust cycled, that is entrained and deposited, all over Mars. Therefore, it would be possible to obtain and examine mineral dust from all of the Martian surface at a single surface location. Examination of deposited mineral dust for signs of life could be done with optical or electron microscopy or after sample return to earth.