Robotic ecological mapping: Habitats and the search for life in the Atacama Desert

Abstract

[1] As part of the three-year 'Life in the Atacama' (LITA) project, plant and microbial abundance were mapped within three sites in the Atacama Desert, Chile, using an automated robotic rover. On-board fluorescence imaging of six biological signatures (e.g., chlorophyll, DNA, proteins) was used to assess abundance, based on a percent positive sample rating system and standardized robotic ecological transects. The percent positive rating system scored each sample based on the measured signal strength (0 for no signal to 2 for strong signal) for each biological signature relative to the total rating possible. The 2005 field experiment results show that percent positive ratings varied significantly across Site D (coastal site with fog), with patchy zones of high abundance correlated with orbital and microscale habitat types (heaved surface crust and gravel bars); alluvial fan habitats generally had lower abundance. Non-random multi-scale biological patchiness also characterized interior desert Sites E and F, with relatively high abundance associated with (paleo)aqueous habitats such as playas. Localized variables, including topography, played an important, albeit complex, role in microbial spatial distribution. Site D biosignature trends correlated with culturable soil bacteria, with MPN ranging from 10-1000 CFU/g-soil, and chlorophyll ratings accurately mapped lichen/moss abundance (Site D) and higher plant (Site F) distributions. Climate also affected biological patchiness, with significant correlation shown between abundance and (rover) air relative humidity, while lichen patterns were linked to the presence of fog. Rover biological mapping results across sites parallel longitudinal W-E wet/dry/wet Atacama climate trends. Overall, the study highlights the success of targeting of aqueousassociated habitats identifiable from orbital geology and mineralogy. The LITA experience also suggests the terrestrial study of life and its distribution, particularly the fields of landscape ecology and ecohydrology, hold critical lessons for the search for life on other planets. Their applications to robotic sampling strategies on Mars should be further exploited.Citation: Warren-Rhodes, K., et al. (2007), Robotic ecological mapping: Habitats and the search for life in the Atacama Desert,

Life in the Atacama: Searching for life with rovers (science overview)

“…SPI provided the intermediate scale in contextual imaging, between the global satellite imagery and the local‐to‐microscopic scale obtained from the fluorescence imager. This scaling continuum and nested imagery was critical in the evaluation of the presence of oases at metric to micrometric scale [ Warren‐Rhodes et al , 2007a, 2007b]. The SPI imager was also used to detect atmospheric changes, specifically the presence of morning and late afternoon fog events in the Coastal Range (as shown at Site A in Figure 1), which signaled the location of potential water accumulation on the ground and, possibly, the concentration of life.…”

“…An overview of the scientific and technical results of the field investigation is given in section 6. For detailed results on the geological mapping, mineralogy and biology, see Warren‐Rhodes et al [2007a, 2007b], A. Hock (Life in the Atacama: A scoring system for mapping habitability and the robotic exploration for life, submitted to Journal of Geophysical Research, 2007, hereinafter referred to as Hock et al, submitted manuscript, 2007), J. Piatek et al (Surface and subsurface composition of the Life in the Atacama field sites from rover data and orbital image analysis, submitted to Journal of Geophysical Research, 2007, hereinafter referred to as Piatek et al, submitted manuscript, 2007), and S. Weinstein et al (Application of pulsed‐excitation fluorescence imager for daylight detection of sparse life in tests in the Atacama Desert, submitted to Journal of Geophysical Research , 2007, hereinafter referred to as Weinstein et al, submitted manuscript, 2007). Finally in sections 7 and 8 we discuss and conclude on the main results of the field investigations and how the lessons learned could inform future planetary exploration and serve the exploration of extreme terrestrial environments.…”

Application of pulsed‐excitation fluorescence imager for daylight detection of sparse life in tests in the Atacama Desert

“…The ability to acquire fluorescence data in daylight provided the LITA team a tool to potentially map life over large regions as the rover traveled throughout each day. The results of this aspect of the field study are reported by Warren‐Rhodes et al [2007a, 2007b]. More research is required to perfect the dye probes and probe penetration for optimal use.…”

Runoff Generation, Overland Flow and Erosion on Hillslopes

“…Hyper-arid areas can often produce significant biological crusts, sustained by the interception of fog and dew as a moisture source (Kidron, 2005;Lange et al, 2007;Shanyengana et al, 2002;Warren-Rhodes et al, 2007).…”