Driving on the Roadmap

"On this single planet called Earth, there co-exist (among countless other life forms), algae, beetles, sponges, jellyfish, snakes, condors, and giant sequoias. Imagine these seven living organisms lined up next to each other in size-place. If you didn’t know better, you would be hard-pressed to believe that they all came from the same universe, much less the same planet". –Neil DeGrasse Tyson, director of the Hayden Planetarium
Credit: NGS

The NASA Astrobiology Roadmap provides guidance for research and technology development across the NASA enterprises that encompass the space, Earth, and biological sciences. The ongoing development of astrobiology roadmaps embodies the contributions of diverse scientists and technologists from government, universities, and private institutions. The Roadmap addresses three basic questions: How does life begin and evolve, does life exist elsewhere in the universe, and what is the future of life on Earth and beyond?

One of the most interesting lists in the Roadmap include example investigations. For those who are inclined to ‘doing’, the list is fertile and rich with ideas for thinking deeper about how scientists answer some of the most difficult and enduring questions posed by astrobiology. This survey highlights those examples, with links to help understand the more complex endeavors.

Study the relationship between stellar metallicity and planet formation. Determine if there is a galactic habitable zone. Model the origin of planetary systems, especially water delivery to and loss from terrestrial-like planets of various size and mass. Determine how water loss affects climate, surface, and interior processes, and how these changes affect habitability. Develop comprehensive models of the environments of terrestrial-like planets to investigate the evolution of habitability.

Investigate novel methods for detecting and characterizing extrasolar planets, particularly those that might lead to an improved understanding of the frequency of habitable Earthlike planets.

Use atmospheric models to understand the range of planetary conditions that can be determined from low-resolution, full-disk spectra at visible, near-infrared, and thermal wavelengths. Use data on Venus, Earth, and Mars to validate these models. Model a variety of biosignatures, including the ozone 9.7 mm band and oxygen A band signatures and their variations over Earth’s geological and biological history.

Target well-instrumented robotic rovers to sites of past aqueous sedimentation to analyze rocks for geochemistry, aqueous minerals, organic matter, and fossil biosignatures. Develop flight-capable instrumentation for the unambiguous detection of biosignatures preserved in surface and subsurface rocks, soils, and ices.

Explore the atmosphere and surface environments of Titan for evidence of complex organic chemistry and water, to provide a context for understanding potential habitability and prebiotic chemistry. Simulate the environment of Titan to aid in designing in situ missions and to interpret data returned therefrom. Develop astrobiology instrumentation that can survive the low temperature, high radiation environments of the surface of Europa. Use in situ methods to test models that predict the presence of energy sources for supporting life.

Trace the cosmic formation of prebiotic materials from the formation of interstellar molecules and solids through the processing of these materials to produce more complex compounds. Conduct laboratory experiments and simulations to provide a framework for analyzing meteorites and samples returned from asteroids and comets, and for interpreting spectra of interstellar clouds. Analyze meteorites and returned samples to understand the nature of extraterrestrial organic compounds. Identify the organic compounds and complexes produced under primordial planetary conditions through laboratory simulation experiments.

Search for mechanisms of enantiomeric enhancement that introduced chirality into biological systems. Investigate polymers other than nucleic acids that have the potential to have been precursor molecules capable of containing genetic information. Investigate the RNA-catalyzed active site in ribosomes to better understand how RNA could have first evolved to mediate translation in early forms of life.

Image of star HD 28185
HD 28185 b is the first exoplanet discovered with a circular orbit within its star’s habitable zone. Astrobiology: the study of how life begins and evolves – that is, where did we come from? Does life exist elsewhere in the universe – are we alone? And, what is life’s future on Earth and beyond – where are we going in space. Albertus Magnus (1193-1280) crafted one of the first statements that could easily be recognizable on an astrobiology roadmap today: "Since one of the many wondrous and noble questions in Nature is whether there is one world or many,…it seems desirable for us to inquire about it."
Credit: STScI Digitized Sky Survey

Search for pigments that were plausible components of the prebiotic environment and have the capacity to capture and transduce light energy into chemical energy. Investigate redox reactions in which hydrogen serves as a source of free energy that could plausibly be available for early forms of life. Investigate mechanisms by which early boundary membranes could couple the energy available in ion gradients to the synthesis of highenergy compounds such as pyrophosphate.

Determine how ionic and polar nutrients could permeate membrane boundaries to supply monomers and energy for intracellular metabolism and biosynthesis. Investigate polymerase reactions that can take place in membrane-bounded microenvironments, using external sources of monomers and chemical energy. Establish membrane-bounded protein synthesis systems that incorporate ribosomes and mRNA in lipid vesicles.

Examine the earliest sedimentary rocks for biosignatures, such as microfossils and chemical fossils. Search for biosignatures of key microorganisms and metabolic processes (e.g., photosynthesis) in rocks of Archean age. Analyze genomic sequence data of prokaryotes and identify correlations between lineage divergence and events in the history of the biosphere.

Study carbon isotopes and other proxies of environmental change in Neoproterozoic rocks to better understand the history of global climatic perturbations that may have influenced the early evolution of complex life. Search for fossil evidence of eukaryotes in rocks of Proterozoic age to determine the morphology, ecology, and diversity of early eukaryotes. Analyze genomic sequence data of unicellular eukaryotes to gain insights into the early evolution of eukaryotic complexity, including the acquisition of cellular organelles.

Examine the evolutionary, ecological, and taxonomic changes in Earth’s biota following a known asteroid impact event. Investigate a known mass extinction event in the fossil record to determine whether it was caused or intensified by an extraterrestrial event, such as an impact or a nearby supernova.

Experimentally observe the assembly of genes into novel metabolic pathways as an adaptive response to environmental changes. Examine microbial genome rearrangements, including gene deletion and acquisition processes, in response to nutrient change and physical-chemical stress. Investigate the diversity of genome stability in physiologically and genomically different microbes.

Investigate small molecule interactions and their role in coordinating metabolic activities in mixed phototrophic/chemotrophic microbial communities. Examine adaptive mutations in individual microbial species of mixed communities in response to environmental perturbations. Examine the susceptibility of established microbial communities to invasion by foreign microbes.

Investigate the intrinsic properties and stability of critical biomolecules that allow microorganisms to survive severe freezing and thawing cycles. Biochemically characterize DNA-repair mechanisms that allow microorganisms to recover from radiation damage. Study survival strategies that might allow microbes to maintain their viability for very long periods of time (thousands to millions of years).

Construct biogeochemical models of ecosystems and test the models with isotopic and functional genomic analyses of the constituent parts of the ecosystems. Document the ecological impact of changes in climate, habitat complexity, and nutrient availability upon the structure and function of a selected ecosystem, as a guide for understanding changes that might occur over time scales ranging from abrupt events (a few years or less) to millions of years.

Star field
The statistical argument for life elsewhere may trump philosophical purity

Document the impact of the space environment upon microbial ecosystems that might be ejected into space by an impact event. Examine the survival, genomic alteration, and adaptation of microbial ecosystems in a simulated martian habitable environment. Interpret the significance of the findings regarding the potential for the forward biological contamination of Mars. Examine the effects of the space environment upon the biosynthesis and utilization of microbial biomolecules that play key roles in biogeochemical processes.

Determine additional organic biomarkers that will help to chart the presence and development of photosynthetic microbiota in Precambrian rocks. Determine the features of sedimentary laminated textures that uniquely require biological processes. Identify examples of chemical, mineralogical, and stable isotopic biosignatures that can indicate the presence of subsurface biota (e.g., microbes living in aquifers), and that can be preserved in ancient rocks.

Determine the nature and fate of reduced gases that are produced by specific microbial ecosystems in an anoxic ("pre-oxygenated") biosphere. Carry out laboratory, observational, and modeling studies to separate false from true biosignatures [e.g., atmospheric O2 in a range of planetary environments].

Related Web Pages

Long, Strange Trips
Astrobiology Roadmap
Bombarded by Mysteries
Frequent Wet Earths?
Defining Life
Entropy and Evolution
What is Life?