Astrobiology asks three questions fundamental to our understanding of our origins, the future of human evolution, and life in the universe:
- How does life begin and evolve?
- Does life exist elsewhere in the universe?
- What is the future of humans and life in general, on Earth and beyond?
As a framework for the discussion of Astrobiology and its goals, we’re going to explore NASA’s Astrobiology roadmap (the current roadmap was initially developed in 2008). It shares many things in common with the objectives of our site, including:
(1) It is multidisciplinary, its success depends on coordination among diverse scientific disciplines.
(2) It encourages planetary stewardship and exploration ethics by emphasizing the prevention of biological contamination.
(3) It recognizes society’s interest in the search for extraterrestrial biospheres, assesses implications of discovering other forms of life, and envisions the future of discovery.
(4) Astrobiology offers an opportunity to educate and inspire the next generation of scientists and citizens.
Astrobiology study is interdisciplinary, it combines biology and the study of planetary and cosmic phenomena with:
Inside Astrobiology and the Future of Human Evolution
The Roadmap has defined seven science goals introducing additional key domains for investigation
- Understanding the nature and distribution of habitats in the universe that may support life.
- Exploration for habitable environments and life in our own Solar System.
- Understanding how life emerges in an environment.
- Determining how early life on Earth interacted and evolved.
- Understanding mechanisms for evolution and environmental limits of life.
- Determining principles that will shape future life.
- Recognizing signs of life on other worlds and here on Earth.
Goal I – Life Beyond the Solar System
Goal One of the NASA Astrobiology program is to determine where and how life exists beyond the solar system. Along the way, we may find that our definition of habitability may change, our current level of understanding defines three requirements:
- An environment for the assembly of complex organic molecules
- Energy to sustain metabolism
We search for planets that already support life, or that are able to support life based on these requirements. NASA estimates in 2013 that there are 100 Billion Earth-like planets in our galaxy (16 sextillion in the universe). We now have the technology to travel, albeit relatively slowly, to the closer of these to see for ourselves. If we discover life, are the conditions in place for that life to travel to other appropriate sites for colonization?
As life is discovered, can we find a pattern or series of steps that fit together to create the proper life supporting environment? The place to start is to find planets that have water, this is the most important prerequisite. We also expect to find oxygen on life-supporting planets, especially oxygen that is formed through biological processes (photosynthesis).
Investigations of these characteristics may include developing models of the proper environments that are consistent across planetary bodies. Space-based telescopes such as the tremendously successful Kepler may continue to help us screen for the planets that fit within a certain range of qualities for habitability. Then, we can conduct spectroscopic investigations to plan missions to directly explore planets that show promise for supporting life.
Goal 2 – Intra and Inter-Planetary Spread of Life
Goal 2 is to discover how life is distributed on any given planet, and from one planet to another. We have made much progress in understanding past and present habitable planets. The Mars expeditions revealed that early in its history, surface water was widespread, thus fulfilling one of our requirements. We also discovered the potential for an expanded groundwater system. We have found methane in the Martian atmosphere. During the Galileo missions to Jupiter, three of its four moons were found to have subsurface brines, also evidence of the existence of water. Titan, one of Saturn’s moons, has a surface enriched with prebiotic organic compounds. Here, we may have a laboratory to study origins of life. These discoveries and explorations drive NASA scientists to plan missions further into space.
We can build upon these discoveries by;
- continuing to refine our understanding of the nature of planetary life
- developing experiments to find ways to find subsurface life on planets
- developing robotic drilling systems to bring evidence to the surface
- collecting and returning the evidence to Earth for further study.
There is renewed interest in analyzing new data from the Moon. As we study far-flung sites, we are coaxed to come back to earlier sites to take a closer look. As we develop reliable robotic systems, we can expand our search to asteroids, comets and icy satellites. Perhaps we can use robots to study samples in place, thus eliminating the danger of losing them on a trip back to Earth.
Goal 3 – How does Life Begin?
Goal 3 is to open our minds to move beyond the assumption that life develops only one way, the way it has on Earth. We must dig further into the past to see if planets have a history of supporting life, and from those studies, see if there are patterns to the cycle of life. The way life developed on Earth may not be the only pathway. How are organic compounds assembled into more complex configurations that we see in living things? Our new robotic explorations may find ways to dig for fossils, dissect those samples, and help develop further models for alternative pathways to life.
Astrobiology as a discipline may expand to become a study of “Universal Biology”. Is there a specific set of circumstances that combine to create life or a precise moment when life begins? We must have a multidisciplinary approach to looking at these factors. Chemistry, organic chemistry and physics all play a part in dissecting the building blocks for life, and we cannot exclude other disciplines that may provide relevant insights. This is true “Universal Biology”, the marriage of many disciplines to study origins of life. New technical advances have made it possible to identify emerging elements of life on such diverse entities as asteroids, interplanetary dust particles and comets, and we have devised laboratory simulations that help us understand how these elements can travel throughout space to colonize other planets.
Darwin showed us that sudden mutations were necessary to cause diversity among species. Is this true at the chemical level? Does it require a sudden, spontaneous joining of chemical entities to create life? There is so much we do not know, how do we begin to understand the evolution of events that must occur?
There needs to be a reliable source of energy to promote the emergence of life. The emergence of life depends on the development of reliable mechanisms for capturing and channeling energy at just the right time, and in a certain way. So we need to develop logical experiments to study these truths and expand actual exploration beyond our solar system. Regardless of how life developed on Earth, we need to learn how chemical reactions organized to form primitive cellular processes across metabolic networks.
Goal 4 – Life and the Environment: Mutual Influences
Learn how life on Earth and nearby environments evolved through geologic time. We need to understand how life and extraterrestrial processes have influenced each other. Knowing how life developed in extreme circumstances improves our ability to define, detect and interpret key steps in the process. For example, the study of cherts (sedimentary rock) in Australia continues to reveal insights about Earth’s early biosphere. It underscores the importance of studying similar deposits on Mars. As in other areas of astrobiology, integration of knowledge from many disciplines is needed to understand the evolution of life in a broader, planetary context.
Astrobiologists must understand the complex relationships and interactions between organisms to learn what conditions for life existed at the time of the earliest geological formations made from water (sedimentary rock)? How has the evolution of our atmosphere and oceans altered life’s course on Earth? What can we learn by studying life at the cellular level?
NASA is determined to understand the relationship between Earth and its biology. Clues from studies in the geosciences and biosciences have combined to provide a platform for learning about the intricate relationships among factors that contribute to forming and sustaining life. This is the essence of Astrobiology. It is the study of the historical interconnections between Earth and its biota.
We can use evidence discovered in our studies of genomes to understand early evolution of key microbial processes such as aerobic metabolism. Most instructive of all, we can develop timelines of events that lead to life so we can observe the same on other worlds.
How do extraterrestrial events affect the biosphere? Do phenomena like cosmic radiation, supernovae, and the appearance of nearby comets and asteroids affect life? What are the environmental limits of life?
Goal 5 – The Tenacity and Diversity of Life
The diversity of life on Earth today is a result of the dynamic interplay between genetic opportunity, metabolic capability, and environmental change. Life survives and sometimes thrives under what seems like extremely harsh conditions such as high or low temperature, acidity of soil, or presence or exposure to radiation. While all organisms are similar, evolution has enabled microbes to cope with a broad range of physical and chemical conditions. What are the features that enable some microbes to thrive under extreme conditions that are lethal to many others? We need to understand the tenacity and diversity of life.
We lack understanding of how mutational events on the genetic level spiral upward to alter entire populations. There are molecular systems that some organisms use to survive extreme conditions. What are these systems and can organisms share them? We can learn more by understanding the evolution of biochemical and metabolic machinery that drives global cycles of the elements. The study of microbes and viruses can create advanced experimental laboratories for understanding biochemical, genetic and genomic phenomena. Of special interest is learning more about adaptability. This ephemeral characteristic of the evolutionary cycle is hard to define and pull apart for study.
It is exciting when we find that an environment previously found to be uninhabitable becomes, through study, to be a source of life. For example, we find thriving communities in the boiling hot springs of Yellowstone, and life in the deepest parts of the ocean. These extraordinary examples invite us to broaden our very concept of habitability. We need to keep our minds open to similar possibilities in outer space.
Goal 6 – Understand the principles of future of life
Other goals have looked at the past and present of the study of life. Goal 6 is to look forward, into the future. Viewing Earth’s ecosystems in the context of astrobiology challenges us to consider how resilient life is on a planetary scale. We must explore the potential for microbial life to survive and evolve in environments beyond Earth, especially regarding aspects relevant to the future of U.S. Space Policy.
Can life forms travel through space to colonize other planets? We know that seeds travel hundreds of miles across the sea inside the bellies of birds to be deposited on other shores.
Humans are increasingly disturbing Earth’s biogeochemical cycles. The effects of our activities have appeared rapidly. We need to understand how these changes will affect planetary climate, ecosystem structure, and human habitats. NASA has made this an urgent research priority and astrobiology can play a substantive role. We have studied extinctions in terms of long stretches of time. Now, we need to shorten the time frame for examination. We need to move from “what is happening now”, to “why is this happening”?
To investigate, we can look at the ecological impact of changes in climate, habitat complexity, and the availability of nutrients on an ecosystem. We can identify biosignatures associated with global change and develop techniques for sensing patterns of change.
We can develop automated tools that we can employ remotely to study the adaptation of organisms in lunar and Martian environments, especially those areas most likely to be visited by humans in the next century.
Goal 7 – Recognizing Biosignatures
A biosignature is any substance – such as an element, isotope, molecule, or phenomenon – that provides scientific evidence of past or present life. Our concepts of life and biosignatures are linked. Habitable planets may create non-biological features that mimic biosignatures. We need to understand this dynamic.
Our choices for remote exploration are based on the idea that biosignatures can be recognized in the context of their environments. A biosignature is an object, substance or pattern whose origin specifically requires a biological agent. If our assumptions about life are challenged by exploration to other planets, how will we alter our rigid rules for the origins of life? Can we keep a scientific open mind? Are all basic principles of biological evolution universal?
We will be bringing back specimens for study from Mars and other worlds. Will digging in ancient rocks reveal biosignatures in a traditional sense, or will we need to adjust the way we approach our study of life?
Goal 7 will help us develop novel and new approaches for detecting evidence of biosignatures in any environment.