Expecting the unexpected in the search for extraterrestrial life

EMBO reports, 2007

Acta Astronautica, 2008

Current searches for evidence of extraterrestrial (ET) life are accomplished in a number of distinctly different ways. The various searches can be viewed in three general categories: (1) 'SETI' searches for messages from extraterrestrial civilizations, (2) exploration for extrasolar or habitable planets, and (3) searches and research within the solar system (e.g., planetary missions, meteorites, cosmochemistry). Each search-type occurs in different locations, uses different scientific instruments and methods, and seeks different types of evidence and data. Moreover, the meaning and implications of a 'discovery' in each of the categories are different, as are the policy, legal and societal ramifications. In considering how to manage future communications about the discovery of extraterrestrial life, it will be important to understand these distinctions, anticipate relevant concerns and issues, and be prepared to explain them clearly to the public.

Zenodo (CERN European Organization for Nuclear Research), 2023

Recently, NASA scientists and administrators have proposed a numerical scale for quantifying the Confidence of Life Detection-the CoLD scale [1]. Although the stated goal is to minimize damaging public trust with premature or overly-confident claims of detecting life beyond Earth, the CoLD scale is an inapt and easily abused tool that will do little to address the misleading terminology and sensational narratives that plague both public and scientific communications from the astrobiology community. By failing to acknowledge, much less address, the root cause(s) of these communication problems, the CoLD scale can only address the symptoms while allowing the underlying disease to progress. That the arrival of misleading claims could be confidently anticipated by the developers of the CoLD scale is itself a measure of the strength of the disease. The root cause(s) run deep and cannot be cured with a numerical scale.

Astrobiology

According to the 2015 Astrobiology Strategy, a central goal of astrobiology is to provide a definition of life. A similar claim is made in the 2018 CRC Handbook of Astrobiology. Yet despite efforts, there remains no consensus on a definition of life. This essay explores an alternative strategy for searching for extraterrestrial life: Search for potentially biological anomalies (as opposed to life per se) using tentative (vs. defining) criteria. The function of tentative criteria is not, like that of defining criteria, to provide an estimate (via a decision procedure) of the likelihood that an extraterrestrial phenomenon is the product of life. Instead, it is to identify phenomena that resist classification as living or nonliving as worthy of further investigation for novel life. For as the history of science reveals, anomalies are a driving force behind scientific discovery and yet (when encountered) are rarely recognized for what they represent because they violate core theoretical beliefs about the phenomena concerned. While the proposed strategy resembles that of current life-detection missions, insofar as it advocates the use of a variety of lines of evidence (biosignatures), it differs from these approaches in ways that increase the likelihood of noticing truly novel forms of life, as opposed to dismissing them as just another poorly understood abiological phenomenon. Moreover, the strategy under consideration would be just as effective at detecting forms of life closely resembling our own as a definition of life.

Nature, 2021

Bulletin of the AAS, 2021

Co-Signers This white paper is submitted as part of a collaborative effort organized by the Equity, Diversity, and Inclusion Working Group (EDIWG), a cross Assessment Group (AG) committee.

Life (Basel, Switzerland), 2017

In this study, we attempt to illustrate the competition that constitutes the main challenge of astrobiology, namely the competition between the probability of extraterrestrial life and its detectability. To illustrate this fact, we propose a simple statistical approach based on our knowledge of the Universe and the Milky Way, the Solar System, and the evolution of life on Earth permitting us to obtain the order of magnitude of the distance between Earth and bodies inhabited by more or less evolved past or present life forms, and the consequences of this probability for the detection of associated biosignatures. We thus show that the probability of the existence of evolved extraterrestrial forms of life increases with distance from the Earth while, at the same time, the number of detectable biosignatures decreases due to technical and physical limitations. This approach allows us to easily explain to the general public why it is very improbable to detect a signal of extraterrestrial ...

Advances in Space Research, 2002

While formal principles have been adopted for the eventuality of detecting intelligent life in our galaxy (SETI Principles), no such guidelines exist for the discovery of non-intelligent extraterrestrial life within the solar system. Current scientifically based planetary protection policies for solar system exploration address how to undertake exploration, but do not provide clear guidance on what to do if and when life is detected. Considering that martian life could be detected under several different robotic and human exploration scenarios in the coming decades, it is appropriate to anticipate how detection of non-intelligent, microbial life could impact future exploration missions and activities, especially on Mars. This paper discusses a proposed set of interim guidelines based loosely on the SETI Principles and addresses issues extending from the time of discovery through future handling and treatment of extraterrestrial life on Mars or elsewhere. Based on an analysis of both scientific and ethical considerations, there is a clear need for developing operating protocols applicable at the time of discovery and a decision making framework that anticipates future missions and activities, both robotic and human. There is growing scientific confidence that the discovery of extraterrestrial life in some form is nearly inevitable.

Preface; Part I. The Imperative of Exploration: 1. Exploration as a metaphor; Part II. How Can We Know Life?: 2. The molecular basis of life on Earth; 3. The limits to life; 4. The transfer of life between planets; 5. What are the signatures of life?; 6. After the discovery/life as a cosmic phenomenon; Part III. The Search for Life Beyond Earth: 7. The prospects for long-duration human space-flight; 8. Human exploration and the search for life; 9. Interplanetary ethics; Part IV. The Cosmic Biological Imperative: 10. The key technologies for human planetary exploration; 11. Exploration in space; 12. Exploration in time; 13. Prediction, imagination and the role of technology; Part IV. Our Cosmic Destiny: 14. Our cosmic destiny; Appendices; Index.

Astrobiology

The search for an inhabited planet, other than our own, is a driver of planetary exploration in our solar system and beyond. Using information from our own planet to inform search strategies allows for a targeted search. It is, however, worth considering some span in the strategy and in a priori expectation. An inhabited, Earth-like planet is one that would be similar to Earth in ways that extend beyond having biota. To facilitate analysis, we employ a metric akin to the Earth-similarity index of Schulze-Makuch et al. [2011]. The metric extends from zero, for an inhabited planet that is like Earth in all other regards (i.e., zero differences), toward end-member values for planets that differ from Earth but maintain life potential. The analysis shows how finding inhabited planets that do not share all other Earth characteristics could improve our ability to assess galactic life potential without a large increase in time-commitment costs. Search strategies that acknowledge the possibility of such planets can also minimize the potential of exploration losses (e.g., searching for long durations to reach conclusions that are search strategy biased). Discovering such planets could additionally provide a test of the Gaia hypothesis-a test that has proved difficult using only the Earth as a laboratory. Lastly, we discuss how an Earth2.0 narrative that has been presented to the public as a search strategy comes with nostalgia-laden philosophical baggage that does not best serve exploration.

Astrobiology, 2014

2003

The International Space University was founded to advance the exploration and use of space in the service of people throughout the world. Its central goal is to bring together those young people who are motivated and able to lead humanity into a peaceful and abundant future both on and off our planet. With personal relationships forged during an intense period of study and work as students, ISU alumni are expected to go out and create a worldwide network of friendship and achievement as they rise in the space professions. With grounding in the whole wide variety of space-related disciplines, they then can call on each other for help and counsel as they build the international space programs of the future. More than 2000 ISU graduates in more than 60 countries are already realizing this objective. ISU has two main programs: a peripatetic summer session and a Master of Space Studies curriculum at its permanent headquarters in Strasbourg. In each program students, in addition to their multidisciplinary core courses and individual assignments, carry out design projects intended to give experience in teamwork under stress and to generate influential results. The topics of these projects are deliberately selected to be difficult and important. In the 2002 summer session one project focused on space in the service of human health and the other focused on the new interdisciplinary realm of astrobiology-the study of possible universal life. This report deals with that project. Astrobiology has emerged from the world of speculation into the world of investigation because of suggestive new findings in several scientific fields: increased understanding of the fundamental processes of life on Earth, observation of life's main elements and molecules throughout space, discovery of living microbes in extreme terrestrial environments, detection of the signatures of planets orbiting many stars, and above all the realization that life may be a common, perhaps even inevitable, result of cosmic evolution. With these tantalizing hints before us, it is time for a broad attack on the question-especially one that engages talent in each of the many relevant fields and in each of the many places where skills and resources exist. The students of the ISU 2002 astrobiology team devoted their energy to defining this attack. Here is their report. James Burke v FACULTY PREFACE Faculty Preface At every Summer Session Program of the International Space University, students carry out two design projects intended to give teamwork experience under stress and to generate analyses and recommendations on topics of current interest in the world's space programs. In 2002, the two projects were about astrobiology and the use of space systems in improving human health. This document presents the results of the astrobiology project. Astrobiology is emerging as a new, interdisciplinary scientific field with information sources both on and off Earth. The ancient concept of a plurality of inhabited worlds has received new stimuli from recent discoveries-planets around other stars, microbes in extreme terrestrial environments, interstellar and stellar evolution involving the elemental building blocks of life. Given the rich diversity of the subject, the first task of the student team was to narrow the scope of their inquiry. They decided to focus on likely progress over the next twenty years, concentrating on both ground-based and space-based activities that may realistically advance human understanding of the origins and distribution of Earth-like life in the solar system and around nearby stars. In choosing this focus, they deliberately excluded entities that may possibly live somewhere in the cosmos, not violating any currently known law of nature, yet being so different from our water and carbon based life that we might not even recognize them as alive. Within this scope, the team examined ways to investigate and possibly discover other life, from bacteria to galactic civilizations, and they also considered the likely social effects of a confirmed discovery. The focus of the report, along with the format, style, and management behind it, is the product of the participating students. The document you are reading is unique-its breadth and perspective could not be matched by a consultant, company, or national space agency. More than the results of an academic exercise, this report will be a valuable tool to scientists, educators and future mission designers. We, the project's faculty, advisors and teaching assistant, are honored and proud to have been associated with this talented and energetic team of students.

Frontiers in astronomy and space sciences, 2024

Editorial on the Research Topic Editor's challenge in planetary science: the future of planetary exploration and the next generation of planetary missions s

Astronomy & Geophysics, 2016

summarize a Royal Astronomical Society Specialist Discussion Meeting which examined how science will benefit from the use of extraterrestrial resources. To-date, all human economic activity has depended on the resources of a single planet, and it has long been recognized that developments in space exploration could in principle open our closed planetary economy to external resources of energy and raw materials. Recently, there has been renewed interest in these possibilities, with several private companies established with the stated aim of exploiting extraterrestrial resources. Space science and exploration are among the potential beneficiaries of space resources because their use may permit the construction and operation of scientific facilities in space that will be unaffordable if all the required material and energy resources have to be lifted out of Earth's gravity. Examples may include the next generation of large space telescopes, sample return missions to the outer Solar System, and human research stations on the Moon and Mars. These potential scientific benefits of extraterrestrial resource utilisation were the topic of a Specialist Discussion meeting held at Burlington House on 8 April 2016. Martin Elvis (Harvard Smithsonian Center for Astrophysics) got the meeting underway by asking "What can space resources do for astronomy?" Martin made the point that in order to observe the distant Universe, or make detailed studies of planets around other stars, astronomers will require larger telescopes in space across the electromagnetic spectrum, but these are currently unaffordable. The aging 'Great Observatories' (Chandra, HST, and Spitzer) will soon come to an end, and although the infra-red capabilities of Spitzer will be taken over, and enhanced, by the JWST from 2018, the cost of just this one telescope will have consumed almost two decade's worth of NASA's available funding for large astrophysics missions. The prospects for providing simultaneous coverage at other wavelengths with comparable instruments, or building the much larger instruments that will be required, for example, to resolve surface features on Earth-sized exoplanets (Fig. 1), seem bleak based on existing funding models. As the cost of large space telescopes (and also of planetary missions) increases much faster than economic growth, a 'funding wall' will soon be encountered, effectively ending the growth in space astronomy to which we have become accustomed. Martin therefore argued that a change in paradigm is required. The astronomy community should exploit synergies with the emerging 'new space' entrepreneurs who are seeking to reduce launch costs, develop space tourism, and mine the Moon and asteroids for profitable materials (e.g. Elvis, 2012). Within 5 years these commercial activities should cut mission costs significantly, and