From time immemorial, humanity has asked the question, Are we alone in the universe? Perhaps no scientific discovery would have a greater impact on humanity’s relationship to the cosmos than the discovery of extraterrestrial life. In order to investigate this possibility, the National Aeronautics and Space Administration (NASA) has funded missions, research programs, and institutes that contribute to the interdisciplinary field of astrobiology, some of which are directed to the search for life. NASA has also sponsored discussions about the broader preparedness of the scientific community to both verify and communicate a potential biosignature detection. No matter where or how the potential discovery of life may come about, NASA will likely make critical contributions in follow-up studies, verification of potential claims, and communicating those results to the general public. The significance of this potential discovery and NASA’s preeminence as a leader in astrobiological research therefore necessitates an assessment of its readiness for this momentous task.
To discuss the issues of the assessment, verification and communication of a possible future claim of life detection, two of NASA’s Research Coordination Networks (RCN), the Network for Life Detection (NfoLD) and the Nexus for Exoplanet System Science (NExSS), hosted the virtual “Standards of Evidence for Life Detection Community Workshop,” held from July 19-22, 2021, with the goal of creating a framework to increase the scientific confidence in biosignature detections and to effectively convey this continuum of confidence to the general public. The Science Organizing Committee (SOC) and attendees from this workshop wrote, as a result of these discussions, the “Community Report from the Biosignatures Standards of Evidence Workshop” (henceforth Community Workshop Report).
Within the Community Workshop Report, the authors suggested two related proposals: (1) an assessment framework composed of five separate questions that can guide both the path of research and the best practices for its communication within and outside the science community and (2) a reporting protocol by which life detection claims can be assessed and verified. The Community Workshop Report suggests ways to incentivize the proposed framework with funding and scientific recognition for verification studies and suggests ways to implement it by establishing a committee to coordinate verification and scientific peer review.
This report responds to NASA’s request for the Committee on Astrobiology and Planetary Sciences (CAPS) to conduct an independent review of the accuracy, assumptions, and conclusions of the Community Workshop Report. CAPS considered both the assumptions and the conclusions of the Community Workshop Report. The committee’s findings are based on internal committee discussions informed by external community input from 75 respondents. The committee offers the following specific findings related to the proposed framework offered by the Community Workshop Report:
Finding 1: The Community Workshop Report introduces a scientific framework for biosignature detection that spans disciplines to accommodate the evolving understanding of biosignatures and planetary habitability. The workshop lays the foundation for future, community-based discussions that consider and evolve the framework. The committee agrees with the value of a periodic review of the progress of life detection science to develop consensus and priorities, an effort that might be executed on a timescale and via a process similar to the Planetary Science and Astrobiology Decadal Survey or Astrobiology Strategy development efforts.
Finding 2: The concept of an assessment framework is beneficial for establishing a common language for communicating between and among scientists and journalists, and for calibrating the significance and caveats of a potential life detection discovery. The framework presented in the workshop report, as well as the proposed Confidence of Life Detection Scale, and the existing Rio scale, all are useful for this purpose. The diversity of opinion from the broader community
indicates that universal adoption of any one framework or scale would be challenging; however, the committee found the five guiding questions clearly defined and valuable.
Finding 3: The Community Workshop Report highlights the challenges of communicating nuance in life detection discoveries and their degree of consensus to the media and recommends a reporting protocol. The committee agrees that clear communication requires a collaborative approach between the scientific community and journalists and supports further efforts to engage the many layers of media; however, the committee cautions against any specific verification or media reporting protocols which could inhibit open, peer-reviewed science.
Finding 4: Verification protocols developed to aid scientific communication are not appropriate for use in the direct review and evaluation of proposals for basic biosignature research, nor biosignature instrument development. The unintentional consequences of using the proposed protocols in this way could hinder the open execution of science and add gatekeepers in the scientific process.
Finding 5: The scientific process of multiple working hypotheses is the most rigorous and time-proven means by which to assess evidence and claims related to life detection. The establishment of a new external verification entity to oversee assessment and publication of life detection claims could have unintended negative consequences for open science and for fairness.