One of the biggest questions in human history is are we alone in the universe. The hunt for extraterrestrial life has been going on for decades, and so far, none has been discovered. At some point in the future, we may discover extraterrestrial life, be that in the form of intelligent beings or simple single-celled organisms remains to be seen. NASA has been preparing to discover extraterrestrial life for about as long as it’s been an organization. The agency is now calling for a new framework that scientists can use to help identify extraterrestrial life.
NASA chief scientist Jim Green recently published an article discussing a sample scale that could be a starting point for discussing a potential discovery of extraterrestrial life among scientists and other communicators. What NASA wants is a scale based on decades of experience gathered in astrobiology. As a field, astrobiology is responsible for investigating the origins of life on earth and the possibility of life on other planets.
Green believes that a scale would help us understand where we are when it comes to the search for life in particular locations in the cosmos and better understand the capabilities of missions and technologies being used to search for that life. The scale would have seven levels and would be similar to a staircase that would lead to the declaration that life has been found beyond Earth. Green feels like the scale would be similar to the one that NASA uses to judge how ready spacecraft or a specific technology is to be deployed. That scale is called the Technology Readiness Level scale.
The goal of creating the scale for extraterrestrial life would be to allow scientists to note in published studies where their astrobiology results would be on the scale. The scale could also be used by journalists when referring to work that fits into the scale to help manage expectations for readers. Currently, the challenge for NASA is that the public following scientific research is conditioned to believe there are only two possible conditions, either there is life beyond earth, or there isn’t.
NASA believes a new scale can help share the excitement about new discoveries while showing how each discovery builds on previous discoveries. With this scale, progress could take small steps instead of appearing to take leaps up or down the scale. Adding such a scale is important because NASA missions on Mars have found evidence of water in the planet’s distant past. Where there is water, there is the potential to find evidence that life in some form was on Mars at some point in its history.
The exact details of the scale haven’t been worked out just yet, but NASA has an idea of how it might be organized. The first step of the scale would have any data with the hint of a signature of life, like a biologically relevant molecule. At the second level of the scale, researchers would have to verify that the detection of some sort of biologically relevant molecule wasn’t influenced by contamination or measuring instruments. The third level would describe how the biological signals are found in an analog environment.
Higher levels of the scale would add more information to the initial detections, including details on whether the environment could support life while ruling out any potential of non-biological sources for the molecules. NASA envisions a combination of evidence leading to the sixth step on the scale. To reach the final step in the staircase, scientists would have to be sure they had detected life on Mars (or elsewhere), and NASA says a mission to another part of the planet might be required.
NASA is clear that achieving that highest level of confidence to move to the last step on the scale would require the active participation of the overall scientific community. While NASA is using the example of Mars to describe their suggested scale, the system could also be applied to exoplanets. The scale isn’t meant to encourage a race to the top. Rather it’s meant to help show the importance of groundwork laid by various missions without directly discovering biological signals in the environment.