Are we alone? Humans have been asking this question throughout history. We want to know where we came from, how we fit into the cosmos, and where we are going. We want to know whether there is life beyond the Earth and whether any of it is intelligent.

Since the middle of the twentieth century we have had astronomical tools that permit us to embark on a scientific exploration to try to answer this old question. Extremophiles and exoplanets (maybe even exomoons) have been game changers. We haven’t yet found life beyond Earth but we now know there is a vast amount of potentially-habitable real estate to explore.

The proper tools for exploration depend on whether you are looking for microbes or mathematicians. Around the globe, space agencies and federally funded, ground-based observatories are charting multi-decade missions for in-situ and remote sensing searches for biosignatures. Searches for technosignatures still depend on private resources, but these too are growing more ambitious and comprehensive. Because of the enormous public interest, citizen scientists are a substantial resource, eager to be participate in this exploration in meaningful ways. Unsupervised machine learning is another emerging discipline that is being harnessed to expand the searches in innovative ways.

There have always been false negatives, missed discoveries at the limits of detection sensitivity, and searches for life beyond Earth will encounter those as well as. However, in searches for life and technology as-we-don’t-yet-know-it, there is a significant potential for false positives as well. Broad and deep contextual understanding will be required to assess future results.