The Vera Rubin Observatory Will Find Alien Life — If It Exists Anywhere Near Us

The new Vera Rubin Observatory's survey capabilities could detect biosignatures on nearby exoplanets. Here is how astronomers plan to look and what they actually expect to find.

The direct search for biosignatures — chemical or spectral indicators of biological activity — on exoplanets is primarily the domain of space telescopes rather than ground-based observatories like Vera Rubin. But the Rubin Observatory's 10-year southern sky survey contributes to the search for life through several indirect pathways that are worth understanding.

First: planet discovery. The Rubin Observatory's sensitivity and cadence make it capable of detecting planetary transits — the periodic dimming that occurs when a planet passes in front of its host star from Earth's perspective — for stars throughout the southern sky. The 20 billion galaxies in its survey sample include billions of stars, and the transit detections it produces will feed the exoplanet characterisation pipeline that determines which planets are subsequently observed by space telescopes capable of atmospheric spectroscopy.

Second: the specific stellar variability data that the survey produces will allow astronomers to characterise the habitability of stars around which exoplanets exist. Stars that produce frequent flares — energetic radiation events that sterilise planetary surfaces — are less interesting as targets for biosignature searches than quiet, stable stars. The Rubin survey will categorise stellar variability for millions of stars simultaneously.

Third: the possibility of detecting Oumuamua-class interstellar objects — the mysterious cigar-shaped object that passed through our solar system in 2017 and whose properties remain unexplained by natural object models — is significantly enhanced by the Rubin survey's ability to detect fast-moving transient objects. If interstellar objects exist in meaningful numbers and if some of them are artificial, the Rubin survey dramatically increases the probability of detecting them.

The search for life in space is a field in which honest engagement requires acknowledging the absence of confirmed evidence alongside the genuinely expanding capability to look. The Vera Rubin Observatory is the most powerful looking instrument ever built. Whether there is something to find is the question it cannot answer for us.