Produced by: Tarun Mishra Designed by: Mohsin Shaikh
A breakthrough in the Search for Extraterrestrial Intelligence (SETI) could expedite the quest to detect alien radio signals, thanks to groundbreaking research that refines how these signals would shift in frequency due to Doppler effects. The findings were published in the November 2023 edition of 'The Astronomical Journal'
To understand the crux of this achievement, one needs to understand Doppler shift phenomenon, a change in signal frequency resulting from the transmitter's motion. As an object approaches, the signal's frequency increases; as it moves away, the frequency decreases, similar to how a siren's sound alters as it nears and passes by
Earth's orbital and daily rotational motions significantly influence the frequency drift of signals transmitted from distant exoplanets. While Earth's orbital motion yields a drift rate of 0.019 nanoHertz (nHz), the daily spin contributes an additional 0.1 nHz
Machine learning algorithms play a pivotal role in SETI searches, and having a well-defined maximum drift value aids in signal detection. SETI typically assumes a drift rate less than 10 nHz
By modelling approximately 5,300 actual exoplanets, a team led by UCLA's Megan Li redefines the maximum drift rate attributed to exoplanetary motion to a narrower range of plus or minus 53 nHz
This updated figure reflects an improved understanding of drift rates by considering all points in an exoplanet's orbit, reducing computational resources, and expediting signal analysis in SETI searches
Li's team ventured beyond current detection biases and measured drift rates for over 5,000 simulated planets representing a more diverse spectrum of exoplanets, resulting in much lower drift rate values
These revised figures, including plus or minus 0.27 nHz for low-eccentricity orbits and plus or minus 0.44 nHz for high-eccentricity orbits, challenge the prior 53 nHz calculation and present more accurate scenarios
As missions like the European Space Agency's PLATO uncover a broader range of exoplanets, real exo-planetary data should increasingly align with these simulated results, bolstering the efficiency of SETI signal analysis
Drift rates serve as crucial indicators of whether a signal originates from deep space. They aid in distinguishing signals from terrestrial sources, such as radio frequency interference (RFI) and certain satellites
Accelerating data analysis in SETI searches is pivotal, especially with the targeting of up to a million stars. The enhanced precision in drift rate calculations reduces computational demands and substantially expedites the hunt for potential extraterrestrial signals, ultimately bringing us closer to the possibility of contact with alien civilisations