SETI in 2020

Brief

Jason T. Wright (Penn State) systematically surveyed 75 SETI-relevant papers published in 2020, sorting them into searches, methods, target/frequency selection, technosignature development, ETI theory, and social aspects. Breakthrough Listen produced four radio null-detection papers using high-bandwidth backends at Green Bank and Parkes, including Price et al.'s survey of over 1,300 stars in L and S bands (1–3.5 GHz) and the Allen Telescope Array's ~100-hour follow-up of the Wow! Signal field. ETI theory was the largest single category at 19 papers, covering Drake Equation refinements, Fermi Paradox variants, and post-Singularity detectability. The year was marked by the death of Freeman Dyson and the structural collapse of the Arecibo telescope.

Metadata

Category

Search

Venue

Acta Astronautica

Type

Peer-reviewed

Year

2022

Authors

Jason T. Wright

DOI

10.1016/j.actaastro.2021.09.024

arXiv

2107.07512

Access

Open access

Length

304.4 K

Programs

Breakthrough Listen, PanoSETI, VASCO, Penn State Extraterrestrial Intelligence Center, CATS (Characterizing Atmospheric Technosignatures), NExSS, NASA Goddard Technosignatures Seminar, PSETI Seminar

Instruments

Green Bank Telescope, Parkes Radio Telescope, Allen Telescope Array, Murchison Widefield Array, Five-hundred-meter Aperture Spherical radio Telescope (FAST), Arecibo Observatory, Palomar Observatory (PanoSETI prototype), JWST

Data sources

ADS SETI bibliography, Gaia DR2, Kepler mission lightcurves, CMB temperature spectrum

Tags

SETI, technosignature, radio-SETI, anomaly detection, Drake Equation, Fermi Paradox, ETI theory, METI, biosignature

Key points

• The review spans 75 papers and books published or made public in 2020, sorted into six categories: search results, methods, target/frequency selection, technosignature development, ETI theory, and social aspects.p.1
• Breakthrough Listen published four radio null-detection papers in 2020 using high-bandwidth backends at Green Bank and Parkes, representing a substantial increase in the fraction of the Cosmic Haystack searched.p.2
• Price et al. (2020) reported null detections for over 1,300 stars across the entire sky in L and S bands (1–3.5 GHz); Sheikh et al. (2020) reported null results in C band (4–8 GHz) for stars in the restricted Earth Transit Zone.p.2
• Harp et al. (2020) conducted the longest follow-up of the Wow! Signal field in history, covering the entire consistent sky region with 10 MHz bandwidth and approximately 100 hours of ATA observation.p.2
• Tremblay & Tingay (2020) reported the deepest narrowband SETI search yet with the Murchison Widefield Array, targeting the Vela region and exploring large regions of the Wright et al. (2018) Cosmic Haystack parameter space.p.2
• ETI theory was the largest single category in 2020 with 19 papers, covering the Drake Equation, Fermi Paradox, Kardashev scale extensions, and post-Singularity ETI detectability.p.5
• Lesnikowski et al. (2020) showed that an unsupervised neural network applied to lunar imagery successfully recovered the Apollo 15 landing site, validating the artifact-detection methodology as a proof of concept.p.3
• Wisian & Traphagan (2020) argued that successful SETI contact would trigger geopolitically dangerous competition among states seeking a monopoly on advanced scientific knowledge, framing detection as a potential security threat.p.6

Verbatim

• “The heart of SETI is the actual searches, and 2020 brought several new important results and upper limits.”

  p.2

• “The first was by Price et al. (2020), reporting null detections for over 1300 stars over the entire sky in L and S bands (1–3.5 GHz).”

  p.2

• “This work, by Harp et al. (2020), scanned the entire field consistent with the original signal, and included a 10 MHz bandwidth and ∼ 100 hours of observation, the longest follow-up yet performed.”

  p.2

• “Perhaps the most offbeat and unconventional search of 2020 was that of Hippke (2020a), who followed a suggestion by Hsu & Zee (2006) that there could be a message embedded in the cosmic microwave background, presumably put there intentionally at the observable universe's beginning.”

  p.2

• “2020 is also a notable landmark for SETI because it marks the target for which the "SETI 2020" roadmap was written (Ekers et al. 2002).”

  p.2

• “Wisian & Traphagan (2020) argued that SETI practitioners need to be concerned about the geopolitical implications of success, presenting a realpolitik analysis of the potentially deadly competition among states that would follow to secure a monopoly on the advanced scientific ideas that would flow from contact.”

  p.6

Most interesting

• The 2020 ATA follow-up of the Wow! Signal was the longest such observation ever conducted at approximately 100 hours, and returned a null result.
• Hippke (2020a) searched the cosmic microwave background power spectrum for an embedded message, then published a 1,000-bit representation of the CMB temperature spectrum for others to scrutinize independently.
• 2020 was the exact target year named in the 2002 'SETI 2020' roadmap, and Wright notes the field has 'probably made less progress than that work aspired to.'
• Freeman Dyson, who proposed Dyson Spheres in 1960, died in February 2020 at age 96; the Arecibo telescope collapsed in December 2020, eliminating both a field pioneer and its most iconic instrument within twelve months.
• Lacki et al. (2020) produced an 'exotica catalog' for Breakthrough Listen, one representative example of every major class of astronomical object, as a systematic target list for detecting technology at cosmic scales.
• Wlodarczyk-Sroka et al. (2020) extended SETI upper limit calculations beyond the central target star to every source within the telescope beam, substantially widening the effective sample of prior searches retroactively.