Searching for technosignatures in exoplanetary systems with current and future missions

Brief

Haqq-Misra et al. synthesize recommendations from TechnoClimes 2020, a 53-participant, 13-country online workshop, for detecting non-radio technosignatures using existing and future missions including JWST, ELTs, LUVOIR, and LIFE. The paper maps five technosignature classes (atmospheric gases, surface modifications, optical beacons, megastructures, interstellar flight) against a matrix of ~20 missions, color-coded by detectability confidence. No new quantitative detection limits are derived; the stated goal is to lower the barrier for exoplanet astronomers to consider technosignature science as a secondary objective of primary-mission observations. Lin et al. (cited within) estimate that CFC concentrations ten times modern Earth levels would be required to clear JWST minimum detectability thresholds for a white dwarf transit geometry.

Metadata

Category

Search

Venue

Acta Astronautica

Type

Peer-reviewed

Year

2022

Authors

Jacob Haqq-Misra, Edward W. Schwieterman, Hector Socas-Navarro, Ravi Kopparapu, Daniel Angerhausen, Thomas G. Beatty

DOI

10.1016/j.actaastro.2022.05.040

arXiv

2206.00030

Access

Open access

Length

1.1 M

Programs

Breakthrough Listen, TechnoClimes 2020, PANOSETI, LIFE, Nautilus Space Observatory, Allen Telescope Array

Instruments

JWST NIRSpec/MIRI, Hubble Space Telescope, TESS, Kepler/K2, Gaia, CHEOPS, NeoWISE, Spitzer, Vera C. Rubin Observatory, Nancy Grace Roman Space Telescope, PLATO, ARIEL, ELTs (E-ELT, GMT, TMT), EarthFinder, LUVOIR, HabEx, Origins Space Telescope, LIFE interferometer, Nautilus Space Observatory, Parkes Radio Telescope

Data sources

Kepler/K2 archive (MAST), TESS planet catalog, Gaia astrometric catalog

Tags

SETI, technosignature, biosignature, atmospheric-spectroscopy, exoplanet, megastructure, optical-SETI, mission-planning

Key points

• Bryson et al. found roughly half of Sun-like stars should host a terrestrial planet in the liquid water habitable zone, implying approximately four nearby habitable terrestrial planets on average within 10 pc among G- and K-dwarf systems.p.2
• Dressing and Charbonneau found that about 1 in 6 M-dwarf systems should host an Earth-sized planet in the habitable zone, motivating M-dwarf targets for technosignature searches.p.2
• Breakthrough Listen, launched in 2015 as a 10-year $100M program, is the most comprehensive ongoing technosignature search, covering over a million stars in radio and optical; its candidate signal BLC-1 (toward Proxima Centauri via Parkes) was subsequently attributed to local radio frequency interference.p.4
• Lin et al. estimate that CFC concentrations (CF4, CCl3F) ten times modern Earth levels are required to reach JWST minimum detectability thresholds in the mid-infrared for an Earth-like planet transiting a white dwarf, and no qualifying white dwarf planetary target has yet been identified.p.11
• The paper's technosignature capability matrix (Fig. 2) shows that no single mission covers all five technosignature classes; commensal and dedicated programs across multiple facilities are required to maximize detection probability.p.7
• LIFE (4-telescope space-based mid-infrared nulling interferometer with at least 2 m apertures) is projected to detect more than 300 sub-Neptune sized planets, including dozens of rocky and temperate worlds, in its survey phase.p.10
• Atmospheric technosignature candidates derived from Earth's own industrial outputs include NO2, CFCs, HFCs, PFCs, SF6, and NF3; the paper notes that a comprehensive accounting of detectability limits for this class remains an active and incomplete research area.p.11
• TESS has already detected over 5,000 planets and planet candidates as of the paper's writing, with projections of over 12,000 detections during its extended seven-year mission, creating a large statistical base for commensal technosignature searches.p.7

Verbatim

• “TechnoClimes was organized as a 5-day online event to accommodate participation during the COVID-19 pandemic, with a total of 53 participants from 13 countries.”

  p.4

• “concentrations of ten times modern concentrations of such CFCs are required to meet minimum detectability thresholds with JWST.”

  p.11

• “about half of Sun-like stars should host a terrestrial planet within the liquid water habitable zone, so that there should be about four nearby habitable terrestrial planets, on average, among the G- and K-dwarf systems within 10 pc from Earth.”

  p.2

Most interesting

• The paper's Fig. 2 matrix shows TESS, Gaia, CHEOPS, and ground-based photometry all rated 'YES' for detecting optical beacons, meaning technosignature-relevant data is already accumulating in archives without dedicated analysis pipelines.
• The Nautilus concept proposes 35 identical unit telescopes each with an 8.5 m Multi-order Diffractive Engineered Material (MODE) lens, a replication strategy specifically designed to collapse the per-unit mirror cost that makes large-aperture arrays prohibitive.
• BLC-1, Breakthrough Listen's only publicly disclosed candidate signal of interest (toward Proxima Centauri via Parkes), was used not as evidence of ETI but as a pipeline stress-test, its RFI origin validated the verification framework rather than invalidating the program.
• The LUVOIR-B 8-m architecture, which the 2020 Astrophysics Decadal Survey effectively endorsed as a template for a future flagship observatory, is assessed as capable of contributing to technosignature science at UV/optical/NIR wavelengths, a science case not formally in its mission charter.
• The paper notes that the Square Kilometer Array (SKA) explicitly includes radio technosignature detection among its stated science objectives, making it the only major upcoming facility to formally list SETI in its design requirements.
• No qualifying exoplanetary system transiting a white dwarf, the geometry that would make CFC detection feasible with JWST, had been identified at time of publication, meaning the JWST atmospheric technosignature pathway remains blocked by a target-availability bottleneck rather than an instrument-sensitivity bottleneck.