Technical Document: Dark and Quiet Skies II Working Group Reports

Image credit: NOIRLab/@UNOOSA/IAU/Government of Spain/M. Lewinsky

NOIRLab has published The Working Group reports from the recent Dark & Quiet Skies II conference.

NOIRLab is the preeminent US national center for ground-based, nighttime optical and infrared astronomy.

The reports focus on the feasibility of implementing specific measures to mitigate the impact of artificial interferences.


About the Document

Release date:Jan. 10, 2022,


  1. Scientific access to sky and spectrum
    Scientific access to sky and spectrum is eroding under the relentless pressure of commercial
    development of radio communication technology. Meanwhile, radio spectrum regulators are focused
    on the protection of frequency allocations and have no obvious means to address the biological,
    environmental, and broader scientific concerns that are the subject of the Dark and Quiet Skies
    conferences. Radio spectrum regulators authorize vast mega-constellations that occupy wide swaths
    of the radio spectrum used by radio astronomy while inadvertently reflecting sunlight at levels visible
    to the naked eye, disrupting optical astronomy. The dark and quiet sky threatens to become a nightly
    theater of artificial objects and artificially generated radiation that isolates us from the cosmos.
    The common lesson of all the studies conducted for the Dark and Quiet Skies effort, whether in regard
    to artificial light at night, to reflection of solar radiation by satellites, or to use of satellites for
    radiocommunication, is the principle that artificial radiation of whatever kind should not be
    produced if it is not needed and should not be detectable where it is not used. The radio
    astronomy recommendations embody this principle in the context of radio astronomy and
    implementing them is a critical step in maintaining scientific access to sky and spectrum and the
  2. Towards implementation of the recommendations
    Radio astronomy requires portions of the radio spectrum (not constrained to the protected radio
    astronomy bands) to be interference-free, for sufficiently long periods of time, to enable scientific
    discoveries that can advance the human knowledge of the Universe, contribute to planetary defense,
    and create terrestrial reference frames used for global positioning, among many other applications.
    The invaluable work done by administrations and radio astronomy protection groups at the ITU-R,
    should be complemented by the Dark and Quiet Skies proposed work at COPUOS to raise the
    awareness on the vulnerability of radio astronomy to activities in space. The significant effect that
    satellite systems (as a space activity under the mandate of COPUOS) can have on radio astronomy, at
    all frequencies of the radio spectrum, requires urgent attention in this new era of unprecedentedly fast
    The radio astronomy working group recommends that the potential impacts of space activities on
    radio astronomy are presented at COPUOS and national delegations are urged to consider these as
    part of the general assessment of environmental impact of any proposed space activity.

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