SPACE.com Columnist Leonard David

Astronomers call for radio silence on the far side of the moon

the grey, cratered surface of the moon
The lunar farside as imaged by NASA’s Lunar Reconnaissance Orbiter using its powerful wide angle camera. (Image credit: NASA/Goddard Space Flight Center/Arizona State University)

There's a growing and passionate call for preserving radio silence on the far side of the moon.

A first-of-its-kind international symposium is being held this week, turning up the volume to mull over the prospect of protecting real estate on the moon's far side exclusively for dedicated scientific purposes. Despite the moon being surrounding by a vacuum, there's an air of urgency to the meeting. 

Held under the auspices of the International Academy of Astronautics (IAA), the first IAA Moon Farside Protection Symposium is taking place March 21-22 in Turin, Italy. The goal of the gathering is to set off a wake-up call that engages the global scientific, political, and industrial community to be aware of a growing list of concerns.

Related: The moon could be perfect for cutting-edge telescopes — but not if we don't protect it

Electromagnetic pollution

Earth's neighboring celestial body has the unique property of naturally shielding radio waves generated by chatter on Earth and around it. What some meeting organizer's see is need for a radio silence zone, dubbing it a shielded zone on the moon.

That idea has been championed by Claudio Maccone of the Istituto Nazionale di Astrofisica (National Institute for Astrophysics). In December 2021, the IAA established a new permanent committee devoted to the moon far side protection, chaired by Maccone as IAA technical director.

Maccone and colleagues contend that the moon's far side is a region of paramount scientific interest as it provides an environment free from the electromagnetic pollution typical on Earth.

Maccone points to the quickening pace of lunar missions by multiple nations that may well irreversibly compromise the current condition of the moon's radio quietness.

Some of the branches of science that would greatly benefit from operating on the farside, Maccone explains, are cosmology, astrobiology, planetary defense, as well as the search for other intelligent life that might populate the heavens.

Efforts like Breakthrough Listen could employ the radio silence of the moon's far side to scan the universe for signs of intelligent life. (Image credit: Breakthrough Listen/Danielle Futselaar)

Lunar deliverables

Science on the moon is already taking shape, says Jack Burns, professor emeritus in the department of astrophysical and planetary sciences at the University of Colorado, Boulder. 

"Radio astronomy from the moon has begun," Burns says.

NASA's first radio telescope, ROLSES, was recently delivered to the lunar south pole by the Intuitive Machines Odysseus lander, Burns points out. ROLSES stands for Radio wave Observation at the Lunar Surface of the photo-Electron Sheath. He is a co-investigator on the ROLSES instrument now on the moon.

Furthermore, additional radio telescopes are scheduled to land on two other NASA Commercial Lunar Payload Services landers in 2026: ROLSES-2 to the nearside and the Lunar Surface Electromagnetics Experiment — Night (LuSEE-Night) to the far side. Burns is a LuSEE-Night co-investigator.

 Headed for the moon's farside, the Lunar Surface Electromagnetics Experiment-Night (LuSEE-Night), built to probe the "Dark Ages" of the early universe.  (Image credit: Firefly Aerospace)

Years of anticipation

"After many years of anticipation, we are actively doing radio science from the moon. Thus, we also need to actively work to protect, in particular, the far side of the moon from radio frequency interference from lunar orbiting satellites and infrastructure on the lunar surface," Burns tells Space.com.

This week's moon far side protection workshop involves thought leaders in science, engineering, space policy, and space law, says Burns, to develop modern approaches to shielding the far side of the moon from anthropogenic radio emission. 

"We need to preserve the far side for exciting science that includes measuring magnetic fields associated with potentially habitable exoplanets and uncovering the mysteries of the unexplored Dark Ages of the early universe — using low radio frequency observations." Burns says.

Top-tier tasks

There are a number of themes running through this week's symposium.

In defining how several science branches benefit by a radio silence zone, the IAA's Maccone flags top-tier exploration tasks:

  • Cosmology: To detect the extremely feeble radiation of the hydrogen line at 1,420 Megahertz and downshifted to much lower frequencies. The radio silence of the lunar far side would ensure a major leap forward in research.
  • Astrobiology: To study pre-biological interstellar molecules by searching for weak spectral lines utilizing advanced radio telescopes in combination with the radio silence of the moon's far side.
  • Planetary defense: From the far side, radar and optical telescopes can be used for accurate measurements of near-Earth objects to augment the lead time of their detection and provide warning of a possible space rock pummeling our planet. 
  • SETI and technosignatures: To search, with very low noise, for "signatures" of alien civilizations that would reach us extremely faint due to the vast distances between stars in the Milky Way, if not from other galaxies.

Logo for the Moon Farside Protection meeting staged by the International Academy of Astronautics. (Image credit: IAA)

Shielded zone

Recent lunar missions and, even more so, newer programs will bring more and more artificial systems around and on the lunar surface, occupying space and emitting radio waves at various frequencies, Maccone explains.

There are already international regulations and resolutions aimed at protecting any shielded zone on the moon — SZM in lunar lingo — such as International Telecommunication Union (ITU) radio regulations.

"However, it is of paramount importance to take a further step, both to extend the protected frequencies to encompass all other scientifically relevant ones — in addition to those already included — and to preserve a portion of the far side exclusively for scientific installations," Maccone suggests.

Diplomatic efforts

There is a pressing need, says Maccone, to elevate regulations into enforceable and binding treaties for every space agency and private company.

Maccone adds that all objectives can only be pursued and achieved through diplomatic efforts involving spacefaring nations, current and future, from around the world.

The newly formed IAA committee and the symposium's ultimate goal is to help form an international agreement, ideally under relevant specialized organizations, such as the ITU and the United Nations Committee on the Peaceful Uses of Outer Space, for example.

Unified articulation

Richard Green is chair of the International Astronomical Union group delving into the issues of staging astronomy from the moon. He is also an assistant director for government relations at Steward Observatory, run by the University of Arizona in Tucson.

"I think this meeting is important because we can make some progress on a unified articulation of astronomy needs and suggested policy approach for the moon," Green says.

Additionally, there is an immediate opportunity to do so, Green explains, through a proposed United Nations space scientific and technical subcommittee action team.

That UN action team would explore communication and collaboration for lunar activities and may well be approved at the full UN Committee on the Peaceful Uses of Outer Space gathering this June, Green observes.

Wild West scenario

"My concern is that lunar projects are rapidly developing and are not coordinated," says Joseph Silk, an astrophysicist at Johns Hopkins University in Baltimore, Maryland and professor of physics at the Institut d'Astrophysique de Paris.

Science projects are in the forefront, Silk says, such as unique radio telescopes that can peer back in time to the dark ages of the universe. The far side offers a unique environment, he adds, and optical telescopes in permanently shadowed polar craters will eventually image the nearest exoplanets.

"Yet we are at risk of a Wild West scenario due to the rivalries between competing space agencies and commercial interests," Silk tells Space.com. "The number of desirable lunar sites is limited. The last major outer space treaty dates to 1967, and has no means of enforcement. A new International space treaty is urgently needed," he concludes. 

Editor's note: This story was update at 11:20 p.m. ET on March 21 to fix a typo: The hydrogen line is at 1,420 MHz, not 142 MHz.

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Leonard David
Space Insider Columnist

Leonard David is an award-winning space journalist who has been reporting on space activities for more than 50 years. Currently writing as Space.com's Space Insider Columnist among his other projects, Leonard has authored numerous books on space exploration, Mars missions and more, with his latest being "Moon Rush: The New Space Race" published in 2019 by National Geographic. He also wrote "Mars: Our Future on the Red Planet" released in 2016 by National Geographic. Leonard  has served as a correspondent for SpaceNews, Scientific American and Aerospace America for the AIAA. He was received many awards, including the first Ordway Award for Sustained Excellence in Spaceflight History in 2015 at the AAS Wernher von Braun Memorial Symposium. You can find out Leonard's latest project at his website and on Twitter.

  • Unclear Engineer
    This article states the problem, but the explanation of the solution seems to not include the technically obvious issue of how to use a science base on the far side of the Moon without introducing some electromagnetic pollution.

    There is a need for location and communication that would seem to require radio frequency transmissions to and from lunar satellites in order to communicate with Earth.

    I guess the frequencies used, and maybe the timing of the emissions could be controlled so as to not interfere with the scientific goals. But, I think that deserves some explanation in an article such as this.
    Reply
  • Classical Motion
    By the time we have any worth while instruments on the far side, we will have laser networks covering the moon and earth. The radio and most of the IR EM should remain quiet. Unless you get a CB-er.
    Reply
  • 24launch
    It's a challenge to be sure and definitely the time to discuss and make agreements is now as things are moving fast. The biggest challenge will be getting nations like China & Russia on board who as of late are making their own plans and are not interested in discussions with the rest of the Western and Asian nations. One would hope these kinds of concerns are on their minds as well since we as a species are attempting much of the same science and investigations despite our differences.

    While this article doesn't go into the specifics - I think mainly because so far everyone has their own needs and ideas - thus the need for international agreement and cooperation. As Unclear Engineer alluded to, it will most likely be banned frequencies and even cessation of perhaps "unidirectional" EMF over certain locations. Tight beam laser communications would be ideal but I don't know how practical or cost-effective that will be.

    No doubt in short order there will be networks of satellites orbiting the moon for communications and lunar positioning - the new LPS (vs GPS). Fortunately, unless there are massive quantities of super-rare resources on the far side of the moon, the majority of activity will be on the near-side for continuous communication with Earth.
    Reply
  • Classical Motion
    It would be interesting to see what reflections could be picked up on the far side from moon orbiting satellites. It might be noisy there now.

    Who knows, if we could tie into the moon's electrostatic surface field, we might have a very sensitive natural transducer. If the noise from the earth side doesn't drown it out.
    Reply