A team of radio astronomers has outlined a proposed observatory for one of the quietest radio environments currently accessible in the Solar System: the farside of the Moon. The Lunar Farside Transients and Technology Telescope, or LFT3, is designed to observe radio frequencies from 0.1 MHz to 2.7 GHz while using the Moon itself as a shield against much of the radio-frequency interference generated on and around Earth.
The researchers argue that there is a limited window in which to make such measurements. As lunar exploration expands and more communications and navigation spacecraft enter lunar orbit, artificial radio signals could increasingly reach locations that are currently exceptionally quiet. LFT3 is therefore being proposed as a mission that could operate before 2030 and establish both a scientific survey and a baseline record of the lunar farside radio environment.
Why the Lunar Farside Matters for Radio Astronomy
Radio telescopes on Earth face two fundamental limitations. The first is radio-frequency interference, or RFI, produced by terrestrial transmitters, satellites, aircraft and communications systems. Even observatories in remote regions cannot completely escape these signals.
The second limitation is Earth’s ionosphere. The electrically charged upper atmosphere blocks radio waves at frequencies below roughly 10 MHz and can significantly distort observations below about 30 MHz. As a result, some of the lowest-frequency regions of the electromagnetic spectrum remain extremely difficult or impossible to study from the ground.
The lunar farside addresses both problems. The solid body of the Moon blocks direct radio transmissions from Earth, while the Moon lacks a substantial ionosphere comparable to Earth’s. LFT3 would therefore gain access to frequencies that are either heavily contaminated or inaccessible to terrestrial observatories.
The International Telecommunication Union has long recognised this advantage through the Shielded Zone of the Moon, a region protected by the Moon from emissions originating close to Earth. The proposed LFT3 landing site lies within this zone, near the planned location of the LuSEE-Night radio experiment.
A Radio Observatory Covering 0.1 MHz to 2.7 GHz
LFT3 would divide its observing range among three principal receiver systems. A high-frequency system would cover approximately 0.1 to 50 MHz, a very-high-frequency system would operate from about 60 to 260 MHz, and an ultra-high-frequency array would span approximately 300 to 2,700 MHz.
The UHF instrument is planned as a 48-element dual-polarisation phased array installed across much of the lander’s upper surface. Its signals would be combined to form 10 dual-polarised beams, enabling the telescope to survey a large region of the sky as the Moon slowly rotates. According to the mission concept, the array could eventually sweep roughly 70% of the lunar sky.
The slower apparent movement of the sky from the lunar surface also offers an observational advantage. A region of sky remains within view considerably longer than it does for a fixed telescope on Earth, giving LFT3 longer dwell times for sensitive searches.
Searching for Technological Signals Without Earth’s Radio Noise
One of LFT3’s central objectives would be a search for technosignatures: electromagnetic signals whose characteristics could indicate technology rather than a known natural astrophysical process. Narrowband or pulsed signals are particularly interesting in such searches, but on Earth they can also resemble interference from human transmitters.
Operating behind the Moon would substantially reduce that ambiguity. LFT3 would use multiple beams and polarisation measurements to examine candidate signals, while onboard processing could generate spectra with frequency resolution of about 10 Hz for specialised technosignature searches.
The proposed survey includes stars within roughly 100 light-years. The researchers estimate that, for some nearby targets and observing bands, the telescope could reach effective transmitter powers comparable to the former Arecibo planetary radar, which is often used as a reference level in radio SETI studies.
The mission would also deliberately observe artificial signals associated with spacecraft around Mars and the Moon. These known transmitters would provide a practical way to test whether LFT3's hardware and processing systems can correctly identify narrowband technological radio signals.
Looking for Radio Transients in an Unexplored Frequency Range
The same quiet environment could make LFT3 a wide-ranging transient observatory. Its science programme includes searches for pulsars, fast radio bursts, long-period radio transients, magnetically active stars and other short-lived signals.
Of particular interest are frequencies below about 30 MHz and the terrestrial FM broadcast band between 87 and 108 MHz. These regions are exceptionally challenging from Earth because of the ionosphere or intense human transmissions. Observing them from the lunar farside could reveal populations of nearby, low-dispersion radio transients that terrestrial surveys have difficulty detecting.
The instrument design includes a one-second buffer of raw digitised data. If onboard processing identifies an unusual event, the system could preserve a short segment of high-detail data for later transmission to Earth rather than continuously downlinking enormous quantities of raw measurements.
Listening to the Sun and the Outer Planets
LFT3 would also study natural radio emissions across the Solar System. Solar observations could include Type II and Type III radio bursts, coronal mass ejection-related emissions and other rapidly evolving phenomena at frequencies that are difficult to observe from Earth.
Jupiter is expected to be one of the strongest planetary radio sources accessible to the instrument. Its powerful magnetosphere produces intense auroral emissions extending to frequencies below those routinely observed by ground-based facilities.
The mission could go further by observing radio emissions from Saturn and Uranus. Saturn's kilometric radiation has been studied by spacecraft including Voyager and Cassini, while Uranus' auroral radio emission has been directly sampled only during the Voyager era. A lunar observatory could provide new long-duration measurements without requiring another spacecraft to travel to the outer Solar System.
LFT3 would also search for low-frequency radio signatures associated with planetary lightning, including signals from bodies where lightning has been predicted but not conclusively detected.
A New Route to Exoplanet Magnetic Fields
Another major target is auroral radio emission from exoplanets. Detecting such radiation could provide evidence for planetary magnetic fields, which in turn can reveal information about planetary interiors, atmospheric evolution and interactions with stellar winds.
Direct measurements of exoplanet magnetic fields remain extremely difficult. LFT3 would concentrate particularly on the 0.1 to 10 MHz range, where models predict radio emission from some smaller or more weakly magnetised planets could peak but where Earth-based telescopes cannot operate effectively.
The researchers do not expect individual weak exoplanet bursts to necessarily stand out in a single observation. Instead, data collected over many planetary orbits could be combined to search for periodic, circularly polarised signals. Even non-detections could help constrain competing models for exoplanet radio emission.
Low-Frequency Spectral Lines and the Early Universe
The mission's scientific scope extends beyond transient sources. LFT3 could search for neutral hydrogen, radio recombination lines and previously undetected spectral features in frequency ranges affected by terrestrial interference.
Low-frequency measurements of redshifted hydrogen are also important for cosmology because they can probe periods extending back toward the Cosmic Dark Ages and the formation of the first luminous structures. The expected cosmological signals are extraordinarily faint compared with foreground radio emission from the Milky Way, making instrumental stability and an exceptionally quiet observing environment essential.
The authors do not expect LFT3 itself to have sufficient sensitivity for a definitive detection of the Dark Ages or Epoch of Reionization global signal. Instead, the mission could provide valuable measurements of low-frequency radio backgrounds, calibration behaviour and the lunar environment while complementing experiments such as LuSEE-Night.
A Mission Designed Around Tight Power and Data Limits
The proposed observatory would have to conduct this broad science programme with relatively modest spacecraft resources. The concept assumes a science payload of about 100 kilograms on a lander roughly three metres across, with approximately 100 watts available during the lunar day and about 20 watts during the lunar night.
Communications are another major constraint because the farside has no direct line of sight to Earth. Scientific data would need to pass through a lunar relay spacecraft. The current concept assumes a downlink allowance of about 100 gigabytes per month and around 20 terabytes of onboard storage.
That is far below the amount of uncompressed data the observatory could generate. LFT3 would therefore process and prioritise information onboard, returning high-resolution data for important targets and triggered events while producing lower-resolution, sky-complete spectra for long-term surveys.
The baseline mission calls for approximately 20 weeks of science operations. Engineers would also have to manage the severe lunar thermal cycle, including roughly two-week-long nights, as well as dust, radiation exposure and the need to prevent the lander itself from contaminating observations with radio emissions.
Recording the Moon Before Its Radio Environment Changes
A distinctive part of the proposal is its emphasis on documenting the lunar radio environment itself. The LFT3 team expects the number of spacecraft operating around the Moon to rise substantially during the coming years, creating new potential sources of interference. Their modelling indicates that by the later 2020s there could be extended periods when one or more lunar-orbiting spacecraft are visible above the telescope's horizon.
For that reason, LFT3 would continually monitor its radio environment and catalogue detected events. Such measurements could establish a reference spectrum for the lunar farside before communications infrastructure becomes more extensive, while also contributing evidence relevant to future spectrum-management decisions around the Moon.
LFT3 Remains a Proposal
LFT3 is not presented in the paper as an approved lunar mission. The manuscript describes a proposed architecture, science programme and operational concept intended to fit within a mission budget of roughly US$150 million including launch, broadly comparable in scope to a Commercial Lunar Payload Services-class effort.
The proposed schedule aims for deployment before 2030, but the eventual launch date, lander provider, final hardware configuration and funding would depend on future mission development and selection decisions.
If realised, LFT3 would test whether a comparatively compact lunar observatory can use the farside's unusual radio environment to conduct science that is difficult or impossible from Earth. Its significance would extend beyond any single search for a transient, exoplanet or technological signal: the mission would also record a radio environment that may become progressively harder to recover as human activity around the Moon expands.