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US FCC’s approval of Reflect Orbital’s mirror in space has caused a bit of a stir: lot of updates in the governance sector as well as science and commerce. Having trouble with links? Click the link below to read the unclipped publication. ↓

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NISAR or the NASA-ISRO Synthetic Aperture Radar is an Earth-observation satellite jointly built by NASA and the Indian Space Research Organisation. It launched July 30, 2025, from the Satish Dhawan Space Centre in India aboard ISRO's GSLV-F16 rocket, deployed its 12-meter radar reflector on August 15, and began science operations that autumn. It is the first free-flying mission to carry two radar frequencies, and among the most expensive Earth-observation satellites built, at a cost commonly cited near $1.5 billion.

NISAR maps the surface using synthetic aperture radar (SAR): it transmits microwave pulses and records the echoes. Because it supplies its own illumination, it works day or night, and its microwaves pass through cloud, smoke, and rain, giving all-weather coverage that optical satellites cannot match. SAR synthesizes a large virtual antenna from signals gathered along the orbit track, producing resolution far finer than the physical antenna would allow — here, 3 to 10 meters depending on mode.

The satellite carries two radars. The L-band (24 cm wavelength), built by NASA, penetrates dense forest canopy and stays coherent between passes, and carries most of the global science. The S-band (9.4 cm), built by ISRO, is more sensitive to lighter vegetation and is used primarily over India. Running both lets scientists compare how a surface responds at two wavelengths.

The engineering advance that sets NISAR apart is a technique called SweepSAR. Conventional radar trades swath width against resolution. NISAR transmits across its full 12-meter reflector and receives on each feed element independently, imaging a swath wider than 240 kilometers without sacrificing resolution. That width lets it cover nearly all of Earth's land and ice every 12 days, on both ascending and descending passes. The tradeoff is data volume: the two radars generate more than 40 terabits per day.

NISAR tracks change over time across three areas: deformation of Earth's crust, including earthquakes, landslides, volcanic activity, and land subsidence; the growth and retreat of ice sheets, glaciers, and sea ice; and changes in forests, wetlands, and other ecosystems, including carbon storage. Using interferometry, i.e., comparing the phase of returns from repeat passes, it resolves vertical ground motion down to the millimeter. An early result mapped millimeter-scale subsidence across Mexico City, showing how groundwater extraction is sinking parts of the city.

NISAR is the first large joint NASA-ISRO mission, developed over roughly a decade and presented as a marker of US-India civil-space cooperation. NASA supplied the L-band radar and the reflector-boom system; ISRO supplied the spacecraft, the launch, and the S-band electronics.

NISAR data is free and openly available, distributed through two archives that mirror the mission's split. NASA hosts data at its Alaska Satellite Facility, which had released more than 100,000 L-band products by February 2026. ISRO hosts data at its Bhoonidhi portal (bhoonidhi.nrsc.gov.in), which released S-band sample products from its January–February 2026 collections. A continuous, open, high-resolution radar record of the entire planet at 12-day cadence is new, and it lowers the barrier for anyone building analysis on top of SAR.

Michigan State University (U.S.) researchers reported that modern AI systems can be easily misled into detecting false signs of life, raising concerns for future astrobiology missions. The study, to be presented at the 2026 Conference on Artificial Life, used the Avida digital‑life platform to generate tens of thousands of self‑replicating and non‑replicating code organisms. A neural network trained to distinguish them achieved 99.97% accuracy on familiar data but misclassified altered sequences 100% of the time, demonstrating a high risk of false positives, and a vulnerability to out‑of‑distribution samples.

The researchers warned that AI‑powered sensors on missions analyzing mass‑spectrometry data on Mars, Venus, icy moons and exoplanets could incorrectly flag biosignatures, underscoring the need for independent verification and human oversight. NASA researchers said improved algorithms may help identify unknown categories, but the study shows the need for independent verification.

Saturn’s haze‑shrouded moon Titan and the distant dwarf planet Pluto seem utterly unrelated, billion so kilometers apart and shaped by radically different environments. Yet both worlds display the same mysterious infrared surface signature, hinting at shared chemical processes despite their stark contrasts.

James Webb Space Telescope observations revealed an identical, unexplained infrared absorption feature on Saturn’s moon Titan and the dwarf planet Pluto, indicating the presence of an unknown surface compound with matching spectral behavior on both worlds. The signal, detected independently by JWST’s NIRSpec and MIRI instruments, does not correspond to any cataloged planetary ice or known molecule.

Researchers led by Bruno Bézard of the Paris Observatory found the feature weakens toward Titan’s limb, consistent with a surface origin, and noted Pluto’s thin atmosphere cannot produce an absorption of similar depth. The compound likely forms through nitrogen‑methane photochemistry and settles onto the surface, a process absent on Ganymede, where JWST saw no such feature. Possible candidates include complex hydrocarbons such as allenes, though complete spectra are lacking. Upcoming JWST mapping and NASA’s Dragonfly mission may help identify the molecule. The study was accepted by Astronomy & Astrophysics.

NASA outlined new details for Artemis III, scheduled for 2027, which would become the first U.S. crewed mission to rendezvous and dock with two separate spacecraft capable of carrying their own crews. It is considered to be one of the most complex crewed flights ever attempted, a feat matched only by the Soviet Soyuz T-15 in 1986. Rather than a landing, the roughly two-week flight is a test run. A four-person Orion crew, launched on the Space Launch System (SLS), will separately conduct rendezvous and docking operations with Blue Origin's Blue Moon and SpaceX's Starship in low Earth orbit.

Blue Moon, flying its Mark 2 on New Glenn, launches first from SLC‑36 and can loiter 30 days; Orion then arrives, docks for about two days, with two astronauts boarding to test life-support, avionics and a prototype spacesuit. Starship, in its uncrewed Version 3 configuration with a docking adapter, launches afterward for about a day of communications and maneuvering tests; astronauts will not enter it. Both landers remain developmental, neither in its final lunar‑landing form. Starship must still demonstrate orbital cryogenic propellant transfer, requiring an estimated 15 refueling launches for Artemis IV. Meanwhile, a New Glenn exploded during a May engine test, though Blue Origin expects a return to flight by year's end. Success would clear the way for Artemis IV's crewed landing, targeted for 2028.

22 July, 2026

Separately, NASA astronaut Victor Glover urged the agency to begin crewed Artemis landings at equatorial sites rather than the lunar south pole, citing simpler access, shorter surface stays and reduced operational risk. Speaking July 21 at the NASA Exploration Science Forum, he warned that south‑polar missions staged from near‑rectilinear halo orbit could leave crews stranded for up to a week before Orion could return, complicating medical contingencies and navigation in low‑sun conditions.

NASA officials said equatorial options remain under consideration as lander capabilities mature, even as Artemis 4 and 5 are still planned for the south polar region. The agency has dropped Gateway from early missions and is evaluating alternative lunar orbits, with SpaceX proposing a low‑lunar‑orbit approach for Artemis 3. Glover emphasized his comments reflected personal views, not agency policy.

21 July, 2026

SpaceX launched Northrop Grumman’s Mission Robotic Vehicle (MRV) and three Mission Extension Pods (MEPs) July 21 on a Falcon 9, marking the first deployment of a commercial spacecraft designed to install propulsion modules on multiple geostationary satellites. The four spacecraft were developed by Northrop Grumman’s SpaceLogistics subsidiary and launched toward geosynchronous transfer orbit, where they will use their own propulsion systems to reach the intended orbit at about 35,786 kilometers / 22,236 miles above Earth.

The mission required the Falcon 9 booster's full performance to send the MRV and three pods to geostationary orbit, so SpaceX did not recover the first stage, ending its service after a record 32 flights.

MRV and the pods will maneuver to GEO, where each pod will move into position near their assigned satellites, and the MRV, equipped with two 10-foot-long / 3 meters robotic arms, will retrieve each pod and use two robotic arms to attach it to customer satellites operated by Intelsat and Optus. Each pod provides electric‑propulsion station‑keeping, extending satellite life by about six years. The mission advances DARPA’s RSGS program, which supplied MRV’s robotics, and follows earlier MEV servicing missions. Northrop plans additional pods while keeping MRV in orbit for future installations.

Astronomers warned that proposed orbital data‑center constellations and solar‑reflecting spacecraft could create a bright, permanent band of satellites along the dawn‑dusk terminator, visible worldwide and outshining stars and planets. Companies including SpaceX, Starcloud, Cowboy Space, Orbital and Blue Origin have filed FCC applications to deploy more than one million data‑center satellites, while China plans a similar network within five years. Reflect Orbital separately received FCC approval July 10 to launch Eärendil‑1, a 60‑by‑60‑foot demonstration mirror ahead of a planned 50,000‑satellite fleet intended to redirect sunlight to Earth after dark.

Researchers said these systems would cluster in a single sun‑synchronous plane, forming a luminous “Saturn’s ring” that would sweep across the sky twice daily and remain visible for hours due to scattered light. Modeling showed severe impacts on twilight observations, near‑Earth asteroid searches and the effectiveness of major observatories, with some configurations producing additional X‑shaped bands. The American Astronomical Society criticized the FCC decision, citing risks to telescope equipment, aviation safety and public eyesight, while noting no U.S. agency evaluates night‑sky impacts. Astronomers said mitigation efforts on other constellations have been offset by increasing satellite size and lower operational altitudes.

Launch costs have fallen 96% since 1960, according to a July 14 PNAS Nexus study analyzing 4,405 launches across 330 rocket configurations from major spacefaring nations. The average cost per kilogram dropped from $87,000 in 1960 to $3,868 in 2025, with a 21.2% learning rate for each doubling of cumulative payload, one of the fastest declines recorded in any industry. Researchers attributed the trend to post–Cold War commercial activity and the acceleration triggered by SpaceX’s Falcon 9 reusability. If the relationship holds, costs could reach $1,600 per kilogram by 2030 and $300 by 2040, with Starship potentially pushing prices below $1,000 sooner.

However, certain situations could slow or reverse future reductions. The average launch costs may rise, the researchers said, citing debris growth, market concentration, and geopolitical tension. The earlier studies understated true costs by focusing on rocket price rather than lifetime payload. The team warned that accelerating orbital debris, traveling about 27,000 kmph / 16,800 mph, increases collision risk and could trigger cascading fragmentation known as the Kessler syndrome. They also noted SpaceX now accounts for roughly 75% of global payload to orbit, creating incentives for higher pricing that could reduce launch demand. Rising international tensions may push governments to avoid reliance on a single U.S. provider, reviving Cold War‑style pursuit of independent, and often more expensive, domestic launch systems.

21 July, 2026

The U.K. Space Agency and Space Florida signed a memorandum of understanding at the Farnborough International Airshow to launch the first funding partnership under the Florida International Aerospace Innovation Fund. Each organization committed $200,000 to support joint research, innovation and commercialization projects beginning in 2027. Eligible proposals must include at least one Florida‑based aerospace company, an international partner and clear commercial potential, with awards reviewed by a joint panel.

The agreement follows a 2023 U.K.–Florida trade cooperation pact and complements Space Florida’s existing partnerships with Switzerland, Japan, France and Israel, the latter having provided more than $23 million across 13 funding rounds. British firms including BAE Systems and Space Forge already operate in Florida, with officials citing growing interest in cross‑border collaboration.

Meanwhile, Poland will invest about $745 million in the European Union’s planned IRIS² (Infrastructure for Resilience, Interconnectivity and Security by Satellite) secure satellite‑communications constellation, funding six medium Earth orbit and six low Earth orbit satellites. Officials said the contribution will enhance national security and create opportunities for Poland’s space sector, with more than 400 domestic companies positioned to benefit.

The agreement was signed July 21 in Warsaw with EU defence and space commissioner Andrius Kubilius. IRIS² will provide government‑grade communications and broadband connectivity across the EU, ultimately comprising 292 satellites in multiple orbits. The investment follows Poland’s selection to host a new ESA civil security and resilience center and rising national space spending, including expanded ESA contributions and a planned state fund for space companies.

The constellation can be compared to a blend of the Space Development Agency's Proliferated Warfighter Space Architecture for the resilient military-comms layer, and SpaceX's Starshield (the government/defense variant of Starlink) for the secure sovereign-connectivity role. However, the US mostly buys commercial capacity rather than building a state-led flagship, so IRIS²'s government-owned, sovereignty-first model has no direct counterpart.

21 July, 2026

SpaceX’s proposed South Texas land swap faced new legal action as conservation and tribal groups filed an emergency injunction July 20 to halt the transfer of 727 acres from the Lower Rio Grande Valley National Wildlife Refuge to the company. The suit argues the exchange violates the National Wildlife Refuge System Improvement Act and the National Historic Preservation Act, noting some parcels include Palmito Ranch Battlefield.

The plaintiffs cite wildlife impacts from Starbase operations, including a 2024 study reporting egg damage or loss in all monitored shorebird nests after a launch. SpaceX would provide 683 acres of its own land in return. Starship has conducted 12 suborbital tests from Starbase and is preparing for Flight 13 on July 23.

22 July, 2026

The U.S. Federal Communications Commission voted July 22 to reclaim 160 megahertz of upper C-band from satellite operators for a July 2027 5G auction. The move follows a 2020 sale of 280 MHz of lower C-band that raised more than $80 billion from Verizon, AT&T and T-Mobile. Combined, the frequencies form a 440 MHz contiguous band for wireless carriers, with service in the top 75 U.S. markets slated by December 2030. Incumbents SES and Eutelsat, both European, use C-band to distribute television to U.S. networks and must relocate to the remaining 40 MHz or other bands such as Ku-band. Relocation incentives will total less than the $13.4 billion paid in 2020 but remain roughly commensurate per megahertz cleared. SES, the largest incumbent, which had urged the FCC to cap clearing at 160 MHz, withheld comment. The FCC coordinated with the FAA on aircraft radio altimeters in adjacent spectrum, with rebates for upgrades.

Commissioner Anna Gomez dissented over the lack of tribal priority access. An equity issue, the tribal nations were not given a window to claim frequencies over their own lands before the spectrum goes to open auction, a recurring problem given how underserved and historically excluded those areas are.

In a separate unanimous vote, the FCC adopted new Part 100 satellite and Earth‑station licensing rules intended to accelerate commercial‑space application processing. The overhaul replaces legacy Part 25 rules, expands categories of minor modifications that do not require prior authorization, and aims to reduce review timelines for non‑geostationary constellations from years to months or weeks. This matters most for NGSO constellations, the large low-orbit fleets like Starlink and Amazon Leo, as opposed to a single geostationary satellite parked over one longitude, which constantly launch replacements and are throttled by slow approvals.

The FCC also sought comment on additional reforms, including space‑based experimental licensing, to keep pace with rapid industry growth.

23 July, 2026

NASA’s major programs are reporting widespread effects from a sharp loss of civil‑servant staff, according to a July 23 Government Accountability Office assessment. Twenty‑five of 36 projects cited impacts from a 22% workforce reduction driven by deferred‑retirement departures, with Goddard Space Flight Center losing 34% of its civil servants. Orion lost 10% of its staff, SLS nearly 20%, and DAVINCI (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging) faced delays in risk‑reduction work before funding was restored in the fiscal 2026 appropriations bill.

GAO noted $478.2 million in net overruns, concentrated in SLS Block 1B and Orion, though schedule impacts remain limited. NASA is pursuing new hiring pathways, including contractor conversions and the NASA Force talent program, but warned future budget uncertainty could trigger additional reductions.

23 July, 2026

The U.S. Office of Space Commerce said July 23 it is advancing a voluntary mission-authorization system for novel space activities not overseen by existing regulators, following what Director Taylor Jordan cast as White House backing after months of interagency work. The office will soon issue a Federal Register "call for interest," with initial applicants serving as a pilot to refine the process.

Rolled out in March as Space Commerce Certification, the scheme routes company filings through an interagency review under a "presumption of approval" which means applications are automatically granted after 120 days absent action. It is voluntary because OSC lacks statutory authority to compel it; the office frames it as meeting Outer Space Treaty obligations to authorize and supervise national space activities. Jordan said certification could relieve firms of some FAA payload-review or FCC orbital-debris-mitigation work.

Mission authorization seeks to provide regulatory clarity for space activities not covered by existing agencies, such as satellite servicing and commercial space station development. Gaps were exposed when the FCC, approving Reflect Orbital's sunlight-reflecting satellite, said environmental and astronomy impacts fell outside its review. In a July 21 letter, House Science Committee leaders Brian Babin and Zoe Lofgren urged Chairman Brendan Carr to defer a satellite-licensing vote, arguing the 1934 Communications Act grants no authority over space safety. The FCC adopted the rules unanimously July 22.

24 July, 2026

The European Union ordered a 24‑hour delay on Sentinel‑1 and Sentinel‑2 imagery covering a defined area of the Gulf of Oman after a May 26 U.S. request citing security risks linked to the ongoing conflict with Iran. The July 13 Council decision marks a rare exception to Copernicus’ free and open data policy and follows similar restrictions imposed by U.S. commercial operators Planet and Vantor.

The delay affects imagery used by energy firms, insurers, media and open‑source analysts monitoring shipping routes near the Strait of Hormuz. The Council said the measure was needed to prevent misuse under the EU’s Space Threat Response Architecture. The decision does not specify when the delay began, how long it will remain in force or when it will be reviewed.

21 July, 2026

U.S.-defense contractor, KBR said July 21 it is expanding investment in digital engineering, space surveillance and missile‑defense capabilities as it positions to compete for work on Golden Dome, the Trump administration’s planned multilayered defense architecture. The company assigned two senior executives to lead the effort and is increasing spending on modeling, simulation, prototyping and classified facilities intended to support system testing and integration.

KBR is among hundreds of firms eligible for task orders under the Missile Defense Agency’s SHIELD contracting vehicle, which will support Golden Dome and other programs. The company is targeting engineering and integration roles across sensors, command‑and‑control, data fusion, threat analysis, counter‑drone systems and directed energy. KBR said expanded facilities will enable government and industry to test technologies without committing to a single supplier.

23 July, 2026

A classified Chinese satellite is operating in an unprecedented orbit, giving it a sweeping vantage over the geostationary belt. Shijian-31, launched June 16 on a Long March 3B from Xichang and described by the China Aerospace Science and Technology Corporation (CASC) only as a "space environment" mission, was tracked into a modified Molniya‑type reaching apogee (the highest or farthest point of an orbit around Earth) over the equator rather than the usual northern hemisphere.Tracking by Integrity ISR and COMSPOC shows the satellite completes a 12.5‑hour orbit that shifts about 15.7 degrees in longitude each cycle, enabling full GEO coverage roughly every 23 days. They also noted that a small 50-meters-per-second burn could drop it through GEO.

The Secure World Foundation called it unusual and possibly part of a wider turn toward inspector satellites, alongside U.S. GSSAP and Russia's Luch 2. Shijian‑31 joins earlier Shiyan-10 satellites and TJS-13 and TJS-21 spacecraft using creative high‑inclination, highly elliptical orbits for space‑situational‑awareness missions.

19 July, 2026

Zenno Astronautics will relocate its headquarters from New Zealand to Los Angeles, US after completing an in‑orbit demonstration of its Z01 Supertorquer, a superconducting magnetic attitude‑control actuator flown in June on Impulse Space’s Mira satellite, the first superconducting product to have successfully operated in space. The company said the move positions it closer to U.S. aerospace customers, investors and talent, and will enable higher‑scale production and new product development. The company develops high-temperature superconducting (HTS) magnet systems to enable fuel-free satellite control and orientation.

Zenno plans to open a facility by early fall and expand its U.S. workforce. Founded in 2017, the firm is developing superconducting systems for spacecraft mobility and long‑term lunar infrastructure, supported by prior seed funding and investment from Mitsubishi Electric’s Innovation Fund.

China’s LegendSpace, German deltaVision and Italian ORiS each secured new funding to advance AI‑driven rocket engine development, spacecraft refueling hardware and laser‑based satellite power‑beaming technologies.

19 July, 2026

LegendSpace or Linjie Hangtian, a Beijing‑based startup developing AI‑driven liquid rocket engines, raised 200 million yuan / $29.5 million in an angel round backed by Vitalbridge, Oasis Capital, Source Code Rhythm, Yuanma Lüdong, Shangshi Capital and others. The company plans to advance multiple engines through approval, ground tests and hot‑fire verification, upgrade its proprietary “Prime” agent‑based design and simulation platform, and build production and test infrastructure. LegendSpace presents itself as an AI‑native liquid‑engine developer and not a software company, built around its “Prime” platform, created with the Beijing Institute for AI for Science (AISI).

Prime integrates AI‑driven design, multiphysics simulation, additive manufacturing, and cold‑ and hot‑fire testing into a closed loop the company says can cut engine iteration from years to about two weeks. LegendSpace reports completing one full design‑to‑test cycle, using DeepFlame, a GPU‑native reacting‑flow code from Peking University. A 2.5‑ton‑thrust engine is in 3D‑printed trial production, and construction is underway on a new test facility. The firm was founded in 2026 by Chen Zhi, an aerospace engineer at Peking University, a Cambridge University alumnus and vice dean of AISI. The round comes amid rapid growth in China’s commercial launch and propulsion sector.

21 July, 2026

German propulsion‑component developer deltaVision raised €10.2 million / $11.6 million in its first funding round to scale production of valves and related hardware used in spacecraft propulsion and future in‑orbit refueling systems. The Munich firm, now 125 employees, plans to expand output to 5,000 units annually, citing strong demand and supply‑chain constraints.

Investors include KT Ventures, Valemount Capital and Futury Capital. DeltaVision supplies more than 60 customers, including major primes and government agencies, and supports ESA’s Argonaut lunar‑lander program. The company is developing a modular technology stack for interoperable refueling and recently opened a French subsidiary. Founded in 2022, deltaVision has been profitable since inception, with backers citing international growth potential.

21 July, 2026

Italian startup ORiS raised €5 million / $5.7 million to advance laser‑based wireless power‑beaming for satellites, including €4.5 million in pre‑seed funding led by Earlybird and Pitchdrive and a €500,000 regional grant. The 15‑person Turin firm has demonstrated ground‑based laser power transfer to drones 100 meters away and plans two in‑orbit tests next year, including a 10‑meter demonstration with Dcubed ahead of a third mission with an unnamed satellite‑hosting customer. ORiS expects to support networks of small spacecraft and is developing LOONA, a terrestrial laser‑power system backed by NATO’s DIANA program. The company also sees long‑term applications for lunar missions facing extended darkness.

21 July, 2026

Orienspace, the Chinese launch company conducted its third Gravity‑1 sea launch on July 21, sending nine satellites to orbit from waters off Shanghai. The 30‑meter vehicle, world's most powerful solid-fuel rocket, capable of lifting 6,500 kilograms to low Earth orbit, conducted its first long‑range sea launch. The payloads included six Dongpo satellites for the Huantian constellation (two optical spacecraft with AI payloads and four SAR satellites for millimeter‑level deformation monitoring) along with Xiguang‑2 (01), Tianyi‑49 and Zidingxiang‑3. Orienspace is preparing its reusable, liquid‑propellant Gravity‑2 for a planned fourth‑quarter debut.

The flight followed early‑July launches of Haiyang‑2E and 38 Qianfan satellites and marked China’s 49th orbital attempt of 2026. A Long March 5 for the Chang’e‑7 lunar south pole mission arrived at Wenchang ahead of an August 23 window.

22 July, 2026

Relativity Space reached an agreement with Space Florida, the official aerospace finance, development, and spaceport authority for the State of Florida, to build new manufacturing, test and launch infrastructure for its Terran R rocket on the Space Coast. The deal includes financing of up to $134 million through Florida’s Spaceport Improvement Program for a production facility near Cape Canaveral and expanded operations at Kennedy Space Center and Cape Canaveral Space Force Station.

Relativity, which will launch Terran R from Launch Complex 16, has not disclosed a factory timeline but says the investment will support scaling for commercial, scientific and national security missions. The move comes amid concerns that rising launch activity could push KSC to capacity by 2029, prompting legislative proposals to enable industry‑funded infrastructure upgrades.

22 July, 2026

Vast, the space stations and spacecraft developer has created a new special programs division to support U.S. national security projects and hired Melanie Stricklan, co‑founder and former chief executive of Slingshot Aerospace, as senior vice president to lead it. The company said the unit will deliver space‑based capabilities for defense and intelligence customers and aligns with its development of high‑power satellite buses announced in May.

Vast has drawn interest from the national security community, including investment from In‑Q‑Tel and a 2023 visit by Space Force Maj. Gen. Stephen Purdy to its Long Beach facilities. Chief executive Max Haot said the company is building in‑house technologies with direct defense applications as it advances commercial station and spacecraft programs.

A new modeling study led by University of California Riverside researcher Michelle Hill found that rocky planets in the habitable zones of sun‑like stars must be at least 0.8 Earth radii to retain an atmosphere for billions of years, narrowing the search for potentially life‑supporting exoplanets. The Smaller Than Earth Habitability Model (STEHM) shows smaller worlds lose gas faster than volcanic activity can replenish it because of weaker gravity, faster interior cooling and reduced outgassing.

Under extreme conditions, such as unusually carbon‑rich mantles, planets as small as 0.6 Earth radii could maintain atmospheres, though such compositions are rare. The study also notes that airless planets might rebuild atmospheres through late comet or asteroid impacts. Future STEHM simulations will examine planets around red dwarfs and tidally heated worlds. The researchers published their work in June in The Planetary Science Journal.

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