--- title: "Mirrors that change shape — Smart Reflectors" description: "Plain-text version of a concept study (TRL 1–2) of inflatable, steerable thin-film reflectors that concentrate sunlight into heat on the Moon or Mars, after Alder, Lagarde & Cohen, ASCE Earth & Space 2024." canonical: "https://space-smartreflectors.pages.dev/" last_updated: "2026-10-03" --- # Don't launch the hull. Carve it Seven inflatable mirrors focus sunlight on a cliff until the rock spalls away. What is left is a home under 15 m of basalt: the rock holds the air in. Then the same ~10 kg-per-disc array re-focuses to heat, light and grow food. A concept study — numbers are estimates. This is the plain-text version of , a concept study (TRL 1–2) with no hardware and no test data yet. The chapter texts below are copied from the interactive page. ## 00 · Orbit — Mass is the budget. The hull is already there Every kilogram launched is expensive. This habitat never launches its pressure hull: it carves one out of the rock with sunlight. ## 01 · Approach — A basalt butte, near ice The habitat is carved sideways into the cliff, 15 m under rock: that overburden holds 1 bar inside. ## 02 · Reflectors — Seven discs. One blinding point Inflatable Mylar, ~3.8 m each, standing on the sun side; aim and curvature adjust. A secondary mirror sharpens the beam. Heritage: STS-77 (1996) and NASA NIAC TransFormers (Stoica, JPL, 2013–2017). ## 03 · Carving — Heat the skin. The rock gives way At tight focus the surface heats faster than it can conduct away, expands and spalls off in chips — far faster than melting. Defocused, the beam glazes the wall. ## 04 · Interior — The rock is the hull. Nothing to launch 15 m of basalt overhead holds 1 bar inside (concept estimate). An oval window feeds a Mylar wedge that lights ~50 m² of plants per crew member; the rock stores the heat. ## 05 · Departure — The mirrors leave. The home stays The array rolls up — about 10 kg per disc (concept estimate). The hull stays behind, inside the Moon. ## 06 · Mars — Same sun, further out Less than half the sunlight (~590 W/m² above the atmosphere, less through dust) — still enough, focused, to carve the next home. ## Why Smart Reflectors — Most habitats launch their hull. This one carves it Concentrating sunlight isn't new, and neither are shape-changing thin-film reflectors — NASA's TransFormers studies proposed them. This concept builds on that work and applies it to habitat building: one soft, light kit that carves rock, then heats, lights and grows food. - **15 m — hull: the rock.** Carved 15 m into the cliff, the overburden holds 1 bar inside, so no pressure hull is launched. The mirrors still are. - **250 W/kg — heat per kilogram, concept estimate.** A ~10 kg inflatable disc delivers ~2.5 kW of concentrated sun. Concentrated heat, not electricity — a concept estimate, not measured. - **4 jobs — from one kit, one at a time.** Tight focus carves rock. Wide focus warms it, lights the rooms and grows the food. The array switches between them on site. Versus the alternatives (re-aims on site · variable focus · direct heat, no conversion · stows soft, deploys by inflation): rigid concentrator (tracking) — re-aims on site and direct heat; solar PV + electric heater — none; landed excavation rig — re-aims on site only; Smart Reflectors — all four. The table shows typical configurations; variants exist. Concept estimates after Alder, Lagarde & Cohen (ASCE Earth & Space 2024). Figures to be confirmed by the 3–4 m ground demonstrator. ## 07 · Focus calculator Drag one mirror 1°. The beam moves 2°. Seven mirrors aim at a 1 m target; each mirror's pointing error doubles in the reflected beam, then grows with distance to the target. The calculator shows spot drift, beam overlap, focal flux, an idealised equilibrium temperature and the concentration needed for a target temperature, for the Moon or Mars (with Mars dust). ## 08 · Figures — Why pointing, not cosine - Usable sunlight: Moon surface 1361 W/m²; Mars top of atmosphere 586 W/m² (mean); Mars direct beam about 434 W/m² in clear sky (τ 0.3), 216 W/m² dusty (τ 1) and 3.9 W/m² in a dust storm (τ 5). - Spot drift at 100 m: the spot moves L·tan 2ε. At 1° of pointing error the cosine loss is 0.02 %, but the spot is 3.5 m away. This is what the 3–4 m ground demonstrator measures: flux at the focus, pointing accuracy and film ageing. ## Methodology The beam turns by twice the mirror's error. Spot position = L·tan 2ε. Spot size is at least L × the sun's angular diameter. Flux = C × G × ρ × cos(incidence) × share of heat on target. Mars direct beam = G·e^(−τ/cos z). Temperature assumes radiative equilibrium (σT⁴ = α × flux) with no conduction or convection loss, so it is an upper bound, not a thermal-design number. Carving in the concept is driven by exfoliation, not steady heating (Alder, Lagarde & Cohen 2024). 40× is the concept study's baseline, not a measured value. ## Prior work The concept claims no novelty and builds on earlier work: the STS-77 inflatable antenna (1996), NASA NIAC TransFormers (Stoica, JPL: Phase I 2013, Phase II 2015, final report 2017) and optical mining. ## Who and contact A Smart Reflectors concept study by Vincent Alder, Thomas Jean-Renaud Lagarde and Marc M. Cohen. Contact: [sun.smartreflectors.com/contact](https://sun.smartreflectors.com/contact/) · [LinkedIn](https://www.linkedin.com/company/smartreflectors) ## Sources - Alder, V., Lagarde, T. J.-R. & Cohen, M. M. (2024). Inflatable SmartReflectors for Multiple Human Space Exploration Applications. ASCE Earth & Space 2024. [Author preprint](https://spacearchitect.org/pubs/ASCE-2024-InflatableSmartReflectors.pdf) · [ResearchGate](https://www.researchgate.net/publication/380096602_Inflatable_SmartReflectors_for_Multiple_Human_Space_Exploration_Applications)