LASSO: Lunar Asteroid Salvage by Slower-impact Operation — delivering a co-orbital near-Earth asteroid to the lunar surface by uncontrolled low-velocity impact

Everything we want to build in space is made of iron, and the Moon has almost none of it in usable form. Lunar iron is oxide, chemically bound, and the most efficient plant anyone has modeled needs about 109 kWh to make a kilogram of metal from it. Asteroids carry iron that was already reduced four and a half billion years ago. Every proposal for getting it to the Moon has assumed you must slow the asteroid down: fly out and mine it, or brake it into orbit and park it. Both pay for every meter of the descent.

This preprint proposes the opposite. Don't land it — drop it. Let the asteroid hit the Moon, unbraked, and let the impact do the ore processing. The crater and its debris blanket are the mine.

What makes that work rather than merely destructive is that arrival speed cannot be chosen. A body falling to the Moon from outside the Earth–Moon system cannot arrive slower than 2.42 km/s, a floor set by the Moon's escape velocity, Earth's pull at lunar distance, and the Moon's own orbital motion. At every speed orbital mechanics permits, the pressure at impact is ten to a hundred times more than enough to shatter rock and far short of what melts it. The body breaks apart and stays solid. Fragmentation is not a risk to engineer around; it is the delivery mechanism, and no braking system is required.

Pushing the same calculation upward locates where that stops being true. Rock melts through at 7.4 km/s, and metal holds out past 8.6, which places the floor inside a survivable corridor with a factor of three to spare. The two bounds come from entirely separate physics — three orbital constants on one side, laboratory melting measurements on the other — and neither was chosen with reference to the other.

Kamil crater in southern Egypt is the field calibration. A nine-tonne iron meteorite arriving at or above these speeds left roughly 3,400 kg of recoverable metal fragments in and around a 45 m crater, with microscopic dust accounting for only 1.5–3.5% of the surviving mass. On Earth, whether an iron arrives whole or as a shotgun blast is decided by atmospheric loading. The Moon has no atmosphere, so every lunar impact is necessarily the Kamil mode.

Version 1.1 replaces version 1.0's single-object result with a survey. Screening 14,085 known near-Earth asteroids from 4 m to 3.5 km leaves 4,269 from which the Moon can be reached at all, of which 1,124 arrive below 7.4 km/s carrying 655 million tonnes of material. Fourteen objects have been checked against measured close-approach data and all fourteen arrive cleanly. They span three propulsion regimes: six small objects movable with a propellant load a spacecraft has already flown; two objects near 100 m carrying roughly a million tonnes each that pass so close naturally they need only 2–3 kilowatts; and six larger bodies, up to Ryugu at 450 million tonnes, requiring 0.14 to 3.0 megawatts against a NASA lithium-fed thruster that reached 120 kW in February 2026.

Version 1.0 reported exactly one movable object. That result was an artifact of requiring the nudge to fit a flown spacecraft's propellant tank — a budget test, not a physics test. Removing it, widening the size range, and replacing the velocity criterion with a derived ceiling produces the portfolio above. Version 1.0 also contained an arithmetic error in the filter chain, corrected here; no candidate was lost, but two derived percentages change. Appendix C is the full change log.

The likeliest failure mode is composition. Every small object in an Earth-like orbit for which anyone has obtained a spectrum has turned out to be lunar debris — four out of four. The orbits that make an object reachable are the orbits that material blasted off the Moon naturally falls into, so the selection filter may be, structurally, a filter for the one material the Moon already has. Of the 4,269 reachable objects, five have any composition measurement at all. Metal is the motivating case, not a proven one. Three quantities remain unmeasured throughout and are carried as explicit free parameters: fragment size distribution, composition, and recoverable fraction.

Scale cuts both ways, and the document says so. A 22 m body arriving at 2.5 km/s releases about 8 kilotonnes TNT equivalent, on a body with no atmosphere to carry a blast wave and no radiation of any kind. Ryugu would release 1,008 megatonnes, and the material it throws off the Moon would exceed a natural impact already judged to warrant a satellite-hazard paper by roughly a factor of 500. The near-term tier is unremarkable against what the Moon absorbs naturally; the upper tier is not, and is treated as a governing constraint rather than a footnote. 99942 Apophis satisfies the selection criteria, is named for that reason, and is explicitly declined as a target.

Section 16 states the disclosure in enumerated form, extended from ten items to eighteen. All catalog queries are given verbatim and were run on 15 August 2026. One action is time-critical: 2026 AC4 can be observed from the ground on 14 October 2026 and then not for 29.6 years.

No commercial interest is asserted, and no patent is sought.