Data

Orbits, absolute magnitudes, diameters, albedos and spectral classes come from the NASA/JPL Small-Body Database, retrieved 13 October 2026. The set is every asteroid with a Tholen or SMASSII spectral class (2,174 bodies) plus every main-belt and Mars-crossing asteroid larger than 7 km in diameter, for 20,844 bodies in total. Planets use the JPL approximate Keplerian elements, valid 1800 to 2050.

Motion

Every body moves on a two-body Kepler orbit from its JPL elements at the 2026-06-09 epoch. Planetary perturbations are ignored, so asteroid positions are good to a small fraction of a degree in the 2020s and drift slowly outside that decade. Planet sizes are exaggerated so they stay visible; distances are to scale.

Composition

Classes follow the Bus-DeMeo (SMASSII) taxonomy with Tholen as a fallback: C-complex (B, C, Cb, Cg, Cgh, Ch), S-complex (S, Sa, Sq, Sr, Sk, Sl), X-complex (X, Xc, Xe, Xk; Tholen E, M, P) and the end members. A class is a reflectance spectrum, not an assay. The link to minerals rests on meteorite analogues, and 90 percent of the bodies here have no class at all.

Going and coming back

The estimate used for the colours and the ranking is a two-burn Hohmann transfer each way: escape from a 300 km Earth orbit onto a transfer ellipse, a rendezvous burn at the target's perihelion or aphelion that also absorbs the plane change, the same burn in reverse to leave, and an Earth arrival that is free for a capsule, 0.15 km/s for aerocapture, or a full propulsive capture. A capsule or aerocapture arriving faster than 13.5 km/s brakes first. The stay at the target is whatever the return window demands, with at least the chosen number of days on site. Both bodies are treated as circular for the phasing, so windows repeat once per synodic period. "Earliest return" adds the wait for the next outbound window from the map date.

For a selected target the map then solves Lambert's problem (universal variables, prograde, single revolution) for every departure date over the next four years and every flight time from 60 to 1500 days, keeps the cheapest outbound trip, and repeats the search for the way home starting after the minimum stay. The two legs are chosen one after the other, not jointly. The drawn arcs are integrated two-body motion from the solved velocities.

Value estimate

Value is gross contained value at fixed prices: mass times the recoverable fractions for the body's composition type. Mass is a sphere of the listed diameter at a bulk density typical for the type, 1.4 to 3.6 g/cm³. Fractions come from meteorite analogues: ordinary chondrites for the S-complex (about 10 percent metallic iron, 1.4 percent nickel, 4 ppm precious metals), carbonaceous chondrites for the C-complex (5 to 12 percent bound water, little metal), iron meteorites for M-types (55 percent iron, 4.5 percent nickel, 18 ppm precious metals), and so on for the rarer types.

Prices: iron $0.20/kg, nickel $17/kg, cobalt $30/kg, a precious-metal basket (platinum, palladium, iridium, rhodium, ruthenium, osmium, gold) at $48,000/kg, and water at $2,000/kg delivered to orbit, or $0 on the Earth market. Bodies without a spectral class get a type from albedo alone and are marked as inferred.

Mission planner

Each scenario scores every body with the same model: a craft class sets dry mass, processing rate, return capacity, build cost and yearly cost; sunlight at the target scales the processing rate; the product is water, precious metals, a whole small rock, or a sample; the stay is the longer of the mining time and the return window, with mining capped at three years; xenon for the heliocentric legs and a chemical stage out of low Earth orbit follow the rocket equation; launch cost is the mass in orbit times the price per kilogram. A body is skipped when a leg needs more Δv than a solar-electric stage can deliver in its flight time, about 4 km/s per year. Delivered value is the product mass times its price. Nothing here is a cost estimate anyone should fly on. It is a way to see which parts of the physics and which assumptions decide the answer.

Not yet here

Low-thrust trajectories, gravity assists, propellant made from the asteroid's own water, and what selling the product would do to its price.