Lunar Surface: Where Waste Heat Becomes Feedstock

Every lunar-base architecture hits the same fundamental constraint: ISRU needs a heat source whose cost doesn't break the program.

In orbit, the answer to thermal management is to throw heat away as efficiently as possible, Centradiant's spinning-disk droplet radiator does that at 4.4 kg/kW(th), 6–8× lighter than conventional panel radiators. On the lunar polar surface the answer inverts. Every kilowatt of GPU waste heat at ~90 °C, instead of being rejected to space at near-zero benefit, can drive water-ice extraction from polar regolith. The radiator that is the only sink in orbit becomes the last step in a cascade on the surface, after the heat has already done useful work.

This page documents Centradiant's surface-side application of the same thermal-management thesis: data center as the head of the ISRU cascade.

---

Why Lunar Now?

In February 2026, SpaceX publicly reordered its roadmap: Moon before Mars, a self-growing city in ~10 years, "data centers manufactured on the Moon," an AI satellite factory, first Starship V3 cargo to the lunar surface targeted for 2028. Every credible lunar-base program in the literature, NASA Artemis FSH, ESA Argonaut, CNSA/Roscosmos ILRS, Blue Moon, treats compute as a future luxury and ISRU as an agency-funded science exercise. The Feb 2026 SpaceX plan calls for data centers on the Moon but does not connect them to ISRU heat. This is the missing connection.

---

The Heat Problem on the Surface

The lunar polar surface has both halves of the thermal cascade available in close proximity:

• Peak-of-Near-Eternal-Light ridges at ~85–93% annual illumination (Connecting Ridge near Shackleton crater: 89.44°S, 222.69°E) support continuous solar PV.
• Permanently Shadowed Regions at 40–100 K, immediately adjacent, function as a passive cryogenic sink, for radiator overflow, for water-vapor cold-trap condensation, and for passive LOX storage at ~80 K with near-zero boil-off.

The cascade closes one direction:

1. Solar PV → GPU compute at ~90 °C waste heat
2. Waste heat → thermal bus (pumped fluid loop, Lunar Ice Miner heritage, ICES-2022-130)
3. Thermal bus → ORC turbine (~13% efficiency at 90 °C source / 0 °C polar radiator sink) → offsets array draw
4. Thermal bus → ISRU water plant (~100 kW thermal → ~1.2 t/day H₂O via auger-dryer + cold-trap)
5. Thermal bus → regolith TES + survival heating
6. Remainder → radiator → PSR cold sky

Compute is the funded product. ISRU process heat is the near-zero-marginal-cost byproduct.

---

Why Previous Lunar Architectures Did Not Scale

Existing waste-heat cascades for lunar ISRU all anchor on heat sources whose only product is heat:

• RTG (Lunar Ice Miner, ICES-2022-130; ACT + Honeybee Robotics), radioisotope cost and supply limit scale.
• Fission Surface Power (NASA FSP, 40 kWe target 2030), not flight-ready before ~2030, nuclear launch approvals add a separate regulatory track.
• Solar concentrator (Sowers & Dreyer, New Space 2019), large optical aperture; mechanically complex.
• Generic crew-base equipment, agency-funded, no revenue mechanism.

A heat source funded by independent compute revenue does not appear in the published literature. No credible lunar-base program carries a self-funded surface revenue mechanism. That is the gap this branch addresses.

---

The Inversion

Put a revenue-generating GPU compute facility, 500 kW installed, ~360 commercial-GPU-class accelerators, NVL72-class racks, at the head of the cascade. Compute is the primary, independently financed product. ISRU process heat falls out as a byproduct of heat that would otherwise cost a radiator to discard.

Two consequences follow:

1. Compute revenue funds the mission, rather than waiting for an agency appropriation. Mission-1 standalone does not pay back at the seed scale (~$2–4 B CapEx vs ~$5–10 M/yr Year-1 revenue), but break-even shifts into reach at multi-mission scale: base case ~18–20 missions and ~25 years to cumulative positive ROI; optimistic ~8–10 missions / ~10 years.
2. Waste heat becomes the means of transforming lunar matter into water, propellant, and shielding. The ISRU dividend bends the cost-per-MW curve down with each subsequent mission.

The mineral-rights position established by first operational presence at Connecting Ridge is a separate, larger-than-the-operating-business asset: at $3,000/kg Starship-delivered displacement value, one km³ of polar regolith holds ~$45 T notional in oxygen + metals; the adjacent Shackleton PSR water-ice inventory is ~$1,800 T notional. After a 99% execution-risk haircut, the reachable monetizable subset over 25 years is ~$200–300 B, ~15× cumulative program CapEx, enforceable under Artemis Accords commercial-resource and safety-zone provisions backed by 54 signatories.

---

Built on Proven Heritage

Every rung of the cascade has published precedent. The contribution is the integration around a compute anchor, not invention of the rungs.

Proven physics, mostly-flight-demonstrated components, well-mapped polar siting.

---

The De-Risking Artifact

The whole revenue thesis rests on commercial GPUs surviving the lunar polar radiation environment via ECC + lockstep + watchdog + a 50 cm regolith berm, not rad-hard silicon, which runs 10–100× slower than commercial parts and lags state-of-the-art by ~10 years. If that survival assumption fails, the compute thesis collapses.

cosmo-regulus is the Apache-2.0 open-source library that makes the assumption falsifiable. It anchors its fault model on measured Chang'E-4 LND lunar-surface dose data (13.2 ± 1 µGy(Si)/hr → ~116 mGy(Si)/yr unshielded) rather than CREME96 extrapolation, and produces an economic Pareto curve linking shielding mass × replica count × scrubbing rate → $/M-tokens at iso-quality. A first-cut version of that curve and its underlying numbers is at /lunar/cosmo-regulus.

---

Engagement

This branch is open research. The artifacts to evaluate at whatever depth is useful:

• Full 15-section program plan (700+ lines): linked from the Contact page on request.
• cosmo-regulus open-source repository: github.com/dubthree/cosmo-regulus (Apache-2.0).
• Phase-0 deliverables and engineering analyses: covered in the program plan §12.

Centradiant welcomes partner conversations with satellite operators, launch providers, agency programs, and commercial-compute customers whose interest in surface-based compute infrastructure complements the company's existing orbital thermal work.