# Mru docs

> Reference for Mru's open core, for unattended missions with no repair path: the shrinking-quorum decision crate and its fault-injection demo (Rust, no_std, nine Kani proofs: four on the core, five on the C interface), the Dusk simulator and the Mru 2049 browser flight simulator. The quorum demo ran once in orbit on ESA's OPS-SAT PRETTY satellite (exp4051, 18 Oct 2026); the F´ components have not run on flight hardware. Code under Apache 2.0.

Product pages, use cases and research results are at https://mru.space/llms.txt. Questions: contact@mru.space.

## Start

- [Mru Docs](https://docs.mru.space/index.md): Reference for Mru's open core: the quorum decision crate, the fault-injection demo, the Dusk simulator and Mru 2049. Apache 2.0.

## Concepts

- [Shrinking quorum](https://docs.mru.space/concepts/shrinking-quorum/index.md): Vote on three replicas, compare on two, self-check on one. What Kani proves per tick, what is tested per run, the cost and the command path.
- [Architecture status](https://docs.mru.space/concepts/architecture/index.md): Where each part of Mru's six-layer design stands: what is built, where the code is, and the evidence. Only Layer 1 has code today.
- [Prior art and related work](https://docs.mru.space/concepts/prior-art/index.md): TMR, degradable systems, Byzantine agreement, Space Shuttle redundancy management and deep-space fault protection, and how Mru relates.
- [Qualification path](https://docs.mru.space/concepts/qualification/index.md): What exists for Mru against NPR 7150.2, NASA-STD-8739.8, ECSS-E-ST-40C and ECSS-Q-ST-80C, and what has not started. No compliance claim.

## Core runtime

- [quorum crate API reference](https://docs.mru.space/core/quorum-crate/index.md): API reference for the quorum crate: Policy, Mode, Reply, Outcome, Verdict, decide(), Health. no_std, no allocation, nine Kani proofs.
- [quorum CLI reference](https://docs.mru.space/core/quorum-cli/index.md): Options for the quorum demo: policy, fault injection, resource limits, radiation sensor, logging, and the OPS-SAT package that ran in orbit.
- [F´ components for the shrinking quorum](https://docs.mru.space/core/fprime/index.md): RedundancyManager, HealthRegistry, ReplicaHost and FaultInjector for F´ v4.4.1, the C interface to the core, and how they were verified.
- [Bench results for Layer 1](https://docs.mru.space/core/bench/index.md): The shrinking quorum against fixed TMR on the same injected faults, 300 runs per host: correct and wrong results, GDI, detection latency and limits.

## Simulation

- [Dusk simulator reference](https://docs.mru.space/simulation/dusk/index.md): Run Dusk, the Monte Carlo of redundancy policies: options, the fault model, results and their definitions, sweeps, ground support and limits.

## Lab

- [Mru 2049 browser flight simulator](https://docs.mru.space/lab/2049/index.md): A browser flight simulator on real astronomical data: controls, URL switches, architecture and the Float64 floating-origin coordinate system.

## mru.space

- [Mru, llms.txt](https://mru.space/llms.txt): Products, use cases, research and company.