TESTNETTESTNETGalaxy SIGNAL · Public Whitepaper · Draft v0.1
A blockchain whose "work" is never wasted: every block is a real Breakthrough Listen radio detection, triaged by a live, checkable classifier instead of an arbitrary hashing puzzle.
Galaxy SIGNAL is a blockchain in which mining a block requires doing real, verifiable radio-astronomy data triage — not solving an arbitrary cryptographic puzzle. We call this consensus mechanism Proof-of-Useful-Verification (PoUV).
Every block on the network starts from a real detection ("hit") published by Breakthrough Listen, the largest funded SETI (Search for Extraterrestrial Intelligence) survey. A block can only be closed once that hit clears a classifier trained on the survey's own ON/OFF observation methodology — the same class of decision a real radio-SETI pipeline has to make to separate a genuine candidate signal from terrestrial radio interference (RFI). Only after that verification step does a GPU-resistant proof-of-work hashing layer, SignalX, finish the block.
The result is a network where the electricity spent on consensus is spent doing something that has value independent of the blockchain itself: real triage of public scientific data, at a continuous, incentivized, auditable pace. This document lays out the mechanism, the protocol, the security model, and — deliberately — what it does not claim.
Bitcoin's proof-of-work spends enormous amounts of electricity solving puzzles whose only purpose is securing the network itself — the computation has no value outside of Bitcoin. Distributed-computing citizen-science projects like SETI@home showed, over two decades, that millions of people are willing to donate real processing power to sift through actual telescope data — but with no reward beyond curiosity, which is not a sustainable long-term incentive on its own. SETI@home itself shut down in 2020, largely for that reason.
Galaxy SIGNAL asks a simple question: what if a blockchain's proof-of-work were real scientific work, and whoever did it were actually paid for it? PoUV is the answer — not a discovery claim, but a systems answer: a way to make continuous, incentivized, independently-auditable data triage the actual consensus mechanism of a running network, instead of throwing the electricity away on numbers with no meaning outside the chain.
PoUV replaces a single-step "guess a nonce" puzzle with a two-step gate:
Every node independently re-derives both steps when it receives a new block: it recomputes the verification score from the raw hit data with the same classifier, and it recomputes the hash from the same inputs. Nothing about "usefulness" is taken on trust — it's re-checked the same way the hash itself is.
Every hit on the network comes from a real, publicly published Breakthrough Listen L-band survey — tens of millions of individual radio detections across hundreds of real observed stars, in the standard turboSETI format the project's own pipeline produces. Nothing in the dataset is synthetic or simulated.
The classifier isn't trained on synthetic labels. It's trained the same way the source survey itself separates signal from noise: each observing campaign alternates pointing the telescope ON the target star and OFF it, several times in sequence. A signal seen in an ON scan is labeled interference if the same frequency (within the drift tolerance between scans) also shows up in an OFF scan — proof the source isn't following the telescope, so it can't be coming from the star. If it only appears while pointed ON, it's labeled a genuine candidate. This is exactly the logic real radio-SETI pipelines use before ever reporting something as worth a human's attention.
A Random Forest classifier scores each hit on four real, physically meaningful features: frequency, drift rate, signal-to-noise ratio, and whether the frequency falls in a band already known to be crowded with terrestrial transmitters (air-traffic radar, GPS). The output is a single number from 0 to 1 — the model's confidence that a hit is not interference. Scoring is fully deterministic: the same hit, scored by the same model, produces the same number on every node, every time — a requirement for independent verification to mean anything.
A block can only be mined once a hit's score clears a fixed, network-wide threshold, deliberately set on the selective side: the network is tuned to favor confidence in what gets rewarded over catching every possible candidate.
Which hits are even eligible to be tried for the next block is itself part of the protocol, not left to whatever order a miner happens to read the dataset in. Three rules, all independently re-checked by every node the same way the hash and the score are:
Verification alone doesn't fix a block's timing or cost — that's still the job of proof-of-work hashing. SignalX is Galaxy SIGNAL's own memory-hard hashing VM, designed specifically to keep GPUs from getting an outsized advantage over ordinary CPU hardware, and internally red-teamed against real GPU implementations during development rather than assumed to be GPU-resistant on paper.
| Property | Design |
|---|---|
| Registers | 32 × 64-bit general-purpose |
| Working memory | a rotating 32 MiB table, regenerated every epoch (~45 blocks) from the previous block hash |
| Memory access | roughly even split between register-only and memory-touching instructions, so the cost is real memory bandwidth pressure, not just arithmetic throughput |
| Cryptographic core | real BLAKE2b, used both for memory regeneration and as a mixing instruction inside the VM itself |
| Build targets | native (CPU miners), WebAssembly (browser-based webminer), and a GPU-attack harness used internally for red-teaming — the exact same source, byte-for-byte, across all three |
The register pressure specifically reduces how many parallel threads a GPU streaming multiprocessor can run at once — one of the concrete levers that showed a measurable effect during internal red-teaming. Consistent with the honesty standard set out in section 12, this document does not cite exact GPU-vs-CPU benchmark numbers here: those figures need a fresh, reproducible run before they're fit to publish, and stale numbers are worse than none.
Each block carries: its index, timestamp, the full hit that produced it, the previous block's hash, the verification score, the nonce and resulting hash, the miner's address and signature, the difficulty it was mined at, the fingerprint of the classifier model that scored the hit (section 4.4), and optionally a single transfer.
Every address is derived from an Ed25519 keypair generated locally on the client — the private key never touches the server. An address is SIG followed by a hash of the public key, a one-way derivation: the public key can't be recovered from the address alone. Every block is signed by whoever mined it, and the miner's address is part of what gets signed — a mined block's reward can never be silently reassigned afterward.
A block may carry at most one transfer, which can pay multiple recipients in a single signed transaction. Sequential per-sender nonces prevent replay; a small fixed minimum fee (paid to whoever mines the block the transfer lands in, not to the recipient) discourages spamming the pending-transaction pool.
Every node recomputes difficulty independently from the chain's own history — a block's claimed difficulty is never trusted at face value, which would let a node simply declare an easy difficulty for itself. Galaxy SIGNAL uses a linearly-weighted moving average (LWMA) over a rolling window of recent blocks, a retargeting algorithm chosen specifically because it reacts faster to genuine, sustained swings in network hashrate than a simple trailing average, while still damping short-term noise.
Two of the three rules described in section 4.4 exist specifically to close consensus-level gaps, not just to describe the mechanism: without an unpredictable candidate window, a public dataset and a fixed reading order would let anyone pre-score candidates for future blocks off-network, ahead of time; without the authenticity check, nothing would stop a hand-crafted set of numbers — engineered to clear the classifier but never actually observed — from being accepted as a genuine detection. Both are re-derived and re-checked by every node independently, the same way the hash and the score are, not taken on trust from whoever mined the block.
Nodes refuse to accept a chain reorganization deeper than a fixed checkpoint depth, even if the competing chain is longer and otherwise cryptographically valid. This directly mirrors how established proof-of-work networks have responded to real 51%-style attacks in the wild: limiting how much damage a deep reorg can do, even though it cannot by itself prevent one. Real decentralization — not this mechanism alone — is what actually prevents an attack from becoming possible in the first place (see section 12).
Newly mined block rewards only become spendable after the same checkpoint depth's worth of confirmations — the same maturity model conventional proof-of-work chains use for coinbase rewards. Received transfers, by contrast, are spendable immediately; only freshly minted supply has to mature.
Private keys never leave the client. Native tools encrypt keys locally before storing them; the browser-based webminer generates and holds its key entirely client-side as well, so mining requires no account and no custodial trust in the network operator.
The round 21M cap is a deliberate nod to Bitcoin's own; because reward scales with real verification confidence, blocks only close when the network is actually confident in what it found. The dataset the network currently mines against would realistically settle well under the nominal cap on its own — the cap only becomes the binding constraint if future real survey data is added to keep feeding the network.
A hard cutoff to zero removes the incentive to keep doing verification work at exactly the moment the cap is reached. Rather than a cliff, Galaxy SIGNAL decays the reward smoothly in the final stretch before the cap and then holds a small constant reward forever after — the same principle Monero adopted for its own tail emission, applied here to a reward that is earned by triage work rather than pure hashing.
Instead of halving on a fixed block-count schedule, the reward curve halves each time the network completes a full pass over the source dataset. A "cycle" only ever advances forward, one full pass at a time — it can't be skipped or reversed by any single block.
Every genesis block on this network starts with zero pre-allocated supply — independently verifiable on-chain, since a genesis carrying any inherited balance would show it directly in that block's own record (see section 6). Every SGNL in existence came from a real, mined block; none was minted to a founder or team allocation, and none was sold. The infrastructure this testnet runs on is funded by the project's scientific and technology partners, not by token sales or a pre-allocated founder supply.
A peer-to-peer network of always-on nodes discovers new peers by gossip, each learning about new nodes from the peer lists its own neighbors already expose. A dedicated pool coordinator aggregates hashrate from many individual miners using a PPLNS (Pay-Per-Last-N-Shares) payout model, anchored to when each block was actually found rather than only to the most recent shares at payout time.
Three ways to participate, all client-side key custody:
A whitepaper's numbers go stale the moment they're published. Because every hit's verification score is deterministic and every block is public, Galaxy SIGNAL's actual output can be checked live, at any time, against the real chain — not just cited from a document.
This is deliberate: rather than asking a reader to trust a fixed set of numbers in this document, the intent is that the network's actual, growing body of real verification work is the evidence — and it keeps accumulating whether or not anyone reads this page.
The four pages above are all live, which is exactly the point — but a live page isn't a stable thing to cite: its content changes under the same URL every time a block is mined. /dataset exists to solve that specific problem. Periodically (currently every 100 confirmed blocks, published automatically), the network's confirmed-block record is deposited on Zenodo — a research-data archive operated by CERN and OpenAIRE, the standard place independent and citizen-science work gets a permanent, citable DOI without needing a journal's gatekeeping first.
Each deposit contains three things: the full record of every hit each block triaged (frequency, drift rate, SNR, sky position, and its exact row position in the original Breakthrough Listen survey file), the verification score the classifier assigned it, and the exact classifier model file that produced that score — so any row can be independently re-scored and reproduced by a third party, without needing to trust this project's own infrastructure. Every new snapshot is published as a new version of the same Zenodo record, under one permanent "concept" DOI that always resolves to whichever version is most recent, while every earlier version stays exactly as it was published — a snapshot, once deposited, can never be silently altered afterward. Licensed CC-BY 4.0.
Worth stating plainly, not burying in a footnote.
Galaxy SIGNAL does not claim to have found a technosignature, and it is not trying to. The underlying survey data is public, and the classifier used here is deliberately simpler than the real pipelines the original survey teams run — it is not a substitute for, or a competitor to, that science.
What is novel here is not the astronomy — it's the system: a way to turn continuous, incentivized, independently-auditable triage of real scientific data into the actual consensus work of a blockchain, instead of spending that electricity on numbers that mean nothing outside the chain itself.
Galaxy SIGNAL is a testnet today, and this document describes it as such. Two things worth being direct about:
Both are stated here because a whitepaper that omits known limitations isn't a credible one.