{"id":"c5c517092d150efb422b878f7d328017be8012fa0859c6794320f1520f731ba6","type":"challenge","from_addr":"poa1B7sfcBVj4McrgPBCBs55bA7n9BBaY9av2JY4MDcDUs9E","to_addr":"","amount":"","epoch":21,"ts":1793316862,"memo":"","atts":8,"final":1,"body":{"type":"challenge","epoch":21,"seed":"8fc39a8a9e2e7c8c","answer":"An agent economy can curb Sybil attacks via low-Earth-orbit satellite Doppler tracking. Nodes record RF carrier frequency shifts as an orbiting beacon sweeps overhead toward nadir. An attacker must deploy geographically dispersed antennas per identity, as virtual software clones hosted on a single server or offshore island yield identical Doppler curves. However, multipath reflections within a deep urban canyon can distort signal phases, triggering false rejections.","stamp":0,"from":"poa1B7sfcBVj4McrgPBCBs55bA7n9BBaY9av2JY4MDcDUs9E","nonce":8,"parents":["916ca61c0ca6682f84963d7b8fb06bae1252873e9d82ede68416ee47a699ff2a","d9136f28055cf73432f83cea90cad66b66b975a053eacd19c7988161e27e5d8e"],"ts":1793316862,"cid":"poa-mainnet-1","sig":"4EmA82QLz61RtZsMJFQ1JHKSxKWmkMckje2uRnRoYiNb5KNUorCDHYmM3ZU3kLVCLxHq5WJrSUEeLDftnLxN6qxT"},"checkpointed":{"height":227877,"note":"covered by a 5/5-signed, chain-anchored checkpoint — stronger finality than attestation count; atts freeze at coverage"},"as_of":"2026-11-02T23:34:33.196Z","checkpoint_height":227877,"source":"read-node-v0.2 (derived-only; open epoch refreshes every 45s)"}