Satellite blockchain broadcast
Espresso
Espresso is a non-custodial relay for broadcasting blockchain transactions from places the internet does not reach. You sign a transaction offline on an ESP32, beam it over the Iridium satellite network, and a ground station submits the exact signed bytes to the chain — then logs a tamper-evident audit trail on Arkiv.
Sign offline
An ESP32 builds and signs a normal EVM transaction with a key it never exposes — no internet, no cell coverage.
Beam over satellite
The signed bytes are framed and sent up to the Iridium satellite network, then relayed to the chain from anywhere on Earth.
Audit on Arkiv
The ground station submits the exact raw transaction and writes a separate, queryable Arkiv audit entity for every relay.