HASTE (Hypersonic Accelerator Suborbital Test Electron) is Rocket Lab's active suborbital test vehicle derived from Electron. It retains Electron's carbon-composite structure and Rutherford propulsion but uses a modified third stage, tailored fairings, and up to 700 kg of payload capacity for hypersonic and reentry tests. Rocket Lab's archive lists nine completed HASTE missions through June 2026, five of which remain undisclosed.