stratoexplorer

StratoExplorer 2.0 / pre-launch (1/4)

mathias

Introduction

StratoExplorer is a privately operated technology demonstration for an edge-of-space flight of a stratospheric balloon probe. High altitude ballooning (HAB) got popular in recent years to send all sorts of electronics gadgets (such as smartphones, action-cams, sat-trackers) to the upper atmosphere – and eventually return and retrieve them safely. In contrast, StratoExplorer project focus is set on:

  • engineering (digital electronics, hardware) of lightweight and robust payload
  • software design and implementation (fault-tolerant, x-architecture, x-language: C++, Py)
  • long-range telemetry and IoT connectivity (multi-sensor, data replication, monitoring)

The project relies on ARM-Cortex M7 (“Teensy 4.1”) and ESP8266-12E micro-controller hardware for probe (“StratoExplorer”) and (mobile) ground station (“StratoExplorerRX”) respectively. Both devices make use of identical, proprietary libraries for task scheduling, data sampling and air-ground communications via 433 MHz LoRa. Moreover, both units are synchronized to GPS-based reference time. Therefore, switching of LoRa spreading factors (data rate and range) and bi-directionality (airborne probe acknowledges up-link messages) are available. For the “human” interface, an InfluxDb + Grafana stack is operated on raspberry-pi hardware: a) a Pi-zero device in a LAN with a smartphone (as: display, WiFi access point, Internet gateway), b) a Pi-4 device with replicated telemetry for “world”-access.

StratoExplorer: architecture diagram

StratoExplorerRX preview:

PyStratoExplorerRX “Cockpit” receiving (test) telemetry data from StratoExplorerRX. This gives an impression of the air-to-ground telemetry data received by the ground station: direct and derived information.

PyStratoExplorerRX cockpit web-interface, showing critical telemetry data and map view of 3 targets: payload, predicted landing site, tracking receiver.

Status & next steps

  • done:
    • Successful integration-testing-I (hw/sw, static non-flight) of StratoExplorer, StratoExplorerRX & PyStratoExplorerRX
  • next:
    • physical mounting of hardware + (long range) telemetry testing
    • integration-testing-II (hw/sw, simulated flight)
    • assembly with balloon + parachute and camera units
    • legal paperwork and flight scheduling
  • expect further pre-launch posts:
    • 2/4: StratoExplorer 2.0: payload details
    • 3/4: (Py)StratoExplorerRX details
    • 4/4: reports from telemetry testing & integration-test-II