Welcome to the Stratosonde development blog - where we document the engineering challenges of building an ultra-lightweight, solar-powered radiosonde for multi-day stratospheric flights.

Why Document Everything?

Building a <15g platform that survives days at -50°C in the stratosphere requires solving problems most embedded systems never face. By documenting design decisions, test results, and failures openly, we:

  • Create a knowledge base for others tackling similar challenges
  • Enable peer review and improvement of our approaches
  • Demonstrate that complex aerospace projects are accessible beyond large institutions
  • Build a community around open atmospheric science

What We’re Building

An autonomous radiosonde weighing less than 15 grams that can:

  • Float at 12-18km altitude for extended periods
  • Harvest solar energy through extreme temperature cycles
  • Detect and adapt to global LoRaWAN regulatory regions automatically
  • Log and transmit atmospheric measurements opportunistically

Validation First

Our first missions focus on proving the platform itself:

  • Do our thermal models predict actual temperatures accurately?
  • Can we sustain operation through full day/night cycles?
  • Do trajectory predictions match real flight paths?
  • Does autonomous region detection work globally?

Only after validating these fundamentals will we focus on atmospheric science objectives.

What to Expect from This Blog

Technical Deep-Dives
Detailed explanations of subsystems: power management, thermal modeling, H3 geospatial indexing, LoRaWAN communication, sensor integration

Design Decisions
Why we chose specific components, architectures, and approaches - including what didn’t work

Test Results
Ground testing data, component characterization, and flight telemetry analysis

Tools & Resources
Interactive calculators, visualization tools, and utilities we’ve built

Progress Updates
Regular status reports on firmware development, hardware iterations, and integration testing

Building on Community Foundation

This work stands on decades of innovation by amateur radio operators and the picoballoon community. They proved ultra-lightweight stratospheric platforms are possible. We’re extending their work with:

  • Autonomous LoRaWAN region detection via embedded H3 geospatial indexing
  • Validated thermal and power models through structured testing
  • Scientific methodology for reproducible measurements
  • Open documentation accessible to newcomers

Get Involved

Follow Development

  • Subscribe to this blog for technical updates
  • Join our Discord for real-time discussion
  • Watch repositories on GitHub

Contribute

  • Review hardware designs and firmware code
  • Test our calculators and share feedback
  • Propose improvements and optimizations
  • Build your own platform and share results

Ask Questions

  • No question is too basic - if something’s unclear, ask
  • Help us improve documentation by pointing out gaps
  • Share your expertise in relevant domains

Coming Posts

Look for upcoming deep-dives on:

  • Power system architecture and solar harvesting optimization
  • H3Lite: Embedded geospatial indexing for region detection
  • Thermal modeling for extreme cold operation
  • Flight trajectory prediction and validation
  • LoRaWAN reception analysis from altitude

Project Resources

  • Landing Page: github.com/stratosonde/.github - Mission overview
  • Documentation: This site - Technical details and progress
  • Interactive Tools: Calculators for balloon design and power budgeting
  • Repositories: All code and hardware designs open source

Thanks for joining us on this journey. Whether you’re here to learn, contribute, or just follow along - welcome aboard.

Let’s see what we can accomplish with 15 grams and open collaboration.