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STELLA-1.1 Technical Details

Instrument Description

STELLA-1.1 (Science and Technology Education for Land/Life Assessment) is a low-cost (~$200) do-it-yourself handheld instrument designed for scientific engagement, inquiry, and discovery. It features a color display screen with touch-response controls and weighs less than 100 grams, making it easily adaptable for drone use.

Core Components

  • Microprocessor: Feather RP2040
  • Data Logger: Adalogger Featherwing with PCF8523 Real Time Clock and SD Card Reader
  • Display: 2.8″ TFT with capacitive touch interface

Sensor Array

STELLA-1.1 includes multiple sensors for comprehensive data collection:

  • VIS Spectral Sensor: AS7262 measuring light intensity at wavelengths 450, 500, 550, 570, 600, 650 nm, each with 40nm FWHM
  • NIR Spectral Sensor: AS7263 measuring near-infrared spectral data at 610nm, 680nm, 730nm, 760nm, 810nm and 860nm, each with 20nm FWHM
  • Thermal Infrared Sensor: MLX90614ESF-BCC for surface temperature measurements
  • Air Temperature Sensor: MCP9808 with accuracy of ±0.25°C
  • Ambient Weather Sensor: BME280 measuring relative humidity (±3%), barometric pressure (±1 hPa), and altitude

Data Collection & Storage

  • Records measurements to a micro SD card (8GB)
  • Each measurement includes time/date stamp (UTC) and batch number
  • Clock accuracy: ±2 seconds per day

Power System

  • Powered by a 2200 mAh lithium-ion battery
  • Optional 400 mAh battery available for drone applications
  • Battery voltage monitoring included

Software

  • Operates on CircuitPython, a beginner-friendly open-source programming language
  • Drag-and-drop programming capability (no coding expertise required)
  • Includes a STELLA dataviewer for real-time data visualization and analysis

Optional Add-ons

  • Cuvette attachment for liquid transmissivity measurements

Applications

  • Spectral measurements of various land cover surfaces
  • Environmental monitoring
  • Educational demonstrations of remote sensing principles
  • Data can be used to calculate reflectance from raw irradiance values

Assembly

STELLA-1.1 requires soldering skills and can be housed in 3D printed parts.