Menu Close

STELLA-AM (Atmosphere Monitor)

Start Building

The STELLA-AM measures and records carbon dioxide concentration, particulate matter in the PM2.5 and PM10 size ranges, barometric pressure, air temperature, humidity, 3-axis magnetic field, and 3-axis acceleration. Data are recorded to a micro-SD card with a time and date stamp in CSV format.

No soldering is required to build the instrument. Components connect with small cables and can be mounted on a piece of cardboard or a paint stirring stick, or enclosed in a 3D-printable housing. All software and 3D geometry files are freely available. The software works automatically with any subset of sensors, making the instrument configurable for different budgets. All components are commercially available, with a complete set costing approximately $180 in 2025 prices.

The STELLA-AM is powered by USB-C and does not require an internal battery, apart from a coin cell to maintain the clock. The housing measures approximately 6x3x1 inches, and the completed instrument weighs 115 g (4 oz).

To build your own STELLA-AM download the STELLA-AM files and follow the build steps.

STELLA Atmosphere Instrument Highlights

green leaf with droplets

“The Golden Pathos Theory” – Single Plant Testing

•
August 23, 2025

Students test common houseplants as space life-support systems using STELLA-Q2 sensors to measure CO2 consumption. …

Lynn Nichols presenting her work with STELLA logo

Preparing Tomorrow’s STEM Workforce: STELLA Technology in Education

•
July 21, 2025

Lynn Nichols now PK-12 Director of Education Technology at Gilman, showcases how NASA's STELLA technology …

Lynn Nichols presenting her work with STELLA logo

Bringing NASA Technology to the Classroom: One Educator’s Mission to Transform STEM Learning

•
July 14, 2025

Lynn Nichols transforms STEM education using NASA's STELLA instrument, bridging 3D printing, robotics & space …

Download STELLA-AM Files

Build Your Own STELLA-AM

STELLA-AM parts
STELLA-AM parts
STELLA-AM 3D prints
STELLA-AM 3D prints
STELLA-AM Atmosphere Monitor instrument parts list
Line QuantityType of partPart NameManufacturerModel NumberPart NumberMaterialColor change at Z mmColor change at Z mmNote:
11Power source requiredUSB-C type power supply and cable[-][-][-][-][-][-]
21Mediamicro SD card: 8GB or greaterSanDisk or Kingston[-][-][-][-][-]
31ElectronicsmicrocontrollerAdafruit IndustriesAdalogger RP20405980[-][-][-]
41Electronicsbaro/temp/humidity sensorAdafruit IndustriesBME2802652[-][-][-]The instrument will work without this sensor but will be missing the relevant data.
51ElectronicsCO2 sensorAdafruit IndustriesSCD-415190[-][-][-]SCD-41 is higher accuracy than SCD-40 which is $5 cheaper. Both will work.
61Electronicsparticulates sensorAdafruit IndustriesPMSA003I4632[-][-][-]The instrument will work without this sensor but will be missing the relevant data.
71Electronicsreal time clock moduleAdafruit IndustriesPCF85235189[-][-][-]
81Electronicsmagnetometer accelerometer sensorAdafruit IndustriesLSM303AGR4413[-][-][-]The instrument will work without this sensor but will be missing the relevant data.
91Electronicsdisplay, OLEDAdafruit Industries1.12” 128x1285297[-][-][-]
101Electronicsbutton module, redSparkFun ElectronicsBOB—15932BOB—15933[-][-][-]
112WiringQwiic/ QT cable 100mmAdafruit or SparkFunQwiic JST SH 4 pin 100 mm4210 or PRT-14427[-][-][-]
125WiringQwiic/ QT cable 50mmAdafruit or SparkFunQwiic JST SH 4 pin 50 mm4399 or PRT-14426[-][-][-]
1313D printAM top housing[-][-]PLA0.81.6Use file orientation to print.
1413D printAM bottom housing[-][-]PLA1.4[-]Use file orientation to print.
1513D printA. baro CO2 retainer[-][-]PLA[-][-]Use file orientation to print.
1613D printC. clock retainer[-][-]PLA[-][-]Use file orientation to print.
1713D printD. processor retainer[-][-]PLA[-][-]Use file orientation to print.
1813D printE. mag accel retainer[-][-]PLA[-][-]Use file orientation to print.
1913D printF. button retainer[-][-]PLA[-][-]Use file orientation to print.
2013D printG. screen holder[-][-]PLA[-][-]Use file orientation to print.
2113D printlamp optic cc[-][-]clear PLA[-][-]Use file orientation to print.
2213D printwall mount: optional [-][-]PLA[-][-]Use file orientation to print.
2313D printbattery holder: optional[-][-]PLA[-][-]Use file orientation to print.
1BatteryBatteryAdafruitCR1220380[-][-][-]Put in RTC
241Battery: NOT FOR FLIGHTBattery: optionalAdafruit IndustriesBattery 3.7 V 500 mAh1578Lithium Ion Polymer[-][-]do not use primary (alkaline) batteries
Spreadsheet version:20250423parts cost as of 2025 April

Step 1: Connect Components for Initial Testing

Connect the sensors in this order using the small cables:

  1. Microprocessor → Time Clock – insert CR1220 battery
  2. Time Clock → Button
  3. Button → Display

Large cables:

  1. Display → Magnetometer
  2. Magnetometer → Particulates

Small cables:

  1. Particulates → CO2
  2. CO2 → Barometer 

Step 2: Install CircuitPython

  1. Hold down the BOOT button on the RP2040 microprocessor while connecting it to your computer via USB-C
  2. The device will appear as an RP1-RP2 drive
  3. Drag and drop the UF2 file onto the drive (replace any existing files)
  4. The device will reboot and appear as CircuitPy drive 
  5.  
microprocessor boot button

Step 3: Install Software Libraries

  1. Once the CircuitPy drive appears, drag and drop the code.py and lib folder onto the drive
  2. Go to your test codes folder and drag the code.py file for the clock onto the drive 

Step 4: Set the Real-Time Clock

  1. Navigate to time.is/UTC to check the current UTC time
  2. Open your code editor and open the serial monitor
  3. Set the time in UTC format
    • Tip: Add 5-10 seconds to the current time to account for saving delays
  4. Save the time settings and verify it saved correctly
  5. Check the time multiple times to ensure accuracy

Step 5: Install Main Operating Code

  1. From your code and libraries folder, drag code.py into the CircuitPy drive
  2. Make sure to overwrite any other code that was previously there
  3. The STELLA-AM should boot up and the screen should display data
  4. Test to ensure everything lights up properly 

Step 7: Install the Time Clock (Most Difficult Component)

  1. Locate the retainer marked for the clock (retainers have letters marking their positions)
  2. Clean up the retaining bar with an exacto knife if needed for proper fit
  3. Slide the time clock into its retainer
  4. Make sure it fits snugly but don’t push too hard
  5. The bar should slide in easily once properly cleaned
  6. Trim any rough edges if necessary 

Step 8: Install Microprocessor

  1. Flip the housing with the long side down
  2. Insert the microprocessor into its designated retainer
  3. Ensure it sits nice and snug (no need to push down too hard) 

Step 9: Install Particulate Sensor

  1. Slide the particulate sensor under its retainer
  2. Snap it into place
  3. The particulate sensor helps hold the time clock bar in position 

Step 10: Install CO2 Sensor

  1. Curl the wire slightly for better wire management
  2. Insert the CO2 sensor into its retainer
  3. Tuck it right in next to the barometer position 

Step 11: Install Barometer

  1. Place the barometer in its retainer next to the CO2 sensor
  2. They should sit side by side
  3. Get the retaining clip and install it from side to side
  4. The clip holds both the CO2 and barometer sensors in place
  5. Give it a little nudge to ensure both are held securely 

Step 12: Install Magnetometer

  1. The magnetometer has its own dedicated clip
  2. Pop the magnetometer into its retainer with the clip 

Step 13: Install Button

  1. Make sure the button orientation is correct before installing
  2. Place the button in its retainer
  3. Clip the button down with its retaining clip 

Step 14: Wire Management and Screen Installation

Note: Wire length can be an issue. You may need to rearrange wires for proper fit.

  1. If needed, pull out the particulate sensor temporarily
  2. Rearrange wires to get more length for the screen connection
  3. Reinstall the particulate sensor and button
  4. Wrap and organize the wires neatly
  5. Ensure the screen has adequate wire length and clearance 

Step 15: Install the Display Screen

  1. Insert the screen into the top lid/housing
  2. Slide the retaining door down to secure it
  3. Verify everything fits properly
  4. Tuck the wires back into the housing
  5. Check that all components are properly positioned 

Step 16: Close the Housing

  1. Verify all wires are properly tucked in
  2. Snap the top and bottom housings together
  3. Ensure all clips engage properly 

Step 17: Install the Translucent Window

  1. Place the 3D printed translucent lamp window into position
  2. This allows you to see indicator lights while protecting the components 
Completed STELLA-AM instrument

Step 18: Final Boot and Testing

  1. Connect the USB-C power cable
  2. The instrument should boot up automatically
  3. Verify the screen displays data properly
  4. Check that all sensors are reporting values
  5. Confirm data is being recorded to the micro-SD card

Congratulations! You’ve successfully built a STELLA-AM!

Troubleshooting Tips

  • Wire length issues: Rearrange wire connections or carefully extend wire routing
  • Tight 3D print fits: Use an exacto knife to clean up edges and support material
  • Screen clearance: Adjust wire positioning and ensure proper seating in the top housing
  • Component retention: Ensure all clips are properly engaged and retainers are clean

Important Notes

  • The instrument is modular – you can use any subset of sensors if working with a limited budget
  • All components are commercially available
  • Power: USB-C (no internal battery except coin cell for clock)
  • Data format: CSV files with time/date stamps on micro-SD card
  • Housing dimensions: approximately 6″ x 3″ x 1″
  • Total weight: 115g (4 oz)