STELLA-AA1
STELLA-1.2 Air Analyzer (AA1) module
The STELLA-1.2 AA (Air Analyzer) is a portable, low-cost, self-assembled air quality monitoring module developed as part of the NASA STELLA instrument family. It simultaneously senses and records humidity, air temperature, barometric pressure, CO₂ concentration, methane, and airborne particulates using five sensors: the BME280, MCP9808, SCD-40, MQ-4, and PMSA003I. All sensor data are timestamped and recorded to a micro-SD card in a standard .CSV format for easy analysis.
The STELLA-1.2 AA is fully modular and swappable — the instrument operates even if individual sensors are not present, allowing builders to reduce cost by excluding sensors they don’t need. The Air Analyzer module can also be exchanged with other STELLA-1.2 sensor modules on the same base platform, making the overall instrument adaptable to a wide range of monitoring applications.
Important for beta users: The official STELLA-1.2 requires new housing and is not compatible with beta sensor modules. A conversion video guides beta testers through rewiring for the new platform.
STELLA-1.2 Highlights
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STELLA-AA1 Module Build Steps
Commercial Off The Shelf (COTS) Parts
| STELLA-1.2 Air Analyzer parts list | ||||
|---|---|---|---|---|
| Line | Description | Quantity each | Manufacturer/ Vendor | Manufacturer PN |
| 1 | PMSA003I air quality particulates sensor | 1 | Adafruit | 4632 |
| 2 | methane sensor | 1 | SparkFun | SEN--09404 |
| 3 | methane sensor adapter board | 1 | SparkFun | BOB--08891 |
| 4 | 4.7kΩ resistor | 1 | Digikey | RNMF14FTC4K70 |
| 5 | 100kΩ resistor | 2 | Digikey | 13-CFR-12JR-52-1KCT-ND |
| 6 | Permaproto board, half size | 1 | Adafruit | 1609 |
| 7 | Qwiic cable 50mm | 1 | Adafruit | 4210 |
| 8 | MCP9808 precision air temperature sensor | 1 | Adafruit | 5027 |
| 9 | SCD-40 CO2 sensor | 1 | Adafruit | 5187 |
3D Parts
| Line | Description | Quantity |
|---|---|---|
| 1 | Main Housing | 1 |
| 2 | End Cap | 1 |
| 3 | Particulate Spacer | 1 |
| 4 | Sensor Clamp | 1 |
| STELLA-1.2 Air Analyzer 1 module build procedure — updated 3-21-2026 | ||||||||
|---|---|---|---|---|---|---|---|---|
| Line | Description | Function | MC pin | Front/ Rear | Location 1 | Location 2 | color/ note | Notes |
| 1 | 3D print | spacer | - | - | - | particulate sensor spacer | ||
| 2 | cut traces | bus traces | Rear | 30 AB, BC, CD | cut traces with a sharp knife, remove segment | test continuity | ||
| 3 | cut traces | analog traces | Rear | 30 Hi, iJ | cut traces with a sharp knife, remove segment | test continuity | ||
| 4 | magnet coupler 4 pos | 4 pin, pin face | Front | A30, B30,C30, D30 | [x] | use alignment fixture | don’t solder before wire placement | |
| 5 | magnet coupler 3 pos | 3 pin, pin face | Front | H30, i30, J30 | [x] | use alignment fixture | don’t solder before wire placement | |
| 6 | bus coupler wires | GND | Front | B30 | GND (-) below A30 | GND | ||
| 7 | bus coupler wires | 3V | Front | A30 | 3V (+) below A30 | +3.3V | ||
| 8 | bus coupler wires | I2C_SCL | Front | C30 | SCL (-) above J30 | i2c Serial | ||
| 9 | bus coupler wires | I2C_SDA | Front | D30 | SDA (+) above J30 | i2c Serial Data | ||
| 10 | bus coupler wires | 5V power | Front | J30 | J8, solder after particulate sensor put in | 5V | leave plenty of slack in wire to go over particulate sensor, don't solder until resistor put in | |
| 11 | bus coupler wires | 5V power | Front | H8 | H9 | 5V | ||
| 12 | bus coupler wires | Analog input 1 | Front | H30 | D12, solder after particulate sensor put in | Analog input 1 | leave plenty of slack in wire to go over particulate sensor | |
| 13 | bus coupler wires | GND | Front | GND (-) below A8 | A8 | GND | ||
| 14 | install resistor | 4.7kΩ resistor (not polarized) | Front | GND (-) below A9 | C9 | yellow-violet-red-gold, enable pull-down | ||
| 15 | install resistor | 100kΩ resistor (not polarized) | Front | E9 | E12 | brown-black-yellow-gold, divider high | ||
| 16 | install resistor | 100kΩ resistor (not polarized) | Front | C12 | GND (-) below A12 | brown-black-yellow-gold, divider high | ||
| 17 | Header Pins | Header Pins | Front | G3-G7 | ||||
| 18 | bus coupler wires | GND | Front | H5 | GND (-) below A3 | GND | Leave some slack to go around header pins towrds 1 | |
| 19 | bus coupler wires | 3V | Front | H7 | 3V (+) below A2 | +3.3V | ||
| 20 | bus coupler wires | I2C_SCL | Front | J4 | SCL (-) above J4 | i2c Serial Clock | ||
| 21 | bus coupler wires | I2C_SDA | Front | J3 | SDA (+) above J3 | i2c Serial Data | ||
| 22 | Adapter Board/ Header Pins | Header Pins | Front | GND | B1 | Solder Header pins to adapter board first, sticking out of sides with labels | ||
| 23 | Adapter Board/ Header Pins | Header Pins | Front | GND-B1 | H1-A1 | |||
| 24 | Methane Sensor | Install Methane Sensor to Adapter creating methane breakout | Rear | [-] | [-] | |||
| 25 | Methane Breakout | Rear | D8,D9 | G8, G9 | Adapter GND to D8, Adapter B1 to D9, Adapter H1 to G8, Adapter A1 to G9 | |||
| 26 | install CO2 Breakout | install CO2 breakout | Front | G3-G7 | after soldering connect a qwiic cable from 10 facing position | |||
| 27 | install Particulate sensor | install Particulate sensor, use spacer | Front | GND (-) below A13,A29 | GND (+) above J13, J29 | connect qwiic connect from C02 breakout, install another qwiic connect cable, 1 wire approx 110mm to hold down pariculate sensor (over blue), 1 wire approx 70mm | ||
| 28 | install Temperature sensor | install Temperature sensor, qwiic connect from Particulate sensor | ||||||