L2-RAD-MON ESSENTIAL ENVIRONMENTAL Level 2 · hardware

Radiation Monitoring System

Radiation Environment Monitoring and Dosimetry Subsystem

The Radiation Environment Monitoring and Dosimetry Subsystem is a distributed network of active silicon dosimeters, scintillators, and passive thermoluminescent detectors deployed across at least ten settlement locations. It measures instantaneous dose rates from 0.01 to 100,000 µSv/h and tracks cumulative exposure across a 100-year operational lifetime. Operating without a protective magnetosphere, the system uses active detectors sampling at 1 Hz or higher to detect solar particle events within 60 seconds, autonomously triggering protective shielding responses. The hardware must endure full lunar thermal cycles and function without crew presence, employing radiation-hardened electronics to identify shielding degradation over time.

Distributed network of radiation sensors including dosimeters and particle detectors providing real-time dose rate measurement, cumulative dose tracking, and SPE early warning for autonomous shielding response.

Purpose

Provide continuous characterization of the radiation environment both outside and inside all shielding layers, enabling verification of shielding performance, cumulative dose tracking for payload lifetime management, and triggering of autonomous protective responses during solar particle events.

Context

Radiation monitoring is the sensory component of the shielding system. It feeds data to the CDH system for logging and alerting, provides the trigger for storm shelter activation during SPEs, and enables long-term trending to detect shielding degradation or unexpected radiation environment changes over the 100-year mission.

Principles

▸Radiation monitoring requires both instantaneous dose rate and cumulative dose measurement
▸Different detector types are needed for different particle species: charged particles, neutrons, gamma rays
▸Passive dosimeters (TLDs, OSLDs) provide cumulative dose without power but require periodic readout
▸Active detectors (silicon diodes, scintillators) provide real-time data but require continuous power
▸SPE detection requires rapid response time to trigger protective actions within minutes

Typical implementations

▸Silicon solid-state dosimeters for real-time dose rate monitoring
▸Thermoluminescent dosimeters (TLDs) for passive cumulative dose
▸Scintillator-based particle detectors for spectral characterization
▸Neutron rem counters or bubble detectors for neutron dose
▸RADFET (radiation-sensitive FET) devices for integrated dose
▸Distributed sensor network with exterior, wall, and interior measurement points

Lunar considerations

▸Sensors must operate across full lunar thermal cycle or be thermally protected
▸100-year operation requires radiation-hard sensor electronics or periodic replacement
▸Autonomous operation essential since no crew is present for manual readout
▸SPE warning may come from external sources (DSN, solar observatories) or local particle detection
▸Sensor calibration drift over decades must be managed through redundancy and cross-calibration

Specifications

Functional

primary function	Continuously monitor radiation environment at multiple locations, track cumulative dose, and provide SPE alerts for autonomous protective response
inputs	Ambient radiation field at each sensor location, External SPE warning data from L1-COM (if available), Calibration data and sensor health status
outputs	Real-time dose rate data at all monitored locations, Cumulative dose trending and projection, SPE onset detection and alert signals, Radiation environment characterization data for science return, Shielding performance verification data
dose rate measurement range uSv per hr	0.01, 100000
dose rate accuracy percent	10
cumulative dose accuracy percent	5
spe detection time seconds	<60
spatial coverage locations	>=10
data sampling rate Hz	>=1 for active detectors
sensor operational lifetime years	>=20 with replacement

Physical

materials	Silicon diode detectors, Scintillator crystals (CsI, BGO), TLD chips (LiF:Mg,Ti), RADFET devices, Neutron-sensitive materials (Li-6, He-3 tubes), Radiation-hardened readout electronics
temperature range c	-173, 127
vacuum	True
radiation exposure	True
some sensors external	True

Operational

thermal range c	-40, 60
lifetime years	100

Interfaces

Provides

→Command & Data Handlingdatacritical
Real-time dose rate telemetry, cumulative dose data, and SPE alert signals for autonomous response
→Radiation Vaultdatacritical
Interior vault dose measurements for shielding verification and storm shelter activation trigger
→Communicationsdatadesirable
Radiation environment science data for downlink and mission status reporting

Requires

←Power Generation Systempowercritical
Continuous electrical power for active detector operation and data processing
←Command & Data Handlingdatacritical
Data bus interface for sensor data collection, processing, and storage
←Robotic Operationsmechanicalessential
Robotic capability for sensor replacement and passive dosimeter retrieval over mission lifetime