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Hybrid Electronic Radiation Assessor
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Hybrid Electronic Radiation Assessor

Six radiation sensors aboard Orion measuring crew exposure beyond Earth's magnetosphere.

Last refreshed: 2 April 2026

Key Question

What will HERA's radiation data mean for future Mars missions?

Timeline for Hybrid Electronic Radiation Assessor

#57 Apr

Radiation Data Gap Persists at Maximum Distance

Artemis II Moon Mission
#45 Apr

G3 Storm Passes With Zero Crew Dose Data Published

Artemis II Moon Mission
#34 Apr

G3 storm hits crew in deep space

Artemis II Moon Mission
#131 Mar

Activated during X-class solar flare on 31 March and G1 geomagnetic watch

Artemis II Moon Mission: Solar Flare Creates Radiation Risk During Moon Burn Window
View full timeline →
Common Questions
What is HERA on Artemis II?
A suite of six radiation sensors in Orion's cabin measuring crew exposure beyond Earth's magnetosphere in real time.Source: Lowdown briefing analysis
How much radiation do Artemis astronauts receive?
The Artemis II baseline target is approximately 5% of each crew member's career radiation limit, monitored by HERA sensors.Source: Lowdown briefing analysis
Why is Artemis II radiation data important?
It will be the first systematic crewed radiation dataset from deep space in over 50 years, informing shielding for Mars missions.Source: Lowdown briefing analysis

Background

The Hybrid Electronic Radiation Assessor (HERA) is a suite of six radiation sensors distributed throughout Orion's cabin to measure the real-time and cumulative dose received by the Artemis II crew. The mission baseline exposure target is approximately 5% of career radiation limit for each crew member.

HERA is particularly significant because Artemis II flies at solar maximum, when the flux of energetic particles is highest. The sensor data will constitute the first systematic crewed radiation dataset from beyond the magnetosphere in over 50 years, filling a critical gap in deep-space health risk modelling.

Data from HERA feeds directly into NASA flight surgeon assessments and SWPC solar weather correlation studies. It will inform radiation shielding requirements for future Artemis landings and eventually for crewed Mars missions where exposure durations are FAR longer.