NASA has outlined its comprehensive strategies to protect astronauts from space weather radiation during the Artemis II mission. This 10-day flight will transport four astronauts beyond Earth's protective magnetic field, with the Orion spacecraft serving as the primary shield. NASA and NOAA will continuously monitor the Sun to provide real-time data for astronaut safety decisions, aiming to minimize radiation exposure risks.
NASA is implementing comprehensive strategies to protect Artemis II astronauts from space weather radiation during their 10-day mission beyond Earth's magnetic field.
Mission Overview and Radiation Concerns
The Artemis II mission is designed to send four astronauts on a lunar flyby, venturing into deep space where they are exposed to radiation sources beyond Earth's magnetosphere. A key objective of the mission involves testing procedures for cabin reconfiguration to enhance radiation shielding.
During the mission, astronauts will face potential exposure to:
- Solar particle events (SPEs): These events, often triggered by solar flares or coronal mass ejections (CMEs), accelerate particles to near light speed, potentially increasing radiation levels inside the Orion spacecraft.
- Earth's Van Allen Radiation Belts: Regions of energetic charged particles trapped by Earth's magnetic field.
- Galactic cosmic rays (GCRs): High-energy radiation originating from outside our solar system.
Prolonged high exposure to radiation can heighten the risk of cancer, other health disorders, and cognitive impairment.
Understanding Space Weather Phenomena
Space weather refers to changing conditions driven by solar wind and eruptions from the Sun. Key phenomena include:
- Solar flares: Powerful eruptions that release significant energy.
- Coronal Mass Ejections (CMEs): Giant clouds of solar particles that burst from the Sun, capable of being hundreds of times the size of Earth.
While both flares and CMEs can impact technology, the primary concern for astronauts is the SPEs they can trigger.
Tracking Solar Activity
The space weather analysis office at NASA’s Goddard Space Flight Center will conduct real-time analysis of solar energetic particles and their triggers, such as flares or CMEs. This team tracks solar eruptions, measuring their size, speed, and potential to generate energetic particles that could intersect Orion's trajectory.
They utilize data from a network of Sun-watching spacecraft:
- NASA’s Interstellar Mapping and Acceleration Probe (IMAP)
- NASA’s Solar Dynamics Observatory
- The ESA/NASA Solar and Heliospheric Observatory (SOHO)
- NOAA’s Geostationary Operational Environmental Satellites-19 (GOES-19)
Additionally, NASA’s Perseverance Mars rover contributes by observing sunspots on the far side of the Sun, offering up to two weeks' advance notice of potential solar flares before these sunspots rotate into Earth’s view.
Crew Exposure Monitoring and Protection Measures
Energetic solar particles spiral along the Sun’s magnetic field lines, scattering as they travel and leading to a gradual rise in radiation levels. This allows analysts time to evaluate the situation.
The Orion spacecraft is equipped with six radiation sensors as part of the Hybrid Electronic Radiation Assessor (HERA) system, which measures dose rates. Artemis II astronauts will also wear personal crew active dosimeters to track their individual radiation exposure.
Should radiation levels increase beyond established thresholds, Orion’s systems will display warnings and sound an alarm. NASA has set two primary dosage level thresholds:
- A caution threshold, prompting increased monitoring and coordination with medical and flight operations teams.
- A higher threshold, which recommends the crew seek shelter.
Radiation shielding in space relies on mass. Astronauts are trained to reconfigure the cabin during an SPE by securing stowed equipment along cabin areas to increase the mass positioned between themselves and incoming particles. Testing this specific procedure within Orion is a key objective of the Artemis II mission.
Other Radiation Sources and Collaborative Efforts
In addition to solar events, astronauts must account for radiation exposure from Earth’s Van Allen Radiation Belts and galactic cosmic rays. The combined baseline exposure from these sources is estimated to be comparable to a one-month stay on the International Space Station, representing approximately 5% of an astronaut’s career radiation limit. Any exposure from solar radiation events would add to this baseline.
Continuous collaboration between NASA Goddard, Johnson Space Center, and NOAA will provide real-time forecasts and data to inform flight control decisions.
The Moon to Mars Space Weather Analysis Office at NASA Goddard continuously assesses solar activity. This analysis is shared with the Space Radiation Analysis Group at NASA’s Johnson Space Center. Forecasts from these groups, combined with data from NOAA’s Space Weather Prediction Center and real-time measurements from Orion, will inform recommendations for the flight control team throughout the mission.