5APR

Solar Region 4409 Carries X-Class Flare Risk Through Flyby

1 min read

16:13UTC

NOAA forecasts a one-in-five daily chance of an X-class flare from the Sun's most active region during the crew's closest lunar approach.

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Key takeaway

A one-in-five daily X-class flare chance persists through the flyby window.

NOAA's Space Weather Prediction Centre forecast a 20% daily probability of an X-class flare from solar Region 4409 through the flyby period on 6 April. The region also carries a 55% chance of M-class flares daily. ¹

The probability is moderate, not high. A major flare during closest lunar approach cannot be excluded, but it is not the forecast expectation. The G3 storm that peaked on Day 3 to 4 originated from a different solar event. Region 4409 is an independent source of risk. If an X-class flare fires during the flyby, the crew will be at their most distant point from Earth, behind the Moon, and in a 40-minute communications blackout. Radiation shelter protocols exist aboard Orion but have not been activated during the mission.

The crew has already transited through the mission's worst space weather. Day 5 conditions are quiet, with a maximum Kp of 3.67. The residual risk from 4409 is statistical, not imminent, but it persists through the highest-consequence phase of the flight.

Deep Analysis

In plain English

The Sun's surface is not uniform. It has active regions where magnetic field lines become tangled and can snap, releasing enormous bursts of energy. Region 4409 is one of these active areas right now. An X-class flare is the most powerful category. NOAA forecasts a 20% chance of one firing from Region 4409 each day through the flyby. That is roughly the same probability as rolling a specific number on a five-sided die. It is not likely to happen today, but it is not unlikely either, and the consequences at closest lunar approach would be at their worst: the crew will be far from Earth, behind the Moon, and unable to communicate for 40 minutes.

Deep Analysis

Root Causes

Region 4409's elevated activity is a product of Solar Cycle 25, which reached its predicted maximum in late 2025 and is currently in a high-activity plateau. Solar maximum periods historically produce the highest X-class flare rates and the largest coronal mass ejections.

The G3 storm that peaked on Days 3-4 originated from a separate solar event, not Region 4409. Two independent active regions producing elevated space weather simultaneously is a feature of solar maximum conditions, not a coincidence.

What could happen next?

Risk
A 20% daily X-class flare probability from Region 4409 through the flyby period represents a meaningful and uncontrollable hazard at the mission's most exposed phase.

Sources:NOAA SWPC·NOAA SWPC

Mentions:Region 4409 →NOAA →Orion →

First Reported In

Update #4 · Day 5: Lunar Gravity Reclaims Humans for the First Time Since 1972

NOAA SWPC· 5 Apr 2026

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Causes and effects

Caused by

Solar Flare Creates Radiation Risk During Moon Burn Window

The X-class flare at launch began the solar weather escalation chain that includes Region 4409's ongoing flyby-period flare risk.

Occurred 31 Mar 2026

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This Event

Solar Region 4409 Carries X-Class Flare Risk Through Flyby

Region 4409 is the primary uncontrollable variable for the flyby; a major flare at closest approach would test radiation protocols at the mission's most exposed point.

Different Perspectives

ESA

The European Service Module has operated without anomaly for five consecutive days, with the OMS-E engine's translunar injection precision directly responsible for eliminating both correction burns. ESA's hardware contribution is the mission's highest-performing subsystem.

NASA

NASA cancelled a second consecutive outbound correction burn and confirmed Orion in lunar gravitational dominance, while declining to publish any crew radiation dose data through a complete G3 storm cycle. Bipartisan congressional rejection of its $18.8 billion FY2027 budget proposal means the agency faces a political fight even as its spacecraft performs above expectations.

Dual-framework nations

Signing both the Artemis Accords and the ILRS framework is rational hedging, not defection; smaller nations maximise access without exclusive commitment. Lunar governance is genuinely multipolar, and the US coalition count of 61 overstates exclusivity.

Boeing / Northrop Grumman

SLS component production spans more than 40 US states, giving the industrial base strong political protection regardless of commercial alternatives. Congressional mandates guarantee contracts through FY2029, insulating the supply chain from technical programme changes.

NASA Office of Inspector General

The IRB heat shield findings should have been published before launch. The Starship HLS is two years behind schedule with a worsening manual control dispute. NASA has no crew rescue capability for lunar surface operations. The programme is proceeding with documented, unresolved risks.

SpaceX

Starship HLS development is ongoing. SpaceX disputes the characterisation of the manual crew control requirement as unresolved, maintaining its autonomous landing architecture meets mission safety objectives. The company has not publicly responded to the OIG's worsening-trend characterisation.