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Artemis II Moon Mission
2APR

M7.5 flare fires during crew's transit

2 min read
11:46UTC

A new solar flare at 01:17 UTC on 4 April triggered an R2 radio blackout while the crew coasted at their deepest point from Earth.

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ScienceDeveloping
Key takeaway

Second solar hazard fired during transit; no mainstream outlet reported it.

An M7.5 solar flare fired at 01:17 UTC on 4 April, triggering an R2 Moderate radio blackout 1. No mainstream outlet had covered this flare at the time of publication. Update 2 showed the same gap: the GOES-19 electron flux alert that exceeded 1,000 pfu on 3 April also went unreported. On 4 April the flux alert continued, with a prior-day maximum of 4,465 pfu 2.

Each reading feeds the Michigan forecasting models and SRAG's operational picture, yet none has reached the public. The space weather escalation chain across this mission now runs: X-class flare at launch , G1 watch, G2 storm , G3 peak, M7.5 flare. Each step exceeded the prior severity level.

Deep Analysis

In plain English

Solar flares are explosions on the Sun's surface that fire X-rays and energetic particles outward at light speed. They are classified by intensity: M-class flares are moderately powerful, with M9 the strongest before jumping to the X-class. An M7.5 is a significant event. The R2 radio blackout it triggered affects high-frequency radio communications on the Earth-facing side. For a spacecraft already beyond Earth's magnetosphere, the more relevant concern is whether this flare launched a coronal mass ejection toward the crew. No assessment of that has been published.

Deep Analysis
Root Causes

Media coverage of space weather during crewed missions relies almost entirely on NASA public affairs outputs, which do not include real-time solar event data beyond officially issued statements. NOAA SWPC publishes machine-readable alert feeds but no mainstream science desk monitors them during missions.

The escalation chain from launch day (X-class flare, ID:1896) through the G3 storm to this M7.5 flare spans the mission's first 72 hours without triggering a single mainstream news cycle on space weather, reflecting the absence of specialist space weather correspondents at general news organisations.

What could happen next?
  • Risk

    If the M7.5 flare produced a CME directed toward the crew's return trajectory, a secondary elevated radiation environment may occur before splashdown on 11 April.

  • Consequence

    The gap between NOAA machine-readable alert data and mainstream public reporting creates a permanent information asymmetry on crew safety during deep-space missions.

Sources:NOAA SWPC·NOAA SWPC
Mentions:GOES-19 →Prima →SRAG →Russia →NOAA →
First Reported In

Update #3 · G3 storm hits crew; NASA stays silent

NOAA SWPC· 4 Apr 2026
Read original →
Causes and effects
Caused by
Solar Flare Creates Radiation Risk During Moon Burn Window
The X-class solar flare at launch (ID:1896) initiated the space weather escalation chain that continued with the M7.5 flare at event 1.
Occurred 31 Mar 2026
Read story →
This Event
M7.5 flare fires during crew's transit
Adds a second concurrent solar hazard to the G3 storm already under way. The flare may produce an additional CME; no assessment of that potential has been published.
Different Perspectives
ESA
ESA
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NASA
NASA
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Dual-framework nations
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Boeing / Northrop Grumman
Boeing / Northrop Grumman
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NASA Office of Inspector General
NASA Office of Inspector General
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SpaceX
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