4APR

M7.5 flare fires during crew's transit

2 min read

15:01UTC

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 blackout⁠¹. 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 pfu⁠².

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, ) 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.

Source Landscape

This story draws on neutral-leaning sources

Primary parallel: The 4 August 1972 proton storm (part of the broader August 1972 solar particle event) was preceded by a series of M and X-class flares across several days initiated a similar chain. The multi-flare sequence before the main event is a recognised pattern; this M7.5 following the G3 storm fits a familiar escalation shape.

Counter-parallel: The 10 September 2017 X8.2 flare, the second-largest of Solar Cycle 24, produced a significant radio blackout but a CME that was directed off-centre from Earth, causing less geomagnetic impact than the flare intensity alone suggested. Flare magnitude does not reliably predict CME impact direction.

Consensus view: The Space Weather Prediction Centre at NOAA classifies M7.5 flares as having a moderate probability of producing an associated CME, though CME generation is not guaranteed and depends on the active region's magnetic geometry.

Counter-view: The Russian Hydromet Space Weather Lab (operated from the Institute of Applied Geophysics) notes that western solar active regions, from which this flare originated at N04W04, have a higher CME propagation rate toward the Earth-Moon system than eastern or central regions, raising the probability estimate.

Key tension: Whether the M7.5 flare generated a CME directed toward the crew during their deepest translunar transit phase remains unassessed in public reporting.

Sources:NOAA SWPC·NOAA SWPC

Mentions:SRAG →Russia →NOAA →GOES-19 →M7.5 solar flare →

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

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.

JAXA

JAXA is an Artemis Accords signatory with the Lunar Cruiser rover planned for south-pole surface operations; Chang'e 7's first-arrival timeline compresses the window those surface systems were designed to operate in alongside American crew.

Space Research Institute RAS / Roscosmos

The LILEM instrument on Chang'e 7 gives Russia science-cooperation presence at Shackleton's rim with no independent crewed lunar capability on a public timeline. This is Roscosmos's only confirmed path to south-pole science in the current decade.

CNSA / China Manned Space Agency

Chang'e 7 at Wenchang confirmed a second-half 2026 launch for Shackleton rim, 18 to 24 months before any American crewed arrival. The mission carries a Russian LILEM instrument, giving Roscosmos a south-pole science foothold inside China's programme.

Jeremy Hansen / Canadian Space Agency

Hansen appeared at the 16 April JSC press conference in his only public moment since splashdown. Canada's Canadarm3 remains without a confirmed deployment host after Gateway cancellation, with CSA maintaining institutional silence on the programme's status.