Scientists have used a rapid solar-flare alert system to launch NASA sounding rockets while flares were still active, overcoming a timing problem that has challenged solar researchers for decades. Sounding rockets spend only about five minutes above the atmosphere, while many flares brighten and fade just as quickly. The new system combines X-ray and ultraviolet observations to locate a flare and estimate how long it will last within minutes of detection. It guided two successful rocket launches in April 2024 and an enhanced campaign in May 2026, when the FOXSI-5 instrument observed three small flares. The method was described in a peer-reviewed Astrophysical Journal paper published on 4 November 2026. It is a forecasting tool for research launches, not yet a complete operational warning system for every solar storm.
Key takeaways
- Sounding rockets have only a few minutes to observe the Sun above most of Earth’s atmosphere.
- The alert system rapidly identifies a flare’s position and estimates its remaining lifetime.
- It supported successful flare observations in 2024 and 2026.
- FOXSI-5 observed three small flares after launching from Alaska on 14 May 2026.
- The method could support future observatories and space-weather forecasting, but development continues.
What is a solar flare?
A solar flare is a rapid release of energy from a magnetically active region of the Sun. Magnetic fields rearrange through a process called magnetic reconnection, heating plasma and accelerating particles. Flares produce radiation across the electromagnetic spectrum, including radio waves, visible light, ultraviolet and X-rays.
Flares are related to, but distinct from, coronal mass ejections. A flare is a burst of radiation; a coronal mass ejection launches a vast cloud of magnetised plasma. Earth Site’s guide to solar flares, coronal mass ejections and space weather explains why the terms should not be used interchangeably.
Energetic solar activity can disturb radio communication, satellite operation and navigation. It can also increase radiation exposure for spacecraft and astronauts.
Why use a sounding rocket?
A sounding rocket carries instruments on a short suborbital flight. It rises above the atmosphere, collects data and returns to Earth without entering orbit. Such missions are generally faster and less expensive to develop than satellites, making them useful for testing new instruments.
Earth’s atmosphere absorbs much of the Sun’s X-ray and extreme-ultraviolet radiation. That protection is valuable for life, but it prevents ground telescopes from measuring important flare emissions. A rocket can briefly lift detectors above the absorbing layers.
The weakness is time. A sounding rocket may provide only about five minutes of useful observing. If launched too early, the flare may not have started; if launched too late, the event may have faded before the instrument reaches altitude.
How the rapid alert system works
The system analyses observations from NASA’s Solar Dynamics Observatory, NOAA’s Geostationary Operational Environmental Satellites and ground-based observatories. It looks at X-ray and ultraviolet emission from magnetically complex active regions.
Within minutes, software estimates the flare’s position and likely duration. A rocket team can then judge whether the event should remain active through launch preparation and ascent. The system does not predict all flares days in advance. It detects an event that has begun and makes a short-term estimate of its development.
This distinction matters. “Alert” can sound like a general public-warning service, but the published application is a decision aid for time-critical scientific observations.
The 2024 and 2026 launches
Two rockets in April 2024
The initial system helped teams coordinate two sounding-rocket launches from Poker Flat Research Range near Fairbanks, Alaska. Both reached observing altitude while a flare was still active, demonstrating that rapid analysis could improve the odds of a successful campaign.
FOXSI-5 in May 2026
An enhanced version supported the fifth Focusing Optics X-ray Solar Imager mission. A Black Brant IX rocket launched at 11:23 a.m. local time on 14 May 2026 and observed three small flares during its flight.
FOXSI uses focusing optics to produce sensitive X-ray images. These measurements help locate where energetic electrons travel and deposit energy in the solar atmosphere. Comparing X-rays with ultraviolet and other wavelengths builds a more complete picture of a flare.
What scientists want to learn from flares
Researchers still investigate how magnetic energy is converted into heat, radiation and particle acceleration. The Sun offers a nearby plasma laboratory, while similar processes occur around other stars and in planetary magnetospheres.
Earth Site’s article on NASA’s TRACERS mission describes how twin satellites study magnetic reconnection near Earth. Flares study the same broad physical process in a much hotter and more energetic solar setting.
High-energy particles are also related to the wider particle environment described in how scientists detect cosmic rays and energetic particles. The sources and energies differ, but both topics show why Earth’s atmosphere and magnetic field are important shields.
Could the method improve space-weather forecasting?
Rapid classification of active events could help observatories decide where to point and allow several instruments to coordinate. A network of telescopes can capture the same flare at different wavelengths, producing richer science than one detector alone.
The technique may also contribute to operational forecasting, but that is a future possibility rather than an accomplished capability. Forecasting effects at Earth requires more than measuring flare duration. Scientists must determine whether a coronal mass ejection occurred, its direction and speed, and how its magnetic field is oriented when it reaches Earth.
The consequences depend on Earth’s magnetosphere, introduced in Earth Site’s guide to Earth’s magnetic field. A strong solar eruption can have limited impact if it misses Earth or carries an unfavourable magnetic orientation for transferring energy.
Why the research is a useful engineering lesson
The project did not make the rocket faster or extend its observing time. It improved the information available before launch. This is an example of using data and prediction to make a limited instrument more effective.
It also shows why automation matters in astronomy. Humans cannot manually inspect every incoming image quickly enough during a short-lived event. Software performs rapid measurements, while scientists retain responsibility for interpreting the alert and deciding whether to launch.
Conclusion
The solar-flare alert system turns a difficult gamble into a better-informed decision. By combining current observations with rapid duration estimates, it helped sounding rockets reach space while their targets remained active. The successful campaigns and peer-reviewed publication establish that the approach works for selected events. Continued development is still needed before it can be described as a broad forecasting service, but the method could allow future instruments to capture more of the Sun’s brief and energetic outbursts.
Frequently asked questions
Can the system predict a solar flare before it begins?
The published system detects developing flares and rapidly estimates their location and duration; it is not a general long-range flare predictor.
Why not observe X-rays from the ground?
Earth’s atmosphere absorbs most solar X-rays, so instruments must travel above much of the atmosphere.
How long can a sounding rocket observe?
The useful observing period for these flights is about five minutes.
What did FOXSI-5 observe?
It recorded three small solar flares during its 14 May 2026 flight from Alaska.
Will this prevent damage from solar storms?
No single alert system can prevent space weather. It may improve observations and, eventually, contribute information to wider forecasting systems.
