- Jan 27, 2020
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Almost once a week, Spaceweather.com and the students of Earth to Sky Calculus fly space weather balloons into the stratosphere over California. These balloons are equipped with sensors that detect secondary cosmic rays, a form of radiation from space that can penetrate all the way down to Earth's surface. Our monitoring program has been underway without interruption for 7 years, resulting in a unique dataset of in situ atmospheric measurements.
Latest results (Nov. 2021): Our balloons have just measured a sudden drop in atmospheric radiation. It happened during the strong geomagnetic storms of Nov. 3-4, 2021. Here are the data:
This is called a "Forbush decrease," named after American physicist Scott Forbush who studied cosmic rays in the early 20th century. It happens when a CME from the sun sweeps past Earth and literally pushes cosmic rays away from our planet. Radiation from deep space that would normally pepper Earth's upper atmosphere is briefly wiped out.
We have measured Forbush decreases before. For example, here's one from Sept. 2014. The Forbush Decrease of Nov. 3-4, 2021, was the deepest in the history of our 7-year atmospheric monitoring program. Radiation levels in the stratosphere over California dropped nearly 20%, more than doubling the previous record from our dataset.
En route to the stratosphere, our sensors also pass through aviation altitudes, so we can sample radiation where planes fly. This plot shows how the Forbush decrease was restricted to the stratosphere; it did not affect lower levels of the atmosphere:
The dose rates shown above are expressed as multiples of sea level. For instance, we see that boarding a plane that flies at 25,000 feet exposes passengers to dose rates ~10x higher than sea level. At 40,000 feet, the multiplier is closer to 50x. The higher you fly, the more radiation you will absorb.
.Who cares? Cosmic rays are a surprisingly "down to Earth" form of space weather. They can seed clouds, trigger lightning, and penetrate commercial airplanes. According to a study from the Harvard T.H. Chan school of public health, crews of aircraft have higher rates of cancer than the general population. The researchers listed cosmic rays, irregular sleep habits, and chemical contaminants as leading risk factors. Somewhat more controversial studies (#1, #2, #3, #4) link cosmic rays with cardiac arrhythmias and sudden cardiac death.
.Technical notes: The radiation sensors onboard our helium balloons detect X-rays and gamma-rays in the energy range 10 keV to 20 MeV. These energies span the range of medical X-ray machines and airport security scanners.
Data points in the first graph ("Stratospheric Radiation") correspond to the peak of the Regener-Pfotzer maximum, which lies about 67,000 feet above central California. When cosmic rays crash into Earth's atmosphere, they produce a spray of secondary particles that is most intense at the entrance to the stratosphere. Physicists Eric Regener and Georg Pfotzer discovered the maximum using balloons in the 1930s and it is what we are measuring today.
Since 2015, the flux of cosmic rays at the Moon has nearly doubled.
In 2011, NASA launched the Curiosity rover to Mars. Inside its spacecraft, the rover was protected by about as much shielding (20 gm/cm^2) as a human astronaut would have. A radiation sensor tucked inside kept track of Curiosity’s exposure.
The results were surprising. During the 9-month journey to Mars, radiation from solar flares (including the strongest flare of the previous solar cycle) accounted for only about 5% of Curiosity’s total dose. The remaining 95% came from cosmic rays.
Why the imbalance? Solar flares of the size we’ve seen during the Space Age can be largely mitigated by achievable amounts of spacecraft shielding. However, the highest energy cosmic rays can't be stopped. They penetrate the walls of any foreseeable and buildable spacecraft.
See: https://www.swpc.noaa.gov
See: https://www.atoptics.co.uk
See: https://sdo.gsfc.nasa.gov
See: https://stereo.gsfc.nasa.gov
See: https://solarmonitor.org
See: https://www.swpc.noaa.gov/products/weekly-highlights-and-27-day-forecast
See: https://www.swpc.noaa.gov/products/aurora-30-minute-forecast
See: https://spaceweatherarchive.com/2019/07/16/cosmic-ray-update-new-results-from-the-moon/
To sum up the above, we note the following:
Galactic cosmic rays come from outside the solar system. They are a mixture of high-energy photons and sub-atomic particles accelerated toward Earth by supernova explosions and other violent events in the far cosmos. Our first line of defense is Jolly Old Mr Sun: The Sun’s magnetic field and its solar wind combine to create a porous ‘shield’ that fends off cosmic rays attempting to enter the solar system. The shielding action of the sun is strongest during Solar Maximum and weakest during Solar Minimum – hence the 11-year rhythms of mission durations.
The problem is the Sun's shield is weakening. Over the last decade, the solar wind has exhibited low densities and magnetic field strengths, representing anomalous states that have never been observed during our many investigations during the Space Age. As a result of this flagging solar activity, the highest historical cosmic ray fluxes have been observed infiltrating the impaired solar flux.
Cosmic rays penetrate commercial airlines, dosing passengers and flight crews so much that pilots are classified by the International Commission on Radiological Protection as occupational radiation workers. Some research shows that cosmic rays can seed clouds and trigger snow and rain, potentially altering weather and climate. Furthermore, there are also studies linking cosmic rays with cardiac arrhythmias in the general population.
Cosmic rays will intensify even more as the sun moves toward what may be the steepest Solar Minimum in more than a century.
Hartmann352
Latest results (Nov. 2021): Our balloons have just measured a sudden drop in atmospheric radiation. It happened during the strong geomagnetic storms of Nov. 3-4, 2021. Here are the data:
This is called a "Forbush decrease," named after American physicist Scott Forbush who studied cosmic rays in the early 20th century. It happens when a CME from the sun sweeps past Earth and literally pushes cosmic rays away from our planet. Radiation from deep space that would normally pepper Earth's upper atmosphere is briefly wiped out.
We have measured Forbush decreases before. For example, here's one from Sept. 2014. The Forbush Decrease of Nov. 3-4, 2021, was the deepest in the history of our 7-year atmospheric monitoring program. Radiation levels in the stratosphere over California dropped nearly 20%, more than doubling the previous record from our dataset.
En route to the stratosphere, our sensors also pass through aviation altitudes, so we can sample radiation where planes fly. This plot shows how the Forbush decrease was restricted to the stratosphere; it did not affect lower levels of the atmosphere:
The dose rates shown above are expressed as multiples of sea level. For instance, we see that boarding a plane that flies at 25,000 feet exposes passengers to dose rates ~10x higher than sea level. At 40,000 feet, the multiplier is closer to 50x. The higher you fly, the more radiation you will absorb.
.Who cares? Cosmic rays are a surprisingly "down to Earth" form of space weather. They can seed clouds, trigger lightning, and penetrate commercial airplanes. According to a study from the Harvard T.H. Chan school of public health, crews of aircraft have higher rates of cancer than the general population. The researchers listed cosmic rays, irregular sleep habits, and chemical contaminants as leading risk factors. Somewhat more controversial studies (#1, #2, #3, #4) link cosmic rays with cardiac arrhythmias and sudden cardiac death.
.Technical notes: The radiation sensors onboard our helium balloons detect X-rays and gamma-rays in the energy range 10 keV to 20 MeV. These energies span the range of medical X-ray machines and airport security scanners.
Data points in the first graph ("Stratospheric Radiation") correspond to the peak of the Regener-Pfotzer maximum, which lies about 67,000 feet above central California. When cosmic rays crash into Earth's atmosphere, they produce a spray of secondary particles that is most intense at the entrance to the stratosphere. Physicists Eric Regener and Georg Pfotzer discovered the maximum using balloons in the 1930s and it is what we are measuring today.
Since 2015, the flux of cosmic rays at the Moon has nearly doubled.
In 2011, NASA launched the Curiosity rover to Mars. Inside its spacecraft, the rover was protected by about as much shielding (20 gm/cm^2) as a human astronaut would have. A radiation sensor tucked inside kept track of Curiosity’s exposure.
The results were surprising. During the 9-month journey to Mars, radiation from solar flares (including the strongest flare of the previous solar cycle) accounted for only about 5% of Curiosity’s total dose. The remaining 95% came from cosmic rays.
Why the imbalance? Solar flares of the size we’ve seen during the Space Age can be largely mitigated by achievable amounts of spacecraft shielding. However, the highest energy cosmic rays can't be stopped. They penetrate the walls of any foreseeable and buildable spacecraft.
See: https://www.swpc.noaa.gov
See: https://www.atoptics.co.uk
See: https://sdo.gsfc.nasa.gov
See: https://stereo.gsfc.nasa.gov
See: https://solarmonitor.org
See: https://www.swpc.noaa.gov/products/weekly-highlights-and-27-day-forecast
See: https://www.swpc.noaa.gov/products/aurora-30-minute-forecast
See: https://spaceweatherarchive.com/2019/07/16/cosmic-ray-update-new-results-from-the-moon/
To sum up the above, we note the following:
Galactic cosmic rays come from outside the solar system. They are a mixture of high-energy photons and sub-atomic particles accelerated toward Earth by supernova explosions and other violent events in the far cosmos. Our first line of defense is Jolly Old Mr Sun: The Sun’s magnetic field and its solar wind combine to create a porous ‘shield’ that fends off cosmic rays attempting to enter the solar system. The shielding action of the sun is strongest during Solar Maximum and weakest during Solar Minimum – hence the 11-year rhythms of mission durations.
The problem is the Sun's shield is weakening. Over the last decade, the solar wind has exhibited low densities and magnetic field strengths, representing anomalous states that have never been observed during our many investigations during the Space Age. As a result of this flagging solar activity, the highest historical cosmic ray fluxes have been observed infiltrating the impaired solar flux.
Cosmic rays penetrate commercial airlines, dosing passengers and flight crews so much that pilots are classified by the International Commission on Radiological Protection as occupational radiation workers. Some research shows that cosmic rays can seed clouds and trigger snow and rain, potentially altering weather and climate. Furthermore, there are also studies linking cosmic rays with cardiac arrhythmias in the general population.
Cosmic rays will intensify even more as the sun moves toward what may be the steepest Solar Minimum in more than a century.
Hartmann352
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