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LT RBR:

Long Term Radiation Belt Remediation

Joshua Davis

ASTE 527

Space Concepts Studio

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LT RBR:

RBR means removing the trapped electrons and ions from the near Earth environment for the benefit of manned and unmanned spacecraft.

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Radiation Environment’s Impact on Manned Spaceflight

A majority of the radiation Astronauts receive on orbit is attributed to the trapped radiation particles in the inner Van Allen belt.

Time on orbit is limited by an Astronaut’s total radiation exposure, limiting the ability to study long term micro-gravity effects on Humans.

Temporary and permanent eye damage.

Increased risk of cancers as well as heart, digestive, and respiratory diseases.

The daily dosage of radiation on the ISS is equal to 8 chest X-rays per day.

Career exposure cannot exceed 3 percent risk of exposure-induced death (REID) at a 95% confidence level.

NASA Career Exposure Limits	Male	Female
25 Years Old	52 rem	37 rem
55 Years Old	147 rem	112 rem

Average annual exposure on the Earth’s surface is .125 rem/year, on board ISS during solar maximum is .1 rem/day

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Solar array power decrease due to radiation damage

Single event effects in microelectronics: bit flips, fatal latch-ups

Spacecraft components become radioactive

False stars in star tracker CCDs

before after

Surface degradation from radiation

Electronics degrade due to total radiation dose

Solar array arc discharge

Cryogenic systems experience notable charged particle heating

Electromagnetic pulse from vehicle discharge

Induced Voltage

Time

Energetic Particle & Plasma Hazards

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Energetic Particle & Plasma Hazards

Arc Discharging

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Energetic Particle & Plasma Hazards

Solar Panel Power Decrease

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Energetic Particle & Plasma Hazards

Bit Flips/Single Event Upsets

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Particle Motion in Earth’s Magnetic Field

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Radiation Belts are Highly Dynamic

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Radiation Belts are Highly Dynamic

Video reconstructing belts with SAMPEX data from Oct 18, 2003 to Jan 1, 2004

http://www.youtube.com/watch?v=QwNNh4c9bR0

Oct 25

Oct 27

Oct 30

Nov 3

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Natural Remediation

Solar or Nuclear Events

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How RBR Works:

Change the particle’s pitch cone angle such that its velocity vector is pointed roughly parallel to the magnetic field lines.

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VLF:

Very Low Frequency Radio Waves

Ground Based

Space Based

- Current theory is that VLF (man-made and natural) dominates electron loss mechanism during non-storm times.

- Change velocity vector by inducing wave oscillations by exciting the plasma using VLF radio waves.

- Potential for rapid remediation (1-3 days)

- Radio transmitters can easily access most regions of the belts. Some facilities are already in place such as the High Frequency Active Auroral Research Program (HAARP) in Alaska

- Proven method for electron remediation. Active transmission of VLF has led to an observed decrease in electron flux

Space based or ground based radio transmitters excite the particles and induce turbulent waves. *Ground based architecture is highly dependant on location to provide remediation benefits.

Gamble, Rory. Et al. "Radiation Belt Electron Precipitation by Man-made VLF Transmissions." Journal of Geophysical Research 113 (2008): American Geophysical Union, 21 Oct. 2008. Web. <http://www.agu.org/pubs/crossref/2008/2008JA013369.shtml>.

http://arizonaskywatch.com/articles/articles/hf1.bmp

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Experimental Data for Ground Based VLF RBR

Increase in loss-cone electron flux during VLF operation

Ambient flux conditions

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AFRL DSX to test Space Based VLF RBR

“The overall primary objective of DSX is to resolve critical feasibility issues of injecting VLF waves into the magnetosphere to determine how efficiently, how effectively, and to what degree of efficacy this can be accomplished. The goal is to assess the particle distribution, perturbations, and scattering effects on the particles as a result of the VLF waves produced by nature and by man-made systems on the ground and in space.”

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Starfish Prime – High Altitude Nuclear Explosion

Crippled 1/3 of operational satellites and disabled 7 satellites in the months that followed due to the particles injected into the radiation belts, some of which persisted for 5 years.

“It has been suggested that even a “small” HANE (~10–20 kilotons) occurring at altitudes of 125–300 km would raise peak radiation fluxes in the inner radiation belt by 3–4 orders of magnitude, and lead to the loss of 90% of all low-Earth-orbit satellites within a month [Dupont, 2004].”

“the manned space program would need to be placed on hold for a year or more”

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Rapid Response Remediation

Solar or Nuclear Event Occurs

Particles Remain

Event Ends

Rapid Remediation Occurs

Ionospheric Distortion Begins

Ionospheric Distortion Subsides

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Issues with RBR

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Radio Communication Fade vs. Solar Cycle – Thule

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Enhanced Remediation vs. Natural Remediation

Long Term Radiation Belt Remediation

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Conclusion and Future Work for LT RBR

VLF ground based architecture study for geographic locations of interest

Feasibility study of Long Term operation of VLF stations (power, cost, effectiveness)

VLF should be further researched as the primary method for LTRBR

VLF has the advantage of using ground station already available and in use.

VLF has observational satellite data to back up its methods

Tethers and Neutral Particles require launching a system into orbit. For long term remediation, a ground based system is far less costly.

*Airforce DSX (Demonstrations and Science Experiment) mission to carry out VLF RBR experiments dubbed Wave Particle Interaction Experiment (WPIx)

Avoiding RBR Issues

Experimental data has shown that temporary RBR is possible.

Experts argue that RBR may cause temporary damage to the Ionosphere and Ozone layer.

Initial remediation should be slow or pulsed to allow the atmosphere to “heal” to minimize disruptions caused by the flushing of the high energy particles.

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References

Odenwald, Sten. "What Are Space Radiation Effects?" NASA. <http://radbelts.gsfc.nasa.gov/outreach/effects.html>.
Hess, Wilmot N. "Energetic Particles in the Inner Van Allen Belt." Space Science Reviews 1.2 (1962). <http://rd.springer.com/article/10.1007%2FBF00240580>
Hoyt, Robert P., and Forward, Robert L. "Radiation Remediation." Tethers Unlimited. <http://www.tethers.com/HiVOLT.html>.

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References Cont.

Gamble, Rory. Et al. "Radiation Belt Electron Precipitation by Man-made VLF Transmissions." Journal of Geophysical Research 113 (2008): American Geophysical Union, 21 Oct. 2008. <http://www.agu.org/pubs/crossref/2008/2008JA013369.shtml>.
Rodger, Craig J. "The Atmospheric Implications of Radiation Belt Remediation." Annales Geophysicae 24 (2006). European Geosciences Union. <http://www.ann-geophys.net/24/2025/2006/angeo-24-2025-2006.pdf>.

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References Cont.

Basu, Santimay, and MacKenzie, E. “Ionospheric constraints on VHF/UHF communications links during solar maximum and minimum periods” Radio Science 23 (1988): American Geophysical Union, 17 Jan. 1988. <http://www.agu.org/journals/rs/v023/i003/RS023i003p00363/RS023i003p00363.pdf>.
Scherbath, Mark. Et al. "AFRL's Demonstration and Science Experiments (DSX) mission", Proc. SPIE 7438, Solar Physics and Space Weather Instrumentation III, 74380B (September 23, 2009); doi:10.1117/12.824898; <http://dx.doi.org/10.1117/12.824898>

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Backup Slides

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Why does the Earth have a Radiation Belt?

A Radiation Belt is

more stylish than

Radiation Suspenders!

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Tethers Unlimited : HiVOLT

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Neutral Particle Injection

Ion-Cyclotron Turbulence Generation

- Change the velocity vector by inducing wave oscillations into the ambient plasma by releasing a plasma cloud at orbital velocity that will transform the orbital kinetic energy into turbulent wave energy.

- Neutral Particles become photo-ionized and transform the orbital kinetic energy into turbulent wave energy.

- This turbulence is a result of the new artificial plasma cloud and the natural plasma environment attempting to reach a thermodynamic equilibrium.

- This requires lofting a large mass of particles & injection system into orbit and then dispersing the cloud. Estimates of ~ 10 tons of material to be injected

- Once the particles have been released, there is no control of the process.

The new plasma particles may be difficult to get rid of, as they have virtually no parallel velocity component by design.

Chang, Ouliang. "Numerical Simulation of Ion-Cyclotron Turbulence Generated by Artificial Plasma Cloud Release." Thesis. Virginia Tech, 2009. Web. 1 Oct. 2012. <http://scholar.lib.vt.edu/theses/available/etd-07152009-125531/>.

Papadopoulos, Konstantinos. Et al. "Generation and Evolution of Intense Ion Cyclotron Turbulence by Artificial Plasma Cloud in the Magnetosphere." Journal of Geophysical Research 112 (2007)

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Natural Remediation - Analogy

Water is poured into the top of the bucket and exits through a porous plug at the bottom of the bucket.

If the rate of water being poured into the system increases, the water level rises until the pressure causes an equilibrium condition

If there is no water, there is still a bucket.

The radiation belts work in a similar fashion, the more particles coming into the system, the more particles come out of the system.

However, particles in the belts can become stuck for months or years, so equilibrium takes a very long time to reach after an event.

Just as with the bucket, if there are no particles in the radiation belt, the protective magnetosphere is unaffected

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Increasing Density

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Radio Communication %Fade vs. Solar Cycle – Ascension Island