LT RBR: Long Term Radiation Belt Remediation Joshua Davis ASTE 527 Space Concepts Studio

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

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 LimitsMaleFemale 25 Years Old52 rem37 rem 55 Years Old147 rem112 rem Average annual exposure on the Earth’s surface is.125 rem/year, on board ISS during solar maximum is.1 rem/day

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

Arc Discharging

Energetic Particle & Plasma Hazards Solar Panel Power Decrease

Energetic Particle & Plasma Hazards Bit Flips/Single Event Upsets

Particle Motion in Earth’s Magnetic Field

Radiation Belts are Highly Dynamic

Video reconstructing belts with SAMPEX data from Oct 18, 2003 to Jan 1, Oct 25 Oct 27 Oct 30 Nov 3

Natural Remediation Solar or Nuclear Events

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

VLF: Very Low Frequency Radio Waves Ground Based Space Based

Experimental Data for Ground Based VLF RBR Increase in loss-cone electron flux during VLF operation Ambient flux conditions

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.”

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”

Rapid Response Remediation Solar or Nuclear Event Occurs Particles Remain Event Ends Rapid Remediation Occurs Ionospheric Distortion Begins Ionospheric Distortion Subsides

Issues with RBR

Radio Communication Fade vs. Solar Cycle – Thule

Enhanced Remediation vs. Natural Remediation Long Term Radiation Belt Remediation

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)

References Odenwald, Sten. "What Are Space Radiation Effects?" NASA.. Hess, Wilmot N. "Energetic Particles in the Inner Van Allen Belt." Space Science Reviews 1.2 (1962). Hoyt, Robert P., and Forward, Robert L. "Radiation Remediation." Tethers Unlimited..

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 Rodger, Craig J. "The Atmospheric Implications of Radiation Belt Remediation." Annales Geophysicae 24 (2006). European Geosciences Union..

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 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: / ;

Backup Slides

Why does the Earth have a Radiation Belt? A Radiation Belt is more stylish than Radiation Suspenders!

Tethers Unlimited : HiVOLT

Neutral Particle Injection Ion-Cyclotron Turbulence Generation

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

Increasing Density

Radio Communication %Fade vs. Solar Cycle – Ascension Island