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Space Weather Radiation Hazards REU Summer School. By Ron Zwickl NOAA Space Environment Center June 14, 2007. Space Weather Radiation Hazards Outline. Simple Tutorial Cosmic Rays Solar Radiation Storms Earth’s Influence Magnetospheric Shielding Atmospheric Shielding

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Space weather radiation hazards reu summer school

Space Weather

Radiation Hazards

REU Summer School

By

Ron Zwickl

NOAA

Space Environment Center

June 14, 2007


Space weather radiation hazards reu summer school

Space Weather

Radiation Hazards

Outline

  • Simple Tutorial

    • Cosmic Rays

    • Solar Radiation Storms

    • Earth’s Influence

      • Magnetospheric Shielding

      • Atmospheric Shielding

  • Radiation Impacts on Airline Passengers

  • Radiation Dangers to Astronauts

REU Summer School


Space weather radiation hazards reu summer school

Space Radiation

  • Composed of two major components

    • Cosmic Rays

      • Always present and very energetic

      • Composed of many different elements

REU Summer School


Space weather radiation hazards reu summer school

Cosmic Rays

are “born” throughout

the known Universe


Space weather radiation hazards reu summer school

  • Cosmic Rays

  • Composed of many

  • different Elements,

  • such as Hydrogen

  • Helium, Carbon, and Iron

  • They cover a very wide

  • range of energies

  • They are always present

REU Summer School


Galactic cosmic rays

GALACTIC COSMIC RAYS

REU Summer School


Space weather radiation hazards reu summer school

Space Radiation

  • Composed of two major components

    • Cosmic Rays

      • Always present and very energetic

      • Composed of many different elements

      • Intensity varies throughout 11 year Solar Cycle

REU Summer School


Space weather radiation hazards reu summer school

Radiation level varies throughout the solar cycle

REU Summer School


Space weather radiation hazards reu summer school

Space Radiation

  • Composed of two major components

    • Cosmic Rays

      • Always present and very energetic

      • Composed of many different elements

      • Intensity varies throughout 11 year Solar Cycle

      • Intensity varies with Solar Activity

REU Summer School


Space weather radiation hazards reu summer school

Space Radiation

  • Composed of two major components

    • Cosmic Rays

      • Always present and very energetic

      • Composed of many different elements

      • Intensity varies throughout 11 year Solar Cycle

      • Intensity varies with Solar Activity

    • Solar Radiation Storms

      • Infrequent, very intense, with rapid onsets

REU Summer School


Space weather radiation hazards reu summer school

Flight crews

Interested in this curve

S4

Solar Radiation Storm

S3

S2

S1

REU Summer School


Space weather radiation hazards reu summer school

Polar Satellite Image Degradation during July 14, 2000 Solar Radiation Storm


Space weather radiation hazards reu summer school

Space Radiation

  • Composed of two major components

    • Cosmic Rays

      • Always present and very energetic

      • Composed of many different elements

      • Intensity varies throughout 11 year Solar Cycle

      • Intensity varies with Solar Activity

    • Solar Radiation Storms

      • Infrequent, very intense, with rapid onsets

      • Composed of many different elements

      • Origin strongly linked to Solar Activity

      • Variable energy and composition dependence

REU Summer School


Space weather radiation hazards reu summer school

Space Radiation

  • Earth’s Influence on the radiation level

    • Magnetic Field Shielding

      • Always present, but has holes!

REU Summer School


Space weather radiation hazards reu summer school

Open

Closed

Open

Cosmic Ray Access

REU Summer School


Space weather radiation hazards reu summer school

Earth’s

Magnetic Shield

to Cosmic Ray Access

Magnetic Poles: Open

Magnetic Equator: >15 GeV

Red bar varies as function

of magnetic latitude

REU Summer School


Space weather radiation hazards reu summer school

Space Radiation

  • Earth’s Influence on the radiation level

    • Magnetic Field Shielding

      • Always present, but has holes!

    • Geomagnetic Activity

      • Changes magnetic field shield location

REU Summer School


Space weather radiation hazards reu summer school

Influence of Geomagnetic Activity on auroral boundary

(geomagnetic poles expand with increased activity)


Space weather radiation hazards reu summer school

Space Radiation

  • Earth’s Influence on the radiation level

    • Magnetic Field Shielding

      • Always present, but has holes!

    • Geomagnetic Activity

      • Changes magnetic field shield location

    • Atmospheric Shielding

      • Upper atmosphere acts as a target

      • Lower atmosphere acts as absorbing shield

REU Summer School


Space weather radiation hazards reu summer school

Photon cascade in

lead plates in cloud

chamber.

Maximum number

of particles after

passing through

10 cm of lead

Incident photon is

several GeV


Space weather radiation hazards reu summer school

Space RadiationSummary

  • Two primary components

    • Cosmic Rays

      • Steady with some variability

    • Solar Radiation Storms

      • Rare, highly variable, and can be intense

  • Earth’s natural defenses

    • Magnetic field shields Earth

      • Makes calculations very complex

      • Geomagnetic Latitude dependent

      • Geomagnetic activity can expand poles

    • Atmosphere acts as target and as shield

      • Radiation strongly dependent upon altitude

REU Summer School


Space weather radiation hazards reu summer school

Space Weather and Aviation

REU Summer School


Space weather radiation hazards reu summer school

Lt Col Thomas C. Hankins USAF


Space weather radiation hazards reu summer school

FRA to DFW flight

REU Summer School


Space weather radiation hazards reu summer school

Slide 7

Issue Time: 2001 Nov 04 2045 UTC

ALERT: Solar Radiation Alert at Aviation Flight Altitudes

Conditions Began: 2001 Nov 04 2035 UTC

Altitude Solar proton effective dose rate

(feet) (millisieverts/hour) *

---------------------------------------------------------------

20 000 <0.0010

30 000 0.0052

40 000 0.019

50 000 0.040

60 000 0.060

70 000 0.074

80 000 0.088

----------------------------------------------------------------

* Estimates at high latitude locations. Dose rates

are based on near real-time GOES satellite

readings and are recalculated every 3 minutes.

REU Summer School

Kyle Copeland & Wallace Friedberg Civil Aerospace Medical Institute, AAM-610


Space weather radiation hazards reu summer school

Space Weather and Aviation

REU Summer School


Space weather radiation hazards reu summer school

Slide 9

Effective Doses From Solar Radiation at 40 000 ft for Selected Solar Proton Events From January 1986 Through December 2001 (16 y)

Total Effective Dose (mSv)

-----------------------------

DateEventTime (hh:mm)* 3 h 5 h 10 h

----------------------------------------------------------------------------------

Aug. 16, 1989GLE 41 01:10 0.0550.0720.087

Sept. 29, 1989**GLE 42 08:350.260.420.59

Oct. 19, 1989GLE 43 20:300.0740.170.41

Oct. 22, 1989GLE 44 03:250.150.190.23

Oct. 24, 1989GLE 45 10:250.140.370.64

May 24, 1990GLE 48 00:050.130.0190.026

Jun. 15, 1991GLE 52 00:500.0410.0480.055

Nov. 2, 1992GLE 54 00:200.039 0.0540.072

Nov. 6, 1997**GLE 55 08:000.150.260.39

Jul. 14, 2000**GLE 59 07:051.11.31.51

Apr. 15, 2001**GLE 60 07:350.730.971.1

Apr. 18, 2001**GLE 61 01:150.0490.0830.14

Nov. 4, 2001**GLE 62 03:200.0820.120.17

Dec. 26, 2001GLE 63 01:350.0690.0810.090

----------------------------------------------------------------------------------

* Time that recommended maximum flight altitude is below 40 000 ft

** Dose rates are underestimated for more than 0.5 h

REU Summer School

Kyle Copeland & Wallace Friedberg Civil Aerospace Medical Institute, AAM-610


Space weather radiation hazards reu summer school

Radiation Risks to Astronauts

NASA routinely avoids the radiation belts in their scheduling of space walks.

Michael J. Golightly


Deep space gcr doses

DEEP SPACE GCR DOSES

  • Annual bone marrow GCR doses will range up to ~ 15 cGy at solar minimum (~ 40 cSv) behind ~ 2cm Al shielding

  • Effective dose at solar minimum is ~ 45-50 cSv per annum

  • At solar maximum these are ~ 15-18 cSv

  • Secondary neutrons and charged particles are the major sources of radiation exposure in an interplanetary spacecraft

  • No dose limits yet for these missions

REU Summer School


Gcr risks

GCR Risks

  • Clearly, annual doses < 20cGy present no acute health hazard to crews on deep space missions

  • Hence only stochastic effects such as cancer induction and mortality or late deterministic effects, such as cataracts or damage to the central nervous system are of concern.

  • Unfortunately, there are no data for human exposures from these radiations that can be used to estimate risks to crews

  • In fact, it is not clear that the usual methods of estimating risk by calculating dose equivalent are even appropriate for these particles

REU Summer School


Solar particle event doses

SOLAR PARTICLE EVENT DOSES

  • Doses can be large in deep space but shielding is possible

  • August 1972 was largest dose event of space era (occurred between two Apollo missions)

REU Summer School


Space weather radiation hazards reu summer school

REU Summer School


Possible acute effects august 1972 spe

POSSIBLE ACUTE EFFECTSAugust 1972 SPE

  • Bone marrow doses ~ 1 Gy delivered in a day may produce hematological responses and vomiting (not good in a space suit)

  • Skin doses ~15-20 Gy could result in skin erythema and moist desquamation (in some cases)

    - doses inside nominal spacecraft might limit effects to mild erythema

REU Summer School


Solar particle event doses1

SOLAR PARTICLE EVENT DOSES

  • Ice core data from the Antarctic indicate that the largest event in past ~ 500 years was probably the Carrington Flare of 1859

    -fluence ~ 20 larger than Aug 72

    -actual spectrum energy dependence unavailable, assume both hard and softspectra

REU Summer School


Carrington flare doses 9 89 spectrum

CARRINGTON FLARE DOSES(9/89 Spectrum)

  • Bone marrow doses ~ 1-3 Gy possible inside a spacecraft (life threatening)

  • “Storm” shelter of about 18 cm Al needed to shield to the applicable deterministic limits (30 d limits of 0.25 Gy-Eq)

  • Major problem for non radiation hardened electronics built with COTS components

    -up to 50 krads or more of total ionizing dose

REU Summer School


Mars surface mainly protons and neutrons

Mars Surface(mainly protons and neutrons)

REU Summer School


Concluding remarks

CONCLUDING REMARKS

  • GCR exposures will be a problem for Mars missions due to large effective doses

  • Organ doses received from large SPEs can be hazardous to crews of vehicles in deep space

    - exposures that are survivable with proper medical treatment on Earth may not be survivable in space

REU Summer School


Concluding remarks cont

CONCLUDING REMARKS (cont.)

  • Aside from acute effects, a single large SPE can expose a crewmember to an effective dose that exceeds their career limit

  • Due to their relatively soft energy spectra, most SPE doses can be substantially reduced with adequate shielding (several cmAl or equivalent)

  • A worst case event similar to the assumed Carrington Flare of 1859 could be catastrophic in deep space depending on spectral hardness

REU Summer School


Concluding remarks cont1

CONCLUDING REMARKS (cont.)

  • Results presented only for aluminum

  • Other materials with low atomic mass numbers are better  LH2 reduces GCR dose equivalent by ~ one-half

  • In situ materials on lunar or Martian surface can be used to provide shielding (similar to Al in shielding characteristics)

  • Martian atmosphere is a relatively thick shield for operations on Mars surface

    ~ 16-20 g cm-2 CO2

REU Summer School


Parting shot

parting shot …

Kanzelhoehe Solar Observatory, Austria

December 1, 2000


October 1989 spe

October 1989 SPE

REU Summer School


August 1972 skin dose rate

AUGUST 1972 SKIN DOSE RATE

REU Summer School


Space weather radiation hazards reu summer school

UAL POLAR ROUTES

NEW YORK

82 N

CHICAGO

#1

#1A

#2

#3

#4

BEIJING

SHANGHAI

HONG KONG

OSAKA

TOKYO

REU Summer School


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