1. Space Weather Radiation Hazards REU Summer School By Ron Zwickl NOAA Space Environment Center June 14, 2007

2. REU Summer School Simple Tutorial –Cosmic Rays –Solar Radiation Storms –Earth’s Influence Magnetospheric Shielding Atmospheric Shielding Radiation Impacts on Airline Passengers Radiation Dangers to Astronauts Space Weather Radiation Hazards Outline

3. June 14, 2007REU Summer School Space Radiation Composed of two major components –Cosmic Rays Always present and very energetic Composed of many different elements

4. Cosmic Rays are “born” throughout the known Universe

5. June 14, 2007REU 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

6. June 14, 2007REU Summer School GALACTIC COSMIC RAYS

7. June 14, 2007REU 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

8. June 14, 2007REU Summer School Radiation level varies throughout the solar cycle

9. June 14, 2007REU 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

10. June 14, 2007REU 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

11. June 14, 2007REU Summer School Solar Radiation Storm S3 S2 S4 S1 Flight crews Interested in this curve

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

13. June 14, 2007REU 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

14. June 14, 2007REU Summer School Space Radiation Earth’s Influence on the radiation level –Magnetic Field Shielding Always present, but has holes!

15. June 14, 2007REU Summer School Open Closed Cosmic Ray Access

16. June 14, 2007REU 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

17. June 14, 2007REU 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

18. Influence of Geomagnetic Activity on auroral boundary (geomagnetic poles expand with increased activity)

19. June 14, 2007REU 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

20. Photon cascade in lead plates in cloud chamber. Maximum number of particles after passing through 10 cm of lead Incident photon is several GeV

21. June 14, 2007REU Summer School Space Radiation Summary 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

22. June 14, 2007REU Summer School Space Weather and Aviation

23. Lt Col Thomas C. Hankins USAF

24. June 14, 2007REU Summer School FRA to DFW flight

25. June 14, 2007REU Summer School 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. Slide 7 Kyle Copeland & Wallace Friedberg Civil Aerospace Medical Institute, AAM-610

26. June 14, 2007REU Summer School Space Weather and Aviation

27. June 14, 2007REU Summer School 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 Slide 9 Kyle Copeland & Wallace Friedberg Civil Aerospace Medical Institute, AAM-610

28. Radiation Risks to Astronauts Michael J. Golightly NASA routinely avoids the radiation belts in their scheduling of space walks.

29. June 14, 2007REU Summer School 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

30. June 14, 2007REU Summer School 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

31. June 14, 2007REU Summer School 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)

32. June 14, 2007REU Summer School

33. June 14, 2007REU Summer School POSSIBLE ACUTE EFFECTS August 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

34. June 14, 2007REU Summer School 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

35. June 14, 2007REU Summer School 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

36. June 14, 2007REU Summer School Mars Surface (mainly protons and neutrons) GCR Solar Minimum GCR Solar Maximum October 1989 SPE D skin 5.7 cGy/yr2.7 cGy/yr3.2 cGy H skin 13.2 cSv/yr6.7 cSv/yr4.8 cSv D BFO 5.5 cGy/yr2.6 cGy/yr1.7 cGy H BFO 11.9 cSv/yr6.1 cSv/yr2.7 cSv

37. June 14, 2007REU Summer School 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

38. June 14, 2007REU Summer School 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 cm Al or equivalent) A worst case event similar to the assumed Carrington Flare of 1859 could be catastrophic in deep space depending on spectral hardness

39. June 14, 2007REU Summer School CONCLUDING REMARKS (cont.) Results presented only for aluminum Other materials with low atomic mass numbers are better  LH 2 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 CO 2

40. parting shot … Kanzelhoehe Solar Observatory, Austria December 1, 2000

41. June 14, 2007REU Summer School October 1989 SPE

42. June 14, 2007REU Summer School AUGUST 1972 SKIN DOSE RATE

43. June 14, 2007REU Summer School TOKYO OSAKA HONG KONG SHANGHAI CHICAGO NEW YORK 82 N #1 #1A #2 #3 #4 UAL POLAR ROUTES BEIJING