Mike Lockwood

(Space Science and Technology Department, STFC Rutherford Appleton Laboratory

& Southampton University)

4th European Space Weather Week, 9th November 2007

The Space Environment in the Inner Heliosphere

RO

UG

H G

UID

ES

The Moon & Mars

THE ROUGH GUIDE to

Health in Deep Space

1. Galactic Cosmic Rays (GCRs): stochastic effects

2. Solar Energetic Particles (SEPs): acute affects

3. Past space climate and the space weather forecast

RO

UG

H G

UID

ES

The Moon & Mars

THE ROUGH GUIDE to

Health in Deep Space

1. Galactic Cosmic Rays (GCRs): stochastic effects

2. Solar Energetic Particles (SEPs): acute affects

3. Past space climate and the space weather forecast

So

lar

mo

du

late

d G

CR

s

109 1012 1015 1018 1021

Energy (eV)

102

10-1

10-4

10-7

10-10

10-13

10-16

10-19

10-22

10-25

10-28

Flu

x (m

-2 s

r-1 s

-1 G

eV

-1)

► Mass spectrum shows protons up to iron ions & heavier

► Low dose levels – give stochastic effects (e.g. lifetime cancer risk) rather than acute radiation sickness

► High energy/mass particles produce fragments in shielding

Galactic Cosmic

Rays

SolarModulation

Lead

Copper

Iron

Aluminum

Water

Lithium hydride

Liquid Methane

Liquid Hydrogen

H(T

) /

H(T

=0)

T (gm cm-2)

Dose Equivalent, H

T (gm cm-2)0 5 10 15 20 25 30

2.5

2.0

1.5

1.0

0.5

0

C(T

) /

C(T

=0)

Cell Transformations, C

0 5 10 15 20 25 30

2.5

2.0

1.5

1.0

0.5

0

Shielding GCRs

► Traditional dosimetric analysis - H = D RBE

GCR shielding at sunspot minimum

► Repair kinetics model – uses track structure injury coefficients & repair rates(Shimmerling et al., 1996)

RO

UG

H G

UID

ES

The Moon & Mars

THE ROUGH GUIDE to

Health in Deep Space

1. Galactic Cosmic Rays (GCRs): stochastic effects

2. Solar Energetic Particles (SEPs): acute affects

3. Past space climate and the space weather forecast

The Apollo Missions

Above annual dose

Above annual dose

SEPs: just how lucky were the lunar astronauts?

SEPs during the era of the Apollo Missions

Raised cancer risk

Raised cancer risk

Severe radiation sickness

Severe radiation sickness

Instantly fatal

Instantly fatal

Average annual dose at Earth’s surface

Max. annual dose for a radiation worker

103

102

100

10-1

104

103

102

101

100

10-1

2 3 4 5 6 7 8 9 10 11 12Day of August 1972

T = 10 gm cm-2 of Al

T = 5 gm cm-2 of Al

T = 1 gm cm-2 of Al

T = 250 gm cm-2 of Al

T = 50 gm cm-2 of Al

Eff

ectiv

e S

kin

Dos

e (c

Sv)

F>

60M

eV (

cm-2sr

-1s-1

)

T = 2 gm cm-2 of Al

► fluxes ahead of shock intersection are limited by the scattering effect of waves

► gives 12-36 hrs warning of main SEP event

“Halo” (Earthbound)

form most easily seen in C2 difference

movie ►

The Bastille Day Storm CMEseen by SoHO/Lasco C2 and C3 Coronographs

► Ground-level enhancement (GLE) of SEPs seen between Forbush decreases of galactic cosmic rays caused by shielding by the two CMEs

► Here seen at stations in both poles (McMurdo and Thule)

Neutron Monitor counts

Forbush decrease caused by 1st CME

GLEForbush decrease caused by

CME associated with GLE

nm

co

un

ts

The Bastille Day Storm GCRs and SEPs (GLE)

The Bastille Day Storm SEP Proton Aurora – seen by Image FUV-SI12

RO

UG

H G

UID

ES

The Moon & Mars

THE ROUGH GUIDE to

Health in Deep Space

1. Galactic Cosmic Rays (GCRs): stochastic effects

2. Solar Energetic Particles (SEPs): acute affects

3. Past space climate and the space weather forecast

Polar Cap NO From SEP event of April 2002

► Northern hemisphere ► Southern hemisphere

TIMED observations of 5.3 m NO radiative fluxes (Wm2) (Mlynczak et al., 2003)

Major SEP Events From nitrates in polar ice sheets

► SEP (>30MeV) fluence from ice sheet data (McCracken, 2001) ► Open flux model from sunspot number (Solanki et al., 2000)► Open flux derived from aa index (Lockwood et al., 1999)

SEP events from

Ice Core nitrate data

► big SEP events at intermediate open flux (McCracken, 2007)

► McCracken (2005, 2007) proposes thatat low solar activity number and speed V of CMEs increases with increasing activity► but at highest activity large open flux FS gives large IMF B which reduces Alfvén Mach number V(o)1/2/B and hence shock strength

Interplanetary SEP data > 60 MeV proton fluxes

► corrected using Climax GCR data (Lockwood, 2007)

Interplanetary SEP data > 60 MeV proton fluxes

► open flux FS from observations of radial IMF FS = (4R1

2Br) / 2

► use 27-day mean of Br

► daily means of >60MeV proton fluxes, F>60MeV

► GCRs (in black) anticorrelate with FS

► SEPs (in red) rare at high FS

Interplanetary SEP events> 60 MeV proton fluences

► largest fluence events at intermediate open flux FS

Interplanetary SEP eventsFluence > 2 108 cm-2

Interplanetary SEP eventsFluence > 2 108 cm-2

Recent trends - revealed by means over solar cycle length, L

► sunspot number, R

► FS from IMF data

► GCR counts C (Climax n.m.)

► PMOD composite of TSI data

► solar cycle length, L

running mean over T=[9:(1/4):13] yrs

running mean over T=L yrs

► SEP events pose a real health hazard to astronauts outside Earth’s magnetosphere

► Shielding possible and possible to issue warnings to seek shelter

► Issuing “all clears” important

► Declining open solar flux indicates that large SEP events may become more common over the next few decades

Conclusions